Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2006 Mar 24;281(12):7907-18.
doi: 10.1074/jbc.M509682200. Epub 2006 Jan 25.

Nucleoprotein interactions governing cell type-dependent repression of the mouse smooth muscle alpha-actin promoter by single-stranded DNA-binding proteins Pur alpha and Pur beta

Anna M Knapp  1 , Jon E Ramsey, Shu-Xia Wang, Karolyn E Godburn, Arthur R Strauch, Robert J Kelm Jr
Affiliations
Free article

Nucleoprotein interactions governing cell type-dependent repression of the mouse smooth muscle alpha-actin promoter by single-stranded DNA-binding proteins Pur alpha and Pur beta

Anna M Knapp et al. J Biol Chem. .
Free article

Abstract

Pur alpha and Pur beta are structurally related single-stranded DNA/RNA-binding proteins implicated in the control of cell growth and differentiation. The goal of this study was to determine whether Pur alpha and Pur beta function in a redundant, distinct, or collaborative manner to suppress smooth muscle alpha-actin gene expression in cell types relevant to wound repair and vascular remodeling. RNA interference-mediated loss-of-function analyses revealed that, although Pur beta was the dominant repressor, the combined action of endogenous Pur alpha and Pur beta was necessary to fully repress the full-length smooth muscle alpha-actin promoter in cultured fibroblasts but to a lesser extent in vascular smooth muscle cells. The activity of a minimal core enhancer containing a truncated 5' Pur repressor binding site was unaffected by knockdown of Pur alpha and/or Pur beta in fibroblasts. Conversely, gain-of-function studies indicated that Pur alpha or Pur beta could each independently repress core smooth muscle alpha-actin enhancer activity albeit in a cell type-dependent fashion. Biochemical analyses indicated that purified recombinant Pur alpha and Pur beta were essentially identical in terms of their binding affinity and specificity for GGN repeat-containing strands of several cis-elements comprising the core enhancer. However, Pur alpha and Pur beta exhibited more distinctive protein interaction profiles when evaluated for binding to enhancer-associated transcription factors in extracts from fibroblasts and vascular smooth muscle cells. These findings support the hypothesis that Pur alpha and Pur beta repress smooth muscle alpha-actin gene transcription by means of DNA strand-selective cis-element binding and cell type-dependent protein-protein interactions.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

Publication types

MeSH terms

LinkOut - more resources