RETRACTED: Effects of melatonin on fatty liver disease: The role of <scp>NR</scp>4A1/<scp>DNA</scp>‐<scp>PK</scp>cs/p53 pathway, mitochondrial fission, and mitophagy

Background/Aims: Hyperglycaemia stress-induced renal injury is closely associated with mitochondrial dysfunction through poorly understood mechanisms. The aim of our study is to explore the upstream trigger and the downstream effector driving diabetic nephropathy via modulating mitochondrial homeostasis. Methods: A diabetic nephropathy model was generated in wild-type (WT) mice and MAP Kinase phosphatase 1 transgenic (MKP1-TG) mice using STZ injection. Cell experiments were conducted via high-glucose treatment in the human renal mesangial cell line (HRMC). MKP1 overexpression assay was carried out via adenovirus transfection. Renal function was evaluated via ELISA, western blotting, histopathological staining, and immunofluorescence. Mitochondrial function was determined via mitochondrial potential analysis, ROS detection, ATP measurement, mitochondrial permeability transition pore (mPTP) opening evaluation, and immunofluorescence for mitochondrial pro-apoptotic factors. Loss- and gain-of-function assays for mitochondrial fragmentation were performed using a pharmacological agonist and blocker. Western blotting and the pathway blocker were used to establish the signalling pathway in response to MKP1 overexpression in the presence of hyperglycaemia stress. Results: MKP1 was downregulated in the presence of chronic high-glucose stress in vivo and in vitro. However, MKP1 overexpression improved the metabolic parameters, enhanced glucose control, sustained renal function, attenuated kidney oxidative stress, inhibited the renal inflammation response, alleviated HRMC apoptosis, and repressed tubulointerstitial fibrosis. Molecular investigation found that MKP1 overexpression enhanced the resistance of HRMC to the hyperglycaemic injury by abolishing mitochondrial fragmentation. Hyperglycaemia-triggered mitochondrial fragmentation promoted mitochondrial dysfunction, as evidenced by decreased mitochondrial potential, elevated mitochondrial ROS production, increased pro-apoptotic factor leakage, augmented mPTP opening and activated caspase-9 apoptotic pathway. Interestingly, MKP1 overexpression strongly abrogated mitochondrial fragmentation and sustained mitochondrial homeostasis via inhibiting the JNK-CaMKII-Fis1 pathway. After re-activation of the JNK-CaMKII-Fis1 pathway, the beneficial effects of MKP1 overexpression on mitochondrial protection disappeared. Conclusion: Taken together, our data identified the protective role played by MKP1 in regulating diabetic renal injury via repressing mitochondrial fragmentation and inactivating the JNK-CaMKII-Fis1 pathway, which may pave the road to new therapeutic modalities for the treatment of diabetic nephropathy.

Section: Discussionsupporting

confidence: 81%

Hyperglycaemia Stress-Induced Renal Injury is Caused by Extensive Mitochondrial Fragmentation, Attenuated MKP1 Signalling, and Activated JNK-CaMKII-Fis1 Biological Axis

Zhang¹,

Feng²,

Wang³

et al. 2018

“…Furthermore, accumulating evidence describes the regulatory action of Mst1 on p53. Thus, together with the confirmed role of p53 in regulating mitochondrial fission and mitophagy [19], this evidence raises the possibility that Mst1 may govern fission and mitophagy via p53.…”

Section: Introductionmentioning

confidence: 96%

“…Fluorescence intensity of Furo-2 and Rhod-2 was measured by excitation wavelengths of 340 and 550 nm, and emission wavelengths of 500 and 570 nm, respectively. Data (F/F0) were obtained by dividing fluorescence intensity (F) by (F0) at resting level (t = 0) which was normalized by control groups [9,19].…”

Section: Mitochondrial Respiratory Assaysmentioning

confidence: 99%

Effect of Mst1 on Endometriosis Apoptosis and Migration: Role of Drp1-Related Mitochondrial Fission and Parkin-Required Mitophagy

Zhao

Yang

et al. 2018

Background/Aims: Mitochondrial homeostasis is implicated in the development and progression of endometriosis through poorly defined mechanisms. Mst1 is the major growth suppressor related to cancer migration, apoptosis and proliferation. However, whether Mst1 is involved in endometriosis apoptosis and migration via regulating the mitochondrial function remains to be elucidated. Methods: Expression of Mst1 in endometriosis was examined via western blots. Cellular apoptosis was detected via MTT and TUNEL assay. Gain of function assay about Mst1 was conducted via adenovirus over-expression. Mitochondrial functions were evaluated via mitochondrial membrane potential JC-1 staining, ROS flow cytometry analysis, mPTP opening assessment and immunofluorescence of HtrA2/Omi. The mitophagy activity were examined via western blots and immunofluorescence. Results: First, we found that Mst1 was significantly downregulated in the ectopic endometrium of endometriosis compared to the normal endometrium. However, the recovery of Mst1 function was closely associated with the inability of endometrial stromal cells (ESCs) to migrate and survive. A functional study indicated that regaining Mst1 enhanced Drp1 post-transcriptional phosphorylation at Ser616 and repressed Parkin transcription activity via p53, leading to mitochondrial fission activation and mitophagy inhibition. Excessive Drp1-related fission forced the mitochondria to liberate HtrA2/Omi into the cytoplasm. Moreover, Mst1-induced defective mitophagy evoked cellular

“…In response to cardiac ischemia reperfusion, mitophagy activation provides beneficial effects on cardiomyocytes survival [43]. Similarly, high fat-induced liver death could be abrogated via mitophagy activation [21]. Regarding stem cell, mitophagy activation sustains hematopoietic stem cell self-renewal [66], delays induced pluripotent stem cell senescence [67] and enhances the therapeutic potential of umbilical cord blood-derived human mesenchymal stem cell [68].…”

Section: Discussionmentioning

confidence: 99%

“…In oxidative stress-mediated cellular apoptosis, mitochondria have been documented to transmit apoptotic signals through the release of cytochrome c (cyt-c) into cytoplasm [18, 19]. Recently, several researchers have demonstrated that mitochondria use mitophagy, a mitochondrial autophagy system [20], to remove damaged mitochondria and inhibit mitochondrial apoptosis [21, 22]. However, whether mitophagy contributes to stem cell survival is unclear.…”

Section: Introductionmentioning

confidence: 99%

SIRT3 Facilitates Amniotic Fluid Stem Cells to Repair Diabetic Nephropathy Through Protecting Mitochondrial Homeostasis by Modulation of Mitophagy

Feng

Dai

et al. 2018

Background/Aims: Amniotic fluid stem cells (AFSCs) transplantation is a promising therapeutic strategy for diabetic nephropathy. Sirtuin3 (SIRT3) is a novel mitochondrial protective factor. In the present study, we aimed to investigate whether SIRT3 protects against hyperglycemia-induced AFSCs damage and enhances the therapeutic efficiency of AFSCs in diabetic nephropathy. Methods: To establish the diabetic nephropathy model, db/ db mice were used. AFSCs were obtained and transplanted into the kidney tissue of db/ db mice. Gain-of-function assay with SIRT3 overexpression was performed in AFSCs via adenoviral transfections (Ad/SIRT3). Cellular viability and apoptosis were measured via MTT, TUNEL assay and western blotting. Mitochondrial function was assessed via JC1 staining, mPTP opening assay, mitochondrial respiratory function analysis, and immunofluorescence analysis of cyt-c. Mitophagy was assessed via western blotting and immunofluorescence analysis. Renal histopathology and morphometric analysis were conducted via H&E, Masson and PASM staining. Kidney function was detected via ELISA assay, western blotting and qPCR. Results: SIRT3 was downregulated in AFSCs under high glucose stimulation, where its expression was positively correlated with AFSCs survival and proliferation. Regaining SIRT3 activated mitophagy protecting AFSCs against high glucose-induced apoptosis via preserving mitochondrial function. Transplanting SIRT3-overexpressing AFSCs in db/db mice improved the abnormalities in glucose metabolic parameters, including the levels of glucose, insulin, C-peptide, HbA1c and inflammatory markers. In addition, the engraftment of SIRT3-modified AFSCs also reversed renal function, decreased renal hypertrophy, and ameliorated renal histological changes in db/db mice. Functional studies confirmed that SIRT3-modified AFSCs promoted glomerulus survival and reduced renal fibrosis. Conclusion: Collectively, our results demonstrate that AFSCs may be a promising therapeutic treatment for ameliorating diabetes and the development of diabetic nephropathy and that the overexpression of SIRT3 in AFSCs may further increase the efficiency of stem cell-based therapy.