TY - JOUR
T1 - Transforming growth factor-β1 stimulates protein kinase A in mesangial cells
AU - Wang, Lewei
AU - Zhu, Yanqing
AU - Sharma, Kumar
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1998/4/3
Y1 - 1998/4/3
N2 - We recently demonstrated that transforming growth factor-β (TGF-β) stimulates phosphorylation of the type I inositol 1,4,5-trisphosphate receptor (Sharma, K., Wang, K., Zhu, Y., Bokkala, S., and Joseph, S. (1997) J. Biol. Chem. 272, 14617-14623), possibly via protein kinase A (PKA) activation in murine mesangial cells. In the present study, we evaluated whether TGF-β stimulates PKA activation. Utilizing a specific PKA kinase assay, we found that TGF-β increases PKA activity by 3-fold within 15 min of TGF-β1 treatment, and the enhanced kinase activity was completely reversed by the inhibitory peptide for PKA (PKI; 1 μM). In mesangial cells transfected with a PKI expression vector, enhanced PKA activity could not be demonstrated with TGF-β1 treatment. TGF-β1 was also found to stimulate translocation of the α-catalytic subunit of PKA to the nucleus by Western analysis of nuclear protein as well as by confocal microscopy. TGF-β1- mediated phosphorylation of cAMP response element-binding protein was completely reversed by H-89 (3 μM), a specific inhibitor of PKA. Stimulation of fibronectin mRNA by TGF-β1 was also attenuated in cells overexpressing PKI. We thus conclude that TGF-β stimulates the PKA signaling pathway in mesangial cells and that PKA activation contributes to TGF-β stimulation of cAMP response element-binding protein phosphorylation and fibronectin expression.
AB - We recently demonstrated that transforming growth factor-β (TGF-β) stimulates phosphorylation of the type I inositol 1,4,5-trisphosphate receptor (Sharma, K., Wang, K., Zhu, Y., Bokkala, S., and Joseph, S. (1997) J. Biol. Chem. 272, 14617-14623), possibly via protein kinase A (PKA) activation in murine mesangial cells. In the present study, we evaluated whether TGF-β stimulates PKA activation. Utilizing a specific PKA kinase assay, we found that TGF-β increases PKA activity by 3-fold within 15 min of TGF-β1 treatment, and the enhanced kinase activity was completely reversed by the inhibitory peptide for PKA (PKI; 1 μM). In mesangial cells transfected with a PKI expression vector, enhanced PKA activity could not be demonstrated with TGF-β1 treatment. TGF-β1 was also found to stimulate translocation of the α-catalytic subunit of PKA to the nucleus by Western analysis of nuclear protein as well as by confocal microscopy. TGF-β1- mediated phosphorylation of cAMP response element-binding protein was completely reversed by H-89 (3 μM), a specific inhibitor of PKA. Stimulation of fibronectin mRNA by TGF-β1 was also attenuated in cells overexpressing PKI. We thus conclude that TGF-β stimulates the PKA signaling pathway in mesangial cells and that PKA activation contributes to TGF-β stimulation of cAMP response element-binding protein phosphorylation and fibronectin expression.
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U2 - 10.1074/jbc.273.14.8522
DO - 10.1074/jbc.273.14.8522
M3 - Article
C2 - 9525967
AN - SCOPUS:0032478791
VL - 273
SP - 8522
EP - 8527
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 14
ER -