In this review, the impacts of mitochondrial reactive oxygen species (ROS) on diabetes and its complications are described. In endothelial cells, high-glucose treatment increases mitochondrial ROS ...and normalization of the ROS production by inhibitors of mitochondrial metabolism, or by overexpression of UCP-1 or MnSOD, prevents glucose-induced activation of PKC, formation of AGE, and accumulation of sorbitol, all of which are believed to be the main molecular mechanisms of diabetic complications. Glomerular hyperfiltration, one of the characteristics of early diabetic nephropathy, may be caused by mitochondrial ROS through activation of COX-2 gene transcription, followed by PGE2 overproduction. In pancreatic beta cells, hyperglycemia also increases mitochondrial ROS, which suppresses the first phase of glucose-induced insulin secretion, at least in part, through the suppression of GAPDH activity. In liver cells, similar to that in hyperglycemia, TNF-alpha increases mitochondrial ROS, which in turn activates apoptosis signal-regulating kinase 1 (ASK1) and c-jun NH2-terminal kinases (JNK), increases serine phosphorylation of IRS-1, and decreases insulin-stimulated tyrosine phosphorylation of IRS-1, leading to insulin resistance. These results suggest the importance of mitochondrial ROS in the pathogenesis of diabetes mellitus and its complications through modification of various cellular events in many tissues, including vessels, kidney, pancreatic beta cells, and liver.
Recent evidence has revealed a novel signaling mechanism through which brown adipose tissue (BAT)-derived exosomal microRNAs (miRNAs) influence hepatic gene expression. Here, we uncover neuronal ...control of these miRNAs and identify exosomal miR-132-3p as a regulator of hepatic lipogenesis under cold stress conditions. Norepinephrine, a sympathetic nervous system neurotransmitter mediating cold-induced BAT activation, altered the composition of brown adipocyte (BAC)-derived exosomal miRNAs; among them, miR-132-3p was significantly induced. The isolated BAC-derived exosomes suppressed expression of hepatic Srebf1, a predicted target of miR-132-3p. In an indirect co-culture system, BACs suppressed expression of hepatic Srebf1 and its target lipogenic genes; this effect was not seen with miR-132-3p–inhibited BACs. Srebf1 was experimentally validated as an miR-132-3p target. Cold stimuli consistently induced miR-132-3p expression in BAT and attenuated Srebf1 expression in the liver. Our results suggest that BAT-derived exosomal miR-132-3p acts as an endocrine factor that regulates hepatic lipogenesis for cold adaptation.
•The composition of brown adipocyte-derived exosomal miRNAs are controlled by norepinephrine.•Norepinephrine induces miR-132-3p in the brown adipocyte-derived exosomes.•Brown adipocyte-derived exosomes suppress hepatic Srebf1 expression.•Srebf1 was experimentally validated as an miR-132-3p target.
A major target of insulin signaling is the FoxO family of Forkhead transcription factors, which translocate from the nucleus to the cytoplasm following insulin-stimulated phosphorylation. Here we ...show that the Forkhead transcription factors FoxK1 and FoxK2 are also downstream targets of insulin action, but that following insulin stimulation, they translocate from the cytoplasm to nucleus, reciprocal to the translocation of FoxO1. FoxK1/FoxK2 translocation to the nucleus is dependent on the Akt-mTOR pathway, while its localization to the cytoplasm in the basal state is dependent on GSK3. Knockdown of FoxK1 and FoxK2 in liver cells results in upregulation of genes related to apoptosis and down-regulation of genes involved in cell cycle and lipid metabolism. This is associated with decreased cell proliferation and altered mitochondrial fatty acid metabolism. Thus, FoxK1/K2 are reciprocally regulated to FoxO1 following insulin stimulation and play a critical role in the control of apoptosis, metabolism and mitochondrial function.
Aim: To verify the superiority of pemafibrate over placebo and the non-inferiority of pemafibrate to the maximum dose of fenofibrate for determining the percent change in fasting serum triglyceride ...(TG) levels and to investigate safety by assessing the incidence of adverse events (AEs) and adverse drug reactions (ADRs).Methods: This phase III, placebo/active drug-controlled, randomized, double-blind, parallel group comparison study enrolled patients with high TG and low high-density lipoprotein cholesterol levels. Patients were randomly assigned to receive placebo; pemafibrate 0.1 mg/day, 0.2 mg/day, or 0.4 mg/day; or fenofibrate 100 mg/day or 200 mg/day for 12 weeks.Results: Among 526 randomized patients, 489 completed the study, with drop-out rates of 0%, 6.7%, 5.5%, 5.9%, 8.2%, and 10.7% in the placebo; pemafibrate 0.1 mg/day, 0.2 mg/day, and 0.4 mg/day; and fenofibrate 100 mg/day and 200 mg/day groups. The study showed the non-inferiority of pemafibrate 0.4 mg/day and 0.2 mg/day to fenofibrate 200 mg/day as well the non-inferiority and superiority of all pemafibrate doses to fenofibrate 100 mg/day for reducing TG levels. No dose-dependent increase in the incidence of AEs or ADRs was observed among the pemafibrate dose groups. The incidence of AEs and ADRs for all pemafibrate doses was similar to that for placebo and fenofibrate 100 mg/day and significantly lower than that for fenofibrate 200 mg/day (P＜0.05).Conclusions: The favorable safety profile of pemafibrate, with fewer adverse effects on kidney/liver-related laboratory tests and fewer AEs/ADRs, including those leading to treatment discontinuation, over fenofibrate 200 mg/day may justify the use of this novel and potent treatment option for reducing TG levels in a broader range of patients.
PDF
