AMPK agonist alleviate renal tubulointerstitial fibrosis via activating mitophagy in high fat and streptozotocin induced diabetic mice

Ya-Chun Han,Hao Zhang,Ming Yang,Yu-Ting Liu,Na Song,Shi-Qi Tang,Shikun Yang,Xue-Qin Wu,Ming Zhan,Wei Zhang,Can-Hui Peng,Ai-Mei Li

doi:10.1038/s41419-021-04184-8

Abstract

Renal tubulointerstitial fibrosis was a crucial pathological feature of diabetic nephropathy (DN), and renal tubular injury might associate with abnormal mitophagy. In this study, we investigated the effects and molecular mechanisms of AMPK agonist metformin on mitophagy and cellular injury in renal tubular cell under diabetic condition. The high fat diet (HFD) and streptozotocin (STZ)-induced type 2 diabetic mice model and HK-2 cells were used in this study. Metformin was administered in the drinking water (200 mg/kg/d) for 24 weeks. Renal tubulointerstitial lesions, oxidative stress and some indicators of mitophagy (e.g., LC3II, Pink1, and Parkin) were examined both in renal tissue and HK-2 cells. Additionally, compound C (an AMPK inhibitor) and Pink1 siRNA were applied to explore the molecular regulation mechanism of metformin on mitophagy. We found that the expression of p-AMPK, Pink1, Parkin, LC3II, and Atg5 in renal tissue of diabetic mice was decreased obviously. Metformin reduced the levels of serum creatinine, urine protein, and attenuated renal oxidative injury and fibrosis in HFD/STZ induced diabetic mice. In addition, Metformin reversed mitophagy dysfunction and the over-expression of NLRP3. In vitro pretreatment of HK-2 cells with AMPK inhibitor compound C or Pink1 siRNA negated the beneficial effects of metformin. Furthermore, we noted that metformin activated p-AMPK and promoted the translocation of Pink1 from the cytoplasm to mitochondria, then promoted the occurrence of mitophagy in HK-2 cells under HG/HFA ambience. Our results suggested for the first time that AMPK agonist metformin ameliorated renal oxidative stress and tubulointerstitial fibrosis in HFD/STZ-induced diabetic mice via activating mitophagy through a p-AMPK-Pink1-Parkin pathway.

Highlights

Diabetic nephropathy (DN) is one of the most severe microvascular complications in diabetic patients [1]
Our results suggested for the first time that AMPK agonist metformin ameliorated renal oxidative stress and tubulointerstitial fibrosis in high fat diet (HFD)/STZ-induced diabetic mice via activating mitophagy through a p-AMPK-Pink1-Parkin pathway
We have found that the levels of LC3-II and Atg5 both in mitochondria and cytoplasm were dramatically increased by metformin treatment (P < 0.05, Fig. 4C, G, H), while the expression of P62 was decreased in the metformin treatment group (P < 0.05, Fig. 4C, D), suggesting that the mitophagy was inhibited in diabetic condition, while AMPK agonist metformin therapy could promote the occurrence of mitophagy in the renal tubular cell

Summary

INTRODUCTION

Diabetic nephropathy (DN) is one of the most severe microvascular complications in diabetic patients [1]. 30–40% of patients with diabetes mellitus (DM) develop nephropathy and progression to renal injury [2] It significantly decreases the quality of life in people with diabetes. Mitophagy was a special type of autophagy, which could selectivity eliminate disrupted and dysfunctional mitochondria [6] It was an important way of mitochondrial quality control. Some previous studies have showed that mitophagy dysfunction was associated with DN, and some agents targeted on mitophagy have been shown beneficial effects [8, 9]. It could be seen that AMPK-mitophagy pathway might represent an attractive intervention target for DN Given these facts, we performed this study to explore the effects and mechanisms of AMPK-mediated mitophagy in diabetesinduced renal tubulointerstitial fibrosis.

RESULTS

DISCUSSION

CONCLUSION

ETHICS STATEMENT