scholarly journals Naturally occurring and tumor-associated variants of RNF167 promote lysosomal exocytosis and plasma membrane resealing

2020 ◽  
Vol 133 (11) ◽  
pp. jcs239335 ◽  
Author(s):  
Sreeja V. Nair ◽  
Nikhil Dev Narendradev ◽  
Rithwik P. Nambiar ◽  
Rakesh Kumar ◽  
Srinivasa M. Srinivasula
Keyword(s):  
Plasma Membrane ◽  
Naturally Occurring ◽  
Membrane Resealing

scholarly journals Naturally Occurring Shorter and Tumor-associated Mutant RNF167 Variants Facilitates Lysosomal Exocytosis and Plasma Membrane Resealing

2019 ◽  
Author(s):  
Sreeja V. Nair ◽  
Nikhil Dev Narendradev ◽  
Rithwik P. Nambiar ◽  
Rakesh Kumar ◽  
Srinivasa M. Srinivasula
Keyword(s):  
Plasma Membrane ◽  
Short Version ◽  
Membrane Repair ◽  
Primary Tumors ◽  
Upstream Regulator ◽  
Naturally Occurring ◽  
Natural Variants ◽  
Functional Features ◽  
Membrane Resealing ◽  
Isoform B

AbstractLysosomal exocytosis and resealing of damaged plasma membrane play critical roles in physiological and pathological processes, including, restoration of cellular homeostasis and tumor invasion. However, to-date, only a few regulatory molecules of these biological processes have been identified. Moreover, no mutations in any of the known regulators of lysosomal exocytosis in primary tumors of patients have been characterized. Here we demonstrate that RNF167, a lysosomal associated ubiquitin ligase, negatively regulates lysosomal exocytosis by inducing perinuclear clustering of lysosomes. Importantly, we also characterized a set of novel natural mutations in RNF167, which are commonly found in diverse tumor types. We found that RNF167-K97N mutant, unlike the wild-type, localizes in the cytoplasm and does not promote perinuclear lysosomal clustering and that cells expressing RNF167-K97N exhibit dispersed lysosomes, increased exocytosis, and enhanced plasma membrane repair. Interestingly, these functional features of RNF167-K97N were shared with a naturally occurring short version of RNF167, i.e. isoform b. In brief, the results presented here reveal a novel role of RNF167 as well as its natural variants, RNF167-K97N and RNF167-b as an upstream regulator of lysosomal exocytosis and plasma membrane resealing which might play an important role in organelle dynamics or tumor progression or both.

Integrity of the dissociated adult cardiac myocyte: gap junction tearing and the mechanism of plasma membrane resealing

1990 ◽  
Vol 11 (2) ◽  
pp. 154-166 ◽  
Author(s):  
N. J. Severs ◽  
A. M. Slade ◽  
T. Powell ◽  
V. W. Twist ◽  
C. R. Green
Keyword(s):  
Plasma Membrane ◽  
Gap Junction ◽  
Cardiac Myocyte ◽  
Membrane Resealing

scholarly journals Multiple poloxamers increase plasma membrane repair capacity in muscle and nonmuscle cells

2020 ◽  
Vol 318 (2) ◽  
pp. C253-C262 ◽  
Author(s):  
Thomas A. Kwiatkowski ◽  
Aubrey L. Rose ◽  
Rachel Jung ◽  
Ana Capati ◽  
Diana Hallak ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Muscular Dystrophy ◽  
Ethylene Oxide ◽  
Propylene Oxide ◽  
Hek293 Cells ◽  
Mdx Mouse ◽  
Repair Capacity ◽  
Poly Ethylene Oxide ◽  
Membrane Resealing ◽  
Poly Ethylene

Various previous studies established that the amphiphilic tri-block copolymer known as poloxamer 188 (P188) or Pluronic-F68 can stabilize the plasma membrane following a variety of injuries to multiple mammalian cell types. This characteristic led to proposals for the use of P188 as a therapeutic treatment for various disease states, including muscular dystrophy. Previous studies suggest that P188 increases plasma membrane integrity by resealing plasma membrane disruptions through its affinity for the hydrophobic lipid chains on the lipid bilayer. P188 is one of a large family of copolymers that share the same basic tri-block structure consisting of a middle hydrophobic propylene oxide segment flanked by two hydrophilic ethylene oxide moieties [poly(ethylene oxide)80-poly(propylene oxide)27-poly(ethylene oxide)80]. Despite the similarities of P188 to the other poloxamers in this chemical family, there has been little investigation into the membrane-resealing properties of these other poloxamers. In this study we assessed the resealing properties of poloxamers P181, P124, P182, P234, P108, P407, and P338 on human embryonic kidney 293 (HEK293) cells and isolated muscle from the mdx mouse model of Duchenne muscular dystrophy. Cell membrane injuries from glass bead wounding and multiphoton laser injury show that the majority of poloxamers in our panel improved the plasma membrane resealing of both HEK293 cells and dystrophic muscle fibers. These findings indicate that many tri-block copolymers share characteristics that can increase plasma membrane resealing and that identification of these shared characteristics could help guide design of future therapeutic approaches.

scholarly journals Exocytosis of acid sphingomyelinase by wounded cells promotes endocytosis and plasma membrane repair

2010 ◽  
Vol 189 (6) ◽  
pp. 1027-1038 ◽  
Author(s):  
Christina Tam ◽  
Vincent Idone ◽  
Cecilia Devlin ◽  
Maria Cecilia Fernandes ◽  
Andrew Flannery ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lysosomal Enzyme ◽  
Membrane Integrity ◽  
Acid Sphingomyelinase ◽  
Membrane Repair ◽  
Membrane Injury ◽  
Cellular Survival ◽  
Plasma Membrane Repair ◽  
Membrane Resealing ◽  
Niemann Pick

Rapid plasma membrane resealing is essential for cellular survival. Earlier studies showed that plasma membrane repair requires Ca2+-dependent exocytosis of lysosomes and a rapid form of endocytosis that removes membrane lesions. However, the functional relationship between lysosomal exocytosis and the rapid endocytosis that follows membrane injury is unknown. In this study, we show that the lysosomal enzyme acid sphingomyelinase (ASM) is released extracellularly when cells are wounded in the presence of Ca2+. ASM-deficient cells, including human cells from Niemann-Pick type A (NPA) patients, undergo lysosomal exocytosis after wounding but are defective in injury-dependent endocytosis and plasma membrane repair. Exogenously added recombinant human ASM restores endocytosis and resealing in ASM-depleted cells, suggesting that conversion of plasma membrane sphingomyelin to ceramide by this lysosomal enzyme promotes lesion internalization. These findings reveal a molecular mechanism for restoration of plasma membrane integrity through exocytosis of lysosomes and identify defective plasma membrane repair as a possible component of the severe pathology observed in NPA patients.

scholarly journals Impaired membrane resealing and autoimmune myositis in synaptotagmin VII–deficient mice

2003 ◽  
Vol 162 (4) ◽  
pp. 543-549 ◽  
Author(s):  
Sabyasachi Chakrabarti ◽  
Koichi S. Kobayashi ◽  
Richard A. Flavell ◽  
Carolyn B. Marks ◽  
Katsuya Miyake ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Inflammatory Myopathy ◽  
Response Characteristic ◽  
Membrane Repair ◽  
Progressive Muscle Weakness ◽  
Autoimmune Myositis ◽  
Mouse Tissues ◽  
Plasma Membrane Repair ◽  
Membrane Resealing ◽  
Deficient Mice

Members of the synaptotagmin family have been proposed to function as Ca2+ sensors in membrane fusion. Syt VII is a ubiquitously expressed synaptotagmin previously implicated in plasma membrane repair and Trypanosoma cruzi invasion, events which are mediated by the Ca2+-regulated exocytosis of lysosomes. Here, we show that embryonic fibroblasts from Syt VII–deficient mice are less susceptible to trypanosome invasion, and defective in lysosomal exocytosis and resealing after wounding. Examination of mutant mouse tissues revealed extensive fibrosis in the skin and skeletal muscle. Inflammatory myopathy, with muscle fiber invasion by leukocytes and endomysial collagen deposition, was associated with elevated creatine kinase release and progressive muscle weakness. Interestingly, similar to what is observed in human polymyositis/dermatomyositis, the mice developed a strong antinuclear antibody response, characteristic of autoimmune disorders. Thus, defective plasma membrane repair in tissues under mechanical stress may favor the development of inflammatory autoimmune disease.

scholarly journals Repair of injured plasma membrane by rapid Ca2+-dependent endocytosis

2008 ◽  
Vol 180 (5) ◽  
pp. 905-914 ◽  
Author(s):  
Vincent Idone ◽  
Christina Tam ◽  
John W. Goss ◽  
Derek Toomre ◽  
Marc Pypaert ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Immune System ◽  
Repair Process ◽  
Bacterial Toxin ◽  
Rapid Repair ◽  
Streptolysin O ◽  
Membrane Resealing ◽  
Pore Forming Proteins ◽  
Insight Into ◽  
Microbial Toxins

Ca2+ influx through plasma membrane lesions triggers a rapid repair process that was previously shown to require the exocytosis of lysosomal organelles (Reddy, A., E. Caler, and N. Andrews. 2001. Cell. 106:157–169). However, how exocytosis leads to membrane resealing has remained obscure, particularly for stable lesions caused by pore-forming proteins. In this study, we show that Ca2+-dependent resealing after permeabilization with the bacterial toxin streptolysin O (SLO) requires endocytosis via a novel pathway that removes SLO-containing pores from the plasma membrane. We also find that endocytosis is similarly required to repair lesions formed in mechanically wounded cells. Inhibition of lesion endocytosis (by sterol depletion) inhibits repair, whereas enhancement of endocytosis through disruption of the actin cytoskeleton facilitates resealing. Thus, endocytosis promotes wound resealing by removing lesions from the plasma membrane. These findings provide an important new insight into how cells protect themselves not only from mechanical injury but also from microbial toxins and pore-forming proteins produced by the immune system.

scholarly journals Cross-linking of Orai1 channels by STIM proteins

2018 ◽  
Vol 115 (15) ◽  
pp. E3398-E3407 ◽  
Author(s):  
Yandong Zhou ◽  
Robert M. Nwokonko ◽  
Xiangyu Cai ◽  
Natalia A. Loktionova ◽  
Raz Abdulqadir ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fluorescence Recovery After Photobleaching ◽  
Signal Generation ◽  
Cross Linking ◽  
Regulatory Effect ◽  
Superresolution Imaging ◽  
Binding Residue ◽  
Naturally Occurring ◽  
Protein Dimers

The transmembrane docking of endoplasmic reticulum (ER) Ca2+-sensing STIM proteins with plasma membrane (PM) Orai Ca2+ channels is a critical but poorly understood step in Ca2+ signal generation. STIM1 protein dimers unfold to expose a discrete STIM–Orai activating region (SOAR1) that tethers and activates Orai1 channels within discrete ER–PM junctions. We reveal that each monomer within the SOAR dimer interacts independently with single Orai1 subunits to mediate cross-linking between Orai1 channels. Superresolution imaging and mobility measured by fluorescence recovery after photobleaching reveal that SOAR dimer cross-linking leads to substantial Orai1 channel clustering, resulting in increased efficacy and cooperativity of Orai1 channel function. A concatenated SOAR1 heterodimer containing one monomer point mutated at its critical Orai1 binding residue (F394H), although fully activating Orai channels, is completely defective in cross-linking Orai1 channels. Importantly, the naturally occurring STIM2 variant, STIM2.1, has an eight-amino acid insert in its SOAR unit that renders it functionally identical to the F394H mutant in SOAR1. Contrary to earlier predictions, the SOAR1–SOAR2.1 heterodimer fully activates Orai1 channels but prevents cross-linking and clustering of channels. Interestingly, combined expression of full-length STIM1 with STIM2.1 in a 5:1 ratio causes suppression of sustained agonist-induced Ca2+ oscillations and protects cells from Ca2+ overload, resulting from high agonist-induced Ca2+ release. Thus, STIM2.1 exerts a powerful regulatory effect on signal generation likely through preventing Orai1 channel cross-linking. Overall, STIM-mediated cross-linking of Orai1 channels is a hitherto unrecognized functional paradigm that likely provides an organizational microenvironment within ER–PM junctions with important functional impact on Ca2+ signal generation.

scholarly journals Myoferlin is critical for endocytosis in endothelial cells

2009 ◽  
Vol 297 (3) ◽  
pp. C484-C492 ◽  
Author(s):  
Pascal N. Bernatchez ◽  
Arpeeta Sharma ◽  
Pinar Kodaman ◽  
William C. Sessa
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Protein Complex ◽  
Protein Complexes ◽  
Growth Factor Receptor ◽  
Surface Expression ◽  
Membrane Fission ◽  
Membrane Resealing ◽  
Endocytic Vesicles ◽  
Endothelial Growth Factor

Myoferlin is a member of the ferlin family of proteins that promotes endomembrane fusion with the plasma membrane in muscle cells and endothelial cells. In addition, myoferlin is necessary for the surface expression of vascular endothelial growth factor receptor 2 through the formation of a protein complex with dynamin-2 (Dyn-2). Since Dyn-2 is necessary for the fission of endocytic vesicles from the plasma membrane, we tested the hypothesis that myoferlin may regulates aspects of receptor-dependent endocytosis. Here we show that myoferlin gene silencing decreases both clathrin and caveolae/raft-dependent endocytosis, whereas ectopic myoferlin expression in COS-7 cells increases endocytosis by up to 125%. Interestingly, we have observed that inhibition of Dyn-2 activity or caveolin-1 (Cav-1) expression impairs endocytosis as well as membrane resealing after injury, indicating that Dyn-2 and Cav-1 also participate in both membrane fission and fusion processes. Mechanistically, myoferlin partially colocalizes with Dyn-2 and Cav-1 and forms a protein complex with Cav-1 solubilized from tissue extracts. Together, these data describe a new role for myoferlin in receptor-dependent endocytosis and an overlapping role for myoferlin-Dyn-2-Cav-1 protein complexes in membrane fusion and fission events.

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