PI-3 kinase pathway can mediate the effect of TGF-beta1 in inducing the expression of SHARP-2 in LLC-PK1 cells.
We aim to investigate the effect of transforming growth factor (TGF)-beta1 on the expression of enhancer of split- and hairy-related protein-2 (SHARP-2) messenger RNA (mRNA) and its signaling pathway. In this study, several cell lines including LLC-PK1 (a porcine kidney tubular epithelial cell line), MDCK (Madin-Darby canine kidney) and CTLL-2 (cytotoxic T-lymphocyte line) were treated with recombinant human TGF-beta1, and a series of experiments were carried out, involving Northern blot analysis of total RNA from these cells. Further, several specific chemical inhibitors were applied before TGF-beta1 treatment to probe the signaling pathway. The results showed that TGF-beta1 can significantly up-regulate SHARP-2 mRNA expression in the LLC-PK1 cell line. The peak level of induction was found 2 h after TGF-beta1 stimulation. While one phosphoinositide 3-kinases (PI-3) kinase inhibitor, LY294002, completely blocked the effect of TGF-beta1 on SHARP-2 mRNA expression in LLC-PK1 cells at a low concentration, other inhibitors, including PD98059, staurosporine, AG490, wortmannin, okadaic acid and rapamycin, had no effect. The effect of LY294002 was dose-dependent. We conclude that, in LLC-PK1 cells at least, TGF-beta1 can effectively induce the SHARP-2 mRNA expression and that the PI-3 kinase pathway can mediate this effect.
Shou
Zhang-fei
ZF
Kidney Disease Center, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China. zfshou@zju.edu.cn
Zhou
Qin
Q
Cai
Jie-ru
JR
Chen
Jiang-hua
JH
Yamada
Kazuya
K
Miyamoto
Kaoru
K
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D007684:Kidney Tubules / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013552:Swine; D053773:Transforming Growth Factor beta1 / Q000008:administration & dosage*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D051792:Basic Helix-Loop-Helix Proteins; D019869:Phosphatidylinositol 3-Kinases; D012097:Repressor Proteins; D053773:Transforming Growth Factor beta1; C485778:Hey2 protein, mouse