Fig. 4.

HDAC4 is required for induction of Gadd45a mRNA and muscle fiber atrophy during muscle denervation. A: TA muscles of C57BL/6 mice were transfected with 10 μg of p-HDAC4-FLAG plus 20 μg p-miR-Control, 20 μg p-miR-HDAC4 #1, or 20 μg p-miR-HDAC4 #2, as indicated. Muscles were harvested 4 days later for immunoblot analysis with anti-FLAG and anti-actin antibodies. B: bilateral TA muscles of C57BL/6 mice were transfected with 20 μg p-miR-Control, 20 μg p-miR-HDAC4 #1, or 20 μg p-miR-HDAC4 #2. Seven days later, mice underwent unilateral muscle denervation. Two days later, bilateral TAs were harvested for qPCR analysis of HDAC4 and Gadd45a mRNA levels. mRNA levels in denervated muscles were normalized to levels in contralateral control muscles. Data are means ± SE from 8 mice/condition. *P ≤ 0.05. C: bilateral TAs of C57BL/6 mice were transfected with 20 μg p-miR-Control, 20 μg p-miR-HDAC4 #1, or 20 μg p-miR-HDAC4 #2 and then subjected to unilateral muscle denervation. Seven days later, bilateral TAs were harvested for quantification of muscle fiber size. Top left, representative images. Bottom left, mean fiber diameter ± SE. Right, fiber size distributions. n = 5–6 muscles/condition. *P ≤ 0.05.