Endothelin signaling via guanine exchange factor C3G in renal glomerular mesangial cells.
The guanine nucleotide exchange factor C3G is one of the mediators of endothelin-1 (ET-1) intracellular signaling cascades and is vital for kidney development and homeostasis. The aim of the current study was to analyze the specificity of ET-1-induced signaling via C3G in rat glomerular mesangial cells (GMC) and to investigate the biological significance of C3G during mesangioproliferative glomerulonephritis. In GMC, C3G expression was increased (1) in vivo after induction of the anti-Thy1 model of glomerulonephritis and (2) in cell culture experiments after fetal bovine serum incubation. To examine the consequences of C3G up-regulation, adenovirus-mediated gene transfer of C3G into cultured glomerular cells was done, and the GTP loading of the small G proteins Rap1 and R-Ras was analyzed. Overexpression of C3G in mesangial cells resulted in enhanced activation of Rap1, but failed to affect the GTP-bound status of R-Ras in ET-1-stimulated cells. C3G overexpression led to significant changes in GMC spreading and migration patterns in response to ET-1 stimulation and increased stress fiber formation, which was mimicked by Rap1A overexpression. Together, these findings suggest (1) the existence of regulatory mechanisms resulting in disease-related up-regulation of C3G in GMC and (2) that an increase in the C3G protein level may contribute to the resolution stage of mesangioproliferative glomerulonephritis by reducing GMC sensitivity to ET-1, modulating cellular motility, and actin dynamics.
Rufanova
Victoriya A
VA
Department of Medicine, Division of Nephrology and Kidney Disease Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Alexanian
Anna
A
Ostendorf
Tammo
T
Bokemeyer
Dirk
D
Prosser
Simon
S
Miller
Bradley
B
Sorokin
Andrey
A
D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D048430:Cell Shape / Q000187:drug effects / Q000235:genetics; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000494:pharmacology*; D015870:Gene Expression / Q000235:genetics; D015432:Glomerulonephritis, Membranoproliferative / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism*; D020735:Guanine Nucleotide-Releasing Factor 2 / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007678:Kidney Glomerulus / Q000378:metabolism; D008297:Male; D050527:Mesangial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D044967:Serum / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D018800:Thy-1 Antigens / Q000276:immunology; D014161:Transduction, Genetic; D014945:Wound Healing / Q000187:drug effects / Q000235:genetics; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
D000911:Antibodies, Monoclonal; D019332:Endothelin-1; D020735:Guanine Nucleotide-Releasing Factor 2; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D018800:Thy-1 Antigens; D006160:Guanosine Triphosphate; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins