Promoter-binding activity of inflammation-responsive transcription factor SAF is regulated by cyclic AMP signaling pathway.
The serum amyloid A activating factor (SAF) was identified as a family of inducible transcription factors that is activated by many mediators of inflammation. Its activation involves a phosphorylation event, whose mechanism is not fully understood. Here, we show that cAMP treatment of several cell types, including mouse liver-derived BNL CL.2, human monocyte-derived THP-1, and a primary culture of vascular smooth muscle cells from porcine aorta, activated cellular SAF's ability to bind DNA. The protein kinase A (PKA) activity in cytoplasmic extracts of cAMP-treated cells was responsible for the potentiation of the DNA-binding activity of the cellular SAF proteins. Furthermore, treatment of nuclear extracts of untreated cells with purified PKA increased the DNA-binding activity of cellular SAF proteins, and specific inhibitors of PKA abrogated the enhanced DNA-binding ability of SAF in the cAMP-treated cells. Consistent with these findings, overexpression of the catalytic subunit of PKA markedly increased expression of the SAF-regulated promoter. These results imply a functional role for the previously detected protein-protein interaction between SAF-1 transcription factor and the catalytic subunit of PKA and further demonstrate the consequences of cAMP-mediated signaling for the expression of SAF-regulated genes.
Ray
Alpana
A
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211, USA.
Kumar
Deepak
D
Ray
Bimal K
BK
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013552:Swine; D014157:Transcription Factors / Q000378:metabolism*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D014157:Transcription Factors; C076035:c-MYC-associated zinc finger protein; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004247:DNA; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases