1
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Klußmann M, Matijass M, Neundorf I. Impact of Mutational Status on Intracellular Effects of Cell-Permeable CaaX Peptides in Pancreatic Cancer Cells. Chembiochem 2025; 26:e202401076. [PMID: 40270247 PMCID: PMC12117442 DOI: 10.1002/cbic.202401076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2024] [Revised: 03/31/2025] [Indexed: 04/25/2025]
Abstract
Prenyltransferases add a lipid group to the cysteine of a CaaX motif of proteins. This posttranslational modification enables proteins to attach to membranes where they are essential hubs for signaling, trafficking, and apoptosis. Recently, cell-permeable CaaX-peptides are developed as possible tools to interfere with the prenylation machinery. These peptides cause cytotoxic effects, particularly in KRas mutant pancreatic cancer cells (PANC-1) in which they also alter downstream signaling of Ras proteins. Herein, the aim is to get more clues about the relevance of the mutational status of KRas. Therefore, the activity of CaaX-peptides in KRas wildtype BxPC-3 and KRas mutated PANC-1 cells is compared. CaaX-peptides differently influence these two cell lines, although they internalize pretty much to the same extent. Indeed, an altered KRas plasma membrane localization in PANC-1 cells is observed, probably induced by disturbed KRas prenylation based on the presence of CaaX-peptides. The impact of CaaX-peptides on KRas signaling is likely dependent on the KRas mutation in PANC-1 cells in which they further trigger effects on KRas-dependent regulators, e.g., Neurofibromin -1 (NF1) and son of sevenless homolog 1 (SOS1). All in all, CaaX peptides are identified as promising tools for studying and manipulating the function of therapeutically important prenylated proteins.
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Affiliation(s)
- Merlin Klußmann
- Department of Chemistry and BiochemistryInstitute of BiochemistryUniversity of CologneZuelpicher Str. 47a50674CologneGermany
| | - Martin Matijass
- Department of Chemistry and BiochemistryInstitute of BiochemistryUniversity of CologneZuelpicher Str. 47a50674CologneGermany
| | - Ines Neundorf
- Department of Chemistry and BiochemistryInstitute of BiochemistryUniversity of CologneZuelpicher Str. 47a50674CologneGermany
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2
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Viana M, Tonin FS, Ladeira C. Assessing the Impact of Nanoplastics in Biological Systems: Systematic Review of In Vitro Animal Studies. J Xenobiot 2025; 15:75. [PMID: 40407539 PMCID: PMC12101406 DOI: 10.3390/jox15030075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2025] [Revised: 05/08/2025] [Accepted: 05/14/2025] [Indexed: 05/26/2025] Open
Abstract
Nanoplastic (NP) pollution has emerged as a growing concern due to its potential impact on human health, although its adverse effects on different organ systems are not yet fully understood. This systematic scoping review, conducted in accordance with international guidelines, aimed to map the current evidence on the biological effects of NPs. In vitro animal studies assessing cellular damage caused by exposure to any type of NP were searched on PubMed, Web of Science, and Scopus. Data on primary outcomes related to genotoxicity and cytotoxicity (cell viability, oxidative stress, inflammation, DNA and cytoplasmic damage, apoptosis) were extracted from the included studies, and overall reporting quality was assessed. A total of 108 articles published between 2018 and 2024, mostly by China (54%), Spain (14%), and Italy (9%), were included. Polystyrene (PS) was the most frequently studied polymer (85%). NP sizes in solution ranged from 15 to 531 nm, with a higher prevalence in the 40-100 nm range (38%). The overall quality of studies was rated as moderate (60%), with many lacking essential details about cell culture conditions (e.g., pH of the medium, passage number, substances used). A higher frequency of negative effects from NP exposure was observed in respiratory cell lines, while immune, digestive, and hepatic cell lines showed greater resistance. Nervous, urinary, and connective tissue systems were impacted by NPs. Positively charged and smaller PS particles were consistently associated with higher toxicity across all systems. In summary, this review highlights the multifactorial nature of NP toxicity, influenced by size, surface charge, and polymer type. It also reveals a significant knowledge gap, stemming from the predominant use of immortalized monocultures exposed to commercially available PS NPs, the limited use of environmentally relevant particles, and the underutilization of advanced experimental models (e.g., organ-on-chip systems) that better mimic physiological conditions.
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Affiliation(s)
- Maria Viana
- ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, 1990-096 Lisbon, Portugal;
| | - Fernanda S. Tonin
- H&TRC-Health & Technology Research Center, ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, 1990-096 Lisbon, Portugal;
- Pharmacy and Pharmaceutical Technology Department, Social and Legal Pharmacy Section, University of Granada, 18071 Granada, Spain
| | - Carina Ladeira
- ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, 1990-096 Lisbon, Portugal;
- H&TRC-Health & Technology Research Center, ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, 1990-096 Lisbon, Portugal;
- NOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa, 1600-560 Lisbon, Portugal
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3
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Isaković J, Chin BD, Oberwinter M, Rance HK. From lab coats to clinical trials: Evolution and application of electromagnetic fields for ischemic stroke rehabilitation and monitoring. Brain Res 2025; 1850:149391. [PMID: 39662791 DOI: 10.1016/j.brainres.2024.149391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Revised: 12/05/2024] [Accepted: 12/06/2024] [Indexed: 12/13/2024]
Abstract
Stroke is a neurovascular disorder which stands as one of the leading causes of death and disability worldwide, resulting in motor and cognitive impairment. Although the treatment approach depends on the time elapsed, the type of stroke and the availability of care centers, common interventions include thrombectomy or the administration of a tissue plasminogen activator (tPA). While these methods restore blood flow, they fall short in helping patients regain lost function. With that, recent years have seen a rise in novel methods, one of which is the use of electromagnetic fields (EMFs). Due to their ability to impact the charges in their vicinity, thereby altering the immune response and cell signaling, EMFs became suitable candidates for stroke rehabilitation. Based on their characteristics, therapeutic EMFs can be categorized into transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), pulsed (PEMFs) and low frequency (LF-EMFs) electromagnetic fields, among others. In addition to treatment, EMFs are being explored for stroke monitoring, utilizing external EMFs for imaging or recording innate EMFs linked to neural activity. Drawing from research on the effects of EMFs, this review aims to provide a comprehensive overview of the physical principles and molecular mechanisms underlying the action of EMFs, along with a discussion of their application in preclinical studies and clinical trials. Finally, this paper not only addresses the importance of treatment availability and potential side-effects, but also delves into the technical and ethical challenges associated with the use of EMFs, while exploring their prospects and future opportunities.
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Affiliation(s)
- Jasmina Isaković
- School of Medicine, European University Cyprus - Frankfurt Branch, 60488 Frankfurt am Main, Germany.
| | - Benjamin Daniel Chin
- School of Medicine, European University Cyprus - Frankfurt Branch, 60488 Frankfurt am Main, Germany
| | - Moritz Oberwinter
- School of Medicine, European University Cyprus - Frankfurt Branch, 60488 Frankfurt am Main, Germany
| | - Hannah Katarina Rance
- School of Medicine, European University Cyprus - Frankfurt Branch, 60488 Frankfurt am Main, Germany
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4
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Tang C, Pulliam C, Abiodun A, Parris A, Campbell A, Li J. Probing Antimicrobial Activity and Mechanism of Action of a Bile Acid-Derived Antibiotic. ACS OMEGA 2025; 10:1727-1734. [PMID: 39829505 PMCID: PMC11740247 DOI: 10.1021/acsomega.4c09804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2024] [Revised: 12/04/2024] [Accepted: 12/13/2024] [Indexed: 01/22/2025]
Abstract
Antibiotics have revolutionized medicine, saving countless lives since the introduction of penicillin. However, antimicrobial resistance has challenged their efficacy, prompting ongoing efforts to develop new antibiotics. This study explores the antimicrobial effects of a bile acid derivative, BA-3/4-Butyl. By analyzing the interactions of BA-3/4-Butyl with model bacterial (DOPC/DOPG) and mammalian (DOPC/cholesterol) membranes and by probing its mechanism of action against bacteria using a variety of assays and transmission electron microscopy (TEM) imaging, we reveal that BA-3/4-Butyl exerts its antimicrobial activity via membrane permeabilization. Our findings provide insights into how BA-3/4-Butyl compromises bacterial membranes without causing toxicity in its mammalian counterparts. This study advances the understanding of BA-3/4-Butyl's antimicrobial activity and potential mechanisms of action, ultimately aiding the development of similar novel therapeutic agents to help combat antimicrobial resistance.
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Affiliation(s)
- Colin
C. Tang
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Conor Pulliam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Alimi Abiodun
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Adam Parris
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Andrew Campbell
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Jie Li
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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5
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Johnson DH, Kou OH, White JM, Ramirez SY, Margaritakis A, Chung PJ, Jaeger VW, Zeno WF. Lipid Packing Defects are Necessary and Sufficient for Membrane Binding of α-Synuclein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2024.11.14.623669. [PMID: 39829920 PMCID: PMC11741239 DOI: 10.1101/2024.11.14.623669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/22/2025]
Abstract
α-Synuclein (αSyn), an intrinsically disordered protein implicated in Parkinson's disease, is potentially thought to initiate aggregation through binding to cellular membranes. Previous studies have suggested that anionic membrane charge is necessary for this binding. However, these studies largely focus on unmodified αSyn, while nearly all αSyn in the body is N-terminally acetylated (NTA). NTA dramatically shifts the narrative by diminishing αSyn's reliance on anionic charge for membrane binding. Instead, we demonstrate that membrane packing defects are the dominant forces driving NTA-αSyn interactions, challenging the long-standing paradigm that anionic membranes are essential for αSyn binding. Using fluorescence microscopy and circular dichroism spectroscopy, we monitored the binding of NTA-αSyn to reconstituted membrane surfaces with different lipid compositions. Phosphatidylcholine and phosphatidylserine concentrations were varied to control surface charge, while phospholipid tail unsaturation and methylation were varied to control lipid packing. All-atom molecular dynamics simulations of lipid bilayers supported the observation that membrane packing defects are necessary for NTA-αSyn binding and that defect-rich membranes are sufficient for NTA-αSyn binding regardless of membrane charge. We further demonstrated that this affinity for membrane defects persisted in reconstituted, cholesterol-containing membranes that mimicked the physiological lipid composition of synaptic vesicles. Increasing phospholipid unsaturation in these mimics led to more membrane packing defects and a corresponding increase in NTA-αSyn binding. Altogether, our results point to a mechanism for the regulation of NTA-αSyn binding in biological membranes that extends beyond phospholipid charge to the structural properties of the lipids themselves.
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Affiliation(s)
- David H. Johnson
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, United States
| | - Orianna H. Kou
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, 90089, United States
| | - John M. White
- Department of Chemical Engineering, University of Louisville, Ernst Hall, Room 312, 216 Eastern Parkway, Louisville, Kentucky 40292, United States
| | - Stephanie Y. Ramirez
- Department of Biological Sciences, University of Southern California, Los Angeles, 90089, United States
| | - Antonis Margaritakis
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, 90089, United States
| | - Peter J. Chung
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, 90089, United States
- Department of Chemistry, University of Southern California, Los Angeles, California, 90089, United States
- Alfred E. Mann Department of Biomedical Engineering, University of Southern California, Los Angeles, California, 90089, United States
| | - Vance W. Jaeger
- Department of Chemical Engineering, University of Louisville, Ernst Hall, Room 312, 216 Eastern Parkway, Louisville, Kentucky 40292, United States
| | - Wade F. Zeno
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, United States
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6
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McCaig CD. Membrane Surface Charge, Phospholipids, and Protein Localization. Rev Physiol Biochem Pharmacol 2025; 187:89-101. [PMID: 39838010 DOI: 10.1007/978-3-031-68827-0_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2025]
Abstract
Cell membranes contain multiple charged lipids that bind proteins dynamically and their spatial organization on the inner/outer membrane leaflet, or in spatially localized areas has considerable biological importance. Myristoylated alanine-rich C kinase substrate (MARCKS) proteins and their roles as electrostatic switches are one example covered. Cell surface charge needs to be monitored and regulated continually and the roles of lipid flippases and scramblases and their electrical regulation also are considered.
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Affiliation(s)
- Colin D McCaig
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK
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7
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Barbut D, Perni M, Zasloff M. Anti-aging properties of the aminosterols of the dogfish shark. NPJ AGING 2024; 10:62. [PMID: 39702521 DOI: 10.1038/s41514-024-00188-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 11/29/2024] [Indexed: 12/21/2024]
Abstract
The development of anti-aging drugs is challenged by both the apparent complexity of the physiological mechanisms involved in aging and the likelihood that many of these mechanisms remain unknown. As a consequence, the development of anti-aging compounds based on the rational targeting of specific pathways has fallen short of the goal. To date, the most impressive compound is rapamycin, a natural bacterial product initially identified as an antifungal, and only subsequently discovered to have anti-aging properties. In this review, we focus on two aminosterols from the dogfish shark, Squalus acanthias, that we discovered initially as broad-spectrum anti-microbial agents. This review is the first to gather together published studies conducted both in vitro and in numerous vertebrate species to demonstrate that these compounds target aging pathways at the cellular level and provide benefits in multiple aging-associated conditions in relevant animal models and in humans. The dogfish aminosterols should be recognized as potential anti-aging drugs.
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Affiliation(s)
- Denise Barbut
- BAZ Therapeutics, Inc., Philadelphia, PA, 19103, USA
| | - Michele Perni
- BAZ Therapeutics, Inc., Philadelphia, PA, 19103, USA
| | - Michael Zasloff
- BAZ Therapeutics, Inc., Philadelphia, PA, 19103, USA.
- MedStar Georgetown Transplant Institute, Georgetown University School of Medicine, Washington, DC, 20010, USA.
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8
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de Souza Cardoso R, Ono A. The Effects of Viral Structural Proteins on Acidic Phospholipids in Host Membranes. Viruses 2024; 16:1714. [PMID: 39599829 PMCID: PMC11599007 DOI: 10.3390/v16111714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2024] [Revised: 10/23/2024] [Accepted: 10/28/2024] [Indexed: 11/29/2024] Open
Abstract
Enveloped viruses rely on host membranes for trafficking and assembly. A substantial body of literature published over the years supports the involvement of cellular membrane lipids in the enveloped virus assembly processes. In particular, the knowledge regarding the relationship between viral structural proteins and acidic phospholipids has been steadily increasing in recent years. In this review, we will briefly review the cellular functions of plasma membrane-associated acidic phospholipids and the mechanisms that regulate their local distribution within this membrane. We will then explore the interplay between viruses and the plasma membrane acidic phospholipids in the context of the assembly process for two enveloped viruses, the influenza A virus (IAV) and the human immunodeficiency virus type 1 (HIV-1). Among the proteins encoded by these viruses, three viral structural proteins, IAV hemagglutinin (HA), IAV matrix protein-1 (M1), and HIV-1 Gag protein, are known to interact with acidic phospholipids, phosphatidylserine and/or phosphatidylinositol (4,5)-bisphosphate. These interactions regulate the localization of the viral proteins to and/or within the plasma membrane and likely facilitate the clustering of the proteins. On the other hand, these viral proteins, via their ability to multimerize, can also alter the distribution of the lipids and may induce acidic-lipid-enriched membrane domains. We will discuss the potential significance of these interactions in the virus assembly process and the property of the progeny virions. Finally, we will outline key outstanding questions that need to be answered for a better understanding of the relationships between enveloped virus assembly and acidic phospholipids.
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Affiliation(s)
| | - Akira Ono
- Department of Microbiology and Immunology, The University of Michigan, Ann Arbor, MI 48109, USA;
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9
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Williams DM, Peden AA. S-acylation of NLRP3 provides a nigericin sensitive gating mechanism that controls access to the Golgi. eLife 2024; 13:RP94302. [PMID: 39263961 PMCID: PMC11392533 DOI: 10.7554/elife.94302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2024] Open
Abstract
NLRP3 is an inflammasome seeding pattern recognition receptor activated in response to multiple danger signals which perturb intracellular homeostasis. Electrostatic interactions between the NLRP3 polybasic (PB) region and negatively charged lipids on the trans-Golgi network (TGN) have been proposed to recruit NLRP3 to the TGN. In this study, we demonstrate that membrane association of NLRP3 is critically dependant on S-acylation of a highly conserved cysteine residue (Cys-130), which traps NLRP3 in a dynamic S-acylation cycle at the Golgi, and a series of hydrophobic residues preceding Cys-130 which act in conjunction with the PB region to facilitate Cys-130 dependent Golgi enrichment. Due to segregation from Golgi localised thioesterase enzymes caused by a nigericin induced breakdown in Golgi organisation and function, NLRP3 becomes immobilised on the Golgi through reduced de-acylation of its Cys-130 lipid anchor, suggesting that disruptions in Golgi homeostasis are conveyed to NLRP3 through its acylation state. Thus, our work defines a nigericin sensitive S-acylation cycle that gates access of NLRP3 to the Golgi.
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Affiliation(s)
- Daniel M Williams
- School of Bioscience, University of SheffieldSheffieldUnited Kingdom
| | - Andrew A Peden
- School of Bioscience, University of SheffieldSheffieldUnited Kingdom
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10
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Gong T, McNally KL, Konanoor S, Peraza A, Bailey C, Redemann S, McNally FJ. Roles of Tubulin Concentration during Prometaphase and Ran-GTP during Anaphase of Caenorhabditis elegans Meiosis. Life Sci Alliance 2024; 7:e202402884. [PMID: 38960623 PMCID: PMC11222656 DOI: 10.26508/lsa.202402884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/05/2024] Open
Abstract
In many animal species, the oocyte meiotic spindle, which is required for chromosome segregation, forms without centrosomes. In some systems, Ran-GEF on chromatin initiates spindle assembly. We found that in Caenorhabditis elegans oocytes, endogenously-tagged Ran-GEF dissociates from chromatin during spindle assembly but re-associates during meiotic anaphase. Meiotic spindle assembly occurred after auxin-induced degradation of Ran-GEF, but anaphase I was faster than controls and extrusion of the first polar body frequently failed. In search of a possible alternative pathway for spindle assembly, we found that soluble tubulin concentrates in the nuclear volume during germinal vesicle breakdown. We found that the concentration of soluble tubulin in the metaphase spindle region is enclosed by ER sheets which exclude cytoplasmic organelles including mitochondria and yolk granules. Measurement of the volume occupied by yolk granules and mitochondria indicated that volume exclusion would be sufficient to explain the concentration of tubulin in the spindle volume. We suggest that this concentration of soluble tubulin may be a redundant mechanism promoting spindle assembly near chromosomes.
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Affiliation(s)
- Ting Gong
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Karen L McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Siri Konanoor
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Alma Peraza
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Cynthia Bailey
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Stefanie Redemann
- Department of Cell Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Francis J McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
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11
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Nakamura M, Parkhurst SM. Calcium influx rapidly establishes distinct spatial recruitments of Annexins to cell wounds. Genetics 2024; 227:iyae101. [PMID: 38874345 PMCID: PMC11304956 DOI: 10.1093/genetics/iyae101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 02/04/2024] [Accepted: 06/09/2024] [Indexed: 06/15/2024] Open
Abstract
To survive daily damage, the formation of actomyosin ring at the wound edge is required to rapidly close cell wounds. Calcium influx is one of the start signals for these cell wound repair events. Here, we find that the rapid recruitment of all 3 Drosophila calcium-responding and phospholipid-binding Annexin proteins (AnxB9, AnxB10, and AnxB11) to distinct regions around the wound is regulated by the quantity of calcium influx rather than their binding to specific phospholipids. The distinct recruitment patterns of these Annexins regulate the subsequent recruitment of RhoGEF2 and RhoGEF3 through actin stabilization to form a robust actomyosin ring. Surprisingly, while the wound does not close in the absence of calcium influx, we find that reduced calcium influx can still initiate repair processes, albeit leading to severe repair phenotypes. Thus, our results suggest that, in addition to initiating repair events, the quantity of calcium influx is important for precise Annexin spatiotemporal protein recruitment to cell wounds and efficient wound repair.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Susan M Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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12
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Sun M, Otsuka Y, Okada M, Shimma S, Toyoda M. Probe oscillation control in tapping-mode scanning probe electrospray ionization for stabilization of mass spectrometry imaging. Analyst 2024; 149:4011-4019. [PMID: 38953117 DOI: 10.1039/d4an00712c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
Mass spectrometry imaging (MSI) is used for visualizing the distribution of components in solid samples, such as biological tissues, and requires a technique to ionize the components from local areas of the sample. Tapping-mode scanning probe electrospray ionization (t-SPESI) uses an oscillating capillary probe to extract components from a local area of a sample with a small volume of solvent and to perform electrospray ionization of those components at high speed. MSI can be conducted by scanning the sample surface with a capillary probe. To ensure stable extraction and ionization for MSI, the probe oscillation during measurements must be understood. In this study, we examined the changes in oscillation amplitude and phase due to the interaction between the oscillating probe and the brain tissue section when the probe tip was dynamically brought close to the sample surface. The changes in the probe oscillation depended on the oscillation frequency and polarity of the bias voltage applied to the solvent because an electrostatic force shifted the frequency of the probe oscillation. These findings suggest that controlling the probe oscillation frequency is important for stabilizing MSI by t-SPESI.
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Affiliation(s)
- Mengze Sun
- Department of Physics, Graduate School of Science, Osaka University, Japan.
| | - Yoichi Otsuka
- Department of Physics, Graduate School of Science, Osaka University, Japan.
- Forefront Research Center, Graduate School of Science, Osaka University, Japan
| | - Maki Okada
- Department of Physics, Graduate School of Science, Osaka University, Japan.
| | - Shuichi Shimma
- Department of Bioengineering, Graduate School of Engineering, Osaka University, Japan
| | - Michisato Toyoda
- Department of Physics, Graduate School of Science, Osaka University, Japan.
- Forefront Research Center, Graduate School of Science, Osaka University, Japan
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13
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Gong T, McNally KL, Konanoor S, Peraza A, Bailey C, Redemann S, McNally FJ. Roles of Tubulin Concentration during Prometaphase and Ran-GTP during Anaphase of C. elegans meiosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.19.590357. [PMID: 38659754 PMCID: PMC11042349 DOI: 10.1101/2024.04.19.590357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
In many animal species, the oocyte meiotic spindle, which is required for chromosome segregation, forms without centrosomes. In some systems, Ran-GEF on chromatin initiates spindle assembly. We found that in C. elegans oocytes, endogenously-tagged Ran-GEF dissociates from chromatin during spindle assembly but re-associates during meiotic anaphase. Meiotic spindle assembly occurred after auxin-induced degradation of Ran-GEF but anaphase I was faster than controls and extrusion of the first polar body frequently failed. In search of a possible alternative pathway for spindle assembly, we found that soluble tubulin concentrates in the nuclear volume during germinal vesicle breakdown. We found that the concentration of soluble tubulin in the metaphase spindle region is enclosed by ER sheets which exclude cytoplasmic organelles including mitochondria and yolk granules. Measurement of the volume occupied by yolk granules and mitochondria indicated that volume exclusion would be sufficient to explain the concentration of tubulin in the spindle volume. We suggest that this concentration of soluble tubulin may be a redundant mechanism promoting spindle assembly near chromosomes.
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Affiliation(s)
- Ting Gong
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
| | - Karen L McNally
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
| | - Siri Konanoor
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
| | - Alma Peraza
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
| | - Cynthia Bailey
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
| | - Stefanie Redemann
- Department of Cell Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Francis J McNally
- Department of Molecular and Cellular Biology, university of California, Davis, Davis, CA 95616, USA
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14
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Ray J, Sapp DG, Fairn GD. Phosphatidylinositol 3,4-bisphosphate: Out of the shadows and into the spotlight. Curr Opin Cell Biol 2024; 88:102372. [PMID: 38776601 DOI: 10.1016/j.ceb.2024.102372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 04/15/2024] [Accepted: 05/01/2024] [Indexed: 05/25/2024]
Abstract
Phosphoinositide 3-kinases regulate many cellular functions, including migration, growth, proliferation, and cell survival. Early studies equated the inhibition of Class I PI3Ks with loss of; phosphatidylinositol 3,4,5-trisphosphate (PIP3), but over time, it was realised that these; treatments also depleted phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). In recent years, the; use of better tools and an improved understanding of its metabolism have allowed for the; identification of specific roles of PI(3,4)P2. This includes the production of PI(3,4)P2 and the; activation of its effector Akt2 in response to growth factor signalling. In contrast, a lysosomal pool of PI(3,4)P2 is a negative regulator of mTORC1 during growth factor deprivation. A growing body of literature also demonstrates that PI(3,4)P2 controls many dynamic plasmalemmal processes. The significance of PI(3,4)P2 in cell biology is increasingly evident.
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Affiliation(s)
- Jayatee Ray
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David G Sapp
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Gregory D Fairn
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
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15
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Wycisk V, Behnke JS, Nielinger L, Seewald M, Weisner J, Binsch M, Wagner MC, Raisch T, Urner LH. Synthesis of Asymmetric Ionic Hybrid Detergents enables Micelles with Scalable Properties including Cell Compatibility. Chemistry 2024:e202401833. [PMID: 38819585 DOI: 10.1002/chem.202401833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 05/31/2024] [Accepted: 05/31/2024] [Indexed: 06/01/2024]
Abstract
Ionic detergents enable applications and cause harm in biospheres due to cell toxicity. The utility of covalent combinations between ionic and non-ionic detergent headgroups in modulating cell toxicity remains speculative due to the yet rarely explored synthesis. We close this gap and establish the modular synthesis of ionic/non-ionic hybrid detergents. We restructure a combinatorial methallyl dichloride one-pot coupling into a two-step coupling, which reduces by-products, improves product yields, and enables the gram-scale preparation of asymmetric, cationic/non-ionic and anionic/non-ionic hybrid detergents. Our modular synthesis delivers new modalities for the design of ionic detergents, including an unprecedented scaling of properties that determine applications, such as charge, critical micelle concentration, solubilizing properties, hard water tolerance, and cell compatibility. We uncover that shielding the charge in ionic headgroups can switch the detergent species that is toxic to cells from monomers to mixtures of monomers and micellar assemblies. Establishing the chemistry of ionic/non-ionic hybrid detergents provides a missing evolutionary link in the structural comparison of ionic and non-ionic detergents, enables an easy synthesis access to yet unexplored chemical spaces of asymmetric hybrid materials, and delivers new modalities for designing the toxicity of supramolecular nanomaterials.
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Affiliation(s)
- Virginia Wycisk
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Jan-Simon Behnke
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Lena Nielinger
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Marc Seewald
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Jörn Weisner
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Markus Binsch
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Marc-Christian Wagner
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
| | - Tobias Raisch
- Max Planck Institute of Molecular Physiology, Department of Structural Biochemistry, Otto-Hahn-Str. 11, 44227, Dortmund
| | - Leonhard H Urner
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Str. 6, 44227, Dortmund
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16
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Ouyang L, Chen H, Xu R, Shaik R, Zhang G, Zhe J. Rapid Surface Charge Mapping Based on a Liquid Crystal Microchip. BIOSENSORS 2024; 14:199. [PMID: 38667192 PMCID: PMC11047892 DOI: 10.3390/bios14040199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/05/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024]
Abstract
Rapid surface charge mapping of a solid surface remains a challenge. In this study, we present a novel microchip based on liquid crystals for assessing the surface charge distribution of a planar or soft surface. This chip enables rapid measurements of the local surface charge distribution of a charged surface. The chip consists of a micropillar array fabricated on a transparent indium tin oxide substrate, while the liquid crystal is used to fill in the gaps between the micropillar structures. When an object is placed on top of the chip, the local surface charge (or zeta potential) influences the orientation of the liquid crystal molecules, resulting in changes in the magnitude of transmitted light. By measuring the intensity of the transmitted light, the distribution of the surface charge can be accurately quantified. We calibrated the chip in a three-electrode configuration and demonstrated the validity of the chip for rapid surface charge mapping using a borosilicate glass slide. This chip offers noninvasive, rapid mapping of surface charges on charged surfaces, with no need for physical or chemical modifications, and has broad potential applications in biomedical research and advanced material design.
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Affiliation(s)
- Leixin Ouyang
- Department of Mechanical Engineering, University of Akron, Akron, OH 44325, USA; (L.O.); (H.C.); (R.X.)
| | - Heyi Chen
- Department of Mechanical Engineering, University of Akron, Akron, OH 44325, USA; (L.O.); (H.C.); (R.X.)
| | - Ruiting Xu
- Department of Mechanical Engineering, University of Akron, Akron, OH 44325, USA; (L.O.); (H.C.); (R.X.)
| | - Rubia Shaik
- Department of Biomedical Engineering, University of Akron, Akron, OH 44325, USA; (R.S.); (G.Z.)
| | - Ge Zhang
- Department of Biomedical Engineering, University of Akron, Akron, OH 44325, USA; (R.S.); (G.Z.)
| | - Jiang Zhe
- Department of Mechanical Engineering, University of Akron, Akron, OH 44325, USA; (L.O.); (H.C.); (R.X.)
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17
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Kawasaki H, Hariyama T, Kosugi I, Meguro S, Iwata F, Shimizu K, Magata Y, Iwashita T. Human induced pluripotent stem cells are resistant to human cytomegalovirus infection primarily at the attachment level due to the reduced expression of cell-surface heparan sulfate. J Virol 2024; 98:e0127823. [PMID: 38345384 PMCID: PMC10949504 DOI: 10.1128/jvi.01278-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/16/2024] [Indexed: 03/20/2024] Open
Abstract
Cytomegalovirus (CMV), a type of herpes virus, is the predominant cause of congenital anomalies due to intrauterine infections in humans. Adverse outcomes related to intrauterine infections with human cytomegalovirus (HCMV) vary widely, depending on factors such as fetal infection timing, infection route, and viral virulence. The precise mechanism underlying HCMV susceptibility remains unclear. In this study, we compared the susceptibility of neonatal human dermal fibroblast cells (NHDFCs) and human induced pluripotent stem cells (hiPSCs) derived from NHDFCs, which are genetically identical to HCMV, using immunostaining, microarray, in situ hybridization, quantitative PCR, and scanning electron microscopy. These cells were previously used to compare CMV susceptibility, but the underlying mechanisms were not fully elucidated. HCMV susceptibility of hiPSCs was significantly lower in the earliest phase. No shared gene ontologies were observed immediately post-infection between the two cell types using microarray analysis. Early-stage expression of HCMV antigens and the HCMV genome was minimal in immunostaining and in in situ hybridization in hiPSCs. This strongly suggests that HCMV does not readily bind to hiPSC surfaces. Scanning electron microscopy performed using the NanoSuit method confirmed the scarcity of HCMV particles on hiPSC surfaces. The zeta potential and charge mapping of the charged surface in NHDFCs and hiPSCs exhibited minimal differences when assessed using zeta potential analyzer and scanning ion conductance microscopy; however, the expression of heparan sulfate (HS) was significantly lower in hiPSCs compared with that in NHDFCs. Thus, HS expression could be a primary determinant of HCMV resistance in hiPSCs at the attachment level. IMPORTANCE Numerous factors such as attachment, virus particle entry, transcription, and virus particle egress can affect viral susceptibility. Since 1984, pluripotent cells are known to be CMV resistant; however, the exact mechanism underlying this resistance remains elusive. Some researchers suggest inhibition in the initial phase of HCMV binding, while others have suggested the possibility of a sufficient amount of HCMV entering the cells to establish latency. This study demonstrates that HCMV particles rarely attach to the surfaces of hiPSCs. This is not due to limitations in the electrostatic interactions between the surface of hiPSCs and HCMV particles, but due to HS expression. Therefore, HS expression should be recognized as a key factor in determining the susceptibility of HCMV in congenital infection in vitro and in vivo. In the future, drugs targeting HS may become crucial for the treatment of congenital CMV infections. Thus, further research in this area is warranted.
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Affiliation(s)
- Hideya Kawasaki
- Institute for NanoSuit Research, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Takahiko Hariyama
- Institute for NanoSuit Research, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Isao Kosugi
- Department of Regenerative and Infectious Pathology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shiori Meguro
- Department of Regenerative and Infectious Pathology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Futoshi Iwata
- Research Institute of Electronics, Shizuoka University, Hamamatsu, Shizuoka, Japan
| | - Kosuke Shimizu
- Department of Molecular Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yasuhiro Magata
- Department of Molecular Imaging, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Toshihide Iwashita
- Department of Regenerative and Infectious Pathology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
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18
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Papa A, del Rivero Morfin PJ, Chen BX, Yang L, Katchman AN, Zakharov SI, Liu G, Bohnen MS, Zheng V, Katz M, Subramaniam S, Hirsch JA, Weiss S, Dascal N, Karlin A, Pitt GS, Colecraft HM, Ben-Johny M, Marx SO. A membrane-associated phosphoswitch in Rad controls adrenergic regulation of cardiac calcium channels. J Clin Invest 2024; 134:e176943. [PMID: 38227371 PMCID: PMC10904049 DOI: 10.1172/jci176943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/11/2024] [Indexed: 01/17/2024] Open
Abstract
The ability to fight or flee from a threat relies on an acute adrenergic surge that augments cardiac output, which is dependent on increased cardiac contractility and heart rate. This cardiac response depends on β-adrenergic-initiated reversal of the small RGK G protein Rad-mediated inhibition of voltage-gated calcium channels (CaV) acting through the Cavβ subunit. Here, we investigate how Rad couples phosphorylation to augmented Ca2+ influx and increased cardiac contraction. We show that reversal required phosphorylation of Ser272 and Ser300 within Rad's polybasic, hydrophobic C-terminal domain (CTD). Phosphorylation of Ser25 and Ser38 in Rad's N-terminal domain (NTD) alone was ineffective. Phosphorylation of Ser272 and Ser300 or the addition of 4 Asp residues to the CTD reduced Rad's association with the negatively charged, cytoplasmic plasmalemmal surface and with CaVβ, even in the absence of CaVα, measured here by FRET. Addition of a posttranslationally prenylated CAAX motif to Rad's C-terminus, which constitutively tethers Rad to the membrane, prevented the physiological and biochemical effects of both phosphorylation and Asp substitution. Thus, dissociation of Rad from the sarcolemma, and consequently from CaVβ, is sufficient for sympathetic upregulation of Ca2+ currents.
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Affiliation(s)
- Arianne Papa
- Division of Cardiology, Department of Medicine, and
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Pedro J. del Rivero Morfin
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Bi-Xing Chen
- Division of Cardiology, Department of Medicine, and
| | - Lin Yang
- Division of Cardiology, Department of Medicine, and
| | | | | | - Guoxia Liu
- Division of Cardiology, Department of Medicine, and
| | | | - Vivian Zheng
- Division of Cardiology, Department of Medicine, and
| | | | | | - Joel A. Hirsch
- Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | | | | | - Arthur Karlin
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Department of Biochemistry and Molecular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute and Department of Medicine, Weill Cornell Medical College, New York, New York, USA
| | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Department of Pharmacology and Molecular Signaling, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine, and
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
- Department of Pharmacology and Molecular Signaling, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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19
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Nakamura M, Parkhurst SM. Calcium influx rapidly establishes distinct spatial recruitments of Annexins to cell wounds. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.03.569799. [PMID: 38105960 PMCID: PMC10723296 DOI: 10.1101/2023.12.03.569799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
To survive daily damage, the formation of actomyosin ring at the wound periphery is required to rapidly close cell wounds. Calcium influx is one of the start signals for these cell wound repair events. Here, we find that rapid recruitment of all three Drosophila calcium responding and phospholipid binding Annexin proteins (AnxB9, AnxB10, AnxB11) to distinct regions around the wound are regulated by the quantity of calcium influx rather than their binding to specific phospholipids. The distinct recruitment patterns of these Annexins regulate the subsequent recruitment of RhoGEF2 and RhoGEF3 through actin stabilization to form a robust actomyosin ring. Surprisingly, we find that reduced extracellular calcium and depletion of intracellular calcium affect cell wound repair differently, despite these two conditions exhibiting similar GCaMP signals. Thus, our results suggest that, in addition to initiating repair events, both the quantity and sources of calcium influx are important for precise Annexin spatiotemporal protein recruitment to cell wounds and efficient wound repair.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Susan M. Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
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20
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Fahimi P, Matta CF, Okie JG. Are size and mitochondrial power of cells inter-determined? J Theor Biol 2023; 572:111565. [PMID: 37369290 DOI: 10.1016/j.jtbi.2023.111565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/16/2023] [Accepted: 06/21/2023] [Indexed: 06/29/2023]
Abstract
Mitochondria are the central hub of ATP production in most eukaryotic cells. Cellular power (energy per unit time), which is primarily generated in these organelles, is crucial to our understanding of cell function in health and disease. We investigated the relation between a mitochondrion's power (metabolic rate) and host cell size by combining metabolic theory with the analysis of two recent databases, one covering 109 protists and the other 63 species including protists, metazoans, microalgae, and vascular plants. We uncovered an interesting statistical regularity: in well-fed protists, relatively elevated values of mitochondrion power cluster around the smallest cell sizes and the medium-large cell sizes. In contrast, in starved protists and metazoans, the relation between mitochondrion power and cell size is inconclusive, and in microalgae and plants, mitochondrion power seems to increase from smaller cells to larger ones (where this investigation includes plant cells of volume up to ca. 2.18 × 105 μm3). Using these results, estimates are provided of the number of active ATP synthase molecules and basal uncouplers.
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Affiliation(s)
- Peyman Fahimi
- Département de Chimie, Université Laval, Québec, QC G1V0A6, Canada
| | - Chérif F Matta
- Département de Chimie, Université Laval, Québec, QC G1V0A6, Canada; Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, NS B3M2J6, Canada.
| | - Jordan G Okie
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA.
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21
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Cooper A, Girish V, Subramaniam AB. Osmotic Pressure Enables High-Yield Assembly of Giant Vesicles in Solutions of Physiological Ionic Strengths. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5579-5590. [PMID: 37021722 PMCID: PMC10116648 DOI: 10.1021/acs.langmuir.3c00457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Giant unilamellar vesicles (GUVs) are micrometer-scale minimal cellular mimics that are useful for bottom-up synthetic biology and drug delivery. Unlike assembly in low-salt solutions, assembly of GUVs in solutions with ionic concentrations of 100-150 mM Na/KCl (salty solutions) is challenging. Chemical compounds deposited on the substrate or incorporated into the lipid mixture could assist in the assembly of GUVs. Here, we investigate quantitatively the effects of temperature and chemical identity of six polymeric compounds and one small molecule compound on the molar yields of GUVs composed of three different lipid mixtures using high-resolution confocal microscopy and large data set image analysis. All the polymers moderately increased the yields of GUVs either at 22 or 37 °C, whereas the small molecule compound was ineffective. Low-gelling temperature agarose is the singular compound that consistently produces yields of GUVs of greater than 10%. We propose a free energy model of budding to explain the effects of polymers in assisting the assembly of GUVs. The osmotic pressure exerted on the membranes by the dissolved polymer balances the increased adhesion between the membranes, thus reducing the free energy for bud formation. Data obtained by modulating the ionic strength and ion valency of the solution shows that the evolution of the yield of GUVs supports our model's prediction. In addition, polymer-specific interactions with the substrate and the lipid mixture affects yields. The uncovered mechanistic insights provide a quantitative experimental and theoretical framework to guide future studies. Additionally, this work shows a facile means for obtaining GUVs in solutions of physiological ionic strengths.
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Affiliation(s)
- Alexis Cooper
- Department
of Chemistry and Biochemistry, University
of California, Merced, Merced, California 95343, United States
| | - Vaishnavi Girish
- Department
of Bioengineering, University of California,
Merced, Merced, California 95343, United States
| | - Anand Bala Subramaniam
- Department
of Bioengineering, University of California,
Merced, Merced, California 95343, United States
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22
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Cell Surface Charge Mapping Using a Microelectrode Array on ITO Substrate. Cells 2023; 12:cells12040518. [PMID: 36831185 PMCID: PMC9954061 DOI: 10.3390/cells12040518] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/26/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Many cellular functions are regulated by cell surface charges, such as intercellular signaling and metabolism. Noninvasive measurement of surface charge distribution of a single cell plays a vital role in understanding cellular functions via cell membranes. We report a method for cell surface charge mapping via photoelectric interactions. A cell is placed on an array of microelectrodes fabricated on a transparent ITO (indium tin oxide) surface. An incident light irradiates the ITO surface from the backside. Because of the influence of the cell surface charge (or zeta potential), the photocurrent and the absorption of the incident light are changed, inducing a magnitude change of the reflected light. Hence, the cell surface charge distribution can be quantified by analyzing the reflected light intensity. This method does not need physical or chemical modification of the cell surface. We validated this method using charged microparticles (MPs) and two types of cells, i.e., human dermal fibroblast cells (HDFs) and human mesenchymal stem cells (hMSC). The measured average zeta potentials were in good agreement with the standard electrophoresis light scattering method.
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23
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EFR3 and phosphatidylinositol 4-kinase IIIα regulate insulin-stimulated glucose transport and GLUT4 dispersal in 3T3-L1 adipocytes. Biosci Rep 2022; 42:231469. [PMID: 35735144 PMCID: PMC9272592 DOI: 10.1042/bsr20221181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/17/2022] Open
Abstract
Insulin stimulates glucose transport in muscle and adipocytes. This is achieved by regulated delivery of intracellular glucose transporter (GLUT4)-containing vesicles to the plasma membrane where they dock and fuse, resulting in increased cell surface GLUT4 levels. Recent work identified a potential further regulatory step, in which insulin increases the dispersal of GLUT4 in the plasma membrane away from the sites of vesicle fusion. EFR3 is a scaffold protein that facilitates localization of phosphatidylinositol 4-kinase type IIIα to the cell surface. Here we show that knockdown of EFR3 or phosphatidylinositol 4-kinase type IIIα impairs insulin-stimulated glucose transport in adipocytes. Using direct stochastic reconstruction microscopy, we also show that EFR3 knockdown impairs insulin stimulated GLUT4 dispersal in the plasma membrane. We propose that EFR3 plays a previously unidentified role in controlling insulin-stimulated glucose transport by facilitating dispersal of GLUT4 within the plasma membrane.
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