Lysine demethylase KDM5B down-regulates SIRT3-mediated mitochondrial glucose and lipid metabolism in diabetic neuropathy.

Abstract

Diabetic peripheral neuropathy (DPN) is a common neurological complication of diabetes mellitus without efficient interventions. Both lysine demethylase 5B (KDM5B) and sirtuin-3 (SIRT3) have been found to regulate islet function and glucose homeostasis. KDM5B was predicted to bind to the SIRT3 promoter by bioinformatics. Here, we investigated whether KDM5B affected DPN development via modulating SIRT3. The db/db mice and high glucose-stimulated Schwann cells (RSC96) were used as in vivo and in vitro models of DPN, respectively. Glucose level, glucose and insulin tolerance of mice were measured. Neurological function was evaluated by motor nerve conduction velocity (MNCV), tactile allodynia assay and thermal sensitivity assay. Adenosine triphosphate level, oxygen consumption rate, extracellular acidification rate, β-oxidation rate, acetyl-CoA level, acetylation levels and activities of long-chain acyl CoA dehydrogenase (LCAD) and pyruvate dehydrogenase (PDH) were detected. Methyl thiazolyl tetrazolium assay was adopted to determine cell viability. Reactive oxygen species (ROS) production was detected by MitoSox staining. Western blotting for measuring target protein levels. Molecular mechanisms were investigated by co-immunoprecipitine (Co-IP), chromatin immunoprecipitation (ChIP) and luciferase reporter assay. KDM5B was up-regulated, while SIRT3 was down-regulated in DPN models. SIRT3 overexpression or AMPK activation ameliorated mitochondrial metabolism dysfunction and ROS overproduction during DPN. KDM5B overexpression triggered mitochondrial metabolism disorder and oxidative stress via directly transcriptional inhibiting SIRT3 expression by demethylating H3K4me3 or indirectly repressing AMPK pathway-regulated SIRT3 expression. KDM5B contributes to DPN via regulating SIRT3-mediated mitochondrial glucose and lipid metabolism. KDM5B inhibition may be an effective intervention for DPN.