Regulation of GADD153 induced by mechanical stress in cardiomyocytes.

BACKGROUND

Growth arrest and DNA damage-inducible gene 153 (GADD153), an apoptosis regulated gene, increased during endoplasmic reticulum stress. However, the expression of GADD153 in cardiomyocytes under mechanical stress is little known. We aimed to investigate the regulation mechanism of GADD153 expression and apoptosis induced by mechanical stress in cardiomyocytes.

MATERIALS AND METHODS

Aorta-caval shunt was performed in adult Sprague-Dawley rats to induce volume overload. Rat neonatal cardiomyocytes grown on a flexible membrane base were stretched by vacuum to 20% of maximum elongation, at 60 cycles min(-1).

RESULTS

The increased ventricular dimension measured using echocardiography in the shunt group (n = 8) was reversed to normal by treatment with chaperon 4-phenylbutyric acid (PBA) (n = 8) at 500 mg kg(-1) day(-1) orally for 3 days. GADD153 protein and mRNA were up-regulated in the shunt group when compared with sham group (n = 8). Treatment with PBA reversed the protein of GADD153 to the baseline values. The TUNEL assay showed that PBA reduced the apoptosis induced by volume overload. Cyclic stretch significantly increased GADD153 protein and mRNA expression after 14 h of stretch. Addition of c-jun N-terminal kinase (JNK) inhibitor SP600125, JNK small interfering RNA and tumour necrosis factor-alpha (TNF-alpha) antibody 30 min before stretch, reduced the induction of GADD153 protein. Stretch increased, while GADD153-Mut plasmid, SP600125 and TNF-alpha antibody abolished the GADD153 promoter activity induced by stretch. GADD153 mediated apoptosis induced by stretch was reversed by GADD153 siRNA, GADD153-Mut plasmid and PBA.

CONCLUSIONS

Mechanical stress enhanced apoptosis and GADD153 expression in cardiomyocytes. Treatment with PBA reversed both GADD153 expression and apoptosis induced by mechanical stress in cardiomyocytes.