Rho-dependent regulation of cell spreading by the tetraspan membrane protein Gas3/PMP22.
Gas3/PMP22 plays a crucial role in regulating myelin formation and maintenance, and different genetic alterations in gas3/PMP22 are responsible for a set of human peripheral neuropathies. We have previously demonstrated that Gas3/PMP22 could regulate susceptibility to apoptosis in NIH3T3 cells but not in REF 52 cells. In this report we demonstrate that when the apoptotic response triggered by gas3/PMP22 was counteracted by Bcl-2 coexpression, morphological changes were observed. Time-lapse analysis confirmed that Gas3/PMP22 can modulate cell spreading, and this effect was strengthened after inhibition of phosphoinositide 3-kinase. Using the active form of the small GTPase RhoA, we have been able to dissect the different Gas3/PMP22 biological activities. RhoA counteracted the Gas3/PMP22-dependent morphological response but was unable to neutralize the apoptotic response. Treatment of NIH3T3 cells with cytotoxic necrotizing factor 1, which activates endogenous Rho, also counteracted Gas3/PMP22-mediated cell shape and spreading changes. Treatment of REF 52 cells, which are unresponsive to Gas3/PMP22 overexpression, with the C3 exoenzyme, inhibiting Rho activity, renders REF 52 cells responsive to Gas3/PMP22 overexpression for cell shape and spreading changes. Finally, assembly of stress fibers and focal adhesions complexes, in response to lysophosphatidic acid-induced endogenous Rho activation, was impaired in Gas3/PMP22-overexpressing cells. We hypothesize that cell shape and spreading regulated by Gas3/PMP22 through the Rho GTPase might have an important role during Schwann cells differentiation and myelinization.
Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie, 34142 Trieste, Italy.
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C
Brancolini
S
S
Marzinotto
P
P
Edomi
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E
Agostoni
C
C
Fiorentini
H W
HW
Müller
C
C
Schneider
D016475:3T3 Cells / Q000187:drug effects / Q000378:metabolism; D000222:Adaptation, Physiological; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001427:Bacterial Toxins / Q000494:pharmacology; D002454:Cell Differentiation; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics*; D048429:Cell Size / Q000187:drug effects; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics; D003603:Cytotoxins / Q000494:pharmacology; D029968:Escherichia coli Proteins; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009185:Myelin Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012583:Schwann Cells / Q000378:metabolism / Q000473:pathology; D013312:Stress, Physiological; D013997:Time Factors; D000077191:Wortmannin; D020742:rhoA GTP-Binding Protein
D000730:Androstadienes; D001427:Bacterial Toxins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D009185:Myelin Proteins; C073687:PMP22 protein, human; C489545:Pmp22 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; C060296:cytotoxic necrotizing factor type 1; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D000077191:Wortmannin