IRF2BP2 is a skeletal and cardiac muscle-enriched ischemia-inducible activator of VEGFA expression

Abstract

We sought to identify an essential component of the TEAD4/VGLL4 transcription factor complex that controls vascular endothelial growth factor A (VEGFA) expression in muscle. A yeast 2-hybrid screen was used to clone a novel component of the TEAD4 complex from a human heart cDNA library. We identified interferon response factor 2 binding protein 2 (IRF2BP2) and confirmed its presence in the TEAD4/VGLL4 complex in vivo by coimmunoprecipitation and mammalian 2-hybrid assays. Coexpression of IRF2BP2 with TEAD4/VGLL4 or TEAD1 alone potently activated, whereas knockdown of IRF2BP2 reduced, VEGFA expression in C(2)C(12) muscle cells. Thus, IRF2BP2 is required to activate VEGFA expression. In mouse embryos, IRF2BP2 was ubiquitously expressed but became progressively enriched in the fetal heart, skeletal muscles, and lung. Northern blot analysis revealed high levels of IRF2BP2 mRNA in adult human heart and skeletal muscles, but immunoblot analysis showed low levels of IRF2BP2 protein in skeletal muscle, indicating post-transcriptional regulation of IRF2BP2 expression. IRF2BP2 protein levels are markedly increased by ischemia in skeletal and cardiac muscle compared to normoxic controls. IRF2BP2 is a novel ischemia-induced coactivator of VEGFA expression that may contribute to revascularization of ischemic cardiac and skeletal muscles.

A Novel Transcription Complex That Selectively Modulates Apoptosis of Breast Cancer Cells through Regulation of FASTKD2

“…We have not found DIF-1 to act as an activator in the various breast and nonbreast cell lines under the conditions we studied. However, it is of interest that Teng et al (32) reported that cardiac muscle contains very high levels of IRF-2BP2 protein compared with other tissues. The level of IRF-2BP2 protein in muscle is further increased in ischemia and was reported to stimulate expression of vascular endothelial growth factor A.…”

“…The level of IRF-2BP2 protein in muscle is further increased in ischemia and was reported to stimulate expression of vascular endothelial growth factor A. This apparently occurs through the interaction of IRF-2BP2 in cardiac cells with the TEA domain transcription factor TEAD4 and VGLL4, a member of the vestigial-like family or regulators (32). Thus, like other transcription factors (e.g., nuclear hormone receptors), IRF-2BP2 may have the potential to act as a repressor or activator, depending on the cell and possibly promoter context.…”

IRF2BP2 Reduces Macrophage Inflammation and Susceptibility to Atherosclerosis

“…[8][9][10][11][12] Exposure of macrophages to bacterial lipopolysaccharide activates the M1 inflammatory phenotype, whereas exposure to interleukin (IL)-4 favors the M2 anti-inflammatory phenotype. 13 In human monocyte-derived macrophages, IRF2BP2 mRNA levels are elevated in the M2 state, but are suppressed to nearly undetectable levels in the M1 state 14 (Geoprofiles, GDS2430:224570_s_at), suggesting that IRF2BP2 may be involved in macrophage polarization.…”

“…19 A custom rabbit antibody against IRF2BP2 was described. 12 Cryostat sections (10 μm) were subjected to immunofluorescence, TUNEL (Promega, G3250), hematoxylin and eosin (PerkinElmer), and oil red O staining. Primary antibodies to KLF2 (Millipore), mouse ApoB (gift of Dr Ross Milne of the University of Ottawa Heart Institute), Casp3 (Cell Signaling), ApoA1, ApoE, F4/80, iNOS, Arg1, Retnlb, H3K4me3, and GAPDH (Abcam), Ki67, MT-CO2, CD3, CD68, CD206 (Santa Cruz), CD11b (AbD Serotec), and actin (Sigma) were used.…”

“…In KO BMDM, IRF2BP2 mRNA and protein levels were reduced to <10% of WT by quantitative real-time PCR and immunoblot analysis ( Figure 1A and 1B). IRF2BP2 is produced as 2 alternatively spliced isoforms, 9,12 and both are present in macrophages. Trace levels of the upper band in the KO BMDM likely reflect the presence of the long isoform expressed from a minority of nonmyeloid cells in our cultures, where LysMCre is not expressed.…”