title: Differential regulation of soluble guanylyl cyclase expression and signaling by collagens: involvement of integrin-linked kinase.
abstract: Glomerular diseases are characterized by an abnormal synthesis of extracellular matrix proteins, such as collagen type I. Evidence that growth on collagen type I downregulates soluble guanylyl cyclase (sGC) expression and the responsiveness of human mesangial cells to nitric oxide (NO) by activating specific integrin signals involving integrin-linked kinase (ILK) is presented. Human mesangial cells were grown on collagen type I or IV for 24 to 72 h. Compared with collagen IV, growth on collagen I reduced the protein expression and NO-stimulated enzyme activity of sGC. This downregulation was effected at the level of transcription, because steady-state sGC mRNA expression was reduced on collagen I, but inhibition of transcription with Actinomycin D revealed no differences in transcript stability between the two culture conditions. Collagen I also reduced the capacity of cells to relax in response to NO after H2O2 challenge and inhibited NO-induced phosphorylation of vasodilator-activated phosphoprotein, a target of cyclic guanine monophosphate-dependent protein kinase. Examination of the surface expression of integrins, the receptors for extracellular matrix components, revealed that alpha1 and alpha2 integrin subunits were more abundant on cells that were grown on collagen IV and that surface expression of beta1 integrin did not vary with collagen type. However, growth on collagen I induced beta1 integrin to adopt its active conformation, and this activation of beta1 integrin was accompanied by increased activity of its downstream effector ILK. Dominant-negative suppression of ILK signaling relieved the suppression of sGC expression and NO-induced vasodilator-activated phosphoprotein phosphorylation induced by collagen I.
authors: Physiology Department, Alcalá University, Príncipe de Asturias Hospital, Alcalá de Henares, Madrid, Spain.
authors: Sergio
authors: S
authors: De Frutos
authors: Marta
authors: M
authors: Saura
authors: Mercedes
authors: M
authors: Griera
authors: Francisco Javier
authors: FJ
authors: Rivero-Vilches
authors: Carlos
authors: C
authors: Zaragoza
authors: Diego
authors: D
authors: Rodriguez-Puyol
authors: Manuel
authors: M
authors: Rodriguez-Puyol
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism* / Q000494:pharmacology; D024042:Collagen Type I / Q000378:metabolism / Q000494:pharmacology; D024141:Collagen Type IV / Q000378:metabolism / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019012:Integrin beta1 / Q000378:metabolism; D008954:Models, Biological; D009569:Nitric Oxide / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012995:Solubility; D000099200:Scaffold Protein ILK
chemical_list: D003094:Collagen; D024042:Collagen Type I; D024141:Collagen Type IV; D018076:DNA, Complementary; D006162:Guanylate Cyclase; D006861:Hydrogen Peroxide; D019012:Integrin beta1; D009569:Nitric Oxide; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D000099200:Scaffold Protein ILK