c-Myb regulates transcriptional activation of miR-143/145 in vascular smooth muscle cells
Fig 1
c-Myb-regulates expression of miR-143 and miR-145 in mouse embryonic stem cell-derived VEGFR2+ progenitors and adult mouse carotid vascular smooth muscle cells.
(A) Flow cytometry of cardiovascular-directed d3.75 embryoid bodies (EBs), derived from wild-type (wt) or c-myb-/- (knockout) mouse embryonic stem cells, was used to isolate progenitors with cell surface markers VEGFR2 (V) and PDGFRα (P). The known vascular smooth muscle cell (VSMC) progenitor V+/P- derived from c-myb-/- EB had lower expression levels of miR-143 (p<0.05*) and miR-145 (p<0.01**) than V+/P- derived from wt EB. The non-SMC progenitor cells V-/P+ showed no such difference in miR-143 and miR-145 expression, compared to V+/P-. (B) Primary mouse carotid VSMCs isolated from c-myblx/lx mice have reduced expression levels of c-myb (p<0.05*), as well as miR-143 (p<0.01**) and miR-145 (p<0.001***) as compared to VSMCs isolated from wt mice. (C) Carotid VSMCs isolated from mice homozygous for a hypomorphic c-myb allele (c-mybh/h) have no differences in c-myb expression, but their known reductions in c-Myb activity were associated with reduced expression levels of miR-143 (p<0.01**) and miR-145 (p<0.001***) versus wt. qPCR analysis was performed with n = 3 biological samples and three technical repeats. (D) VSMC from c-myblx/lx mice show reduced expression levels of VSMC marker, Sm22α versus wt. (E) Densitometry reveals c-myblx/lx mice have significantly reduced expression of Sm22a relative to GAPDH compared to wt (p<0.05*, n = 4).