FIGURE 1.

Robust and specific knockdown of MEF2 proteins using shRNA adenoviruses. A and D, schematic representations of Mef2b (A) and Mef2d (D) transcripts. shRNA adenoviruses were generated to target the carboxyl-terminal region of the Mef2 transcripts (black bar) for knockdown in C2C12 myoblasts. The target sequences excluded regions containing alternatively spliced exons and were selected based on homology between mouse, human, and rat Mef2b or Mef2d sequences. B and E, Western blot analysis of shMef2b (B) and shMef2d (E) specificity against overexpressed MEF2 constructs in COS cells. Extracts for shMef2b knockdown of MEF2B-FLAG Western blot were cropped for image clarity (B, upper panel) but analyzed on the same gel (B, lower panel). shMef2b 195 (sequence shown in A) was used to generate adenovirus. C and F, quantitative RT analysis of endogenous Mef2b (C) and Mef2d (F) knockdown in C2C12 myotubes at differentiation day 3. The data are means ± S.E. *, p < 0.05; ****, p < 0.0001.