RNA-binding protein HuR suppresses senescence through Atg7 mediated autophagy activation in diabetic intervertebral disc degeneration

Abstract

Objectives: Diabetes is a risk factor for intervertebral disc degeneration (IVDD). Studies have demonstrated that diabetes may affect IVDD through transcriptional regulation; however, whether post-transcriptional regulation is involved in diabetic IVDD (DB-IVDD) is still unknown. This study was performed to illustrate the role of HuR, an RNA-binding protein, in DB-IVDD development and its mechanism.

Materials and methods: The expression of HuR was evaluated in nucleus pulposus (NP) tissues from diabetic IVDD patients and in high glucose-treated NP cells. Senescence and autophagy were assessed in HuR over-expressing and downregulation NP cells. The mRNAs that were regulated by HuR were screened, and immunoprecipitation was applied to confirm the regulation of HuR on targeted mRNAs.

Results: The results showed that the expression of HuR was decreased in diabetic NP tissues and high glucose-treated NP cells. Downregulation of HuR may lead to increased senescence in high glucose-treated NP cells, while autophagy activation attenuates senescence in HuR deficient NP cells. Mechanistic study showed that HuR prompted Atg7 mRNA stability via binding to the AU-rich elements. Furthermore, overexpression of Atg7, but not HuR, may ameliorate DB-IVDD in rats in vivo.

Conclusions: In conclusion, HuR may suppress senescence through autophagy activation via stabilizing Atg7 in diabetic NP cells; while Atg7, but not HuR, may serve as a potential therapeutic target for DB-IVDD.

Keywords: Atg7; HuR; autophagy; diabetes; intervertebral disc degeneration; senescence.