Fig. 5.

HDAC4 induces muscle fiber atrophy independently of ATF4. A and B: in C57BL/6 mice, one TA muscle was transfected with 20 μg p-HDAC4-FLAG plus 2 μg p-eGFP, and the contralateral TA (Control) was transfected with 20 μg empty plasmid (pcDNA3) plus 2 μg p-eGFP. eGFP served as a transfection marker and does not alter muscle fiber size. Bilateral TAs were harvested 7 days posttransfection for histological analysis. A: representative images. B: quantification of muscle fiber size. Left, fiber size distributions. Right, mean fiber diameter ± SE; n = 4 muscles/condition. *P ≤ 0.01. C: in ATF4 mKO mice (left) and wild-type littermates (right), one TA muscle was transfected with 20 μg p-HDAC4-FLAG plus 2 μg p-eGFP, and the contralateral TA (Control) was transfected with 20 μg empty plasmid (pcDNA3) plus 2 μg p-eGFP. Seven days later, bilateral TAs were harvested for histological analysis; n = 5–6 muscles/condition. * P < 0.001.