A key role of PGC ‐1 α transcriptional coactivator in production of VEGF by a novel angiogenic agent COA ‐Cl in cultured human fibroblasts

We previously demonstrated a potent angiogenic effect of a newly developed adenosine‐like agent named COA ‐Cl. COA ‐Cl exerted tube forming activity in human umbilical vein endothelial cells in the presence of normal human dermal fibroblasts ( NHDF ). We therefore explored whether and how COA ‐Cl modulates gene expression and protein secretion of VEGF , a master regulator of angiogenesis, in NHDF . RT ‐ PCR and ELISA revealed that COA ‐Cl upregulated VEGF mRNA expression and protein secretion in NHDF . HIF 1 α (hypoxia‐inducible factor 1 α ), a transcription factor, and PGC ‐1 α (peroxisome proliferator‐activated receptor‐ γ coactivator‐1 α ), a transcriptional coactivator, are known to positively regulate the VEGF gene. Immunoblot and RT ‐ PCR analyses revealed that COA ‐Cl markedly upregulated the expression of PGC ‐1 α protein and mRNA . COA ‐Cl had no effect on the expression of HIF 1 α protein and mRNA in both hypoxia and normoxia. Silencing PGC ‐1 α gene, but not HIF 1 α gene, by small interfering RNA attenuated the ability of COA ‐Cl to promote VEGF secretion. When an N‐terminal fragment of PGC ‐1 α was cotransfected with its partner transcription factor ERR α (estrogen‐related receptor‐ α ) in COS ‐7 cells, COA ‐Cl upregulated the expression of the endogenous VEGF mRNA . However, COA ‐Cl had no effect on the expression of VEGF , when HIF 1 α was transfected. COA ‐Cl induces VEGF gene expression and protein secretion in fibroblasts. The transcriptional coactivator PGC ‐1 α , in concert with ERR α , plays a key role in the COA ‐Cl‐induced VEGF production. COA ‐Cl‐induced activation of PGC ‐1 α ‐ ERR α ‐ VEGF pathway has a potential as a novel means for therapeutic angiogenesis.