Rearrangements of the intermediate filament GFAP in primary human schwannoma cells.
Loss of the tumor suppressor protein merlin causes a variety of benign tumors such as schwannomas, meningiomas, and gliomas in man. We previously reported primary human schwannoma cells to show enhanced integrin-dependent adhesion and a hyperactivation of the small RhoGTPase Rac1. Here we show that the main intermediate filament protein of Schwann cells, the glial fibrillary acidic protein, is collapsed to the perinuclear region instead of being well-spread from the nucleus to the cell periphery. This cytoskeletal reorganization is accompanied by changes in cell shape and increased cell motility. Moreover, we report tyrosine phosphorylation to be enhanced in schwannoma cells, already described earlier in intermediate filament breakdown. Thus, we believe that Rac activation via tyrosine kinase stimulation leads to GFAP collapse in human schwannoma cells, and suggest that this process plays an important role in vivo where schwannoma cells become motile, unspecifically ensheathing extracellular matrix and forming pseudomesaxons.
Utermark
Tamara
T
Department of Neurology, Zentrum für klinische Forschung, University of Ulm, Helmholtzstr. 8/1, 89081 Ulm, Germany.
Schubert
Simone J A
SJ
Hanemann
C Oliver
CO
D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007382:Intermediate Filaments / Q000378:metabolism* / Q000473:pathology*; D009442:Neurilemmoma / Q000378:metabolism* / Q000473:pathology*; D012583:Schwann Cells / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005904:Glial Fibrillary Acidic Protein