MLKL-mediated necroptosis is a target for cardiac protection in mouse models of type-1 diabetes

Abstract

Background Cardiomyocyte death contributes to cardiac pathology of diabetes. Studies have shown that the RIPK3/MLKL necroptosis signaling is activated in diabetic hearts. Deletion of RIPK3 was reported to attenuate myocardial injury and heart dysfunction in streptozocin (STZ)-induced diabetic mice, suggesting a potential role of necroptosis in diabetic cardiomyopathy. This study characterized cardiomyocyte necroptosis in diabetic hearts and investigated whether MLKL-mediated necroptosis is a target for cardiac protection in diabetes. Methods Type 1 diabetes was induced in RIPK3 knockout, MLKL knockout and wild-type mice. Akita Type-1 diabetic mice were injected with shRNA for MLKL. Myocardial function was assessed by echocardiography. Immuno-histological analyses determined cardiomyocyte death and fibrosis in the heart. Cultured adult mouse cardiomyocytes were incubated with high glucose in the presence of various drugs. Cell death and phosphorylation of RIPK3 and MLKL were analysed. Results We showed that the levels of phosphorylated RIPK3 and MLKL were higher in high glucose-stimulated cardiomyocytes and hearts of STZ-induced type-1 diabetic mice, akita mice and type-1 diabetic monkeys when compared to non-diabetic controls. Inhibition of RIPK3 by its pharmacological inhibitor or gene deletion, or MLKL deletion prevented high glucose-induced MLKL phosphorylation and attenuated necroptosis in cardiomyocytes. In STZ-induced type-1 diabetic mice, cardiomyocyte necroptosis was present along with elevated cardiac troponin I in serum and MLKL oligomerization, and co-localized with phosphorylated MLKL. Deletion of RIPK3 or MLKL prevented MLKL phosphorylation and cardiac necroptosis, attenuated serum cardiac troponin I levels, reduced myocardial collagen deposition and improved myocardial function in STZ-injected mice. Additionally, shRNA-mediated down-regulation of MLKL reduced cardiomyocyte necroptosis in akita mice. Interestingly, incubation with anti-diabetic drugs (empagliflozin and metformin) prevented phosphorylation of RIPK3 and MLKL, and reduced cell death in high glucose-induced cardiomyocytes. Conclusions We have provided evidence that cardiomyocyte necroptosis is present in diabetic hearts and that MLKL-mediated cardiomyocyte necroptosis contributes to diabetic cardiomyopathy. These findings highlight MLKL-mediated necroptosis as a target for cardiac protection in diabetes.

Endogenous hydrogen sulphide deficiency and exogenous hydrogen sulphide supplement regulate skin fibroblasts proliferation via necroptosis

“…Noteworthy, necroptosis of distinct cells in different organs (including hepatic stellate cells, pancreatic stellate cells, fibroblasts and myofibroblasts) may cause fibrosis 42 . In diabetic cardiomyopathy, aggravated oxidative stress and promoted necroptosis exacerbated myocardial fibrosis 40,43 . Apoptotic adipocytes promoted necroptosis of macrophage foam cells to activate collagen synthesis in fibroblasts via a paracrine manner 44 .…”

“…42 In diabetic cardiomyopathy, aggravated oxidative stress and promoted necroptosis exacerbated myocardial fibrosis. 40,43 Apoptotic adipocytes promoted necroptosis of macrophage foam cells to activate collagen synthesis in fibroblasts via a paracrine manner. 44 Tubulointerstitial fibrosis was mediated by necroptosis of renal tubular epithelial cells in patients with chronic kidney disease via TGF-β 1 /Smad3 signal pathway.…”

Ferroptosis: Underlying mechanism and the crosstalk with other modes of neuronal death after intracerebral hemorrhage

“…Necroptosis combines both necrosis and apoptosis, hence the term necroptosis ( Vanden Berghe et al, 2014 ). It is a regulated form of necrotic cell death mediated by receptor-interacting kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and mixed lineage kinase domain-like (MLKL) ( Conrad et al, 2016 ; Cao et al, 2022 ). RIPK1 activates RIPK3 and thereby recruits MLKL at the cell membrane, which causes membrane rupture and eventually triggers necroptosis ( Samson et al, 2021 ; Gupta et al, 2022 ).…”

Targeting the programmed cell death (PCD) signaling mechanism with natural substances for the treatment of diabetic cardiomyopathy (DCM)

“…SIRT3‐knockout diabetic mice exhibited more severe cardiac dysfunction, exacerbated mitochondrial dysfunction, excessive ROS production, promoting necroptosis, and worsening DCM compared with the control group, indicating that SIRT3 could serve as a therapeutic target for DCM. Cao et al (2022) found that pharmacological inhibition or knockout of RIPK3 or MLKL in STZ‐induced type‐1 diabetic mice could attenuate necroptosis and protect cardiac cells subjected to high glucose treatment. Furthermore, the study demonstrated that Empagliflozin and metformin could prevent the phosphorylation of RIPK3 and MLKL in cardiac cells under high glucose conditions and inhibit necroptosis, providing benefits for cardiovascular complications in diabetic patients.…”

“…Long noncoding RNA DCRF is upregulated in DCM, activating autophagy, accelerating myocardial fibrosis, and promoting the progression of DCM (Feng et al, 2019). Necroptosis plays an essential role in the pathological process of DCM, and research evidence suggests that MLKL‐mediated necroptosis contributes to DCM (Cao et al, 2022).…”