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Herbst CH, Bouteau A, Menykő EJ, Qin Z, Gyenge E, Su Q, Cooper V, Mabbott NA, Igyártó BZ. Dendritic cells overcome Cre/Lox induced gene deficiency by siphoning cytosolic material from surrounding cells. iScience 2024; 27:109119. [PMID: 38384841 PMCID: PMC10879714 DOI: 10.1016/j.isci.2024.109119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 01/10/2024] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
In a previous report, keratinocytes were shown to share their gene expression profile with surrounding Langerhans cells (LCs), influencing LC biology. Here, we investigated whether transferred material could substitute for lost gene products in cells subjected to Cre/Lox conditional gene deletion. We found that in human Langerin-Cre mice, epidermal LCs and CD11b+CD103+ mesenteric DCs overcome gene deletion if the deleted gene was expressed by neighboring cells. The mechanism of material transfer differed from traditional antigen uptake routes, relying on calcium and PI3K, being susceptible to polyguanylic acid inhibition, and remaining unaffected by inflammation. Termed intracellular monitoring, this process was specific to DCs, occurring in all murine DC subsets tested and human monocyte-derived DCs. The transferred material was presented on MHC-I and MHC-II, suggesting a role in regulating immune responses.
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Affiliation(s)
- Christopher H Herbst
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Aurélie Bouteau
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Evelin J Menykő
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Zhen Qin
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Ervin Gyenge
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Qingtai Su
- OncoNano Medicine, Inc, Southlake, TX 76092, USA
| | - Vincent Cooper
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Neil A Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Botond Z Igyártó
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Handlin LJ, Macchi NL, Dumaire NLA, Salih L, Lessie EN, McCommis KS, Moutal A, Dai G. Membrane Lipid Domains Modulate HCN Channels in Nociceptor DRG Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.02.556056. [PMID: 37732182 PMCID: PMC10508734 DOI: 10.1101/2023.09.02.556056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Cell membranes consist of heterogeneous lipid domains that influence key cellular processes, including signal transduction, endocytosis, and electrical excitability. Using FRET-based fluorescent assays and fluorescence lifetime imaging microscopy (FLIM), we found that the dimension of cholesterol-enriched ordered membrane domains (OMD) varies considerably, depending on specific cell types. The size of OMDs is also dependent on cholesterol levels and the structure of lipid tails. Particularly, nociceptor dorsal root ganglion (DRG) neurons exhibit large OMDs. Disruption of OMDs potentiated action potential firing in nociceptor DRG neurons and facilitated opening of native hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. This increased neuronal firing could be partially due to an increased open probability of HCN channels. In animal models of neuropathic pain, we observed shrunken OMDs and relocalization of HCN channels from OMDs to disordered lipid domains. The gating effect on HCN channels was likely a result of direct modulation of the voltage sensor by OMDs. These findings suggest that disturbances in lipid domains play a role in regulating HCN channels within nociceptor DRG neurons, influencing pain modulation.
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Park J, Evangelopoulos M, Vasher MK, Kudruk S, Ramani N, Mayer V, Solivan AC, Lee A, Mirkin CA. Enhancing Endosomal Escape and Gene Regulation Activity for Spherical Nucleic Acids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306902. [PMID: 37932003 PMCID: PMC10947971 DOI: 10.1002/smll.202306902] [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: 08/11/2023] [Revised: 10/19/2023] [Indexed: 11/08/2023]
Abstract
The therapeutic potential of small interfering RNAs (siRNAs) is limited by their poor stability and low cellular uptake. When formulated as spherical nucleic acids (SNAs), siRNAs are resistant to nuclease degradation and enter cells without transfection agents with enhanced activity compared to their linear counterparts; however, the gene silencing activity of SNAs is limited by endosomal entrapment, a problem that impacts many siRNA-based nanoparticle constructs. To increase cytosolic delivery, SNAs are formulated using calcium chloride (CaCl2 ) instead of the conventionally used sodium chloride (NaCl). The divalent calcium (Ca2+ ) ions remain associated with the multivalent SNA and have a higher affinity for SNAs compared to their linear counterparts. Importantly, confocal microscopy studies show a 22% decrease in the accumulation of CaCl2 -salted SNAs within the late endosomes compared to NaCl-salted SNAs, indicating increased cytosolic delivery. Consistent with this finding, CaCl2 -salted SNAs comprised of siRNA and antisense DNA all exhibit enhanced gene silencing activity (up to 20-fold), compared to NaCl-salted SNAs regardless of sequence or cell line (U87-MG and SK-OV-3) studied. Moreover, CaCl2 -salted SNA-based forced intercalation probes show improved cytosolic mRNA detection.
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Affiliation(s)
- Jungsoo Park
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois, 60208, United States
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
| | - Michael Evangelopoulos
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, 60208, United States
| | - Matthew K. Vasher
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, 60208, United States
| | - Sergej Kudruk
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, United States
| | - Namrata Ramani
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Material Sciences and Engineering, Northwestern University, Evanston, Illinois, 60208, United States
| | - Vinzenz Mayer
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, United States
| | - Alexander C. Solivan
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, United States
| | - Andrew Lee
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, 60208
| | - Chad A. Mirkin
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, Illinois, 60208, United States
- International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Material Sciences and Engineering, Northwestern University, Evanston, Illinois, 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, 60208
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Deisl C, Moe OW, Hilgemann DW. Constitutive Plasma Membrane Turnover in T-REx293 cells via Ordered Membrane Domain Endocytosis under Mitochondrial Control. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.576124. [PMID: 38293164 PMCID: PMC10827192 DOI: 10.1101/2024.01.17.576124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Clathrin/dynamin-independent endocytosis of ordered plasma membrane domains (ordered membrane domain endocytosis, OMDE) can become massive in response to cytoplasmic Ca elevations, G protein activation by non-hydrolyzable GTP analogs, and enhanced oxidative metabolism. In patch-clamped murine bone marrow macrophages (BMMs), cytoplasmic succinate and pyruvate, but not β-hydroxybutyrate, induce OMDE of 75% of the plasma membrane within 2 min. The responses require palmitoylation of membrane proteins, being decreased by 70% in BMMs lacking the acyltransferase, DHHC5, by treatment with carnitine to shift long-chain acyl groups from cytoplasmic to mitochondrial acyl-CoAs, by bromopalmitate/albumin complexes to block DHHCs, and by the mitochondria-specific cyclosporin, NIM811, to block permeability transition pores that may release mitochondrial coenzyme A into the cytoplasm. Using T-REx293 cells, OMDE amounts to 40% with succinate, pyruvate, or GTPγS, and it is inhibited by actin cytoskeleton disruption. Pyruvate-induced OMDE is blocked by the hydrophobic antioxidant, edaravone, which prevents permeability transition pore openings. Using fluorescent 3kD dextrans to monitor endocytosis, OMDE appears to be constitutively active in T-REx293 cells but not in BMMs. After 1 h without substrates or bicarbonate, pyruvate and hydroxybutyrate inhibit constitutive OMDE, as expected for a shift of CoA from long-chain acyl-CoAs to other CoA metabolites. In the presence of bicarbonate, pyruvate strongly enhances OMDE, which is then blocked by β-hydroxybutyrate, bromopalmitate/albumin complexes, cyclosporines, or edaravone. After pyruvate responses, T-REx293 cells grow normally with no evidence for apoptosis. Fatty acid-free albumin (15 μM) inhibits basal OMDE in T-REx293 cells, as do cyclosporines, carnitine, and RhoA blockade. Surprisingly, OMDE in the absence of substrates and bicarbonate is not inhibited by siRNA knockdown of the acyltransferases, DHHC5 or DHHC2, which are required for activated OMDE in patch clamp experiments. We verify biochemically that small CoA metabolites decrease long-chain acyl-CoAs. We verify also that palmitoylations of many PM-associated proteins decrease and increase when OMDE is inhibited and stimulated, respectively, by different metabolites. STED microscopy reveals that vesicles formed during constitutive OMDE in T-REX293 cells have 90 to 130 nm diameters. In summary, OMDE is likely a major G-protein-dependent endocytic mechanism that can be constitutively active in some cell types, albeit not BMMs. OMDE depends on different DHHC acyltransferases in different circumstances and can be limited by local supplies of fatty acids, CoA, and long-chain acyl-CoAs.
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Affiliation(s)
- Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Orson W Moe
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Gundu C, Arruri VK, Yadav P, Navik U, Kumar A, Amalkar VS, Vikram A, Gaddam RR. Dynamin-Independent Mechanisms of Endocytosis and Receptor Trafficking. Cells 2022; 11:cells11162557. [PMID: 36010634 PMCID: PMC9406725 DOI: 10.3390/cells11162557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The GTPase dynamin acts as a “molecular scissor” to form endocytic vesicles and is a critical regulator among the proteins involved in endocytosis. Some GTPases (e.g., Cdc42, arf6, RhoA), membrane proteins (e.g., flotillins, tetraspanins), and secondary messengers (e.g., calcium) mediate dynamin-independent endocytosis. These pathways may be convergent, as multiple pathways exist in a single cell. However, what determines the specific path of endocytosis is complex and challenging to comprehend. This review summarizes the mechanisms of dynamin-independent endocytosis, the involvement of microRNAs, and factors that contribute to the cellular decision about the specific route of endocytosis.
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Affiliation(s)
- Chayanika Gundu
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad 500037, Telangana, India
| | - Vijay Kumar Arruri
- Department of Neurological Surgery, University of Wisconsin, Madison, WI 53792, USA
| | - Poonam Yadav
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Umashanker Navik
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Ashutosh Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Kolkata 700054, West Bengal, India
| | - Veda Sudhir Amalkar
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ajit Vikram
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ravinder Reddy Gaddam
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
- Correspondence:
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Rodrigues T, Piccirillo S, Magi S, Preziuso A, Dos Santos Ramos V, Serfilippi T, Orciani M, Maciel Palacio Alvarez M, Luis Dos Santos Tersariol I, Amoroso S, Lariccia V. Control of Ca 2+ and metabolic homeostasis by the Na +/Ca 2+ exchangers (NCXs) in health and disease. Biochem Pharmacol 2022; 203:115163. [PMID: 35803319 DOI: 10.1016/j.bcp.2022.115163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 11/16/2022]
Abstract
Spatial and temporal control of calcium (Ca2+) levels is essential for the background rhythms and responses of living cells to environmental stimuli. Whatever other regulators a given cellular activity may have, localized and wider scale Ca2+ events (sparks, transients, and waves) are hierarchical determinants of fundamental processes such as cell contraction, excitability, growth, metabolism and survival. Different cell types express specific channels, pumps and exchangers to efficiently generate and adapt Ca2+ patterns to cell requirements. The Na+/Ca2+ exchangers (NCXs) in particular contribute to Ca2+ homeostasis by buffering intracellular Ca2+ loads according to the electrochemical gradients of substrate ions - i.e., Ca2+ and sodium (Na+) - and under a dynamic control of redundant regulatory processes. An interesting feature of NCX emerges from the strict relationship that connects transporter activity with cell metabolism: on the one hand NCX operates under constant control of ATP-dependent regulatory processes, on the other hand the ion fluxes generated through NCX provide mechanistic support for the Na+-driven uptake of glutamate and Ca2+ influx to fuel mitochondrial respiration. Proof of concept evidence highlights therapeutic potential of preserving a timed and balanced NCX activity in a growing rate of diseases (including excitability, neurodegenerative, and proliferative disorders) because of an improved ability of stressed cells to safely maintain ion gradients and mitochondrial bioenergetics. Here, we will summarize and review recent works that have focused on the pathophysiological roles of NCXs in balancing the two-way relationship between Ca2+ signals and metabolism.
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Affiliation(s)
- Tiago Rodrigues
- Center for Natural and Human Sciences (CCNH), Federal University of ABC (UFABC), Santo André, SP, Brazil.
| | - Silvia Piccirillo
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Alessandra Preziuso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Vyctória Dos Santos Ramos
- Interdisciplinary Center for Biochemistry Investigation (CIIB), University of Mogi das Cruzes (UMC), Mogi das Cruzes, SP, Brazil
| | - Tiziano Serfilippi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Monia Orciani
- Department of Clinical and Molecular Sciences, Histology, University "Politecnica delle Marche", Ancona, Italy.
| | - Marcela Maciel Palacio Alvarez
- Department of Biochemistry, São Paulo School of Medicine, Federal University of São Paulo (Unifesp) São Paulo, SP, Brazil
| | | | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
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Charpentier JC, King PD. Mechanisms and functions of endocytosis in T cells. Cell Commun Signal 2021; 19:92. [PMID: 34503523 PMCID: PMC8427877 DOI: 10.1186/s12964-021-00766-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/17/2021] [Indexed: 11/11/2022] Open
Abstract
Once thought of primarily as a means to neutralize pathogens or to facilitate feeding, endocytosis is now known to regulate a wide range of eukaryotic cell processes. Among these are regulation of signal transduction, mitosis, lipid homeostasis, and directed migration, among others. Less well-appreciated are the roles various forms of endocytosis plays in regulating αβ and, especially, γδ T cell functions, such as T cell receptor signaling, antigen discovery by trogocytosis, and activated cell growth. Herein we examine the contribution of both clathrin-mediated and clathrin-independent mechanisms of endocytosis to T cell biology. Video Abstract
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Affiliation(s)
- John C Charpentier
- Department of Microbiology and Immunology, University of Michigan Medical School, 6606 Med Sci II, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-5620, USA
| | - Philip D King
- Department of Microbiology and Immunology, University of Michigan Medical School, 6606 Med Sci II, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-5620, USA.
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Meyer DJ, Bijlani S, de Sautu M, Spontarelli K, Young VC, Gatto C, Artigas P. FXYD protein isoforms differentially modulate human Na/K pump function. J Gen Physiol 2021; 152:211559. [PMID: 33231612 PMCID: PMC7690937 DOI: 10.1085/jgp.202012660] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 10/29/2020] [Indexed: 12/28/2022] Open
Abstract
Tight regulation of the Na/K pump is essential for cellular function because this heteromeric protein builds and maintains the electrochemical gradients for Na+ and K+ that energize electrical signaling and secondary active transport. We studied the regulation of the ubiquitous human α1β1 pump isoform by five human FXYD proteins normally located in muscle, kidney, and neurons. The function of Na/K pump α1β1 expressed in Xenopus oocytes with or without FXYD isoforms was evaluated using two-electrode voltage clamp and patch clamp. Through evaluation of the partial reactions in the absence of K+ but presence of Na+ in the external milieu, we demonstrate that each FXYD subunit alters the equilibrium between E1P(3Na) and E2P, the phosphorylated conformations with Na+ occluded and free from Na+, respectively, thereby altering the apparent affinity for Na+. This modification of Na+ interaction shapes the small effects of FXYD proteins on the apparent affinity for external K+ at physiological Na+. FXYD6 distinctively accelerated both the Na+-deocclusion and the pump-turnover rates. All FXYD isoforms altered the apparent affinity for intracellular Na+ in patches, an effect that was observed only in the presence of intracellular K+. Therefore, FXYD proteins alter the selectivity of the pump for intracellular ions, an effect that could be due to the altered equilibrium between E1 and E2, the two major pump conformations, and/or to small changes in ion affinities that are exacerbated when both ions are present. Lastly, we observed a drastic reduction of Na/K pump surface expression when it was coexpressed with FXYD1 or FXYD6, with the former being relieved by injection of PKA's catalytic subunit into the oocyte. Our results indicate that a prominent effect of FXYD1 and FXYD6, and plausibly other FXYDs, is the regulation of Na/K pump trafficking.
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Affiliation(s)
- Dylan J Meyer
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Sharan Bijlani
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Marilina de Sautu
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Kerri Spontarelli
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Victoria C Young
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Craig Gatto
- School of Biological Sciences, Illinois State University. Normal, IL
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
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Krag TO, Holm-Yildiz S, Witting N, Vissing J. Autophagy is affected in patients with hypokalemic periodic paralysis: an involvement in vacuolar myopathy? Acta Neuropathol Commun 2021; 9:109. [PMID: 34120654 PMCID: PMC8201813 DOI: 10.1186/s40478-021-01212-8] [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: 04/07/2021] [Accepted: 06/07/2021] [Indexed: 11/18/2022] Open
Abstract
Hypokalemic periodic paralysis is an autosomal dominant, rare disorder caused by variants in the genes for voltage-gated calcium channel CaV1.1 (CACNA1S) and NaV1.4 (SCN4A). Patients with hypokalemic periodic paralysis may suffer from periodic paralysis alone, periodic paralysis co-existing with permanent weakness or permanent weakness alone. Hypokalemic periodic paralysis has been known to be associated with vacuolar myopathy for decades, and that vacuoles are a universal feature regardless of phenotype. Hence, we wanted to investigate the nature and cause of the vacuoles. Fourteen patients with the p.R528H variation in the CACNA1S gene was included in the study. Histology, immunohistochemistry and transmission electron microscopy was used to assess general histopathology, ultrastructure and pattern of expression of proteins related to muscle fibres and autophagy. Western blotting and real-time PCR was used to determine the expression levels of proteins and mRNA of the proteins investigated in immunohistochemistry. Histology and transmission electron microscopy revealed heterogenous vacuoles containing glycogen, fibrils and autophagosomes. Immunohistochemistry demonstrated autophagosomes and endosomes arrested at the pre-lysosome fusion stage. Expression analysis showed a significant decrease in levels of proteins an mRNA involved in autophagy in patients, suggesting a systemic effect. However, activation level of the master regulator of autophagy gene transcription, TFEB, did not differ between patients and controls, suggesting competing control over autophagy gene transcription by nutritional status and calcium concentration, both controlling TFEB activity. The findings suggest that patients with hypokalemic periodic paralysis have disrupted autophagic processing that contribute to the vacuoles seen in these patients.
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10
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Deprez J, Lajoinie G, Engelen Y, De Smedt SC, Lentacker I. Opening doors with ultrasound and microbubbles: Beating biological barriers to promote drug delivery. Adv Drug Deliv Rev 2021; 172:9-36. [PMID: 33705877 DOI: 10.1016/j.addr.2021.02.015] [Citation(s) in RCA: 91] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/01/2021] [Accepted: 02/17/2021] [Indexed: 12/13/2022]
Abstract
Apart from its clinical use in imaging, ultrasound has been thoroughly investigated as a tool to enhance drug delivery in a wide variety of applications. Therapeutic ultrasound, as such or combined with cavitating nuclei or microbubbles, has been explored to cross or permeabilize different biological barriers. This ability to access otherwise impermeable tissues in the body makes the combination of ultrasound and therapeutics very appealing to enhance drug delivery in situ. This review gives an overview of the most important biological barriers that can be tackled using ultrasound and aims to provide insight on how ultrasound has shown to improve accessibility as well as the biggest hurdles. In addition, we discuss the clinical applicability of therapeutic ultrasound with respect to the main challenges that must be addressed to enable the further progression of therapeutic ultrasound towards an effective, safe and easy-to-use treatment tailored for drug delivery in patients.
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Affiliation(s)
- J Deprez
- Ghent Research Group on Nanomedicines, Department of Pharmaceutics, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - G Lajoinie
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
| | - Y Engelen
- Ghent Research Group on Nanomedicines, Department of Pharmaceutics, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - S C De Smedt
- Ghent Research Group on Nanomedicines, Department of Pharmaceutics, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium.
| | - I Lentacker
- Ghent Research Group on Nanomedicines, Department of Pharmaceutics, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent, Belgium
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11
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Renard HF, Boucrot E. Unconventional endocytic mechanisms. Curr Opin Cell Biol 2021; 71:120-129. [PMID: 33862329 DOI: 10.1016/j.ceb.2021.03.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/23/2021] [Accepted: 03/05/2021] [Indexed: 02/06/2023]
Abstract
Endocytosis mediates the uptake of extracellular proteins, micronutrients and transmembrane cell surface proteins. Importantly, many viruses, toxins and bacteria hijack endocytosis to infect cells. The canonical pathway is clathrin-mediated endocytosis (CME) and is active in all eukaryotic cells to support critical house-keeping functions. Unconventional mechanisms of endocytosis exit in parallel of CME, to internalize specific cargoes and support various cellular functions. These clathrin-independent endocytic (CIE) routes use three distinct mechanisms: acute signaling-induced membrane remodeling drives macropinocytosis, activity-dependent bulk endocytosis (ADBE), massive endocytosis (MEND) and EGFR non-clathrin endocytosis (EGFR-NCE). Cargo capture and local membrane deformation by cytosolic proteins is used by fast endophilin-mediated endocytosis (FEME), IL-2Rβ endocytosis and ultrafast endocytosis at synapses. Finally, the formation of endocytic pits by clustering of extracellular lipids or cargoes according to the Glycolipid-Lectin (GL-Lect) hypothesis mediates the uptake of SV40 virus, Shiga and cholera toxins, and galectin-clustered receptors by the CLIC/GEEC and the endophilin-A3-mediated CIE.
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Affiliation(s)
- Henri-François Renard
- Biochemistry and Cellular Biology Research Unit (URBC), Namur Research Institute for Life Science (NARILIS), University of Namur, Rue de Bruxelles 61, B-50000, Namur, Belgium.
| | - Emmanuel Boucrot
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London, WC1E 7HX, UK.
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12
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Woodley KT, Collins MO. Regulation and function of the palmitoyl-acyltransferase ZDHHC5. FEBS J 2021; 288:6623-6634. [PMID: 33415776 DOI: 10.1111/febs.15709] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/19/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023]
Abstract
Protein palmitoylation (S-acylation) has emerged as an important player in a range of cellular processes, and as a result, the palmitoyl-acyltransferase (PAT) enzymes which mediate this modification have entered into the spotlight. Palmitoyltransferase ZDHHC5 (ZDHHC5) is among the more unique members of the PAT family as it is mainly localised to the plasma membrane and contains an extended cytoplasmic domain with several regulatory features. ZDHHC5 plays a vital role in a wide range of processes in different cell types. In this review, we offer a summary of the functions of ZDHHC5 in synaptic plasticity, cardiac function, cell adhesion and fatty acid uptake, among other processes. We also explore recent work has revealed several mechanisms to control the activity, localisation and function of ZDHHC5.
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Affiliation(s)
- Keith T Woodley
- Department of Biomedical Science & Centre for Membrane Interactions and Dynamics (CMIAD), Firth Court, Western Bank, University of Sheffield, UK.,Barts Cancer Institute, John Vane Science Centre, Queen Mary University of London, UK
| | - Mark O Collins
- Department of Biomedical Science & Centre for Membrane Interactions and Dynamics (CMIAD), Firth Court, Western Bank, University of Sheffield, UK
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13
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Tian X, Inoue K, Zhang Y, Wang Y, Sperati CJ, Pedigo CE, Zhao T, Yan M, Groener M, Moledina DG, Ebenezer K, Li W, Zhang Z, Liebermann DA, Greene L, Greer P, Parikh CR, Ishibe S. Inhibiting calpain 1 and 2 in cyclin G associated kinase-knockout mice mitigates podocyte injury. JCI Insight 2020; 5:142740. [PMID: 33208557 PMCID: PMC7710277 DOI: 10.1172/jci.insight.142740] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/08/2020] [Indexed: 12/27/2022] Open
Abstract
Evidence for reduced expression of cyclin G associated kinase (GAK) in glomeruli of patients with chronic kidney disease was observed in the Nephroseq human database, and GAK was found to be associated with the decline in kidney function. To examine the role of GAK, a protein that functions to uncoat clathrin during endocytosis, we generated podocyte-specific Gak-knockout mice (Gak-KO), which developed progressive proteinuria and kidney failure with global glomerulosclerosis. We isolated glomeruli from the mice carrying the mutation to perform messenger RNA profiling and unearthed evidence for dysregulated podocyte calpain protease activity as an important contributor to progressive podocyte damage. Treatment with calpain inhibitor III specifically inhibited calpain-1/-2 activities, mitigated the degree of proteinuria and glomerulosclerosis, and led to a striking increase in survival in the Gak-KO mice. Podocyte-specific deletion of Capns1, essential for calpain-1 and calpain-2 activities, also improved proteinuria and glomerulosclerosis in Gak-KO mice. Increased podocyte calpain activity-mediated proteolysis of IκBα resulted in increased NF-κB p65-induced expression of growth arrest and DNA-damage-inducible 45 beta in the Gak-KO mice. Our results suggest that loss of podocyte-associated Gak induces glomerular injury secondary to calcium dysregulation and aberrant calpain activation, which when inhibited, can provide a protective role.
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MESH Headings
- Animals
- Calpain/antagonists & inhibitors
- Diabetic Nephropathies/etiology
- Diabetic Nephropathies/metabolism
- Diabetic Nephropathies/pathology
- Diabetic Nephropathies/therapy
- Female
- Glomerulosclerosis, Focal Segmental/etiology
- Glomerulosclerosis, Focal Segmental/metabolism
- Glomerulosclerosis, Focal Segmental/pathology
- Glomerulosclerosis, Focal Segmental/therapy
- Humans
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Podocytes/metabolism
- Podocytes/pathology
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Protein Serine-Threonine Kinases/physiology
- Renal Insufficiency, Chronic/etiology
- Renal Insufficiency, Chronic/metabolism
- Renal Insufficiency, Chronic/pathology
- Renal Insufficiency, Chronic/therapy
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Affiliation(s)
- Xuefei Tian
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Yan Zhang
- State Key Laboratory of Organ Failure Research, Southern Medical University, Nanfang Hospital, Guangzhou, China
- Center for Bioinformatics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Ying Wang
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - C. John Sperati
- Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher E. Pedigo
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Tingting Zhao
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Meihua Yan
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Marwin Groener
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Dennis G. Moledina
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Karen Ebenezer
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Wei Li
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Zhenhai Zhang
- State Key Laboratory of Organ Failure Research, Southern Medical University, Nanfang Hospital, Guangzhou, China
- Center for Bioinformatics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Dan A. Liebermann
- Fels Institute of Cancer Research and Molecular Biology and Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania USA
| | - Lois Greene
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Peter Greer
- Queen’s Cancer Research Institute, Kingston, Ontario, Canada
| | - Chirag R. Parikh
- Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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14
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Magi S, Piccirillo S, Preziuso A, Amoroso S, Lariccia V. Mitochondrial localization of NCXs: Balancing calcium and energy homeostasis. Cell Calcium 2020; 86:102162. [DOI: 10.1016/j.ceca.2020.102162] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 01/04/2023]
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15
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Cracking the code of sodium/calcium exchanger (NCX) gating: Old and new complexities surfacing from the deep web of secondary regulations. Cell Calcium 2020; 87:102169. [PMID: 32070925 DOI: 10.1016/j.ceca.2020.102169] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 12/14/2022]
Abstract
Cell membranes spatially define gradients that drive the complexity of biological signals. To guarantee movements and exchanges of solutes between compartments, membrane transporters negotiate the passages of ions and other important molecules through lipid bilayers. The Na+/Ca2+ exchangers (NCXs) in particular play central roles in balancing Na+ and Ca2+ fluxes across diverse proteolipid borders in all eukaryotic cells, influencing cellular functions and fate by multiple means. To prevent progression from balance to disease, redundant regulatory mechanisms cooperate at multiple levels (transcriptional, translational, and post-translational) and guarantee that the activities of NCXs are finely-tuned to cell homeostatic requirements. When this regulatory network is disturbed by pathological forces, cells may approach the end of life. In this review, we will discuss the main findings, controversies and open questions about regulatory mechanisms that control NCX functions in health and disease.
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16
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Offringa-Hup A. INAD and Duchenne muscular dystrophy, two ends of the iPLA2β spectrum. Med Hypotheses 2020; 137:109589. [PMID: 32006920 DOI: 10.1016/j.mehy.2020.109589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/21/2019] [Accepted: 01/21/2020] [Indexed: 11/30/2022]
Abstract
Infantile neuroaxonal dystrophy (INAD) and Duchenne muscular dystrophy (DMD) are two deadly neuromuscular degenerative diseases of childhood. Knowledge on their pathophysiological mechanisms may direct us towards treatment or a cure. Although these diseases are caused by two totally different gene-mutations and cause different clinical pictures, in this article I propose a common disease mechanism in the two. This common mechanism is induced by defects in the response to cellular stress and injury. THE HYPOTHESIS: Depletion of iPLA2β in INAD and increased activity of iPLA2β in DMD eventually lead to similar defects in the response to cell stress and injury. According to this hypothesis, the depletion of iPLA2β in INAD primarily blocks repair mechanisms by the inability to form a mitochondrial permeability transition pore (PTP). Forming of the PTP is necessary to release mitochondrial coenzyme A (CoA) into the cytoplasm for activation of palmitoylation and massive endocytosis as a repair response. In DMD the increased activity of iPLA2β causes exhaustion of the stress signalling cascade by increased and prolonged PTP opening. Continuous leaking of mitochondrial CoA through the PTP leads to the inability of the cell to build a sufficient mitochondrial:cytoplasmic CoA gradient, also causing insufficient release of mitochondrial CoA as a response to cell stress and injury. Decreased palmitoylation capacity and decreased endocytosis and membrane remodelling are implicated in proven pathophysiological mechanisms in INAD and DMD. The described mechanism in INAD and DMD, may be considered a common mechanism of repair in case of cell stress and injury. Beside their role in INAD and DMD, they may therefore be implicated in other neurodegenerative diseases as well. Available research shows involvement of iPLA2β in other neurodegenerative diseases. We might be able to divide neurodegenerative diseases in "INAD-like disease-mechanism" or "DMD-like disease-mechanism", depending on decreased or increased iPLA2β activity.
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17
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Gök C, Fuller W. Regulation of NCX1 by palmitoylation. Cell Calcium 2020; 86:102158. [PMID: 31935590 DOI: 10.1016/j.ceca.2019.102158] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/28/2019] [Accepted: 12/29/2019] [Indexed: 11/17/2022]
Abstract
Palmitoylation (S-acylation) is the reversible conjugation of a fatty acid (usually C16 palmitate) to intracellular cysteine residues of proteins via a thioester linkage. Palmitoylation anchors intracellular regions of proteins to membranes because the palmitoylated cysteine is recruited to the lipid bilayer. NCX1 is palmitoylated at a single cysteine in its large regulatory intracellular loop. The presence of an amphipathic α-helix immediately adjacent to the NCX1 palmitoylation site is required for NCX1 palmitoylation. The NCX1 palmitoylation site is conserved through most metazoan phlya. Although palmitoylation does not regulate the normal forward or reverse ion transport modes of NCX1, NCX1 palmitoylation is required for its inactivation: sodium-dependent inactivation and inactivation by PIP2 depletion are significantly impaired for unpalmitoylatable NCX1. Here we review the role of palmitoylation in regulating NCX1 activity, and highlight future questions that must be addressed to fully understand the importance of this regulatory mechanism for sodium and calcium transport in cardiac muscle.
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Affiliation(s)
- Caglar Gök
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - William Fuller
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK. https://twitter.com@FullerLabGlas
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18
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Offringa-Hup A. Alzheimer's disease: The derailed repair hypothesis. Med Hypotheses 2019; 136:109516. [PMID: 31825804 DOI: 10.1016/j.mehy.2019.109516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/27/2019] [Accepted: 11/30/2019] [Indexed: 11/25/2022]
Abstract
A lot of research has been done on Alzheimer's disease, especially focused on factors like amyloid beta, ApoE and tau-protein. However, a complete theory on the disease mechanism of AD, including and connecting all known pathological elements of AD in a conceivable context and order of occurrence, is still lacking. In this article I describe a hypothesis on the entire pathophysiology of Alzheimer's disease, based on the most wellknown pathological elements in AD, filling the gaps with hypothetical mechanisms. This proposed mechanism of derailed repair starts with an insufficiently increased level of injury signalling in the axon by ApoE, DLK, APP, BACE-1, Aβ and iPLA2β, followed by an excessive repair response induced by opening of the mitochondrial permeability transition pore, release of mitochondrial CoA and activation of palmitoylation and massive endocytosis. Excessive compounds, associated with injury signalling and repair, start to accumulate, adding to axonal injury. This increased activation of the repair mechanism causes exhaustion of the repair response by lack of mitochondrial CoA. A vicious circle of increased injury signalling and insufficient repair ensues. Based on this hypothesis, I propose possible markers for early diagnosis and disease-modifying treatments for Alzheimer's disease.
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19
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Scranton K, John S, Escobar A, Goldhaber JI, Ottolia M. Modulation of the cardiac Na +-Ca 2+ exchanger by cytoplasmic protons: Molecular mechanisms and physiological implications. Cell Calcium 2019; 87:102140. [PMID: 32070924 DOI: 10.1016/j.ceca.2019.102140] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/06/2019] [Accepted: 12/07/2019] [Indexed: 01/31/2023]
Abstract
A precise temporal and spatial control of intracellular Ca2+ concentration is essential for a coordinated contraction of the heart. Following contraction, cardiac cells need to rapidly remove intracellular Ca2+ to allow for relaxation. This task is performed by two transporters: the plasma membrane Na+-Ca2+ exchanger (NCX) and the sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA). NCX extrudes Ca2+ from the cell, balancing the Ca2+entering the cytoplasm during systole through L-type Ca2+ channels. In parallel, following SR Ca2+ release, SERCA activity replenishes the SR, reuptaking Ca2+ from the cytoplasm. The activity of the mammalian exchanger is fine-tuned by numerous ionic allosteric regulatory mechanisms. Micromolar concentrations of cytoplasmic Ca2+ potentiate NCX activity, while an increase in intracellular Na+ levels inhibits NCX via a mechanism known as Na+-dependent inactivation. Protons are also powerful inhibitors of NCX activity. By regulating NCX activity, Ca2+, Na+ and H+ couple cell metabolism to Ca2+ homeostasis and therefore cardiac contractility. This review summarizes the recent progress towards the understanding of the molecular mechanisms underlying the ionic regulation of the cardiac NCX with special emphasis on pH modulation and its physiological impact on the heart.
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Affiliation(s)
- Kyle Scranton
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Scott John
- Department of Medicine (Cardiology), UCLA, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, UCLA, Los Angeles, CA 90095, USA
| | - Ariel Escobar
- Department of Bioengineering, School of Engineering, UC Merced, Merced, CA 95343, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Michela Ottolia
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, UCLA, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, UCLA, Los Angeles, CA 90095, USA.
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20
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Targeted enhancement of flotillin-dependent endocytosis augments cellular uptake and impact of cytotoxic drugs. Sci Rep 2019; 9:17768. [PMID: 31780775 PMCID: PMC6882852 DOI: 10.1038/s41598-019-54062-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 11/07/2019] [Indexed: 12/23/2022] Open
Abstract
Cellular uptake is limiting for the efficacy of many cytotoxic drugs used to treat cancer. Identifying endocytic mechanisms that can be modulated with targeted, clinically-relevant interventions is important to enhance the efficacy of various cancer drugs. We identify that flotillin-dependent endocytosis can be targeted and upregulated by ultrasound and microbubble (USMB) treatments to enhance uptake and efficacy of cancer drugs such as cisplatin. USMB involves targeted ultrasound following administration of encapsulated microbubbles, used clinically for enhanced ultrasound image contrast. USMB treatments robustly enhanced internalization of the molecular scaffold protein flotillin, as well as flotillin-dependent fluid-phase internalization, a phenomenon dependent on the protein palmitoyltransferase DHHC5 and the Src-family kinase Fyn. USMB treatment enhanced DNA damage and cell killing elicited by the cytotoxic agent cisplatin in a flotillin-dependent manner. Thus, flotillin-dependent endocytosis can be modulated by clinically-relevant USMB treatments to enhance drug uptake and efficacy, revealing an important new strategy for targeted drug delivery for cancer treatment.
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21
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Corrotte M, Castro-Gomes T. Lysosomes and plasma membrane repair. CURRENT TOPICS IN MEMBRANES 2019; 84:1-16. [PMID: 31610859 DOI: 10.1016/bs.ctm.2019.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ability of repairing damages on the plasma membrane is crucial for cell survival. When damaged, eukaryotic cells are able to recover plasma membrane integrity within a few seconds, thus avoiding cytoplasm leakage and cell death. The process is driven by the influx of extracellular calcium which triggers a multitude of intracellular effects that participate in the process of plasma membrane resealing. One of the landmarks of plasma membrane repair is the triggering of intracellular vesicles recruitment and their exocytosis at damage sites. Since lysosomes are able to respond to calcium influx and that some of the lysosomal enzymes exocytosed after plasma membrane permeabilization are essential to restore cell integrity, these organelles have emerged as essential for the maintenance of plasma membrane integrity. Here we summarize the scientific evidences showing the involvement of lysosomes in plasma membrane repair that allowed researchers to propose a totally different function for this famous organelle.
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Affiliation(s)
- Matthias Corrotte
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Thiago Castro-Gomes
- Department of Parasitology, Federal University of Minas Gerais, Belo Horizonte, Brazil.
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22
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Roovers S, Segers T, Lajoinie G, Deprez J, Versluis M, De Smedt SC, Lentacker I. The Role of Ultrasound-Driven Microbubble Dynamics in Drug Delivery: From Microbubble Fundamentals to Clinical Translation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10173-10191. [PMID: 30653325 DOI: 10.1021/acs.langmuir.8b03779] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size and physicochemistry of the bubble shell) that play a key role in microbubble-cell interactions and in the associated therapeutic outcome. Additionally, new techniques that may provide additional control over the treatment, such as monodisperse microbubble formulations, tunable ultrasound scanners, and cavitation detection techniques, are discussed. An in-depth understanding of the aspects presented in this work could eventually lead the way to more efficient and tailored microbubble-assisted ultrasound therapy in the future.
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Affiliation(s)
- Silke Roovers
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Tim Segers
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Guillaume Lajoinie
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Joke Deprez
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Michel Versluis
- Physics of Fluids Group, MESA+ Institute for Nanotechnology and Technical Medical (TechMed) Center , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Stefaan C De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
| | - Ine Lentacker
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicine, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , Ghent , Belgium
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23
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Escoffre JM, Bouakaz A. Minireview: Biophysical Mechanisms of Cell Membrane Sonopermeabilization. Knowns and Unknowns. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10151-10165. [PMID: 30525655 DOI: 10.1021/acs.langmuir.8b03538] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Microbubble-assisted ultrasound has emerged as a promising method for the delivery of low-molecular-weight chemotherapeutic molecules, nucleic acids, therapeutic peptides, and antibodies in vitro and in vivo. Its clinical applications are under investigation for local delivery drug in oncology and neurology. However, the biophysical mechanisms supporting the acoustically mediated membrane permeabilization are not fully established. This review describes the present state of the investigations concerning the acoustically mediated stimuli (i.e., mechanical, chemical, and thermal stimuli) as well as the molecular and cellular actors (i.e., membrane pores and endocytosis) involved in the reversible membrane permeabilization process. The different hypotheses, which were proposed to give a biophysical description of the membrane permeabilization, are critically discussed.
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Affiliation(s)
- Jean-Michel Escoffre
- UMR 1253, iBrain, Université de Tours, Inserm , 10 bd Tonnellé , 37032 Tours Cedex 1, France
| | - Ayache Bouakaz
- UMR 1253, iBrain, Université de Tours, Inserm , 10 bd Tonnellé , 37032 Tours Cedex 1, France
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24
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Kim H, Kang JY, Mun D, Yun N, Joung B. Calcium chloride enhances the delivery of exosomes. PLoS One 2019; 14:e0220036. [PMID: 31329632 PMCID: PMC6645520 DOI: 10.1371/journal.pone.0220036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 07/07/2019] [Indexed: 12/21/2022] Open
Abstract
Exosomes might have an unimproved potential to serve as effective delivery vehicles. However, when exosomes are developed for therapeutic applications, a method to enhance their delivery is important. This study aimed to evaluate wheather calcium chloride (CaCl2) or other chloride compounds could enhance exosome delivery to various cells without causing toxicity. Exosomes were purified from human serum by using the ExoQuick exosome precipitation kit. Isolated exosomes were mixed with CaCl2 at concentrations ranging from 100 μM to 1 mM, and then washed using Amicon filter for treating the cells. The delivery efficiency of exosomes and the viability of the cells [HEK 293 (human kidney cells) and H9C2 (rat cardiomyocytes)] were evaluated. Cellular uptake of exosomes was observed using a confocal microscope based on PKH26 labeling of exosomes. CaCl2 increased the delivery of exosomes in a dose- and treatment time-dependent manner. In HEK 293 cells, a CaCl2 concentration of 400 μM and exposure time of 12 h increased the delivery of exosomes by >20 times compared with controls. In H9C2 cells, a CaCl2 concentration of 400 μM and exposure time of >24 h increased the delivery of exosomes by >400 times compared with controls. The viability of both cell lines was maintained up to a CaCl2 concentration of 1 mM. However, cobalt chloride, cupric chloride, and magnesium chloride did not change the delivery of exosomes in both cell lines. These results suggest that the use of CaCl2 treatment might be a useful method for enhancing the delivery of exosomes.
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Affiliation(s)
- Hyoeun Kim
- Division of Cardiology, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, Republic of Korea
| | - Ji-Young Kang
- Division of Cardiology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Dasom Mun
- Division of Cardiology, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, Republic of Korea
| | - Nuri Yun
- Institute of Life Science & Biotechnology Yonsei University, Seoul, Republic of Korea
- * E-mail: (BYJ); (NRY)
| | - Boyoung Joung
- Division of Cardiology, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, Republic of Korea
- * E-mail: (BYJ); (NRY)
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25
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Hilgemann DW, Lin MJ, Fine M, Deisl C. On the existence of endocytosis driven by membrane phase separations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183007. [PMID: 31202864 DOI: 10.1016/j.bbamem.2019.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/31/2019] [Accepted: 06/06/2019] [Indexed: 01/15/2023]
Abstract
Large endocytic responses can occur rapidly in diverse cell types without dynamins, clathrin, or actin remodeling. Our experiments suggest that membrane phase separations are crucial with more ordered plasma membrane domains being internalized. Not only do these endocytic processes rely on coalescence of membrane domains, they are promoted by participation of membrane proteins in such domains, one important regulatory influence being palmitoylation. Membrane actin cytoskeleton in general resists membrane phase transitions, and its remodeling may play many roles. Besides membrane 'caging' and 'pinching' roles, typically ascribed to clathrin and dynamins, cytoskeleton remodeling may modify local membrane tension and buckling, as well as the presence and location of actin- and tension-free membrane patches. Endocytosis that depends on membrane phase separations becomes activated in metabolic stress and in response to Ca and PI3 kinase signaling. Internalized membrane traffics normally, and the secretory pathway eventually resupplies membrane to the plasmalemma or directs internalized membrane to other locations, including the extracellular space as exosomes. We describe here that endocytosis driven by membrane phase transitions is regulated by the same signaling mechanisms that regulate macropinocytosis, and it may play diverse roles in cells from nutrient assimilation to membrane recycling, cell migration, and the initiation of quiescent or hibernating cell states. Membrane ordering and phase separations have been shown to promote endocytosis in diverse cell types, including fibroblasts, myocytes, glial cells, and immune cells. We propose that clathrin/dynamin-independent endocytosis represents a continuum of related mechanisms with variable but universal dependence on membrane ordering and actin remodeling. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
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Affiliation(s)
- Donald W Hilgemann
- University of Texas Southwestern Medical Center, Department of Physiology, 5323 Harry Hines Boulevard, Dallas, TX 75235-9040, USA.
| | - Mei-Jung Lin
- University of Texas Southwestern Medical Center, Department of Physiology, 5323 Harry Hines Boulevard, Dallas, TX 75235-9040, USA
| | - Michael Fine
- University of Texas Southwestern Medical Center, Department of Physiology, 5323 Harry Hines Boulevard, Dallas, TX 75235-9040, USA
| | - Christine Deisl
- University of Texas Southwestern Medical Center, Department of Physiology, 5323 Harry Hines Boulevard, Dallas, TX 75235-9040, USA
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26
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Goldshtein M, Shamir S, Vinogradov E, Monsonego A, Cohen S. Co-assembled Ca 2+ Alginate-Sulfate Nanoparticles for Intracellular Plasmid DNA Delivery. MOLECULAR THERAPY. NUCLEIC ACIDS 2019; 16:378-390. [PMID: 31003172 PMCID: PMC6475713 DOI: 10.1016/j.omtn.2019.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 12/28/2022]
Abstract
Successful gene therapy requires the development of suitable carriers for the selective and efficient delivery of genes to specific target cells, with minimal toxicity. In this work, we present a non-viral vector for gene delivery composed of biocompatible materials, CaCl2, plasmid DNA and the semi-synthetic anionic biopolymer alginate sulfate (AlgS), which spontaneously co-assembled to form nanoparticles (NPs). The NPs were characterized with a slightly anionic surface charge (Zeta potential [ζ] = -14 mV), an average size of 270 nm, and their suspension was stable for several days with no aggregation. X-ray photoelectron spectroscopy (XPS) validated their ternary composition, and it elucidated the molecular interactions among Ca2+, the plasmid DNA, and the AlgS. Efficient cellular uptake (>80%), associated with potent GFP gene expression (22%-35%), was observed across multiple cell types: primary rat neonatal cardiac fibroblasts, human breast cancer cell line, and human hepatocellular carcinoma cells. The uptake mechanism of the NPs was studied using imaging flow cytometry and shown to be via active, clathrin-mediated endocytosis, as chemical inhibition of this pathway significantly reduced EGFP expression. The NPs were cytocompatible and did not activate the T lymphocytes in human peripheral blood mononuclear cells. Proof of concept for the efficacy of these NPs as a carrier in cancer gene therapy was demonstrated for Diphtheria Toxin Fragment A (DT-A), resulting in abrogation of protein synthesis and cell death in the human breast cancer cell line. Collectively, our results show that the developed AlgS-Ca2+-plasmid DNA (pDNA) NPs may be used as an effective non-viral carrier for pDNA.
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Affiliation(s)
- Matan Goldshtein
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Stav Shamir
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Ekaterina Vinogradov
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, The National Institute of Biotechnology in the Negev, and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Alon Monsonego
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, The National Institute of Biotechnology in the Negev, and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel; Regenerative Medicine and Stem Cell (RMSC) Research Center, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Smadar Cohen
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel; Regenerative Medicine and Stem Cell (RMSC) Research Center, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel; The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
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Magi S, Piccirillo S, Amoroso S. The dual face of glutamate: from a neurotoxin to a potential survival factor-metabolic implications in health and disease. Cell Mol Life Sci 2019; 76:1473-1488. [PMID: 30599069 PMCID: PMC11105246 DOI: 10.1007/s00018-018-3002-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/12/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system. Beyond this function, glutamate also plays a key role in intermediary metabolism in all organs and tissues, linking carbohydrate and amino acid metabolism via the tricarboxylic acid cycle. Under both physiological and pathological conditions, we have recently found that the ability of glutamate to fuel cell metabolism selectively relies on the activity of two main transporters: the sodium-calcium exchanger (NCX) and the sodium-dependent excitatory amino-acid transporters (EAATs). In ischemic settings, when glutamate is administered at the onset of the reoxygenation phase, the coordinate activity of EAAT and NCX allows glutamate to improve cell viability by stimulating ATP production. So far, this phenomenon has been observed in both cardiac and neuronal models. In this review, we focus on the most recent findings exploring the unusual activity of glutamate as a potential survival factor in different settings.
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Affiliation(s)
- Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy.
| | - Silvia Piccirillo
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
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28
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Lariccia V, Macrì ML, Matteucci A, Maiolino M, Amoroso S, Magi S. Effects of ticagrelor on the sodium/calcium exchanger 1 (NCX1) in cardiac derived H9c2 cells. Eur J Pharmacol 2019; 850:158-166. [PMID: 30721704 DOI: 10.1016/j.ejphar.2019.01.067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 01/08/2019] [Accepted: 01/17/2019] [Indexed: 12/15/2022]
Abstract
Ticagrelor is a direct acting and reversibly binding P2Y12 antagonist approved for the prevention of thromboembolic events. Clinical effects of ticagrelor cannot be simply accounted for by pure platelet inhibition, and off-target mechanisms can potentially play a role. In particular, recent evidence suggests that ticagrelor may also influence heart function and improve the evolution of myocardial ischemic injury by more direct effects on myocytes. The cardiac sodium/calcium exchanger 1 (NCX1) is a critical player in the generation and control of calcium (Ca2+) signals, which orchestrate multiple myocyte activities in health and disease. Altered expression and/or activity of NCX1 can have profound consequences for the function and fate of myocytes. Whether ticagrelor affects cardiac NCX1 has not been investigated yet. To explore this hypothesis, we analyzed the expression, localization and activity of NCX1 in the heart derived H9c2-NCX1 cells following ticagrelor exposure. We found that ticagrelor concentration- and time-dependently reduced the activity of the cardiac NCX1 in H9c2 cells. In particular, the inhibitory effect of ticagrelor on the Ca2+-influx mode of NCX1 was evident within 1 h and further developed after 24 h, when NCX1 activity was suppressed by about 55% in cells treated with 1 μM ticagrelor. Ticagrelor-induced inhibition of exchanger activity was reached at clinically relevant concentrations, without affecting the expression levels and subcellular distribution of NCX1. Collectively, these findings suggest that cardiac NCX1 is a new downstream target of ticagrelor, which may contribute to the therapeutic profile of ticagrelor in clinical practice.
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Affiliation(s)
- Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy.
| | - Maria Loredana Macrì
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy
| | - Alessandra Matteucci
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy
| | - Marta Maiolino
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126 Ancona, Italy
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Bricogne C, Fine M, Pereira PM, Sung J, Tijani M, Wang Y, Henriques R, Collins MK, Hilgemann DW. TMEM16F activation by Ca 2+ triggers plasma membrane expansion and directs PD-1 trafficking. Sci Rep 2019; 9:619. [PMID: 30679690 PMCID: PMC6345885 DOI: 10.1038/s41598-018-37056-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/03/2018] [Indexed: 12/22/2022] Open
Abstract
TMEM16F is a Ca2+ -gated ion channel that is required for Ca2+ -activated phosphatidylserine exposure on the surface of many eukaryotic cells. TMEM16F is widely expressed and has roles in platelet activation during blood clotting, bone formation and T cell activation. By combining microscopy and patch clamp recording we demonstrate that activation of TMEM16F by Ca2+ ionophores in Jurkat T cells triggers large-scale surface membrane expansion in parallel with phospholipid scrambling. With continued ionophore application,TMEM16F-expressing cells then undergo extensive shedding of ectosomes. The T cell co-receptor PD-1 is selectively incorporated into ectosomes. This selectivity depends on its transmembrane sequence. Surprisingly, cells lacking TMEM16F not only fail to expand surface membrane in response to elevated cytoplasmic Ca2+, but instead undergo rapid massive endocytosis with PD-1 internalisation. These results establish a new role for TMEM16F as a regulator of Ca2+ activated membrane trafficking.
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Affiliation(s)
| | - Michael Fine
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, Texas, USA
| | - Pedro M Pereira
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St, London, UK
| | - Julia Sung
- National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Herts, UK
| | - Maha Tijani
- National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Herts, UK
| | - Youxue Wang
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, Texas, USA
| | - Ricardo Henriques
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St, London, UK
| | - Mary K Collins
- UCL Cancer Institute, University College London, Gower St, London, UK.
- National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Herts, UK.
- Okinawa Institute of Science and Technology, Onna-son, Okinawa, Japan.
| | - Donald W Hilgemann
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, Texas, USA.
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Glutamate as a potential "survival factor" in an in vitro model of neuronal hypoxia/reoxygenation injury: leading role of the Na +/Ca 2+ exchanger. Cell Death Dis 2018; 9:731. [PMID: 29955038 PMCID: PMC6023866 DOI: 10.1038/s41419-018-0784-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/04/2018] [Accepted: 06/11/2018] [Indexed: 12/23/2022]
Abstract
In brain ischemia, reduction in oxygen and substrates affects mitochondrial respiratory chain and aerobic metabolism, culminating in ATP production impairment, ionic imbalance, and cell death. The restoration of blood flow and reoxygenation are frequently associated with exacerbation of tissue injury, giving rise to ischemia/reperfusion (I/R) injury. In this setting, the imbalance of brain bioenergetics induces important metabolic adaptations, including utilization of alternative energy sources, such as glutamate. Although glutamate has long been considered as a neurotoxin, it can also be used as intermediary metabolite for ATP synthesis, and both the Na+/Ca2+ exchanger (NCX) and the Na+-dependent excitatory amino-acid transporters (EAATs) are essential in this pathway. Here we analyzed the role of NCX in the potential of glutamate to improve metabolism and survival of neuronal cells subjected to hypoxia/reoxygenation (H/R). In SH-SY5Y neuroblastoma cells differentiated into a neuron-like state, H/R produced a significant cell damage, a decrease in ATP cellular content, and intracellular Ca2+ alterations. Exposure to glutamate at the onset of the reoxygenation phase attenuated H/R-induced cell damage and evoked a significant raise in intracellular ATP levels. Furthermore, we found that in H/R cells NCX reverse-mode activity was reduced, and that glutamate limited such reduction. All the effects induced by glutamate supplementation were lost when cells were transfected with small interfering RNA against NCX1 and EAAT3, suggesting the need of a specific functional interplay between these proteins for glutamate-induced protection. Collectively, our results revealed the potential beneficial effect of glutamate in an in vitro model of H/R injury and focused on the essential role exerted by NCX1. Although preliminary, these findings could be a starting point to further investigate in in vivo systems such protective effect in ischemic settings, shedding a new light on the classical view of glutamate as detrimental factor.
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31
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Ghezzi C, Calmettes G, Morand P, Ribalet B, John S. Real-time imaging of sodium glucose transporter (SGLT1) trafficking and activity in single cells. Physiol Rep 2018; 5:5/3/e13062. [PMID: 28193781 PMCID: PMC5309568 DOI: 10.14814/phy2.13062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/07/2016] [Indexed: 01/12/2023] Open
Abstract
The processes controlling targeting of glucose transporters to apical and basolateral membranes of polarized cells are complex and not-well understood. We have engineered SGLT1 and GLUT4 constructs linked to fluorescent proteins to highlight the differences in transporter expression and trafficking, in real time, in different cell types. Activity was assessed in parallel using a FRET glucose sensor. In COS cells and HEK cells, SGLT1 was distributed between the plasma membrane and intracellular compartments, but there was little expression in CHO cells. Trafficking was investigated using the lysosome inhibitors NH4Cl (10 mmol/L) and chloroquine (150 μmol/L) and the proteasome inhibitors MG-262 (1 μmol/L) and lactacystin (5 μmol/L). Lysosome inhibitors caused SGLT1 accumulation into intracellular bodies, whereas proteasome inhibitors induced SGLT1 accumulation in the plasma membrane, even in CHO cells. Our data suggest that a fraction of SGLT1 is rapidly degraded by lysosomes and never reached the plasma membrane; another fraction reaches the membrane and is subsequently degraded by lysosomes following internalization. The latter process is regulated by the ubiquitin/proteasome pathway, acting at a late stage of the lysosomal pathway. Using the cholesterol inhibitor MβCD (3 mmol/L), a dominant negative dynamin (K44A) and caveolin, we showed that SGLT1 internalization is lipid raft-mediated, but caveolin-independent. In contrast, GLUT4 internalization is dynamin-dependent, but cholesterol-independent. The physiological relevance of these data is discussed in terms of differential membrane compartmentalization of the transporters and expression under stress conditions.
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Affiliation(s)
- Chiara Ghezzi
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Guillaume Calmettes
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Pauline Morand
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Bernard Ribalet
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Scott John
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
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32
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Barthélémy F, Defour A, Lévy N, Krahn M, Bartoli M. Muscle Cells Fix Breaches by Orchestrating a Membrane Repair Ballet. J Neuromuscul Dis 2018; 5:21-28. [PMID: 29480214 PMCID: PMC5836414 DOI: 10.3233/jnd-170251] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Skeletal muscle undergoes many micro-membrane lesions at physiological state. Based on their sizes and magnitude these lesions are repaired via different complexes on a specific spatio-temporal manner. One of the major repair complex is a dysferlin-dependent mechanism. Accordingly, mutations in the DYSF gene encoding dysferlin results in the development of several muscle pathologies called dysferlinopathies, where abnormalities of the membrane repair process have been characterized in patients and animal models. Recent efforts have been deployed to decipher the function of dysferlin, they shed light on its direct implication in sarcolemma resealing after injuries. These discoveries served as a strong ground to design therapeutic approaches for dysferlin-deficient patients. This review detailed the different partners and function of dysferlin and positions the sarcolemma repair in normal and pathological conditions.
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Affiliation(s)
- Florian Barthélémy
- Microbiology Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA.,Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA, USA
| | - Aurélia Defour
- Aix Marseille University, MMG, INSERM, Marseille, France
| | - Nicolas Lévy
- Aix Marseille University, MMG, INSERM, Marseille, France
| | - Martin Krahn
- Aix Marseille University, MMG, INSERM, Marseille, France
| | - Marc Bartoli
- Aix Marseille University, MMG, INSERM, Marseille, France
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33
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Lariccia V, Amoroso S. Calcium- and ATP-dependent regulation of Na/Ca exchange function in BHK cells: Comparison of NCX1 and NCX3 exchangers. Cell Calcium 2018; 73:95-103. [PMID: 29705719 DOI: 10.1016/j.ceca.2018.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 04/16/2018] [Indexed: 12/27/2022]
Abstract
Na+/Ca2+ exchangers (NCX) mediate bidirectional Ca2+ fluxes across cell membranes and contribute to Ca2+ homeostasis in many cell types. Exchangers are regulated by gating reactions that depend on Na+ and Ca2+ binding to transport and regulatory sites. A Na+i-dependent inactivation is prominent in all isoforms, whereas Ca2+i-dependent regulation varies among isoforms. Here we characterize new details of NCX operation and describe differences and similarities between NCX3 and NCX1 regulation by intracellular Ca2+ and ATP. To compare isoforms, we employed BHK cells expressing NCX3 or NCX1 constitutively and exchange activity was analysed in whole-cell and excised patch recordings under "zero-trans" conditions (i.e., with only one transported ion species on each side). Using BHK cells with low cytoplasmic Ca2+ buffering, outward (reverse) currents, reflecting Ca2+ influx, are activated by applying extracellular Ca2+ (Cao) in the presence of Na+ on the cytoplasmic side. When firstly activated, peak outward NCX3 currents rapidly decay over seconds and then typically develop a secondary transient peak with slower kinetics, until Cao removal abolishes all outward current. The delayed rise of outward current is the signature of an activating process since peak outward NCX3 currents elicited at subsequent Cao bouts remain stimulated for minutes and slower decline towards a non-zero level during continued Cao application. Secondary transient peaks and current stimulation are suppressed by increasing the intracellular Ca2+ buffer capacity or by replacing cytoplasmic ATP with the analogues AMP-PNP or ATPγS. In BHK cells expressing NCX1, outward currents activated under identical settings decay to a steady-state level during single Cao application and are significantly larger, causing strong and long-lived run down of subsequent outward currents. NCX1 current run down is not prevented by increasing cytoplasmic Ca2+ buffering but secondary transient peaks in the outward current profile can be resolved in the presence of ATP. Finally, inward currents recorded in patches excised from NCX3-expressing cells reveal a proteolysis-sensitive, Ca-dependent inactivation process that is unusual for NCX1 forward activity. Together, our results suggest that NCX function is regulated more richly than appreciated heretofore, possibly including processes that are lost in excised membrane patches.
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Affiliation(s)
- Vincenzo Lariccia
- Department of Biomedical Science and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Salvatore Amoroso
- Department of Biomedical Science and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
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35
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Sommer AK, Hermawan A, Mickler FM, Ljepoja B, Knyazev P, Bräuchle C, Ullrich A, Wagner E, Roidl A. Salinomycin co-treatment enhances tamoxifen cytotoxicity in luminal A breast tumor cells by facilitating lysosomal degradation of receptor tyrosine kinases. Oncotarget 2018; 7:50461-50476. [PMID: 27409163 PMCID: PMC5226596 DOI: 10.18632/oncotarget.10459] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 06/17/2016] [Indexed: 11/25/2022] Open
Abstract
Luminal A breast cancer is the most common breast cancer subtype which is usually treated with selective estrogen receptor modulators (SERMS) like tamoxifen. Nevertheless, one third of estrogen receptor positive breast cancer patients initially do not respond to endocrine therapy and about 40% of luminal A breast tumors recur in five years. In this study, we investigated an alternative treatment approach by combining tamoxifen and salinomycin in luminal A breast cancer cell lines. We have found that salinomycin induces an additional cytotoxic effect by inhibiting the ligand independent activation of ERα. Thereby salinomycin increases the intracellular calcium level. This leads to a premature fusion of endosomes with lysosomes and thus to the degradation of Egfr family members. Since this process is essential for luminal A breast cancer cells to circumvent tamoxifen treatment, the combination of both drugs induces cytotoxicity in tamoxifen sensitive as well as resistant luminal A breast cancer cell lines.
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Affiliation(s)
- Ann-Katrin Sommer
- Pharmaceutical Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany.,Department of Molecular Biology, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Adam Hermawan
- Pharmaceutical Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Frauke Martina Mickler
- Physical Chemistry, Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Bojan Ljepoja
- Pharmaceutical Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Pjotr Knyazev
- Department of Molecular Biology, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Christoph Bräuchle
- Physical Chemistry, Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Axel Ullrich
- Department of Molecular Biology, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Ernst Wagner
- Pharmaceutical Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Andreas Roidl
- Pharmaceutical Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
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36
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Howie J, Wypijewski KJ, Plain F, Tulloch LB, Fraser NJ, Fuller W. Greasing the wheels or a spanner in the works? Regulation of the cardiac sodium pump by palmitoylation. Crit Rev Biochem Mol Biol 2018; 53:175-191. [PMID: 29424237 DOI: 10.1080/10409238.2018.1432560] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The ubiquitous sodium/potassium ATPase (Na pump) is the most abundant primary active transporter at the cell surface of multiple cell types, including ventricular myocytes in the heart. The activity of the Na pump establishes transmembrane ion gradients that control numerous events at the cell surface, positioning it as a key regulator of the contractile and metabolic state of the myocardium. Defects in Na pump activity and regulation elevate intracellular Na in cardiac muscle, playing a causal role in the development of cardiac hypertrophy, diastolic dysfunction, arrhythmias and heart failure. Palmitoylation is the reversible conjugation of the fatty acid palmitate to specific protein cysteine residues; all subunits of the cardiac Na pump are palmitoylated. Palmitoylation of the pump's accessory subunit phospholemman (PLM) by the cell surface palmitoyl acyl transferase DHHC5 leads to pump inhibition, possibly by altering the relationship between the pump catalytic α subunit and specifically bound membrane lipids. In this review, we discuss the functional impact of PLM palmitoylation on the cardiac Na pump and the molecular basis of recognition of PLM by its palmitoylating enzyme DHHC5, as well as effects of palmitoylation on Na pump cell surface abundance in the cardiac muscle. We also highlight the numerous unanswered questions regarding the cellular control of this fundamentally important regulatory process.
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Affiliation(s)
- Jacqueline Howie
- a Institute of Cardiovascular and Medical Sciences , University of Glasgow , Glasgow , UK
| | | | - Fiona Plain
- b Molecular and Clinical Medicine , University of Dundee , Dundee , UK
| | - Lindsay B Tulloch
- b Molecular and Clinical Medicine , University of Dundee , Dundee , UK
| | - Niall J Fraser
- b Molecular and Clinical Medicine , University of Dundee , Dundee , UK
| | - William Fuller
- a Institute of Cardiovascular and Medical Sciences , University of Glasgow , Glasgow , UK
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Hilgemann DW, Dai G, Collins A, Lariccia V, Magi S, Deisl C, Fine M. Lipid signaling to membrane proteins: From second messengers to membrane domains and adapter-free endocytosis. J Gen Physiol 2018; 150:211-224. [PMID: 29326133 PMCID: PMC5806671 DOI: 10.1085/jgp.201711875] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hilgemann et al. explain how lipid signaling to membrane proteins involves a hierarchy of mechanisms from lipid binding to membrane domain coalescence. Lipids influence powerfully the function of ion channels and transporters in two well-documented ways. A few lipids act as bona fide second messengers by binding to specific sites that control channel and transporter gating. Other lipids act nonspecifically by modifying the physical environment of channels and transporters, in particular the protein–membrane interface. In this short review, we first consider lipid signaling from this traditional viewpoint, highlighting innumerable Journal of General Physiology publications that have contributed to our present understanding. We then switch to our own emerging view that much important lipid signaling occurs via the formation of membrane domains that influence the function of channels and transporters within them, promote selected protein–protein interactions, and control the turnover of surface membrane.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Gucan Dai
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Anthony Collins
- Saba University School of Medicine, The Bottom, Saba, Dutch Caribbean
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Michael Fine
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
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38
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Qin P, Han T, Yu ACH, Xu L. Mechanistic understanding the bioeffects of ultrasound-driven microbubbles to enhance macromolecule delivery. J Control Release 2018; 272:169-181. [PMID: 29305924 DOI: 10.1016/j.jconrel.2018.01.001] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 01/02/2018] [Accepted: 01/03/2018] [Indexed: 12/17/2022]
Abstract
Ultrasound-driven microbubbles can trigger reversible membrane perforation (sonoporation), open interendothelial junctions and stimulate endocytosis, thereby providing a temporary and reversible time-window for the delivery of macromolecules across biological membranes and endothelial barriers. This time-window is related not only to cavitation events, but also to biological regulatory mechanisms. Mechanistic understanding of the interaction between cavitation events and cells and tissues, as well as the subsequent cellular and molecular responses will lead to new design strategies with improved efficacy and minimized side effects. Recent important progress on the spatiotemporal characteristics of sonoporation, cavitation-induced interendothelial gap and endocytosis, and the spatiotemporal bioeffects and the preliminary biological mechanisms in cavitation-enhanced permeability, has been made. On the basis of the summary of this research progress, this Review outlines the underlying bioeffects and the related biological regulatory mechanisms involved in cavitation-enhanced permeability; provides a critical commentary on the future tasks and directions in this field, including developing a standardized methodology to reveal mechanism-based bioeffects in depth, and designing biology-based treatment strategies to improve efficacy and safety. Such mechanistic understanding the bioeffects that contribute to cavitation-enhanced delivery will accelerate the translation of this approach to the clinic.
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Affiliation(s)
- Peng Qin
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
| | - Tao Han
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Alfred C H Yu
- Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Lin Xu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Essential role of the Na +-Ca2 + exchanger (NCX) in glutamate-enhanced cell survival in cardiac cells exposed to hypoxia/reoxygenation. Sci Rep 2017; 7:13073. [PMID: 29026150 PMCID: PMC5638850 DOI: 10.1038/s41598-017-13478-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/26/2017] [Indexed: 12/22/2022] Open
Abstract
Myocardial ischemia culminates in ATP production impairment, ionic derangement and cell death. The provision of metabolic substrates during reperfusion significantly increases heart tolerance to ischemia by improving mitochondrial performance. Under normoxia, glutamate contributes to myocardial energy balance as substrate for anaplerotic reactions, and we demonstrated that the Na+/Ca2+ exchanger1 (NCX1) provides functional support for both glutamate uptake and use for ATP synthesis. Here we investigated the role of NCX1 in the potential of glutamate to improve energy metabolism and survival of cardiac cells subjected to hypoxia/reoxygenation (H/R). Specifically, in H9c2-NCX1 myoblasts, ATP levels, mitochondrial activities and cell survival were significantly compromised after H/R challenge. Glutamate supplementation at the onset of the reoxygenation phase significantly promoted viability, improved mitochondrial functions and normalized the H/R-induced increase of NCX1 reverse-mode activity. The benefits of glutamate were strikingly lost in H9c2-WT (lacking NCX1 expression), or in H9c2-NCX1 and rat cardiomyocytes treated with either NCX or Excitatory Amino Acid Transporters (EAATs) blockers, suggesting that a functional interplay between these transporters is critically required for glutamate-induced protection. Collectively, these results revealed for the first time the key role of NCX1 for the beneficial effects of glutamate against H/R-induced cell injury.
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Yue HY, Bieberich E, Xu J. Promotion of endocytosis efficiency through an ATP-independent mechanism at rat calyx of Held terminals. J Physiol 2017; 595:5265-5284. [PMID: 28555839 DOI: 10.1113/jp274275] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 05/15/2017] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS At rat calyx of Held terminals, ATP was required not only for slow endocytosis, but also for rapid phase of compensatory endocytosis. An ATP-independent form of endocytosis was recruited to accelerate membrane retrieval at increased activity and temperature. ATP-independent endocytosis primarily involved retrieval of pre-existing membrane, which depended on Ca2+ and the activity of neutral sphingomyelinase but not clathrin-coated pit maturation. ATP-independent endocytosis represents a non-canonical mechanism that can efficiently retrieve membrane at physiological conditions without competing for the limited ATP at elevated neuronal activity. ABSTRACT Neurotransmission relies on membrane endocytosis to maintain vesicle supply and membrane stability. Endocytosis has been generally recognized as a major ATP-dependent function, which efficiently retrieves more membrane at elevated neuronal activity when ATP consumption within nerve terminals increases drastically. This paradox raises the interesting question of whether increased activity recruits ATP-independent mechanism(s) to accelerate endocytosis at the same time as preserving ATP availability for other tasks. To address this issue, we studied ATP requirement in three typical forms of endocytosis at rat calyx of Held terminals by whole-cell membrane capacitance measurements. At room temperature, blocking ATP hydrolysis effectively abolished slow endocytosis and rapid endocytosis but only partially inhibited excess endocytosis following intense stimulation. The ATP-independent endocytosis occurred at calyces from postnatal days 8-15, suggesting its existence before and after hearing onset. This endocytosis was not affected by a reduction of exocytosis using the light chain of botulinum toxin C, nor by block of clathrin-coat maturation. It was abolished by EGTA, which preferentially blocked endocytosis of retrievable membrane pre-existing at the surface, and was impaired by oxidation of cholesterol and inhibition of neutral sphingomyelinase. ATP-independent endocytosis became more significant at 34-35°C, and recovered membrane by an amount that, on average, was close to exocytosis. The results of the present study suggest that activity and temperature recruit ATP-independent endocytosis of pre-existing membrane (in addition to ATP-dependent endocytosis) to efficiently retrieve membrane at nerve terminals. This less understood endocytosis represents a non-canonical mechanism regulated by lipids such as cholesterol and sphingomyelinase.
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Affiliation(s)
- Hai-Yuan Yue
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Erhard Bieberich
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Jianhua Xu
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA.,Department of Neurology, Medical College of Georgia, Augusta University, USA
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Lu FM, Hilgemann DW. Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes. J Gen Physiol 2017; 149:727-749. [PMID: 28606910 PMCID: PMC5496509 DOI: 10.1085/jgp.201711780] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022] Open
Abstract
The Na/K pump exports cytoplasmic Na ions while importing K ions, and its activity is thought to be affected by restricted intracellular Na diffusion in cardiac myocytes. Lu and Hilgemann find instead that the pump can enter an inactivated state and that inactivation can be relieved by cytoplasmic Na. Decades ago, it was proposed that Na transport in cardiac myocytes is modulated by large changes in cytoplasmic Na concentration within restricted subsarcolemmal spaces. Here, we probe this hypothesis for Na/K pumps by generating constitutive transsarcolemmal Na flux with the Na channel opener veratridine in whole-cell patch-clamp recordings. Using 25 mM Na in the patch pipette, pump currents decay strongly during continuous activation by extracellular K (τ, ∼2 s). In contradiction to depletion hypotheses, the decay becomes stronger when pump currents are decreased by hyperpolarization. Na channel currents are nearly unchanged by pump activity in these conditions, and conversely, continuous Na currents up to 0.5 nA in magnitude have negligible effects on pump currents. These outcomes are even more pronounced using 50 mM Li as a cytoplasmic Na congener. Thus, the Na/K pump current decay reflects mostly an inactivation mechanism that immobilizes Na/K pump charge movements, not cytoplasmic Na depletion. When channel currents are increased beyond 1 nA, models with unrestricted subsarcolemmal diffusion accurately predict current decay (τ ∼15 s) and reversal potential shifts observed for Na, Li, and K currents through Na channels opened by veratridine, as well as for Na, K, Cs, Li, and Cl currents recorded in nystatin-permeabilized myocytes. Ion concentrations in the pipette tip (i.e., access conductance) track without appreciable delay the current changes caused by sarcolemmal ion flux. Importantly, cytoplasmic mixing volumes, calculated from current decay kinetics, increase and decrease as expected with osmolarity changes (τ >30 s). Na/K pump current run-down over 20 min reflects a failure of pumps to recover from inactivation. Simulations reveal that pump inactivation coupled with Na-activated recovery enhances the rapidity and effectivity of Na homeostasis in cardiac myocytes. In conclusion, an autoregulatory mechanism enhances cardiac Na/K pump activity when cytoplasmic Na rises and suppresses pump activity when cytoplasmic Na declines.
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Affiliation(s)
- Fang-Min Lu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
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Stauffer BB, Cui G, Cottrill KA, Infield DT, McCarty NA. Bacterial Sphingomyelinase is a State-Dependent Inhibitor of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR). Sci Rep 2017; 7:2931. [PMID: 28592822 PMCID: PMC5462758 DOI: 10.1038/s41598-017-03103-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/24/2017] [Indexed: 02/07/2023] Open
Abstract
Sphingomyelinase C (SMase) inhibits CFTR chloride channel activity in multiple cell systems, an effect that could exacerbate disease in CF and COPD patients. The mechanism by which sphingomyelin catalysis inhibits CFTR is not known but evidence suggests that it occurs independently of CFTR's regulatory "R" domain. In this study we utilized the Xenopus oocyte expression system to shed light on how CFTR channel activity is reduced by SMase. We found that the pathway leading to inhibition is not membrane delimited and that inhibited CFTR channels remain at the cell membrane, indicative of a novel silencing mechanism. Consistent with an effect on CFTR gating behavior, we found that altering gating kinetics influenced the sensitivity to inhibition by SMase. Specifically, increasing channel activity by introducing the mutation K1250A or pretreating with the CFTR potentiator VX-770 (Ivacaftor) imparted resistance to inhibition. In primary bronchial epithelial cells, we found that basolateral, but not apical, application of SMase leads to a redistribution of sphingomyelin and a reduction in forskolin- and VX-770-stimulated currents. Taken together, these data suggest that SMase inhibits CFTR channel function by locking channels into a closed state and that endogenous CFTR in HBEs is affected by SMase activity.
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Affiliation(s)
- B B Stauffer
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, 2015 Uppergate Drive, Atlanta, GA, 30322, USA
- Molecular and Systems Pharmacology program, Emory University, 201 Dowman Drive, Atlanta, GA, 20322, USA
| | - G Cui
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, 2015 Uppergate Drive, Atlanta, GA, 30322, USA
| | - K A Cottrill
- Molecular and Systems Pharmacology program, Emory University, 201 Dowman Drive, Atlanta, GA, 20322, USA
| | - D T Infield
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, 2015 Uppergate Drive, Atlanta, GA, 30322, USA
| | - N A McCarty
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, 2015 Uppergate Drive, Atlanta, GA, 30322, USA.
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43
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Muratori C, Pakhomov AG, Pakhomova ON. Effect of Cooling On Cell Volume and Viability After Nanoelectroporation. J Membr Biol 2017; 250:217-224. [PMID: 28243693 DOI: 10.1007/s00232-017-9952-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/17/2017] [Indexed: 02/03/2023]
Abstract
Electric pulses of nanosecond duration (nsEP) are emerging as a new modality for tissue ablation. Plasma membrane permeabilization by nsEP may cause osmotic imbalance, water uptake, cell swelling, and eventual membrane rupture. The present study was aimed to increase the cytotoxicity of nsEP by fostering water uptake and cell swelling. This aim was accomplished by lowering temperature after nsEP application, which delayed the membrane resealing and/or suppressed the cell volume mechanisms. The cell diameter in U-937 monocytes exposed to a train of 50, 300-ns pulses (100 Hz, 7 kV/cm) at room temperature and then incubated on ice for 30 min increased by 5.6 +/- 0.7 μm (40-50%), which contrasted little or no changes (1 +/- 0.3 μm, <10%) if the incubation was at 37 °C. Neither this nsEP dose nor the 30-min cooling caused cell death when applied separately; however, their combination reduced cell survival to about 60% in 1.5-3 h. Isosmotic addition of a pore-impermeable solute (sucrose) to the extracellular medium blocked cell swelling and rescued the cells, thereby pointing to swelling as a primary cause of membrane rupture and cell death. Cooling after nsEP exposure can potentially be employed in medical practice to assist tissue and tumor ablation.
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Affiliation(s)
- Claudia Muratori
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 318, Norfolk, VA, 23508, USA.
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 318, Norfolk, VA, 23508, USA
| | - Olga N Pakhomova
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 318, Norfolk, VA, 23508, USA
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44
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Na+/Ca2+ exchanger 1 inhibition abolishes ischemic tolerance induced by ischemic preconditioning in different cardiac models. Eur J Pharmacol 2017; 794:246-256. [DOI: 10.1016/j.ejphar.2016.11.045] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 01/22/2023]
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45
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Goldshtein M, Forti E, Ruvinov E, Cohen S. Mechanisms of cellular uptake and endosomal escape of calcium-siRNA nanocomplexes. Int J Pharm 2016; 515:46-56. [DOI: 10.1016/j.ijpharm.2016.10.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/27/2016] [Accepted: 10/04/2016] [Indexed: 01/01/2023]
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46
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Lu FM, Deisl C, Hilgemann DW. Profound regulation of Na/K pump activity by transient elevations of cytoplasmic calcium in murine cardiac myocytes. eLife 2016; 5. [PMID: 27627745 PMCID: PMC5050017 DOI: 10.7554/elife.19267] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/09/2016] [Indexed: 01/06/2023] Open
Abstract
Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activation of Ca influx by reverse Na/Ca exchange enhances pump currents and attenuates current decay, while repeated Ca elevations suppress pump currents. Pump current enhancement reverses over 3 min, and results are similar in myocytes lacking the regulatory protein, phospholemman. Classical signaling mechanisms, including Ca-activated protein kinases and reactive oxygen, are evidently not involved. Electrogenic signals mediated by intramembrane movement of hydrophobic ions, such as hexyltriphenylphosphonium (C6TPP), increase and decrease in parallel with pump currents. Thus, transient Ca elevation and Na/K pump inactivation cause opposing sarcolemma changes that may affect diverse membrane processes.
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Affiliation(s)
- Fang-Min Lu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
| | - Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
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47
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Benedetto R, Sirianant L, Pankonien I, Wanitchakool P, Ousingsawat J, Cabrita I, Schreiber R, Amaral M, Kunzelmann K. Relationship between TMEM16A/anoctamin 1 and LRRC8A. Pflugers Arch 2016; 468:1751-63. [PMID: 27514381 DOI: 10.1007/s00424-016-1862-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
TMEM16A/anoctamin 1/ANO1 and VRAC/LRRC8 are independent chloride channels activated either by increase in intracellular Ca(2+) or cell swelling, respectively. In previous studies, we observed overlapping properties for both types of channels. (i) TMEM16A/ANO1 and LRRC8 are inhibited by identical compounds, (ii) the volume-regulated anion channel VRAC requires compartmentalized Ca(2+) increase to be fully activated, (iii) anoctamins are activated by cell swelling, (iv) both channels have a role for apoptotic cell death, (v) both channels are possibly located in lipid rafts/caveolae like structures, and (vi) VRAC and anoctamin 1 currents are not additive when each are fully activated. In the present study, we demonstrate in different cell types that loss of LRRC8A expression not only inhibited VRAC, but also attenuated Ca(2+) activated Cl(-) currents. Moreover, expression of LRRC8A enhanced Ca(2+) activated Cl(-) currents, and both LRRC8A and ANO1 could be coimmunoprecipitated. We found that LRRC8A becomes accessible to biotinylation upon exposure to hypotonic bath solution, while membrane capacitance was not enhanced. When intracellular Ca(2+) was increased in ANO1-expressing cells, the membrane capacitance was enhanced and increased binding of FM4-64 to the membrane was observed. As this was not seen in cells lacking ANO1 expression, a role of ANO1 for exocytosis was suggested. We propose that ANO1 and LRRC8A are activated in parallel. Thus, ionomycin or purinergic stimulation will not only activate ANO1 but also LRRC8 currents. Cell swelling will not only activate LRRC8/VRAC, but also stimulate ANO1 currents by enhancing compartmentalized Ca(2+) increase and/or through swelling induced autocrine release of ATP.
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Affiliation(s)
- Roberta Benedetto
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Lalida Sirianant
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Pankonien
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Podchanart Wanitchakool
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Cabrita
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Margarida Amaral
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany.
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48
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Fekri F, Delos Santos RC, Karshafian R, Antonescu CN. Ultrasound Microbubble Treatment Enhances Clathrin-Mediated Endocytosis and Fluid-Phase Uptake through Distinct Mechanisms. PLoS One 2016; 11:e0156754. [PMID: 27275866 PMCID: PMC4898768 DOI: 10.1371/journal.pone.0156754] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/19/2016] [Indexed: 01/24/2023] Open
Abstract
Drug delivery to tumors is limited by several factors, including drug permeability of the target cell plasma membrane. Ultrasound in combination with microbubbles (USMB) is a promising strategy to overcome these limitations. USMB treatment elicits enhanced cellular uptake of materials such as drugs, in part as a result of sheer stress and formation of transient membrane pores. Pores formed upon USMB treatment are rapidly resealed, suggesting that other processes such as enhanced endocytosis may contribute to the enhanced material uptake by cells upon USMB treatment. How USMB regulates endocytic processes remains incompletely understood. Cells constitutively utilize several distinct mechanisms of endocytosis, including clathrin-mediated endocytosis (CME) for the internalization of receptor-bound macromolecules such as Transferrin Receptor (TfR), and distinct mechanism(s) that mediate the majority of fluid-phase endocytosis. Tracking the abundance of TfR on the cell surface and the internalization of its ligand transferrin revealed that USMB acutely enhances the rate of CME. Total internal reflection fluorescence microscopy experiments revealed that USMB treatment altered the assembly of clathrin-coated pits, the basic structural units of CME. In addition, the rate of fluid-phase endocytosis was enhanced, but with delayed onset upon USMB treatment relative to the enhancement of CME, suggesting that the two processes are distinctly regulated by USMB. Indeed, vacuolin-1 or desipramine treatment prevented the enhancement of CME but not of fluid phase endocytosis upon USMB, suggesting that lysosome exocytosis and acid sphingomyelinase, respectively, are required for the regulation of CME but not fluid phase endocytosis upon USMB treatment. These results indicate that USMB enhances both CME and fluid phase endocytosis through distinct signaling mechanisms, and suggest that strategies for potentiating the enhancement of endocytosis upon USMB treatment may improve targeted drug delivery.
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Affiliation(s)
- Farnaz Fekri
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Ralph Christian Delos Santos
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Raffi Karshafian
- Department of Medical Physics, Ryerson University, Toronto, Ontario, Canada
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between Ryerson University and St. Michael’s Hospital, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science of St. Michael’s Hospital, Toronto, Ontario, Canada
- * E-mail: (RK); (CNA)
| | - Costin N. Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science of St. Michael’s Hospital, Toronto, Ontario, Canada
- * E-mail: (RK); (CNA)
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49
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Yang HQ, Foster MN, Jana K, Ho J, Rindler MJ, Coetzee WA. Plasticity of sarcolemmal KATP channel surface expression: relevance during ischemia and ischemic preconditioning. Am J Physiol Heart Circ Physiol 2016; 310:H1558-66. [PMID: 27037371 DOI: 10.1152/ajpheart.00158.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 03/30/2016] [Indexed: 11/22/2022]
Abstract
Myocardial ischemia remains the primary cause of morbidity and mortality in the United States. Ischemic preconditioning (IPC) is a powerful form of endogenous protection against myocardial infarction. We studied alterations in KATP channels surface density as a potential mechanism of the protection of IPC. Using cardiac-specific knockout of Kir6.2 subunits, we demonstrated an essential role for sarcolemmal KATP channels in the infarct-limiting effect of IPC in the mouse heart. With biochemical membrane fractionation, we demonstrated that sarcolemmal KATP channel subunits are distributed both to the sarcolemma and intracellular endosomal compartments. Global ischemia causes a loss of sarcolemmal KATP channel subunit distribution and internalization to endosomal compartments. Ischemia-induced internalization of KATP channels was prevented by CaMKII inhibition. KATP channel subcellular redistribution was also observed with immunohistochemistry. Ischemic preconditioning before the index ischemia reduced not only the infarct size but also prevented KATP channel internalization. Furthermore, not only did adenosine mimic IPC by preventing infarct size, but it also prevented ischemia-induced KATP channel internalization via a PKC-mediated pathway. We show that preventing endocytosis with dynasore reduced both KATP channel internalization and strongly mitigated infarct development. Our data demonstrate that plasticity of KATP channel surface expression must be considered as a potentially important mechanism of the protective effects of IPC and adenosine.
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Affiliation(s)
| | | | | | | | | | - William A Coetzee
- Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York
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50
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Castro-Gomes T, Corrotte M, Tam C, Andrews NW. Plasma Membrane Repair Is Regulated Extracellularly by Proteases Released from Lysosomes. PLoS One 2016; 11:e0152583. [PMID: 27028538 PMCID: PMC4814109 DOI: 10.1371/journal.pone.0152583] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/16/2016] [Indexed: 12/28/2022] Open
Abstract
Eukaryotic cells rapidly repair wounds on their plasma membrane. Resealing is Ca2+-dependent, and involves exocytosis of lysosomes followed by massive endocytosis. Extracellular activity of the lysosomal enzyme acid sphingomyelinase was previously shown to promote endocytosis and wound removal. However, whether lysosomal proteases released during cell injury participate in resealing is unknown. Here we show that lysosomal proteases regulate plasma membrane repair. Extracellular proteolysis is detected shortly after cell wounding, and inhibition of this process blocks repair. Conversely, surface protein degradation facilitates plasma membrane resealing. The abundant lysosomal cysteine proteases cathepsin B and L, known to proteolytically remodel the extracellular matrix, are rapidly released upon cell injury and are required for efficient plasma membrane repair. In contrast, inhibition of aspartyl proteases or RNAi-mediated silencing of the lysosomal aspartyl protease cathepsin D enhances resealing, an effect associated with the accumulation of active acid sphingomyelinase on the cell surface. Thus, secreted lysosomal cysteine proteases may promote repair by facilitating membrane access of lysosomal acid sphingomyelinase, which promotes wound removal and is subsequently downregulated extracellularly by a process involving cathepsin D.
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Affiliation(s)
- Thiago Castro-Gomes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, 20742, United States of America
| | - Matthias Corrotte
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, 20742, United States of America
| | - Christina Tam
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, 20742, United States of America
| | - Norma W. Andrews
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, 20742, United States of America
- * E-mail:
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