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Yang P, Feng J, Zhu Y, Hao Y. A Novel Cell Volume Sensor for Real-Time Analysis of Ca 2+-Activated K + Channel. ACS Biomater Sci Eng 2023; 9:5255-5259. [PMID: 37639544 DOI: 10.1021/acsbiomaterials.3c00771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Potassium channels play a vital role in cell volume regulation. A cell volume sensor was constructed by integrating regulatory volume decrease (RVD) with quartz-crystal microbalance (QCM) for studying potassium channels and their expression. The sensor successfully monitored the K+ channel's activities during RVD by sensitive and noninvasive means. It showed that Ca2+ activated the K+ channel (KCa) and enhanced the RVD level. The inhibition of blockers on K+ channels exhibited an obvious difference in RVD level between normal and cancerous nasopharyngeal cells, suggesting that the KCa channel contributes a dominant role to the RVD function and provides an approach to identify the activation of various K+ channels.
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Affiliation(s)
- Peihui Yang
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, People's Republic of China
| | - Jingwei Feng
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, People's Republic of China
| | - Yeyan Zhu
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, People's Republic of China
| | - Yan Hao
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, People's Republic of China
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52
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Xu W, Lin Y, Wang Y, Li Y, Zhu H, Zhou H. Phenotypic Analysis and Molecular Characterization of Enlarged Cell Size Mutant in Nannochloropsis oceanica. Int J Mol Sci 2023; 24:13595. [PMID: 37686401 PMCID: PMC10487731 DOI: 10.3390/ijms241713595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
The cell cycle is the fundamental cellular process of eukaryotes. Although cell-cycle-related genes have been identified in microalgae, their cell cycle progression differs from species to species. Cell enlargement in microalgae is an essential biological trait. At the same time, there are various causes of cell enlargement, such as environmental factors, especially gene mutations. In this study, we first determined the phenotypic and biochemical characteristics of a previously obtained enlarged-cell-size mutant of Nannochloropsis oceanica, which was designated ECS. Whole-genome sequencing analysis of the insertion sites of ECS indicated that the insertion fragment is integrated inside the 5'-UTR of U/P-type cyclin CYCU;1 and significantly decreases the gene expression of this cyclin. In addition, the transcriptome showed that CYCU;1 is a highly expressed cyclin. Furthermore, cell cycle analysis and RT-qPCR of cell-cycle-related genes showed that ECS maintains a high proportion of 4C cells and a low proportion of 1C cells, and the expression level of CYCU;1 in wild-type (WT) cells is significantly increased at the end of the light phase and the beginning of the dark phase. This means that CYCU;1 is involved in cell division in the dark phase. Our results explain the reason for the larger ECS size. Mutation of CYCU;1 leads to the failure of ECS to fully complete cell division in the dark phase, resulting in an enlargement of the cell size and a decrease in cell density, which is helpful to understand the function of CYCU;1 in the Nannochloropsis cell cycle.
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Affiliation(s)
- Weinan Xu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361000, China; (W.X.); (Y.L.); (Y.W.); (Y.L.)
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
| | - Yihua Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361000, China; (W.X.); (Y.L.); (Y.W.); (Y.L.)
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
| | - Yu Wang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361000, China; (W.X.); (Y.L.); (Y.W.); (Y.L.)
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
| | - Yanyan Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361000, China; (W.X.); (Y.L.); (Y.W.); (Y.L.)
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
| | - Hongmei Zhu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
| | - Hantao Zhou
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361000, China; (W.X.); (Y.L.); (Y.W.); (Y.L.)
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China;
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Pan X, Giustarini D, Lang F, Rossi R, Wieder T, Köberle M, Ghashghaeinia M. Desipramine induces eryptosis in human erythrocytes, an effect blunted by nitric oxide donor sodium nitroprusside and N-acetyl-L-cysteine but enhanced by Calcium depletion. Cell Cycle 2023; 22:1827-1853. [PMID: 37522842 PMCID: PMC10599211 DOI: 10.1080/15384101.2023.2234177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 08/01/2023] Open
Abstract
Background: Desipramine a representative of tricyclic antidepressants (TCAs) promotes recovery of depressed patients by inhibition of reuptake of neurotransmitters serotonin (SER) and norepinephrine (NE) in the presynaptic membrane by directly blocking their respective transporters SERT and NET.Aims: To study the effect of desipramine on programmed erythrocyte death (eryptosis) and explore the underlying mechanisms.Methods: Phosphatidylserine (PS) exposure on the cell surface as marker of cell death was estimated from annexin-V-binding, cell volume from forward scatter in flow cytometry. Hemolysis was determined photometrically, and intracellular glutathione [GSH]i from high performance liquid chromatography.Results: Desipramine dose-dependently significantly enhanced the percentage of annexin-V-binding cells and didn´t impact glutathione (GSH) synthesis. Desipramine-induced eryptosis was significantly reversed by pre-treatment of erythrocytes with either nitric oxide (NO) donor sodium nitroprusside (SNP) or N-acetyl-L-cysteine (NAC). The highest inhibitory effect was obtained by using both inhibitors together. Calcium (Ca2+) depletion aggravated desipramine-induced eryptosis. Changing the order of treatment, i.e. desipramine first followed by inhibitors, could not influence the inhibitory effect of SNP or NAC.Conclusion: Antidepressants-caused intoxication can be treated by SNP and NAC, respectively. B) Patients with chronic hypocalcemia should not be treated with tricyclic anti-depressants or their dose should be noticeably reduced.
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Affiliation(s)
- Xia Pan
- Physiological Institute, Department of Vegetative and Clinical Physiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Daniela Giustarini
- Department of Biotechnology Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Florian Lang
- Physiological Institute, Department of Vegetative and Clinical Physiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Ranieri Rossi
- Department of Biotechnology Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Thomas Wieder
- Physiological Institute, Department of Vegetative and Clinical Physiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Martin Köberle
- Department of Dermatology and Allergology, School of Medicine, Technical University of Munich, München, Germany
| | - Mehrdad Ghashghaeinia
- Physiological Institute, Department of Vegetative and Clinical Physiology, Eberhard Karls University of Tübingen, Tübingen, Germany
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Ghosh A, Venugopal A, Shinde D, Sharma S, Krishnan M, Mathre S, Krishnan H, Saha S, Raghu P. PI3P-dependent regulation of cell size and autophagy by phosphatidylinositol 5-phosphate 4-kinase. Life Sci Alliance 2023; 6:e202301920. [PMID: 37316298 PMCID: PMC10267561 DOI: 10.26508/lsa.202301920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 06/02/2023] [Accepted: 06/02/2023] [Indexed: 06/16/2023] Open
Abstract
Phosphatidylinositol 3-phosphate (PI3P) and phosphatidylinositol 5-phosphate (PI5P) are low-abundance phosphoinositides crucial for key cellular events such as endosomal trafficking and autophagy. Phosphatidylinositol 5-phosphate 4-kinase (PIP4K) is an enzyme that regulates PI5P in vivo but can act on both PI5P and PI3P in vitro. In this study, we report a role for PIP4K in regulating PI3P levels in Drosophila Loss-of-function mutants of the only Drosophila PIP4K gene show reduced cell size in salivary glands. PI3P levels are elevated in dPIP4K 29 and reverting PI3P levels back towards WT, without changes in PI5P levels, can rescue the reduced cell size. dPIP4K 29 mutants also show up-regulation in autophagy and the reduced cell size can be reverted by depleting Atg8a that is required for autophagy. Lastly, increasing PI3P levels in WT can phenocopy the reduction in cell size and associated autophagy up-regulation seen in dPIP4K 29 Thus, our study reports a role for a PIP4K-regulated PI3P pool in the control of autophagy and cell size.
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Affiliation(s)
- Avishek Ghosh
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | | | - Dhananjay Shinde
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Sanjeev Sharma
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Meera Krishnan
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Swarna Mathre
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Harini Krishnan
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Sankhanil Saha
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
| | - Padinjat Raghu
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bangalore, India
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55
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Michelucci A, Sforna L, Di Battista A, Franciolini F, Catacuzzeno L. Ca 2+ -activated K + channels regulate cell volume in human glioblastoma cells. J Cell Physiol 2023; 238:2120-2134. [PMID: 37431808 DOI: 10.1002/jcp.31072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/10/2023] [Accepted: 06/20/2023] [Indexed: 07/12/2023]
Abstract
Glioblastoma (GBM), the most lethal form of brain tumors, bases its malignancy on the strong ability of its cells to migrate and invade the narrow spaces of healthy brain parenchyma. Cell migration and invasion are both critically dependent on changes in cell volume and shape driven by the transmembrane transport of osmotically important ions such as K+ and Cl- . However, while the Cl- channels participating in cell volume regulation have been clearly identified, the precise nature of the K+ channels involved is still uncertain. Using a combination of electrophysiological and imaging approaches in GBM U87-MG cells, we found that hypotonic-induced cell swelling triggered the opening of Ca2+ -activated K+ (KCa ) channels of large and intermediate conductance (BKCa and IKCa , respectively), both highly expressed in GBM cells. The influx of Ca2+ mediated by the hypotonic-induced activation of mechanosensitive channels was found to be a key step for opening both the BKCa and the IKCa channels. Finally, the activation of both KCa channels mediated by mechanosensitive channels was found to be essential for the development of the regulatory volume decrease following hypotonic shock. Taken together, these data indicate that KCa channels are the main K+ channels responsible for the volume regulation in U87-MG cells.
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Affiliation(s)
- Antonio Michelucci
- Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, Italy
| | - Luigi Sforna
- Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, Italy
| | - Angela Di Battista
- Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, Italy
| | - Fabio Franciolini
- Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, Italy
| | - Luigi Catacuzzeno
- Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, Italy
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56
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Moxon R, Dutton Worsfold R, Davis J, Adams W, England GCW. Luteal phase decrease in packed cell volume in healthy non-pregnant and pregnant bitches. Vet Med Sci 2023; 9:1989-1997. [PMID: 37466012 PMCID: PMC10508517 DOI: 10.1002/vms3.1195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 02/14/2023] [Accepted: 06/03/2023] [Indexed: 07/20/2023] Open
Abstract
OBJECTIVES To establish packed cell volume (PCV) ranges for non-pregnant, pregnant and post-partum bitches from day 10 of proestrus, investigating any relationship with parity and litter size. METHODS This prospective cohort study used 37 healthy breeding bitches to examine PCV counts from routine blood samples collected every 4 weeks, from day 10 of proestrus, as part of routine PCV monitoring. RESULTS For pregnant (n = 19) and non-pregnant (n = 18) bitches, PCV decreased until week 8 (corresponding to 8.5 ± 1.1 days before whelping for pregnant bitches) and recovered by 16-20 weeks after the initial sample; bitches that whelped average and large litters showed greater declines. PCV began to recover sooner for bitches that had previously whelped one or two litters compared to bitches that had previously whelped three or more litters. There was a significant three-way interaction between time after the onset of proestrus, litter size and the number of previous litters which demonstrated that the large decrease in PCV for bitches that had previously whelped three or more litters only occurred in bitches that were expecting an average or large sized litter. CLINICAL SIGNIFICANCE Chronological variation in PCV for pregnant and non-pregnant bitches was established during the reproductive cycle. There was no evidence to suggest that routine PCV measurement for normal, healthy bitches would be beneficial. However, knowledge from this study may be useful when deciding whether to prospectively monitor a bitch where there is a history of previous pregnancy-related anaemia, when performing a caesarean section due to the anticipated blood loss during surgery, or when examining blood profiles for post-litter bitches.
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Affiliation(s)
- Rachel Moxon
- Guide Dogs National CentreLeamington SpaUK
- School of Veterinary Medicine and ScienceUniversity of NottinghamSutton BoningtonUK
| | | | | | | | - Gary C. W. England
- School of Veterinary Medicine and ScienceUniversity of NottinghamSutton BoningtonUK
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57
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Seejarim C, Rautenbach Y, Hooijberg EH, Leisewitz AL, Schoeman JP, Goddard A. Regenerative response in dogs naturally and experimentally infected with Babesia rossi. Vet Clin Pathol 2023; 52:422-432. [PMID: 37638541 DOI: 10.1111/vcp.13228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/16/2022] [Accepted: 12/07/2022] [Indexed: 08/29/2023]
Abstract
BACKGROUND The regenerative response following Babesia rossi infection in dogs is mild, despite severe hemolytic anemia. OBJECTIVE We aimed to compare the admission absolute reticulocyte count (ARC) and reticulocyte indices in 103 dogs naturally infected with B. rossi with 10 dogs suffering from immune-mediated hemolytic anemia (IMHA) and 14 healthy control dogs. The regenerative response was also evaluated in five dogs experimentally infected with B. rossi. METHODS This is a retrospective observational study of records generated on the ADVIA 2120 hematology analyzer. RESULTS The median hematocrits (HCT) of the B. rossi and IMHA groups were significantly lower than the control group (p < .001 for both); however, no differences were seen between the B. rossi and IMHA groups. Compared with the control group, the median ARC was significantly higher in the B. rossi (p = .006) and IMHA (p = .019) groups but significantly lower in the B. rossi group than the IMHA group (p = .041). In the experimentally infected dogs, there was a sudden decrease in the ARC approximately 48 h after the detection of peripheral parasitemia, which was followed by an increase after treatment. Reticulocytes of naturally infected B. rossi dogs were larger, with more variation in cellular volume. The reticulocytes of the experimentally infected dogs decreased in size with decreasing hemoglobin concentrations as the study progressed. CONCLUSIONS The regenerative response in dogs naturally infected with B. rossi is inadequate, given the severity of the anemia observed, and it might be a result of direct suppressive action by the parasite or host response on the bone marrow.
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Affiliation(s)
- Chandini Seejarim
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Yolandi Rautenbach
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Emma H Hooijberg
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Andrew L Leisewitz
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Johan P Schoeman
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Amelia Goddard
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
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Liu H, Polovitskaya MM, Yang L, Li M, Li H, Han Z, Wu J, Zhang Q, Jentsch TJ, Liao J. Structural insights into anion selectivity and activation mechanism of LRRC8 volume-regulated anion channels. Cell Rep 2023; 42:112926. [PMID: 37543949 PMCID: PMC10480491 DOI: 10.1016/j.celrep.2023.112926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 06/12/2023] [Accepted: 07/18/2023] [Indexed: 08/08/2023] Open
Abstract
Volume-regulated anion channels (VRACs) are hexamers of LRRC8 proteins that are crucial for cell volume regulation. N termini (NTs) of the obligatory LRRC8A subunit modulate VRACs activation and ion selectivity, but the underlying mechanisms remain poorly understood. Here, we report a 2.8-Å cryo-electron microscopy structure of human LRRC8A that displays well-resolved NTs. Amino-terminal halves of NTs fold back into the pore and constrict the permeation path, thereby determining ion selectivity together with an extracellular selectivity filter with which it works in series. They also interact with pore-surrounding helices and support their compact arrangement. The C-terminal halves of NTs interact with intracellular loops that are crucial for channel activation. Molecular dynamics simulations indicate that low ionic strength increases NT mobility and expands the radial distance between pore-surrounding helices. Our work suggests an unusual pore architecture with two selectivity filters in series and a mechanism for VRAC activation by cell swelling.
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Affiliation(s)
- Heng Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Maya M Polovitskaya
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany
| | - Linlin Yang
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 45001, China.
| | - Meiling Li
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 45001, China
| | - Hongyue Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Han
- Department of Pharmacology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 45001, China
| | - Jianguo Wu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiansen Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai, China.
| | - Thomas J Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany; Cluster of Excellence NeuroCure, Charité Universitätsmedizin Berlin, Berlin, Germany.
| | - Jun Liao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Miller KE, Vargas-Garcia C, Singh A, Moseley JB. The fission yeast cell size control system integrates pathways measuring cell surface area, volume, and time. Curr Biol 2023; 33:3312-3324.e7. [PMID: 37463585 PMCID: PMC10529673 DOI: 10.1016/j.cub.2023.06.054] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 06/01/2023] [Accepted: 06/20/2023] [Indexed: 07/20/2023]
Abstract
Eukaryotic cells tightly control their size, but the relevant aspect of size is unknown in most cases. Fission yeast divide at a threshold cell surface area (SA) due, in part, to the protein kinase Cdr2. We find that fission yeast cells only divide by SA under a size threshold. Mutants that divide at a larger size shift to volume-based divisions. Diploid cells divide at a larger size than haploid cells do, but they maintain SA-based divisions, and this indicates that the size threshold for changing from surface-area-based to volume-based control is set by ploidy. Within this size control system, we found that the mitotic activator Cdc25 accumulates like a volume-based sizer molecule, whereas the mitotic cyclin Cdc13 accumulates in the nucleus as a timer. We propose an integrated model for cell size control based on multiple signaling pathways that report on distinct aspects of cell size and growth, including cell SA (Cdr2), cell volume (Cdc25), and time (Cdc13). Combined modeling and experiments show how this system can generate both sizer- and adder-like properties.
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Affiliation(s)
- Kristi E Miller
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Cesar Vargas-Garcia
- Grupo de Investigación en Sistemas Agropecuarios Sostenibles, Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, Bogotá 250047, Colombia
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
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60
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Moger-Reischer RZ, Glass JI, Wise KS, Sun L, Bittencourt DMC, Lehmkuhl BK, Schoolmaster DR, Lynch M, Lennon JT. Evolution of a minimal cell. Nature 2023; 620:122-127. [PMID: 37407813 PMCID: PMC10396959 DOI: 10.1038/s41586-023-06288-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 06/06/2023] [Indexed: 07/07/2023]
Abstract
Possessing only essential genes, a minimal cell can reveal mechanisms and processes that are critical for the persistence and stability of life1,2. Here we report on how an engineered minimal cell3,4 contends with the forces of evolution compared with the Mycoplasma mycoides non-minimal cell from which it was synthetically derived. Mutation rates were the highest among all reported bacteria, but were not affected by genome minimization. Genome streamlining was costly, leading to a decrease in fitness of greater than 50%, but this deficit was regained during 2,000 generations of evolution. Despite selection acting on distinct genetic targets, increases in the maximum growth rate of the synthetic cells were comparable. Moreover, when performance was assessed by relative fitness, the minimal cell evolved 39% faster than the non-minimal cell. The only apparent constraint involved the evolution of cell size. The size of the non-minimal cell increased by 80%, whereas the minimal cell remained the same. This pattern reflected epistatic effects of mutations in ftsZ, which encodes a tubulin-homologue protein that regulates cell division and morphology5,6. Our findings demonstrate that natural selection can rapidly increase the fitness of one of the simplest autonomously growing organisms. Understanding how species with small genomes overcome evolutionary challenges provides critical insights into the persistence of host-associated endosymbionts, the stability of streamlined chassis for biotechnology and the targeted refinement of synthetically engineered cells2,7-9.
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Affiliation(s)
| | - J I Glass
- J. Craig Venter Institute, La Jolla, CA, USA
| | - K S Wise
- J. Craig Venter Institute, La Jolla, CA, USA
| | - L Sun
- J. Craig Venter Institute, La Jolla, CA, USA
- Novartis Gene Therapy, San Diego, CA, USA
| | - D M C Bittencourt
- J. Craig Venter Institute, La Jolla, CA, USA
- Embrapa Genetic Resources and Biotechnology, National Institute of Science and Technology in Synthetic Biology, Brasília, Brazil
| | - B K Lehmkuhl
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - D R Schoolmaster
- US Geological Survey, Wetland and Aquatic Research Center, Lafayette, LA, USA
| | - M Lynch
- Arizona State University, Tempe, AZ, USA
| | - J T Lennon
- Department of Biology, Indiana University, Bloomington, IN, USA.
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Abstract
Spatial transcriptomics promises to greatly improve our understanding of tissue organization and cell-cell interactions. While most current platforms for spatial transcriptomics only offer multi-cellular resolution, with 10-15 cells per spot, recent technologies provide a much denser spot placement leading to subcellular resolution. A key challenge for these newer methods is cell segmentation and the assignment of spots to cells. Traditional image-based segmentation methods are limited and do not make full use of the information profiled by spatial transcriptomics. Here we present subcellular spatial transcriptomics cell segmentation (SCS), which combines imaging data with sequencing data to improve cell segmentation accuracy. SCS assigns spots to cells by adaptively learning the position of each spot relative to the center of its cell using a transformer neural network. SCS was tested on two new subcellular spatial transcriptomics technologies and outperformed traditional image-based segmentation methods. SCS achieved better accuracy, identified more cells and provided more realistic cell size estimation. Subcellular analysis of RNAs using SCS spot assignments provides information on RNA localization and further supports the segmentation results.
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Affiliation(s)
- Hao Chen
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Dongshunyi Li
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Ziv Bar-Joseph
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA.
- Machine Learning Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA.
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Ji X, Lin J. Implications of differential size-scaling of cell-cycle regulators on cell size homeostasis. PLoS Comput Biol 2023; 19:e1011336. [PMID: 37506170 PMCID: PMC10411824 DOI: 10.1371/journal.pcbi.1011336] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 08/09/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
Accurate timing of division and size homeostasis is crucial for cells. A potential mechanism for cells to decide the timing of division is the differential scaling of regulatory protein copy numbers with cell size. However, it remains unclear whether such a mechanism can lead to robust growth and division, and how the scaling behaviors of regulatory proteins influence the cell size distribution. Here we study a mathematical model combining gene expression and cell growth, in which the cell-cycle activators scale superlinearly with cell size while the inhibitors scale sublinearly. The cell divides once the ratio of their concentrations reaches a threshold value. We find that the cell can robustly grow and divide within a finite range of the threshold value with the cell size proportional to the ploidy. In a stochastic version of the model, the cell size at division is uncorrelated with that at birth. Also, the more differential the cell-size scaling of the cell-cycle regulators is, the narrower the cell-size distribution is. Intriguingly, our model with multiple regulators rationalizes the observation that after the deletion of a single regulator, the coefficient of variation of cell size remains roughly the same though the average cell size changes significantly. Our work reveals that the differential scaling of cell-cycle regulators provides a robust mechanism of cell size control.
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Affiliation(s)
- Xiangrui Ji
- Yuanpei College, Peking University, Beijing, China
| | - Jie Lin
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
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63
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Saha D, Hadule S, Giri L. A deep learning approach for automation in neurite tracing and cell size estimation from differential contrast images under healthy and hypoxic condition. Annu Int Conf IEEE Eng Med Biol Soc 2023; 2023:1-4. [PMID: 38083674 DOI: 10.1109/embc40787.2023.10340948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Chronic hypoxia is known to be a major cause of neurite length retraction followed be degeneration. Specifically, laser scanning confocal microscopy (LSCM) based-contrast imaging is used for monitoring neuronal morphology under hypoxic condition. Although imaging of neurons using LSCM via differential contrast imaging (DIC) is a powerful tool to identify the neuronal states under degenerative condition, fully automated quantification of neurite length and cell shape remains challenging. In this context, we propose an integrated framework that combines panorama imaging of neuronal morphology using LSCM, and deep learning model that allows automated tracing of neurites and cell shape. First, we establish an in vitro hypoxic model using cobalt chloride treatment of N2A cells and perform the large-scale imaging using DIC optics. Next, we tested the performance of U-Net, U-Net++ and FCN architecture using DIC images, where U-Net and U-Net++ demonstrates robustness and accuracy in tracing neurite length and segmentation of cell shape. The result shows that the U-Net++ is able to depict the difference in cell size and neurite length for control and chronic hypoxic condition. The proposed method was also validated and compared with other CNN models including FCN and U-Net. Moreover, the analysis indicates a significant alteration of cell shape and neurite length under hypoxic condition via deep-learning based automated cell segmentation.Clinical Relevance-The proposed framework assumes importance where quantification of neurite length and cell shape from a large dataset remains challenging due to time-consuming manual segmentation by experts. Specially, the framework based on labeling of a small dataset (15-20 images) can be used to identify the neuronal state under neurodegeneration and image-based assessment of neuroprotective drugs.
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64
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Hansson KA, Eftestøl E. Scaling of nuclear numbers and their spatial arrangement in skeletal muscle cell size regulation. Mol Biol Cell 2023; 34:pe3. [PMID: 37339435 PMCID: PMC10398882 DOI: 10.1091/mbc.e22-09-0424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 03/29/2023] [Accepted: 04/28/2023] [Indexed: 06/22/2023] Open
Abstract
Many cells display considerable functional plasticity and depend on the regulation of numerous organelles and macromolecules for their maintenance. In large cells, organelles also need to be carefully distributed to supply the cell with essential resources and regulate intracellular activities. Having multiple copies of the largest eukaryotic organelle, the nucleus, epitomizes the importance of scaling gene products to large cytoplasmic volumes in skeletal muscle fibers. Scaling of intracellular constituents within mammalian muscle fibers is, however, poorly understood, but according to the myonuclear domain hypothesis, a single nucleus supports a finite amount of cytoplasm and is thus postulated to act autonomously, causing the nuclear number to be commensurate with fiber volume. In addition, the orderly peripheral distribution of myonuclei is a hallmark of normal cell physiology, as nuclear mispositioning is associated with impaired muscle function. Because underlying structures of complex cell behaviors are commonly formalized by scaling laws and thus emphasize emerging principles of size regulation, the work presented herein offers more of a unified conceptual platform based on principles from physics, chemistry, geometry, and biology to explore cell size-dependent correlations of the largest mammalian cell by means of scaling.
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Affiliation(s)
- Kenth-Arne Hansson
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, 2624 Lillehammer, Norway
| | - Einar Eftestøl
- Department of Biosciences, University of Oslo, 0371 Oslo, Norway
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65
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Höglsperger F, Vos BE, Hofemeier AD, Seyfried MD, Stövesand B, Alavizargar A, Topp L, Heuer A, Betz T, Ravoo BJ. Rapid and reversible optical switching of cell membrane area by an amphiphilic azobenzene. Nat Commun 2023; 14:3760. [PMID: 37353493 PMCID: PMC10290115 DOI: 10.1038/s41467-023-39032-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/25/2023] [Indexed: 06/25/2023] Open
Abstract
Cellular membrane area is a key parameter for any living cell that is tightly regulated to avoid membrane damage. Changes in area-to-volume ratio are known to be critical for cell shape, but are mostly investigated by changing the cell volume via osmotic shocks. In turn, many important questions relating to cellular shape, membrane tension homeostasis and local membrane area cannot be easily addressed because experimental tools for controlled modulation of cell membrane area are lacking. Here we show that photoswitching an amphiphilic azobenzene can trigger its intercalation into the plasma membrane of various mammalian cells ranging from erythrocytes to myoblasts and cancer cells. The photoisomerization leads to a rapid (250-500 ms) and highly reversible membrane area change (ca 2 % for erythrocytes) that triggers a dramatic shape modulation of living cells.
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Affiliation(s)
- Fabian Höglsperger
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Bart E Vos
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany
| | - Arne D Hofemeier
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany
| | - Maximilian D Seyfried
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Bastian Stövesand
- Organic Chemistry Institute, University of Münster, Münster, Germany
- Center for Soft Nanoscience, University of Münster, Münster, Germany
| | - Azadeh Alavizargar
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Leon Topp
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Andreas Heuer
- Center for Soft Nanoscience, University of Münster, Münster, Germany
- Institute of Physical Chemistry, University of Münster, Münster, Germany
| | - Timo Betz
- Third Institute of Physics-Biophysics, University of Göttingen, Göttingen, Germany.
| | - Bart Jan Ravoo
- Organic Chemistry Institute, University of Münster, Münster, Germany.
- Center for Soft Nanoscience, University of Münster, Münster, Germany.
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66
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Nieto C, Blanco SC, Vargas-García C, Singh A, Manuel PJ. PyEcoLib: a python library for simulating stochastic cell size dynamics. Phys Biol 2023; 20:10.1088/1478-3975/acd897. [PMID: 37224818 PMCID: PMC10665115 DOI: 10.1088/1478-3975/acd897] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 05/24/2023] [Indexed: 05/26/2023]
Abstract
Recently, there has been an increasing need for tools to simulate cell size regulation due to important applications in cell proliferation and gene expression. However, implementing the simulation usually presents some difficulties, as the division has a cycle-dependent occurrence rate. In this article, we gather a recent theoretical framework inPyEcoLib, a python-based library to simulate the stochastic dynamics of the size of bacterial cells. This library can simulate cell size trajectories with an arbitrarily small sampling period. In addition, this simulator can include stochastic variables, such as the cell size at the beginning of the experiment, the cycle duration timing, the growth rate, and the splitting position. Furthermore, from a population perspective, the user can choose between tracking a single lineage or all cells in a colony. They can also simulate the most common division strategies (adder, timer, and sizer) using the division rate formalism and numerical methods. As an example of PyecoLib applications, we explain how to couple size dynamics with gene expression predicting, from simulations, how the noise in protein levels increases by increasing the noise in division timing, the noise in growth rate and the noise in cell splitting position. The simplicity of this library and its transparency about the underlying theoretical framework yield the inclusion of cell size stochasticity in complex models of gene expression.
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Affiliation(s)
- César Nieto
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, United States of America
- Department of Physics. Universidad de los Andes, Bogotá, Colombia
| | - Sergio Camilo Blanco
- Department of Mathematics and Engineering. Fundacion Universitaria Konrad Lorenz, Bogota, Colombia
| | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Department of Biomedical Engineering and Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, United States of America
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67
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Kratz JC, Banerjee S. Dynamic proteome trade-offs regulate bacterial cell size and growth in fluctuating nutrient environments. Commun Biol 2023; 6:486. [PMID: 37147517 PMCID: PMC10163005 DOI: 10.1038/s42003-023-04865-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/24/2023] [Indexed: 05/07/2023] Open
Abstract
Bacteria dynamically regulate cell size and growth to thrive in changing environments. While previous studies have characterized bacterial growth physiology at steady-state, a quantitative understanding of bacterial physiology in time-varying environments is lacking. Here we develop a quantitative theory connecting bacterial growth and division rates to proteome allocation in time-varying nutrient environments. In such environments, cell size and growth are regulated by trade-offs between prioritization of biomass accumulation or division, resulting in decoupling of single-cell growth rate from population growth rate. Specifically, bacteria transiently prioritize biomass accumulation over production of division machinery during nutrient upshifts, while prioritizing division over growth during downshifts. When subjected to pulsatile nutrient concentration, we find that bacteria exhibit a transient memory of previous metabolic states due to the slow dynamics of proteome reallocation. This allows for faster adaptation to previously seen environments and results in division control which is dependent on the time-profile of fluctuations.
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Affiliation(s)
- Josiah C Kratz
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Shiladitya Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
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68
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Ritzmann D, Jahn M, Heck S, Jung C, Cesetti T, Couturier N, Rudolf R, Reuscher N, Buerger C, Rauh O, Fauth T. The Ca 2+ channel TRPV4 is dispensable for Ca 2+ influx and cell volume regulation during hypotonic stress response in human keratinocyte cell lines. Cell Calcium 2023; 111:102715. [PMID: 36933289 DOI: 10.1016/j.ceca.2023.102715] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/13/2023]
Abstract
Cell swelling as a result of hypotonic stress is counteracted in mammalian cells by a process called regulatory volume decrease (RVD). We have recently discovered that RVD of human keratinocytes requires the LRRC8 volume-regulated anion channel (VRAC) and that Ca2+ exerts a modulatory function on RVD. However, the ion channel that is responsible for Ca2+ influx remains unknown. We investigated in this study whether the Ca2+-permeable TRPV4 ion channel, which functions as cell volume sensor in many cell types, may be involved in cell volume regulation during hypotonic stress response of human keratinocytes. We interfered with TRPV4 function in two human keratinocyte cell lines (HaCaT and NHEK-E6/E7) by using two TRPV4-specific inhibitors (RN1734 and GSK2193874), and by creating a CRISPR/Cas9-mediated genetic TRPV4-/- knockout in HaCaT cells. We employed electrophysiological patch clamp analysis, fluorescence-based Ca2+ imaging and cell volume measurements to determine the functional importance of TRPV4. We could show that both hypotonic stress and direct activation of TRPV4 by the specific agonist GSK1016790A triggered intracellular Ca2+ response. Strikingly, the Ca2+ increase upon hypotonic stress was neither affected by genetic knockout of TRPV4 in HaCaT cells nor by pharmacological inhibition of TRPV4 in both keratinocyte cell lines. Accordingly, hypotonicity-induced cell swelling, downstream activation of VRAC currents as well as subsequent RVD were unaffected both in TRPV4 inhibitor-treated keratinocytes and in HaCaT-TRPV4-/- cells. In summary, our study shows that keratinocytes do not require TRPV4 for coping with hypotonic stress, which implies the involvement of other, yet unidentified Ca2+ channels.
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Affiliation(s)
| | - Magdalena Jahn
- BRAIN Biotech AG, Zwingenberg, Germany; Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | | | - Cristina Jung
- Membrane Biophysics, Department of Biology, TU Darmstadt, Darmstadt, Germany
| | - Tiziana Cesetti
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Nathalie Couturier
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany; Center for Mass Spectrometry and Optical Spectroscopy, Hochschule Mannheim, Mannheim, Germany
| | - Naemi Reuscher
- Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Claudia Buerger
- Department of Dermatology, Venerology and Allergology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Oliver Rauh
- Membrane Biophysics, Department of Biology, TU Darmstadt, Darmstadt, Germany
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69
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Jiang GF, Li SY, Dinnage R, Cao KF, Simonin KA, Roddy AB. Diverse mangroves deviate from other angiosperms in their genome size, leaf cell size and cell packing density relationships. Ann Bot 2023; 131:347-360. [PMID: 36516425 PMCID: PMC9992938 DOI: 10.1093/aob/mcac151] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND AIMS While genome size limits the minimum sizes and maximum numbers of cells that can be packed into a given leaf volume, mature cell sizes can be substantially larger than their meristematic precursors and vary in response to abiotic conditions. Mangroves are iconic examples of how abiotic conditions can influence the evolution of plant phenotypes. METHODS Here, we examined the coordination between genome size, leaf cell sizes, cell packing densities and leaf size in 13 mangrove species across four sites in China. Four of these species occurred at more than one site, allowing us to test the effect of climate on leaf anatomy. RESULTS We found that genome sizes of mangroves were very small compared to other angiosperms, but, like other angiosperms, mangrove cells were always larger than the minimum size defined by genome size. Increasing mean annual temperature of a growth site led to higher packing densities of veins (Dv) and stomata (Ds) and smaller epidermal cells but had no effect on stomatal size. In contrast to other angiosperms, mangroves exhibited (1) a negative relationship between guard cell size and genome size; (2) epidermal cells that were smaller than stomata; and (3) coordination between Dv and Ds that was not mediated by epidermal cell size. Furthermore, mangrove epidermal cell sizes and packing densities covaried with leaf size. CONCLUSIONS While mangroves exhibited coordination between veins and stomata and attained a maximum theoretical stomatal conductance similar to that of other angiosperms, the tissue-level tradeoffs underlying these similar relationships across species and environments were markedly different, perhaps indicative of the unique structural and physiological adaptations of mangroves to their stressful environments.
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Affiliation(s)
| | - Su-Yuan Li
- Guangxi Key Laboratory of Forest Ecology and Conservation, and State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004, PR China
| | - Russell Dinnage
- Institute of Environment, Department of Biological Sciences, Florida International University, Miami, FL 33199USA
| | - Kun-Fang Cao
- Guangxi Key Laboratory of Forest Ecology and Conservation, and State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004, PR China
| | - Kevin A Simonin
- Department of Biology, San Francisco State University, San Francisco, CA 94132USA
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70
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Fujita I, Kimura A, Yamashita A. A force balance model for a cell size-dependent meiotic nuclear oscillation in fission yeast. EMBO Rep 2023; 24:e55770. [PMID: 36622644 PMCID: PMC9986818 DOI: 10.15252/embr.202255770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 12/09/2022] [Accepted: 12/14/2022] [Indexed: 01/10/2023] Open
Abstract
Fission yeast undergoes premeiotic nuclear oscillation, which is dependent on microtubules and is driven by cytoplasmic dynein. Although the molecular mechanisms have been analyzed, how a robust oscillation is generated despite the dynamic behaviors of microtubules has yet to be elucidated. Here, we show that the oscillation exhibits cell length-dependent frequency and requires a balance between microtubule and viscous drag forces, as well as proper microtubule dynamics. Comparison of the oscillations observed in living cells with a simulation model based on microtubule dynamic instability reveals that the period of oscillation correlates with cell length. Genetic alterations that reduce cargo size suggest that the nuclear movement depends on viscous drag forces. Deletion of a gene encoding Kinesin-8 inhibits microtubule catastrophe at the cell cortex and results in perturbation of oscillation, indicating that nuclear movement also depends on microtubule dynamic instability. Our findings link numerical parameters from the simulation model with cellular functions required for generating the oscillation and provide a basis for understanding the physical properties of microtubule-dependent nuclear movements.
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Affiliation(s)
- Ikumi Fujita
- Laboratory for Cell Asymmetry, Center for Biosystems Dynamics ResearchRIKENKobeJapan
| | - Akatsuki Kimura
- Cell Architecture LaboratoryNational Institute of GeneticsMishimaJapan
- Department of Genetics, School of Life ScienceSOKENDAI (The Graduate University for Advanced Studies)MishimaJapan
| | - Akira Yamashita
- Interdisciplinary Research UnitNational Institute for Basic BiologyOkazakiJapan
- Center for Low‐temperature Plasma SciencesNagoya UniversityNagoyaJapan
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71
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Andersen T, Wörthmüller D, Probst D, Wang I, Moreau P, Fitzpatrick V, Boudou T, Schwarz US, Balland M. Cell size and actin architecture determine force generation in optogenetically activated cells. Biophys J 2023; 122:684-696. [PMID: 36635962 PMCID: PMC9989885 DOI: 10.1016/j.bpj.2023.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 12/16/2022] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Adherent cells use actomyosin contractility to generate mechanical force and to sense the physical properties of their environment, with dramatic consequences for migration, division, differentiation, and fate. However, the organization of the actomyosin system within cells is highly variable, with its assembly and function being controlled by small GTPases from the Rho family. To understand better how activation of these regulators translates into cell-scale force generation in the context of different physical environments, here we combine recent advances in non-neuronal optogenetics with micropatterning and traction force microscopy on soft elastic substrates. We find that, after whole-cell RhoA activation by the CRY2/CIBN optogenetic system with a short pulse of 100 ms, single cells contract on a minute timescale in proportion to their original traction force, before returning to their original tension setpoint with near perfect precision, on a longer timescale of several minutes. To decouple the biochemical and mechanical elements of this response, we introduce a mathematical model that is parametrized by fits to the dynamics of the substrate deformation energy. We find that the RhoA response builds up quickly on a timescale of 20 s, but decays slowly on a timescale of 50 s. The larger the cells and the more polarized their actin cytoskeleton, the more substrate deformation energy is generated. RhoA activation starts to saturate if optogenetic pulse length exceeds 50 ms, revealing the intrinsic limits of biochemical activation. Together our results suggest that adherent cells establish tensional homeostasis by the RhoA system, but that the setpoint and the dynamics around it are strongly determined by cell size and the architecture of the actin cytoskeleton, which both are controlled by the extracellular environment.
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Affiliation(s)
- T Andersen
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - D Wörthmüller
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany; BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - D Probst
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany; BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - I Wang
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - P Moreau
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - V Fitzpatrick
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - T Boudou
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France
| | - U S Schwarz
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany; BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany.
| | - M Balland
- Université Grenoble Alpes, CNRS, LIPhy, F-38000 Grenoble, France.
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72
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Adar RM, Vishen AS, Joanny JF, Sens P, Safran SA. Volume regulation in adhered cells: Roles of surface tension and cell swelling. Biophys J 2023; 122:506-512. [PMID: 36609139 PMCID: PMC9941750 DOI: 10.1016/j.bpj.2022.12.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/22/2022] [Accepted: 12/28/2022] [Indexed: 01/07/2023] Open
Abstract
The volume of adhered cells has been shown experimentally to decrease during spreading. This effect can be understood from the pump-leak model, which we have extended to include mechano-sensitive ion transporters. We identify a novel effect that has important consequences on cellular volume loss: cells that are swollen due to a modulation of ion transport rates are more susceptible to volume loss in response to a tension increase. This effect explains in a plausible manner the discrepancies between three recent, independent experiments on adhered cells, between which both the magnitude of the volume change and its dynamics varied substantially. We suggest that starved and synchronized cells in two of the experiments were in a swollen state and, consequently, exhibited a large volume loss at steady state. Nonswollen cells, for which there is a very small steady-state volume decrease, are still predicted to transiently lose volume during spreading due to a relaxing viscoelastic tension that is large compared with the steady-state tension. We elucidate the roles of cell swelling and surface tension in cellular volume regulation and discuss their possible microscopic origins.
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Affiliation(s)
- Ram M Adar
- Collège de France, Paris, France; Laboratoire Physico-Chimie Curie, Institut Curie, Centre de Recherche, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Paris, France; Université Pierre et Marie Curie, Sorbonne Universités, Paris, France.
| | - Amit Singh Vishen
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre de Recherche, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Paris, France; Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Jean-François Joanny
- Collège de France, Paris, France; Laboratoire Physico-Chimie Curie, Institut Curie, Centre de Recherche, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Paris, France; Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Pierre Sens
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre de Recherche, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique, Paris, France; Université Pierre et Marie Curie, Sorbonne Universités, Paris, France.
| | - Samuel A Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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73
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Chaillot J, Cook MA, Sellam A. Novel determinants of cell size homeostasis in the opportunistic yeast Candida albicans. Curr Genet 2023; 69:67-75. [PMID: 36449086 DOI: 10.1007/s00294-022-01260-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022]
Abstract
The basis for commitment to cell division in late G1 phase, called Start in yeast, is a critical but still poorly understood aspect of eukaryotic cell proliferation. Most dividing cells accumulate mass and grow to a critical cell size before traversing the cell cycle. This size threshold couples cell growth to division and thereby establishes long-term size homeostasis. At present, mechanisms involved in cell size homeostasis in fungal pathogens are not well described. Our previous survey of the size phenome in Candida albicans focused on 279 unique mutants enriched mainly in kinases and transcription factors (Sellam et al. PLoS Genet 15:e1008052, 2019). To uncover novel size regulators in C. albicans and highlight potential innovation within cell size control in pathogenic fungi, we expanded our genetic survey of cell size to include 1301 strains from the GRACE (Gene Replacement and Conditional Expression) collection. The current investigation uncovered both known and novel biological processes required for cell size homeostasis in C. albicans. We also confirmed the plasticity of the size control network as few C. albicans size genes overlapped with those of the budding yeast Saccharomyces cerevisiae. Many new size genes of C. albicans were associated with biological processes that were not previously linked to cell size control and offer an opportunity for future investigation. Additional work is needed to understand if mitochondrial activity is a critical element of the metric that dictates cell size in C. albicans and whether modulation of the onset of actomyosin ring constriction is an additional size checkpoint.
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Affiliation(s)
- Julien Chaillot
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
- Centre de Recherche Paul Pascal, Unité Mixte de Recherche 5031, Université de Bordeaux, Centre National de la Recherche Scientifique, 33600, Pessac, France
| | - Michael A Cook
- Department of Biochemistry and Biomedical Sciences, David Braley Center for Antibiotic Discovery, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Adnane Sellam
- Montreal Heart Institute, Université de Montréal, Montréal, QC, Canada.
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
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74
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Abstract
During early embryogenesis, as cells divide in the developing embryo, the size of intracellular organelles generally decreases to scale with the decrease in overall cell size. Organelle size scaling is thought to be important to establish and maintain proper cellular function, and defective scaling may lead to impaired development and disease. However, how the cell regulates organelle size and organization are largely unanswered questions. In this review, we summarize the process of size scaling at both the cell and organelle levels and discuss recently discovered mechanisms that regulate this process during early embryogenesis. In addition, we describe how some recently developed techniques and Xenopus as an animal model can be used to investigate the underlying mechanisms of size regulation and to uncover the significance of proper organelle size scaling and organization.
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Affiliation(s)
- Pan Chen
- Institute of Biochemistry and Molecular Biology, School of Medicine, Ningbo University, Ningbo, Zhejiang 315211, China.
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
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75
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Yang P, Bao S, Xiao S, Feng J, Lu X. QCM sensor provides insight into the role of pivotal ions in cellular regulatory volume decrease. Anal Bioanal Chem 2023; 415:245-254. [PMID: 36399229 DOI: 10.1007/s00216-022-04415-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/15/2022] [Accepted: 10/31/2022] [Indexed: 11/21/2022]
Abstract
All vertebrate cells generally self-regulate for sustaining homeostasis and cell functions. As a major regulatory mechanism, regulatory volume decrease (RVD) occurs in hypotonicity-induced cell swelling, and then shrinking by the efflux of intracellular osmolytes and water, in which the ions K+, Cl-, and Ca2+ play a key role in the RVD process. We observed that these pivotal ions could result in novel RVD behaviors under repeatedly hypotonic stimulation. However, there is a lack of valid means for assessing the effect of pivotal ions on RVD. In this work, we proposed an effective measurement process based on a quartz crystal microbalance (QCM) combined with cell function of RVD for revealing acute variations in cell volume regulation induced by the pivotal ions. A QCM sensor was implemented by adhering MCF-7 cells to a poly-l-lysine-modified gold chip and cyclic stimulation with hypotonic NaCl medium, in which a frequency shift (Δf) showed the superior feasibility of the technique in exhibiting RVD behaviors. With the increase in the number of cycles, the RVD values decreased progressively under three stimulation cycles with hypotonic NaCl alone. Compared with the first cycle, the RVD level in the second and third cycles declined by 60.7±1.7% and 82.1±1.6% (n=3), respectively; conversely, it recovered in NaCl-KCl solution, but was significantly enhanced by 52.2±0.8% in NaCl-CaCl2 solution. Moreover, the inhibition of chloride channels to block Cl- efflux also decreased the RVD level by 56.2±3.0%. The results indicate that these ions (K+, Cl-, Ca2+) are all able to affect the function of RVD, among which intracellular Cl- depletion reduced RVD during measurement, but which recovered with K+ supplement, and Ca2+ enhanced RVD due to activation of ion channels. Therefore, this work provides a comprehensive assessment of cellular behavior and offers an innovative method for gaining insight into cellular functions and mechanisms. A novel strategy was conducted by integrating a quartz crystal microbalance (QCM) with the function of cell volume regulation for analyzing the role of the pivotal ions ( K+, Cl-, Ca2+) in NaCl media on the behaviors of regulatory cell volume decrease (RVD).
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Affiliation(s)
- Peihui Yang
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, People's Republic of China.
| | - Shan Bao
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, People's Republic of China
| | - Suting Xiao
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, People's Republic of China
| | - Jingwei Feng
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, People's Republic of China
| | - Xinxin Lu
- Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, People's Republic of China
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76
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Liu L, Fan M, Kang Y. Effect of nutrient supply on cell size evolution of marine phytoplankton. Math Biosci Eng 2023; 20:4714-4740. [PMID: 36896519 DOI: 10.3934/mbe.2023218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The variation of nutrient supply not only leads to the differences in the phytoplankton biomass and primary productivity but also induces the long-term phenotypic evolution of phytoplankton. It is widely accepted that marine phytoplankton follows Bergmann's Rule and becomes smaller with climate warming. Compared with the direct effect of increasing temperature, the indirect effect via nutrient supply is considered to be an important and dominant factor in the reduction of phytoplankton cell size. In this paper, a size-dependent nutrient-phytoplankton model is developed to explore the effects of nutrient supply on the evolutionary dynamics of functional traits associated with phytoplankton size. The ecological reproductive index is introduced to investigate the impacts of input nitrogen concentration and vertical mixing rate on the persistence of phytoplankton and the distribution of cell size. In addition, by applying the adaptive dynamics theory, we study the relationship between nutrient input and the evolutionary dynamics of phytoplankton. The results show that input nitrogen concentration and vertical mixing rate have significant effects on the cell size evolution of phytoplankton. Specifically, cell size tends to increase with the input nutrient concentration, as does the diversity of cell sizes. In addition, a single-peaked relationship between vertical mixing rate and cell size is observed. When the vertical mixing rate is too low or too high, only small individuals are dominant in the water column. When the vertical mixing rate is moderate, large individuals can coexist with small individuals, so the diversity of phytoplankton is elevated. We predict that reduced intensity of nutrient input due to climate warming will lead to a trend towards smaller cell size and will reduce the diversity of phytoplankton.
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Affiliation(s)
- Lidan Liu
- School of Mathematics and Statistics, Northeast Normal University, Changchun, Jilin 130024, China
| | - Meng Fan
- School of Mathematics and Statistics, Northeast Normal University, Changchun, Jilin 130024, China
| | - Yun Kang
- College of Integrative Sciences and Arts, Arizona State University, Mesa, AZ 85212, USA
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77
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Du Z, Yan Q, Shen E, Weinstein AM, Wang T. Regulation of glomerulotubular balance. IV. Implication of aquaporin 1 in flow-dependent proximal tubule transport and cell volume. Am J Physiol Renal Physiol 2022; 323:F642-F653. [PMID: 36108052 PMCID: PMC9705020 DOI: 10.1152/ajprenal.00167.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022] Open
Abstract
The water channel aquaporin-1 (AQP1) is the principal water pathway for isotonic water reabsorption in the kidney proximal tubule (PT). We investigated flow-mediated fluid (Jv) and [Formula: see text] ([Formula: see text]) reabsorption in PTs of the mouse kidney by microperfusion in wild-type (WT) and AQP1 knockout (KO) mice. Experiments were simulated in an adaptation of a mathematical model of the rat PT. An increase in perfusion rate from 5 to 20 nL/min increased Jv and [Formula: see text] in PTs of WT mice. AQP1 KO mice significantly decreased Jv at low and high flow rates compared with control. In contrast, [Formula: see text] was not reduced at either low or high flow rates. Cell volume showed no significant difference between WT and AQP1 KO mice. Renal clearance experiments showed significantly higher urine flow in AQP1 KO mice, but there was no significant difference in either Na+ and K+ or [Formula: see text] excretion. Acid-base parameters of blood pH, Pco2, [Formula: see text], and urine pH were the same in both WT and KO mice. In model calculations, tubules whose tight junction (TJ) water permeability (Pf) was that assigned to the rat TJ, showed no difference in Jv between WT and KO, whereas TJ Pf set to 25% of the rat predicted Jv concordant with our observations from AQP1 KO. These results affirm the dominance of AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrate that flow-stimulated [Formula: see text] reabsorption is intact and independent of AQP1. With reference to the model, the findings also suggest that TJ water flux in the PT is less prominent in the mouse than in the rat kidney.NEW & NOTEWORTHY We found an absence of flow-dependent modulation of fluid absorption but no effect on either proximal tubule (PT) [Formula: see text] absorption or acid-base parameters in the aquaporin 1 (AQP1) knockout mouse. We affirmed the dominance of the water channel AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrated that flow-stimulated [Formula: see text] reabsorption is independent of AQP1. With reference to the model, the findings also suggest that tight junctional water flux in the PT is less prominent in the mouse than rat kidney.
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Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Qingshang Yan
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Emma Shen
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College, Cornell University, New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
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78
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Serbanescu D, Ojkic N, Banerjee S. Cellular resource allocation strategies for cell size and shape control in bacteria. FEBS J 2022; 289:7891-7906. [PMID: 34665933 PMCID: PMC9016100 DOI: 10.1111/febs.16234] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/21/2021] [Accepted: 10/18/2021] [Indexed: 01/14/2023]
Abstract
Bacteria are highly adaptive microorganisms that thrive in a wide range of growth conditions via changes in cell morphologies and macromolecular composition. How bacterial morphologies are regulated in diverse environmental conditions is a long-standing question. Regulation of cell size and shape implies control mechanisms that couple the growth and division of bacteria to their cellular environment and macromolecular composition. In the past decade, simple quantitative laws have emerged that connect cell growth to proteomic composition and the nutrient availability. However, the relationships between cell size, shape, and growth physiology remain challenging to disentangle and unifying models are lacking. In this review, we focus on regulatory models of cell size control that reveal the connections between bacterial cell morphology and growth physiology. In particular, we discuss how changes in nutrient conditions and translational perturbations regulate the cell size, growth rate, and proteome composition. Integrating quantitative models with experimental data, we identify the physiological principles of bacterial size regulation, and discuss the optimization strategies of cellular resource allocation for size control.
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Affiliation(s)
- Diana Serbanescu
- Department of Physics and Astronomy, University College London, UK
| | - Nikola Ojkic
- Department of Physics and Astronomy, University College London, UK
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79
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Jiang X, Devan SP, Xie J, Gore JC, Xu J. Improving MR cell size imaging by inclusion of transcytolemmal water exchange. NMR Biomed 2022; 35:e4799. [PMID: 35794795 PMCID: PMC10124991 DOI: 10.1002/nbm.4799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 06/27/2022] [Accepted: 07/05/2022] [Indexed: 05/12/2023]
Abstract
The goal of the current study is to include transcytolemmal water exchange in MR cell size imaging using the IMPULSED model for more accurate characterization of tissue cellular properties (e.g., apparent volume fraction of intracellular space v in ) and quantification of indicators of transcytolemmal water exchange. We propose a heuristic model that incorporates transcytolemmal water exchange into a multicompartment diffusion-based method (IMPULSED) that was developed previously to extract microstructural parameters (e.g., mean cell size d and apparent volume fraction of intracellular space v in ) assuming no water exchange. For t diff ≤ 5 ms, the water exchange can be ignored, and the signal model is the same as the IMPULSED model. For t diff ≥ 30 ms, we incorporated the modified Kärger model that includes both restricted diffusion and exchange between compartments. Using simulations and previously published in vitro cell data, we evaluated the accuracy and precision of model-derived parameters and determined how they are dependent on SNR and imaging parameters. The joint model provides more accurate d values for cell sizes ranging from 10 to 12 microns when water exchange is fast (e.g., intracellular water pre-exchange lifetime τ in ≤ 100 ms) than IMPULSED, and reduces the bias of IMPULSED-derived estimates of v in , especially when water exchange is relatively slow (e.g., τ in > 200 ms). Indicators of transcytolemmal water exchange derived from the proposed joint model are linearly correlated with ground truth τ in values and can detect changes in cell membrane permeability induced by saponin treatment in murine erythroleukemia cancer cells. Our results suggest this joint model not only improves the accuracy of IMPULSED-derived microstructural parameters, but also provides indicators of water exchange that are usually ignored in diffusion models of tissues.
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Affiliation(s)
- Xiaoyu Jiang
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sean P Devan
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37232, USA
| | - Jingping Xie
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John C. Gore
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA
| | - Junzhong Xu
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA
- Corresponding author: Address: Vanderbilt University, Institute of Imaging Science, 1161 21 Avenue South, AA 1105 MCN, Nashville, TN 37232-2310, United States. Fax: +1 615 322 0734. (Junzhong Xu). Twitter: @JunzhongXu
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80
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Abstract
Though cell size varies between different cells and across species, the nuclear-to-cytoplasmic (N/C) ratio is largely maintained across species and within cell types. A cell maintains a relatively constant N/C ratio by coupling DNA content, nuclear size, and cell size. We explore how cells couple cell division and growth to DNA content. In some cases, cells use DNA as a molecular yardstick to control the availability of cell cycle regulators. In other cases, DNA sets a limit for biosynthetic capacity. Developmentally programmed variations in the N/C ratio for a given cell type suggest that a specific N/C ratio is required to respond to given physiological demands. Recent observations connecting decreased N/C ratios with cellular senescence indicate that maintaining the proper N/C ratio is essential for proper cellular functioning. Together, these findings suggest a causative, not simply correlative, role for the N/C ratio in regulating cell growth and cell cycle progression.
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Affiliation(s)
- Shruthi Balachandra
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
| | - Sharanya Sarkar
- Department of Microbiology and Immunology, Dartmouth College, Hanover, New Hampshire, USA;
| | - Amanda A Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
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81
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Boyd-Shiwarski CR, Shiwarski DJ, Griffiths SE, Beacham RT, Norrell L, Morrison DE, Wang J, Mann J, Tennant W, Anderson EN, Franks J, Calderon M, Connolly KA, Cheema MU, Weaver CJ, Nkashama LJ, Weckerly CC, Querry KE, Pandey UB, Donnelly CJ, Sun D, Rodan AR, Subramanya AR. WNK kinases sense molecular crowding and rescue cell volume via phase separation. Cell 2022; 185:4488-4506.e20. [PMID: 36318922 PMCID: PMC9699283 DOI: 10.1016/j.cell.2022.09.042] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 07/23/2022] [Accepted: 09/29/2022] [Indexed: 11/24/2022]
Abstract
When challenged by hypertonicity, dehydrated cells must recover their volume to survive. This process requires the phosphorylation-dependent regulation of SLC12 cation chloride transporters by WNK kinases, but how these kinases are activated by cell shrinkage remains unknown. Within seconds of cell exposure to hypertonicity, WNK1 concentrates into membraneless condensates, initiating a phosphorylation-dependent signal that drives net ion influx via the SLC12 cotransporters to restore cell volume. WNK1 condensate formation is driven by its intrinsically disordered C terminus, whose evolutionarily conserved signatures are necessary for efficient phase separation and volume recovery. This disorder-encoded phase behavior occurs within physiological constraints and is activated in vivo by molecular crowding rather than changes in cell size. This allows kinase activity despite an inhibitory ionic milieu and permits cell volume recovery through condensate-mediated signal amplification. Thus, WNK kinases are physiological crowding sensors that phase separate to coordinate a cell volume rescue response.
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Affiliation(s)
- Cary R Boyd-Shiwarski
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Pittsburgh Center for Kidney Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Daniel J Shiwarski
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Shawn E Griffiths
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Rebecca T Beacham
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Logan Norrell
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84132, USA
| | - Daryl E Morrison
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84132, USA
| | - Jun Wang
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Jacob Mann
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - William Tennant
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Eric N Anderson
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Jonathan Franks
- Center for Biological Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Michael Calderon
- Center for Biological Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Kelly A Connolly
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Muhammad Umar Cheema
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Claire J Weaver
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Lubika J Nkashama
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Claire C Weckerly
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Katherine E Querry
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Udai Bhan Pandey
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Center for Protein Conformational Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Christopher J Donnelly
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Center for Protein Conformational Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA
| | - Aylin R Rodan
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84132, USA; Molecular Medicine Program, University of Utah, Salt Lake City, UT 84132, USA; Department of Internal Medicine, Division of Nephrology and Hypertension, University of Utah, Salt Lake City, UT 84132, USA; Medical Service, VA Salt Lake City Health Care System, Salt Lake City, UT 84148, USA
| | - Arohan R Subramanya
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Center for Protein Conformational Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; Pittsburgh Center for Kidney Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA; VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA.
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82
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Abstract
We derive analytical steady-state cell size distributions for size-controlled cells in single-lineage experiments, such as the mother machine, which are fundamentally different from batch cultures where populations of cells grow freely. For exponential single-cell growth, characterizing most bacteria, the lineage-population bias is obtained explicitly. In addition, if volume is evenly split between the daughter cells at division, we show that cells are on average smaller in populations than in lineages. For more general power-law growth rates and deterministic volume partitioning, both symmetric and asymmetric, we derive the exact lineage distribution. This solution is in good agreement with Escherichia coli mother machine data and can be used to infer cell cycle parameters such as the strength of the size control and the asymmetry of the division. When introducing stochastic volume partitioning, we derive the large-size and small-size tails of the lineage distribution and show that the lineage-population bias only depends on the single-cell growth rate. These asymptotic behaviours are extended to the adder model of cell size control. When considering noisy single-cell growth rate, we derive the large-size lineage and population distributions. Finally, we show that introducing noise, either on the volume partitioning or on the single-cell growth rate, can cancel the lineage-population bias.
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Affiliation(s)
- Arthur Genthon
- Gulliver UMR CNRS 7083, ESPCI Paris, Université PSL, 75005 Paris, France
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83
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Abstract
Pioneering work carried out over 60 years ago discovered that bacterial cell size is proportional to the growth rate set by nutrient availability. This relationship is traditionally referred to as the 'growth law'. Subsequent studies revealed the growth law to hold across all orders of life, a remarkable degree of conservation. However, recent work suggests the relationship between growth rate, nutrients, and cell size is far more complicated and less deterministic than originally thought. Focusing on bacteria and yeast, here we review efforts to understand the molecular mechanisms underlying the relationship between growth rate and cell size.
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Affiliation(s)
- Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St Louis, MO 63130, USA; Center for Science & Engineering of Living Systems (CSELS), McKelvey School of Engineering, Washington University in St Louis, St Louis, MO 63130, USA.
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84
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Chatzitheodoridou D, D'Ario M, Jones I, Piñeros L, Serbanescu D, O'Donnell F, Cadart C, Swaffer MP. Meeting report - Cell size and growth: from single cells to the tree of life. J Cell Sci 2022; 135:jcs260634. [PMID: 36259425 DOI: 10.1242/jcs.260634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023] Open
Abstract
In April 2022, The Company of Biologists hosted their first post-pandemic in-person Workshop at Buxted Park Country House in the Sussex countryside. The Workshop, entitled 'Cell size and growth: from single cells to the tree of life', gathered a small group of early-career and senior researchers with expertise in cell size spanning a broad range of organisms, including bacteria, yeast, animal cells, embryos and plants, and working in fields from cell biology to ecology and evolutionary biology. The programme made ample room for fruitful discussions and provided a much-needed opportunity to discuss the most recent findings relating to the regulation of cell size and growth, identify the emerging challenges for the field, and build a community after the pandemic.
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Affiliation(s)
| | - Marco D'Ario
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, NR4 7UH, UK
| | - Ian Jones
- Department of Cancer Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, SW3 6JB, UK
| | - Liliana Piñeros
- Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O&N1bis gebouw 402-20, Herestraat 49, B-3000 Leuven, Belgium
| | - Diana Serbanescu
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, WC1E 6BT, UK
| | - Frank O'Donnell
- The Company of Biologists, 94 Station Road, Histon, Cambridge, CB24 9LF, UK
| | - Clotilde Cadart
- Molecular and Cell Biology Department, University of California, Berkeley, Berkeley, CA 94720-3200, USA
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85
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Sandlin CW, Gu S, Xu J, Deshpande C, Feldman MD, Good MC. Epithelial cell size dysregulation in human lung adenocarcinoma. PLoS One 2022; 17:e0274091. [PMID: 36201559 PMCID: PMC9536599 DOI: 10.1371/journal.pone.0274091] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 08/22/2022] [Indexed: 11/18/2022] Open
Abstract
Human cells tightly control their dimensions, but in some cancers, normal cell size control is lost. In this study we measure cell volumes of epithelial cells from human lung adenocarcinoma progression in situ. By leveraging artificial intelligence (AI), we reconstruct tumor cell shapes in three dimensions (3D) and find airway type 2 cells display up to 10-fold increases in volume. Surprisingly, cell size increase is not caused by altered ploidy, and up to 80% of near-euploid tumor cells show abnormal sizes. Size dysregulation is not explained by cell swelling or senescence because cells maintain cytoplasmic density and proper organelle size scaling, but is correlated with changes in tissue organization and loss of a novel network of processes that appear to connect alveolar type 2 cells. To validate size dysregulation in near-euploid cells, we sorted cells from tumor single-cell suspensions on the basis of size. Our study provides data of unprecedented detail for cell volume dysregulation in a human cancer. Broadly, loss of size control may be a common feature of lung adenocarcinomas in humans and mice that is relevant to disease and identification of these cells provides a useful model for investigating cell size control and consequences of cell size dysregulation.
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Affiliation(s)
- Clifford W. Sandlin
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (CWS); (MCG)
| | - Song Gu
- Nanjing University of Information Science and Technology, Nanjing, China
| | - Jun Xu
- Nanjing University of Information Science and Technology, Nanjing, China
| | - Charuhas Deshpande
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael D. Feldman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Matthew C. Good
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (CWS); (MCG)
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86
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Sethi A, Wei H, Mishra N, Segos I, Lambie EJ, Zanin E, Conradt B. A caspase-RhoGEF axis contributes to the cell size threshold for apoptotic death in developing Caenorhabditis elegans. PLoS Biol 2022; 20:e3001786. [PMID: 36201522 PMCID: PMC9536578 DOI: 10.1371/journal.pbio.3001786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/08/2022] [Indexed: 11/05/2022] Open
Abstract
A cell’s size affects the likelihood that it will die. But how is cell size controlled in this context and how does cell size impact commitment to the cell death fate? We present evidence that the caspase CED-3 interacts with the RhoGEF ECT-2 in Caenorhabditis elegans neuroblasts that generate “unwanted” cells. We propose that this interaction promotes polar actomyosin contractility, which leads to unequal neuroblast division and the generation of a daughter cell that is below the critical “lethal” size threshold. Furthermore, we find that hyperactivation of ECT-2 RhoGEF reduces the sizes of unwanted cells. Importantly, this suppresses the “cell death abnormal” phenotype caused by the partial loss of ced-3 caspase and therefore increases the likelihood that unwanted cells die. A putative null mutation of ced-3 caspase, however, is not suppressed, which indicates that cell size affects CED-3 caspase activation and/or activity. Therefore, we have uncovered novel sequential and reciprocal interactions between the apoptosis pathway and cell size that impact a cell’s commitment to the cell death fate. This study shows that in developing C. elegans neuroblasts, the caspase CED-3 interacts with the RhoGEF ECT-2, leading to changes in actomyosin and the unequal division of these cells. This reveals a non-canonical function of caspases, wherein they help establish ensure that the size of daughter cells fated for apoptosis is below a critical ’lethal’ threshold.
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Affiliation(s)
- Aditya Sethi
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Hai Wei
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Nikhil Mishra
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Ioannis Segos
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Eric J. Lambie
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Esther Zanin
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
- Department Biology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Conradt
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
- * E-mail:
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87
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Abstract
The most fundamental feature of cellular form is size, which sets the scale of all cell biological processes. Growth, form, and function are all necessarily linked in cell biology, but we often do not understand the underlying molecular mechanisms nor their specific functions. Here, we review progress toward determining the molecular mechanisms that regulate cell size in yeast, animals, and plants, as well as progress toward understanding the function of cell size regulation. It has become increasingly clear that the mechanism of cell size regulation is deeply intertwined with basic mechanisms of biosynthesis, and how biosynthesis can be scaled (or not) in proportion to cell size. Finally, we highlight recent findings causally linking aberrant cell size regulation to cellular senescence and their implications for cancer therapies.
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Affiliation(s)
- Shicong Xie
- Department of Biology, Stanford University, Stanford, California, USA;
| | - Matthew Swaffer
- Department of Biology, Stanford University, Stanford, California, USA;
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, California, USA;
- Chan Zuckerberg Biohub, San Francisco, California, USA
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88
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Devan SP, Jiang X, Luo G, Xie J, Quirk JD, Engelbach JA, Harmsen H, McKinley ET, Cui J, Zu Z, Attia A, Garbow JR, Gore JC, McKnight CD, Kirschner AN, Xu J. Selective Cell Size MRI Differentiates Brain Tumors from Radiation Necrosis. Cancer Res 2022; 82:3603-3613. [PMID: 35877201 PMCID: PMC9532360 DOI: 10.1158/0008-5472.can-21-2929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 02/05/2022] [Accepted: 07/21/2022] [Indexed: 11/16/2022]
Abstract
Brain metastasis is a common characteristic of late-stage lung cancers. High doses of targeted radiotherapy can control tumor growth in the brain but can also result in radiotherapy-induced necrosis. Current methods are limited for distinguishing whether new parenchymal lesions following radiotherapy are recurrent tumors or radiotherapy-induced necrosis, but the clinical management of these two classes of lesions differs significantly. Here, we developed, validated, and evaluated a new MRI technique termed selective size imaging using filters via diffusion times (SSIFT) to differentiate brain tumors from radiotherapy necrosis in the brain. This approach generates a signal filter that leverages diffusion time dependence to establish a cell size-weighted map. Computer simulations in silico, cultured cancer cells in vitro, and animals with brain tumors in vivo were used to comprehensively validate the specificity of SSIFT for detecting typical large cancer cells and the ability to differentiate brain tumors from radiotherapy necrosis. SSIFT was also implemented in patients with metastatic brain cancer and radiotherapy necrosis. SSIFT showed high correlation with mean cell sizes in the relevant range of less than 20 μm. The specificity of SSIFT for brain tumors and reduced contrast in other brain etiologies allowed SSIFT to differentiate brain tumors from peritumoral edema and radiotherapy necrosis. In conclusion, this new, cell size-based MRI method provides a unique contrast to differentiate brain tumors from other pathologies in the brain. SIGNIFICANCE This work introduces and provides preclinical validation of a new diffusion MRI method that exploits intrinsic differences in cell sizes to distinguish brain tumors and radiotherapy necrosis.
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Affiliation(s)
- Sean P Devan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, 37232, USA
| | - Xiaoyu Jiang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Guozhen Luo
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jingping Xie
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - James D Quirk
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110, USA
| | - John A Engelbach
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110, USA
| | - Hannah Harmsen
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Eliot T McKinley
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Jing Cui
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Albert Attia
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Joel R Garbow
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110, USA
- Alvin J Siteman Cancer Center, Washington University, St. Louis, MO, 63110, USA
| | - John C. Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA
| | - Colin D McKnight
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Austin N Kirschner
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Junzhong Xu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA
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89
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Verberk WCEP, Sandker JF, van de Pol ILE, Urbina MA, Wilson RW, McKenzie DJ, Leiva FP. Body mass and cell size shape the tolerance of fishes to low oxygen in a temperature-dependent manner. Glob Chang Biol 2022; 28:5695-5707. [PMID: 35876025 DOI: 10.5281/zenodo.6123770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 03/11/2022] [Accepted: 05/22/2022] [Indexed: 05/20/2023]
Abstract
Aerobic metabolism generates 15-20 times more energy (ATP) than anaerobic metabolism, which is crucial in maintaining energy budgets in animals, fueling metabolism, activity, growth and reproduction. For ectothermic water-breathers such as fishes, low dissolved oxygen may limit oxygen uptake and hence aerobic metabolism. Here, we assess, within a phylogenetic context, how abiotic and biotic drivers explain the variation in hypoxia tolerance observed in fishes. To do so, we assembled a database of hypoxia tolerance, measured as critical oxygen tensions (Pcrit ) for 195 fish species. Overall, we found that hypoxia tolerance has a clear phylogenetic signal and is further modulated by temperature, body mass, cell size, salinity and metabolic rate. Marine fishes were more susceptible to hypoxia than freshwater fishes. This pattern is consistent with greater fluctuations in oxygen and temperature in freshwater habitats. Fishes with higher oxygen requirements (e.g. a high metabolic rate relative to body mass) also were more susceptible to hypoxia. We also found evidence that hypoxia and warming can act synergistically, as hypoxia tolerance was generally lower in warmer waters. However, we found significant interactions between temperature and the body and cell size of a fish. Constraints in oxygen uptake related to cellular surface area to volume ratios and effects of viscosity on the thickness of the boundary layers enveloping the gills could explain these thermal dependencies. The lower hypoxia tolerance in warmer waters was particularly pronounced for fishes with larger bodies and larger cell sizes. Previous studies have found a wide diversity in the direction and strength of relationships between Pcrit and body mass. By including interactions with temperature, our study may help resolve these divergent findings, explaining the size dependency of hypoxia tolerance in fish.
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Affiliation(s)
- Wilco C E P Verberk
- Department of Animal Ecology and Physiology, Radboud Institute for Biological and Environmental Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Jeroen F Sandker
- Department of Animal Ecology and Physiology, Radboud Institute for Biological and Environmental Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Iris L E van de Pol
- Department of Animal Ecology and Physiology, Radboud Institute for Biological and Environmental Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Mauricio A Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- Instituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, Chile
| | | | - David J McKenzie
- MARBEC, University of Montpellier, CNRS, IFREMER, IRD, Montpellier, France
| | - Félix P Leiva
- Department of Animal Ecology and Physiology, Radboud Institute for Biological and Environmental Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
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90
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Verberk WCEP, Sandker JF, van de Pol ILE, Urbina MA, Wilson RW, McKenzie DJ, Leiva FP. Body mass and cell size shape the tolerance of fishes to low oxygen in a temperature-dependent manner. Glob Chang Biol 2022; 28:5695-5707. [PMID: 35876025 PMCID: PMC9542040 DOI: 10.1111/gcb.16319] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 03/11/2022] [Accepted: 05/22/2022] [Indexed: 05/04/2023]
Abstract
Aerobic metabolism generates 15-20 times more energy (ATP) than anaerobic metabolism, which is crucial in maintaining energy budgets in animals, fueling metabolism, activity, growth and reproduction. For ectothermic water-breathers such as fishes, low dissolved oxygen may limit oxygen uptake and hence aerobic metabolism. Here, we assess, within a phylogenetic context, how abiotic and biotic drivers explain the variation in hypoxia tolerance observed in fishes. To do so, we assembled a database of hypoxia tolerance, measured as critical oxygen tensions (Pcrit ) for 195 fish species. Overall, we found that hypoxia tolerance has a clear phylogenetic signal and is further modulated by temperature, body mass, cell size, salinity and metabolic rate. Marine fishes were more susceptible to hypoxia than freshwater fishes. This pattern is consistent with greater fluctuations in oxygen and temperature in freshwater habitats. Fishes with higher oxygen requirements (e.g. a high metabolic rate relative to body mass) also were more susceptible to hypoxia. We also found evidence that hypoxia and warming can act synergistically, as hypoxia tolerance was generally lower in warmer waters. However, we found significant interactions between temperature and the body and cell size of a fish. Constraints in oxygen uptake related to cellular surface area to volume ratios and effects of viscosity on the thickness of the boundary layers enveloping the gills could explain these thermal dependencies. The lower hypoxia tolerance in warmer waters was particularly pronounced for fishes with larger bodies and larger cell sizes. Previous studies have found a wide diversity in the direction and strength of relationships between Pcrit and body mass. By including interactions with temperature, our study may help resolve these divergent findings, explaining the size dependency of hypoxia tolerance in fish.
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Affiliation(s)
- Wilco C. E. P. Verberk
- Department of Animal Ecology and PhysiologyRadboud Institute for Biological and Environmental SciencesRadboud University NijmegenNijmegenThe Netherlands
| | - Jeroen F. Sandker
- Department of Animal Ecology and PhysiologyRadboud Institute for Biological and Environmental SciencesRadboud University NijmegenNijmegenThe Netherlands
| | - Iris L. E. van de Pol
- Department of Animal Ecology and PhysiologyRadboud Institute for Biological and Environmental SciencesRadboud University NijmegenNijmegenThe Netherlands
| | - Mauricio A. Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y OceanográficasUniversidad de ConcepciónConcepciónChile
- Instituto Milenio de Oceanografía (IMO)Universidad de ConcepciónConcepciónChile
| | | | - David J. McKenzie
- MARBEC, University of Montpellier, CNRS, IFREMER, IRDMontpellierFrance
| | - Félix P. Leiva
- Department of Animal Ecology and PhysiologyRadboud Institute for Biological and Environmental SciencesRadboud University NijmegenNijmegenThe Netherlands
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91
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Mohanasundaram P, Coelho-Rato LS, Modi MK, Urbanska M, Lautenschläger F, Cheng F, Eriksson JE. Cytoskeletal vimentin regulates cell size and autophagy through mTORC1 signaling. PLoS Biol 2022; 20:e3001737. [PMID: 36099296 PMCID: PMC9469959 DOI: 10.1371/journal.pbio.3001737] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 07/01/2022] [Indexed: 11/19/2022] Open
Abstract
The nutrient-activated mTORC1 (mechanistic target of rapamycin kinase complex 1) signaling pathway determines cell size by controlling mRNA translation, ribosome biogenesis, protein synthesis, and autophagy. Here, we show that vimentin, a cytoskeletal intermediate filament protein that we have known to be important for wound healing and cancer progression, determines cell size through mTORC1 signaling, an effect that is also manifested at the organism level in mice. This vimentin-mediated regulation is manifested at all levels of mTOR downstream target activation and protein synthesis. We found that vimentin maintains normal cell size by supporting mTORC1 translocation and activation by regulating the activity of amino acid sensing Rag GTPase. We also show that vimentin inhibits the autophagic flux in the absence of growth factors and/or critical nutrients, demonstrating growth factor-independent inhibition of autophagy at the level of mTORC1. Our findings establish that vimentin couples cell size and autophagy through modulating Rag GTPase activity of the mTORC1 signaling pathway.
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Affiliation(s)
- Ponnuswamy Mohanasundaram
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Cell Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Leila S. Coelho-Rato
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Cell Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Mayank Kumar Modi
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Cell Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Marta Urbanska
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Dresden, Germany
- Max Planck Institute for the Science of Light & Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Franziska Lautenschläger
- Saarland University, NT Faculty, Experimental Physics, Saarbrücken, Germany
- Center for Biophysics, Saarland University, Germany
| | - Fang Cheng
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Cell Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong, P.R. China
| | - John E. Eriksson
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Cell Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
- * E-mail:
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92
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Huan Y, Sun D, Wang S, Zhang H, Li Z, Zhang Y, He Y. Phytoplankton package effect in oceanic waters: Influence of chlorophyll-a and cell size. Sci Total Environ 2022; 838:155876. [PMID: 35569671 DOI: 10.1016/j.scitotenv.2022.155876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 04/15/2022] [Accepted: 05/08/2022] [Indexed: 06/15/2023]
Abstract
In this study, the interaction between the packaging effect (Qa⁎) and total chlorophyll-a concentration (Ct) or total size index (SIt) was investigated to explore the potential bio-optical mechanism in phytoplankton cells in the global oceans. In addition, the long-term spatiotemporal characteristics of these interactions were necessary for grasping their variation. Numerous in situ surface measurements (phytoplankton pigment and absorption coefficients) from the global oceans were analyzed first, and then correlation and causality analyses were performed on the satellite-deduced Qa⁎, Ct, and SIt in the global oceans during 2002-2020. The results show a negative correlation between Qa⁎ and Ct or SIt in the low latitudes (30°S-30°N) and a positive correlation in the middle latitudes (30°S-55°S and 30°N-55°N). The causality analysis reveals a mutual and asymmetric cause-effect relationship between Qa⁎ and Ct or SIt in the low latitudes. The stabilization effect of Qa⁎ contributes to a 10%-50% variation in Ct and SIt, with 40%-60% uncertainty of Qa⁎ caused by Ct and SIt in the low latitudes, which is inverse in the middle latitudes. The remaining contribution to each variable mainly originates from long-term trends and noise. Combining the analysis between Qa⁎ and the irradiance, the balancing processes in phytoplankton cells are different in the low (phytoplankton-driving mode) and middle latitudes (irradiance-driving mode), which is related to photoacclimation and photoinhibition. The analyses provide insights into the quantitative interpretation of the relationship between Qa⁎ and Ct or SIt, which contribute knowledge that has not been previously reported.
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Affiliation(s)
- Yu Huan
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China
| | - Deyong Sun
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China; The Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources, China.
| | - Shengqiang Wang
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China; The Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources, China
| | - Hailong Zhang
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China; The Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources, China
| | - Zhenghao Li
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China
| | - Yuanzhi Zhang
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China; The Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources, China
| | - Yijun He
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, China; The Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources, China
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93
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Lanz MC, Zatulovskiy E, Swaffer MP, Zhang L, Ilerten I, Zhang S, You DS, Marinov G, McAlpine P, Elias JE, Skotheim JM. Increasing cell size remodels the proteome and promotes senescence. Mol Cell 2022; 82:3255-3269.e8. [PMID: 35987199 PMCID: PMC9444988 DOI: 10.1016/j.molcel.2022.07.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 06/06/2022] [Accepted: 07/25/2022] [Indexed: 01/10/2023]
Abstract
Cell size is tightly controlled in healthy tissues, but it is unclear how deviations in cell size affect cell physiology. To address this, we measured how the cell's proteome changes with increasing cell size. Size-dependent protein concentration changes are widespread and predicted by subcellular localization, size-dependent mRNA concentrations, and protein turnover. As proliferating cells grow larger, concentration changes typically associated with cellular senescence are increasingly pronounced, suggesting that large size may be a cause rather than just a consequence of cell senescence. Consistent with this hypothesis, larger cells are prone to replicative, DNA-damage-induced, and CDK4/6i-induced senescence. Size-dependent changes to the proteome, including those associated with senescence, are not observed when an increase in cell size is accompanied by an increase in ploidy. Together, our findings show how cell size could impact many aspects of cell physiology by remodeling the proteome and provide a rationale for cell size control and polyploidization.
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Affiliation(s)
- Michael C Lanz
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, Stanford, CA 94305, USA
| | | | | | | | - Ilayda Ilerten
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Shuyuan Zhang
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Dong Shin You
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Georgi Marinov
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | | | | | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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94
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Urbaniak P, Wronski S, Tarasiuk J, Lipinski P, Kotwicka M. A new method to estimate 3D cell parameters from 2D microscopy images. Biochim Biophys Acta Mol Cell Res 2022; 1869:119286. [PMID: 35598752 DOI: 10.1016/j.bbamcr.2022.119286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 04/10/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Optical microscopy has been a basic and standard technique in cell biology research for decades. Microscopy techniques function well for thin, optically transparent cultures and allow for the imaging of thicker biological specimens. There is no better method of in vitro cell observation and analysis, hence microscopic techniques are extensively used and constitute an optimal tool for cell culture studies. This paper proposes an original methodology of optical microscopy data processing based on the phase contrast technique during cell culture monitoring. By exploiting images recorded during cell proliferation, a surface reconstruction was performed based on assumption, it can be considered that the local brightness of the image depends on the cells' thickness and thus the obtained results can be interpreted in the form of a surface that represents a three-dimensional structure, which allowed for a quantitative description of the cell evolution. The 3D data obtained enabled the investigation of parameters describing the morphology of the cells and the topology of their proliferation. These parameters included cell sizes in plane but also in the direction perpendicular to it, cell volume changes, their spatial distribution, as well as anisotropy and directivity. The method presented provides data carrying information similar to that obtained using a holographic microscope, e.g. A HoloMonitor (Phase Holographic Imaging PHI Inc.), or from confocal scanning microscopy with the "z-stack" mode. The techniques of bright field or phase contrast cell observation are, however, much cheaper, and widely available when compared to holographic microscopy, for instance. Besides, these also enable monitoring of cell activity over time, i.e. the study and quantitative description of dynamic changes in the cells. The proposed approach uses generally available free tools such as ImageJ software with BoneJ and Particle Analyzer plugins. The methodology is suitable for even a basic microscope, it can be easily implemented as a script, and thus data processing can be significantly shortened, the methodology can be automated, and also applied for data processing in real time.
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Affiliation(s)
- P Urbaniak
- University of Medical Sciences, Department of Cell Biology, Rokietnicka 5D, 60-806 Poznan, Poland
| | - S Wronski
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. A. Mickiewicza 30, 30-059 Kraków, Poland.
| | - J Tarasiuk
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. A. Mickiewicza 30, 30-059 Kraków, Poland
| | - P Lipinski
- Laboratory of Mechanics, Biomechanics, Polymers and Structures (LaBPS), Ecole Nationaled'Ingénieurs de Metz, 1 Route d'ArsLaquenexy, 57078 Metz, France
| | - M Kotwicka
- University of Medical Sciences, Department of Cell Biology, Rokietnicka 5D, 60-806 Poznan, Poland
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95
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Nguyen TL, Pradeep S, Judson-Torres RL, Reed J, Teitell MA, Zangle TA. Quantitative Phase Imaging: Recent Advances and Expanding Potential in Biomedicine. ACS Nano 2022; 16:11516-11544. [PMID: 35916417 PMCID: PMC10112851 DOI: 10.1021/acsnano.1c11507] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Quantitative phase imaging (QPI) is a label-free, wide-field microscopy approach with significant opportunities for biomedical applications. QPI uses the natural phase shift of light as it passes through a transparent object, such as a mammalian cell, to quantify biomass distribution and spatial and temporal changes in biomass. Reported in cell studies more than 60 years ago, ongoing advances in QPI hardware and software are leading to numerous applications in biology, with a dramatic expansion in utility over the past two decades. Today, investigations of cell size, morphology, behavior, cellular viscoelasticity, drug efficacy, biomass accumulation and turnover, and transport mechanics are supporting studies of development, physiology, neural activity, cancer, and additional physiological processes and diseases. Here, we review the field of QPI in biology starting with underlying principles, followed by a discussion of technical approaches currently available or being developed, and end with an examination of the breadth of applications in use or under development. We comment on strengths and shortcomings for the deployment of QPI in key biomedical contexts and conclude with emerging challenges and opportunities based on combining QPI with other methodologies that expand the scope and utility of QPI even further.
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96
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Foroughimehr N, Vilagosh Z, Yavari A, Wood A. The Impact of Base Cell Size Setup on the Finite Difference Time Domain Computational Simulation of Human Cornea Exposed to Millimeter Wave Radiation at Frequencies above 30 GHz. Sensors (Basel) 2022; 22:s22155924. [PMID: 35957481 PMCID: PMC9371411 DOI: 10.3390/s22155924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 05/10/2023]
Abstract
Mobile communication has achieved enormous technology innovations over many generations of progression. New cellular technology, including 5G cellular systems, is being deployed and making use of higher frequencies, including the Millimetre Wave (MMW) range (30-300 GHz) of the electromagnetic spectrum. Numerical computational techniques such as the Finite Difference Time Domain (FDTD) method have been used extensively as an effective approach for assessing electromagnetic fields' biological impacts. This study demonstrates the variation of the accuracy of the FDTD computational simulation system when different meshing sizes are used, by using the interaction of the critically sensitive human cornea with EM in the 30 to 100 GHz range. Different approaches of base cell size specifications were compared. The accuracy of the computation is determined by applying planar sensors showing the detail of electric field distribution as well as the absolute values of electric field collected by point sensors. It was found that manually defining the base cell sizes reduces the model size as well as the computation time. However, the accuracy of the computation decreases in an unpredictable way. The results indicated that using a cloud computing capacity plays a crucial role in minimizing the computation time.
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Affiliation(s)
- Negin Foroughimehr
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC 3122, Australia
- Australian Centre for Electromagnetic Bioeffects Research, Swinburne University of Technology, Melbourne, VIC 3122, Australia
- Correspondence:
| | - Zoltan Vilagosh
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC 3122, Australia
- Australian Centre for Electromagnetic Bioeffects Research, Swinburne University of Technology, Melbourne, VIC 3122, Australia
| | - Ali Yavari
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Melbourne, VIC 3122, Australia
| | - Andrew Wood
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC 3122, Australia
- Australian Centre for Electromagnetic Bioeffects Research, Swinburne University of Technology, Melbourne, VIC 3122, Australia
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97
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Saikot MMH, Sanim KRI. Refreshable Braille Display With Adjustable Cell Size for Learners With Different Tactile Sensitivity. IEEE Trans Haptics 2022; 15:582-591. [PMID: 35714088 DOI: 10.1109/toh.2022.3184265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Braille is one of the most popular mediums of education for the blind. However, learning braille requires trainers and a lot of practice. Additionally, different individuals have different levels of tactile sensitivity at their fingertips. The tactile components get often overlooked in most braille learning devices and related studies. Our solution is a single cell refreshable braille display with six custom-made electromechanical flapper actuators. It incorporates speech functionalities to facilitate self-learning and independent operation. The cell size can be adjusted according to the learner's preference by moving the actuators. The device can provide standard braille cell dimensions and elevation as well. It is designed to help learners with different tactile perceptions improve themselves through practice and adapt to standard size braille. The operational conditions and force analysis of the braille dots were performed. Two tests were also performed with two different cell sizes to evaluate the device with several blind students. The device is very affordable and easy to maintain. It can also be used to teach braille to the sighted.
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98
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Thulborn KR. Gender differences in cell volume fraction (CVF): a structural parameter reflecting the energy efficiency of maintaining the resting membrane potential. NMR Biomed 2022; 35:e4693. [PMID: 35044017 DOI: 10.1002/nbm.4693] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
The cell volume fraction (CVF) of the human brain is high (~82%) and is preserved across healthy aging while the brain declines in volume. These two observations, supported by several independent techniques, suggest that CVF is an important structural parameter. A new biophysical model is presented that incorporates CVF into the Goldman equation of classical membrane electrophysiology. The Goldman equation contains few structural constraints beyond two compartments separated by a semipermeable membrane supporting ion gradients. As potassium is the most permeable ion in the resting state, the resting membrane potential is determined by the potassium ion gradient. This biophysical model indicates that the sodium-potassium ion pumps use less energy at high CVF to maintain the resting membrane potential, explaining the high value of CVF and its conservation with healthy aging. CVF is measured to be statistically significantly higher in the brains of males compared with females, suggesting a structural requirement for higher energy efficiency in the larger male brain to support the greater number of neurons and synapses. As CVF can be measured in humans using quantitative sodium MRI and has potential implications for brain health, CVF may be a quantitative parameter that is useful for assessment of brain health, especially in patients with diseases such as dementia and psychiatric disease that do not have anatomical correlates detectable by clinical proton MRI.
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Affiliation(s)
- Keith R Thulborn
- Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, Illinois
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99
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Yamada K, Ding WG, Omatsu-Kanbe M, Toyoda F, Tsuji S, Katsura D, Kimura F, Matsuura H, Murakami T. Expression and functional maintenance of volume-regulated anion channels in myometrial smooth muscles of pregnant mice. Exp Anim 2022; 71:123-130. [PMID: 34789619 PMCID: PMC9130036 DOI: 10.1538/expanim.21-0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 10/13/2021] [Indexed: 11/15/2022] Open
Abstract
Pregnancy causes changes in the uterus, such as increased cell volume and altered water content. However, the mechanisms that protect the structure and maintain the function of uterine smooth muscle cells against these changes during pregnancy have not been clarified. This study focused on the volume-regulated anion channel (VRAC), which opens with cell swelling under low osmotic pressure and releases Cl- ions and various organic osmolytes to resist cell swelling and regulates a wide range of biological processes such as cell death. In this study, myometrial smooth muscle (MSM) tissues and cells (MSMCs) were collected from non-pregnant and pregnant mice. Using western blotting and immunocytochemistry, leucine-rich repeat containing protein 8A (LRRC8A), an essential membrane protein that constitutes part of the VRAC, was determined to be diffused throughout MSMCs including in the cell membrane. Patch-clamp experiments were performed to investigate the electrophysiology of swelling-induced Cl- currents (ICl, swell) mediated by the VRAC. No significant changes between non-pregnancy and pregnancy groups were observed in either the expression density of LRRC8A or the current density of ICl, swell, however the presence of LRRC8A on the cell membrane was significantly increased in the third trimester of pregnancy compared to the non-pregnancy. This study suggests that the VRAC may play a role, such as maintaining cellular homeostasis in the pregnant MSM.
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Affiliation(s)
- Kazutaka Yamada
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga, 520-2192, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga 520-2192, Japan
| | - Mariko Omatsu-Kanbe
- Department of Physiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga 520-2192, Japan
| | - Futoshi Toyoda
- Department of Physiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga 520-2192, Japan
| | - Shunichiro Tsuji
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga, 520-2192, Japan
| | - Daisuke Katsura
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga, 520-2192, Japan
| | - Fuminori Kimura
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga, 520-2192, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga 520-2192, Japan
| | - Takashi Murakami
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu-shi, Shiga, 520-2192, Japan
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100
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Homan T, Monnier S, Jebane C, Nicolas A, Delanoë-Ayari H. Measuring the average cell size and width of its distribution in cellular tissues using Fourier transform. Eur Phys J E Soft Matter 2022; 45:44. [PMID: 35532848 DOI: 10.1140/epje/s10189-022-00198-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 04/12/2022] [Indexed: 06/14/2023]
Abstract
We present an in-depth investigation of a fully automated Fourier-based analysis to determine the cell size and the width of its distribution in 3D biological tissues. The results are thoroughly tested using generated images, and we offer valuable criteria for image acquisition settings to optimize accuracy. We demonstrate that the most important parameter is the number of cells in the field of view, and we show that accurate measurements can already be made on volume only containing [Formula: see text] cells. The resolution in z is also not so important, and a reduced number of in-depth images, of order of one per cell, already provides a measure of the mean cell size with less than 5% error. The technique thus appears to be a very promising tool for very fast live local volume cell measurement in 3D tissues in vivo while strongly limiting photobleaching and phototoxicity issues.
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Affiliation(s)
- Tess Homan
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69622, Villeurbanne, France
| | - Sylvain Monnier
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69622, Villeurbanne, France
| | - Cécile Jebane
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69622, Villeurbanne, France
| | - Alice Nicolas
- Univ. Grenoble Alpes, CNRS, CEA/LETIMinatec, Grenoble INP, LTM, 38054, Grenoble, France
| | - Hélène Delanoë-Ayari
- Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69622, Villeurbanne, France.
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