title: Three-dimensional collagen regulates collagen gene expression by a mechanism that requires serine/threonine kinases and is independent of mechanical contraction.
abstract: Integrin alpha1beta1, one of the cellular collagen receptors, can participate in the regulation of collagen accumulation by acting as a negative feedback regulator. The molecular mechanism behind this phenomenon has been unknown. We have plated cells inside three-dimensional collagen and analyzed a set of chemical inhibitors for various signal transduction pathways. Only two wide-spectrum serine/threonine kinase inhibitors, H-7 and iso-H-7 could prevent the down-regulation of alpha1(I) collagen mRNA levels in cells exposed to three-dimensional collagen. In monolayer iso-H-7 slightly down-regulated collagen gene expression, indicating that inside collagen it affected integrin signaling rather than having a direct stimulatory effect on collagen mRNA levels. The effect of iso-H-7 was not dependent on its ability to inhibit protein kinases A, C, or G. H-7 and iso-H-7 could also inhibit collagen gel contraction, but this mechanism was independent of collagen gene regulation. Three-dimensional collagen could also up-regulate the mRNA levels of several matrix metalloproteinases (MMPs) but H-7 and iso-H-7 had no effect on the regulation of MMP genes. Our data indicate that three-dimensional collagenous matrix regulates distinct cellular signaling pathways and that collagen gene regulation is independent of the other effects of the matrix.
authors.affiliation: MediCity Research Laboratory, University of Turku, Tykistökatu 6 A, FIN-20520 Turku, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Broberg
authors.forename: L
authors.initials: L
authors.lastname: Nissinen
authors.forename: M
authors.initials: M
authors.lastname: Potila
authors.forename: J
authors.initials: J
authors.lastname: Heino
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics; D001859:Bone Neoplasms; D002448:Cell Adhesion / Q000502:physiology; D003094:Collagen / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology*; D005246:Feedback; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D039421:Integrin alpha2; D007700:Kinetics; D020781:Matrix Metalloproteinase 1 / Q000235:genetics; D012516:Osteosarcoma; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D039421:Integrin alpha2; D019716:Tissue Inhibitor of Metalloproteinase-2; C080501:1-(5-isoquinolinylsulfonyl)-3-methylpiperazine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D020781:Matrix Metalloproteinase 1