TY - JOUR
T1 - Characterization of the c-Myb-responsive Region and Regulation of the Human Type I Collagen alpha 2 Chain Gene by c-Myb
AU - Lucetti, MM
AU - Paroncini, P
AU - Majlingova, P
AU - Frampton, Jonathan
AU - Mucenski, M
AU - Svegliati Baroni, S
AU - Sambo, P
AU - Golay, J
AU - Introna, M
AU - Gabrielli, A
PY - 2003/1/10
Y1 - 2003/1/10
N2 - We have characterized the role of c-Myb and B-Myb in the regulation of human type I collagen alpha2 chain gene expression in fibroblastic cells. We have identified four Myb-binding sites (MBSs) in the promoter. Transactivation assays on wild type and mutant promoter-reporter constructs demonstrated that c-Myb, but not B-Myb, can transactivate the human type I collagen alpha 2 chain gene promoter via the MBS-containing region. Electrophoretic mobility shift assay experiments showed that c-Myb specifically binds to each of the four MBS; however, the mutagenesis of site MBS-4 completely inhibited transactivation by c-Myb, at least in the full-length promoter. In agreement with these results, c-myb(-/-) mouse embryo fibroblasts (MEFs) showed a selective lack of expression of type I collagen alpha 2 chain gene but maintained the expression of fibronectin and type III collagen. Furthermore, transforming growth factor-beta induced type I collagen alpha 2 chain gene expression in c-myb(-/-) MEFs, implying that the transforming growth factor-beta signaling pathway is maintained and that the absence of COL1A2 gene expression in c-myb(-/-) MEFs is a direct consequence of the lack of c-Myb. The demonstration of the importance of c-Myb in the regulation of the type I collagen alpha 2 chain gene suggests that uncontrolled expression of c-Myb could be an underlying mechanism in the pathogenesis of several fibrotic disorders.
AB - We have characterized the role of c-Myb and B-Myb in the regulation of human type I collagen alpha2 chain gene expression in fibroblastic cells. We have identified four Myb-binding sites (MBSs) in the promoter. Transactivation assays on wild type and mutant promoter-reporter constructs demonstrated that c-Myb, but not B-Myb, can transactivate the human type I collagen alpha 2 chain gene promoter via the MBS-containing region. Electrophoretic mobility shift assay experiments showed that c-Myb specifically binds to each of the four MBS; however, the mutagenesis of site MBS-4 completely inhibited transactivation by c-Myb, at least in the full-length promoter. In agreement with these results, c-myb(-/-) mouse embryo fibroblasts (MEFs) showed a selective lack of expression of type I collagen alpha 2 chain gene but maintained the expression of fibronectin and type III collagen. Furthermore, transforming growth factor-beta induced type I collagen alpha 2 chain gene expression in c-myb(-/-) MEFs, implying that the transforming growth factor-beta signaling pathway is maintained and that the absence of COL1A2 gene expression in c-myb(-/-) MEFs is a direct consequence of the lack of c-Myb. The demonstration of the importance of c-Myb in the regulation of the type I collagen alpha 2 chain gene suggests that uncontrolled expression of c-Myb could be an underlying mechanism in the pathogenesis of several fibrotic disorders.
UR - http://www.scopus.com/inward/record.url?scp=0037449713&partnerID=8YFLogxK
U2 - 10.1074/jbc.M204392200
DO - 10.1074/jbc.M204392200
M3 - Article
C2 - 12424255
SN - 1083-351X
VL - 278
SP - 1533
EP - 1541
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 3
ER -