Sox15 and Fhl3 transcriptionally coactivate Foxk1 and regulate myogenic progenitor cells

Abstract

The regulation of myogenic progenitor cells during muscle regeneration is not clearly understood. We have previously shown that the Foxk1 gene, a member of the forkhead/winged helix family of transcription factors, is expressed in myogenic progenitor cells in adult skeletal muscle. In the present study, we utilize transgenic technology and demonstrate that the 4.6 kb upstream fragment of the Foxk1 gene directs b-galactosidase expression to the myogenic progenitor cell population. We further establish that Sox15 directs Foxk1 expression to the myogenic progenitor cell population, as it binds to an evolutionarily conserved site and recruits Fhl3 to transcriptionally coactivate Foxk1 gene expression. Knockdown of endogenous Sox15 results in perturbed cell cycle kinetics and decreased Foxk1 expression. Furthermore, Sox15 mutant mice display perturbed skeletal muscle regeneration, due in part to decreased numbers of satellite cells and decreased Foxk1 expression. These studies demonstrate that Sox15, Fhl3 and Foxk1 function to coordinately regulate the myogenic progenitor cell population and skeletal muscle regeneration.

Nkx2–5 transactivates the Ets-related protein 71 gene and specifies an endothelial/endocardial fate in the developing embryo

“…Promoter occupancy of Nkx2-5 to this evolutionary conserved site in vivo was confirmed using chromatin immunoprecipitation (ChIP) assays (20,21). As shown in Fig.…”

“…20 and 21; see SI Materials and Methods). ChIP assays were performed as described (20,21), with the exception that anti-Nkx2-5 and/or anti-myc and anti-HA sera were used to immunoprecipitate the Nkx2-5-DNA and HA-Etsrp71-DNA complexes to analyze the promoter occupancy, respectively. Transcriptional assays were performed as described with several modifications (refs.…”

“…Etsrp71 transgenic mice were generated as described (16,20), except that a 3.9-kb upstream region of Etsrp71 was PCR amplified and cloned into the hsp68-LacZ reporter plasmid (38). Methods for identification of transgenic mice were performed as described (16,20). Generation of Nkx2-5-EYFP transgenic (16), Nkx2-5 heterozygous (8), Tie2-GFP (19), and Tie2-LacZ mice (18) was previously described.…”

“…We generated Tg mice using this 3.9-kb Etsrp71 promoter fragment to drive the lacZ reporter gene ( Fig. 2A) (20). Expression of the lacZ reporter in transgenic embryos recapitulates the endogenous expression of Etsrp71.…”

Kelch Repeat and BTB Domain Containing Protein 5 (Kbtbd5) Regulates Skeletal Muscle Myogenesis through the E2F1-DP1 Complex

“…Yeast Two-hybrid Screen, Western Blot Analysis, Coimmunoprecipitation, and GST Pulldown Assays-A pGBKT7 vectorKbtbd5 construct was used to screen a skeletal muscle cDNA library as outlined in our previous report (40). Western blot analysis and coimmunoprecipitation (co-IP) assays were performed as described in our previous studies using the following antibodies: anti-HA (Santa Cruz Biotechnology), anti-Myc (Santa Cruz Biotechnology), anti-FLAG (Sigma Aldrich), antitubulin (Sigma Aldrich), and anti-ubiquitin (BD Biosciences) sera (41).…”