Department of Medicine , University of Texas Health Science Center , San Antonio 78284-7882 .
Mol Cell Endocrinol 91 : 185-91 ( 1993)
Abstract
In human renal mesangial cells , platelet derived growth factor ( PDGF)-A chain is subject to regulation by protein kinase C ( PKC ) activator , phorbol ester ( phorbol 12-myristate 13-acetate , PMA ) .
Treatment of mesangial cells with PMA increases PDGF-A chain mRNA abundance as analyzed by Northern blot hybridization .
In contrast to the effect of PMA , the inactive analog phorbol had no effect on PDGF-A chain mRNA levels , while the PKC inhibitor H7 markedly reduced the PMA-induced increment in PDGF-A chain mRNA .
To determine the mechanism by which PMA increases the abundance of this gene , transcription rate was measured by nuclear transcript elongation assay .
Treatment of mesangial cells with PMA resulted in a 2-fold increase in PDGF-A chain gene transcription .
In addition , we analyzed the effects of PMA on PDGF-A chain mRNA half-life as measured directly by pulse-chase method .
PDGF-A chain mRNA has a half-life of about 106 min.
The PDGF-A chain mRNA half-life was reduced by 30% ( t1/2 = 74 min ) when mesangial cells were incubated with PMA .
Our results demonstrate that in human renal mesangial cells , the regulation of PDGF-A chain gene expression by PMA is primarily at the level of transcription .