Graphical Abstract Highlights d KCNH6 regulates insulin secretion and glucose hemostasis in humans and mice d KCNH6 dysfunction causes a phenotype from hyper-to hypoinsulinemia and diabetes d KCNH6 dysfunction increases intracellular calcium levels and hyperinsulinemia d Chronic elevation of intracellular calcium causes b cell loss and hypoinsulinemia In Brief Yang et al. show that KCNH6 plays a key role in insulin secretion and glucose hemostasis in humans and mice. Dysfunction of KCNH6 results in a hyperinsulinemia phenotype in the short term and hypoinsulinemia and diabetes in the long term. SUMMARYGlucose-stimulated insulin secretion from islet b cells is mediated by K ATP channels. However, the role of non-K ATP K + channels in insulin secretion is largely unknown. Here, we show that a non-K ATP K + channel, KCNH6, plays a key role in insulin secretion and glucose hemostasis in humans and mice. KCNH6 p.P235L heterozygous mutation co-separated with diabetes in a four-generation pedigree. Kcnh6 knockout (KO) or Kcnh6 p.P235L knockin (KI) mice had a phenotype characterized by changing from hypoglycemia with hyperinsulinemia to hyperglycemia with insulin deficiency. Islets from the young KO mice had increased intracellular calcium concentration and increased insulin secretion. However, islets from the adult KO mice not only had increased intracellular calcium levels but also had remarkable ER stress and apoptosis, associated with loss of b cell mass and decreased insulin secretion. Therefore, dysfunction of KCNH6 causes overstimulation of insulin secretion in the short term and b cell failure in the long term.

Aim: Atherosclerosis-prone apolipoprotein E (apoE) or low-density lipoprotein receptor (LDL-R) knockout (KO) mice are generally resistant to developing coronary atherosclerosis (CA) and ischemic heart disease (IHD). However, studies have demonstrated the occurrence of spontaneous CA and IHD in scavenger receptor class B type 1 (SR-BI)/apoE double KO (dKO) mice, which suggests that SR-BI could be a potential target for the prevention and therapy of CA and IHD. This possibility was later investigated in SR-BI/LDL-R dKO mice, but no signs of CA or IHD was identified when mice were fed a normal western-type diet. Here we explored whether SR-BI deletion could result in CA and IHD in LDL-R KO mice when fed a modified western-type diet containing higher (0.5%) cholesterol.Methods: Cardiac functions were detected by electrocardiography, single photon emission computed tomography (SPECT), echocardiography (Echo) and 2,3,5-triphenyltetrazolium chloride staining. CA was visualized by hematoxylin-eosin staining.Results: After 12 weeks on the modified diet, SR-BI/LDL-R dKO mice developed cardiac ischemia/infarction, together with systolic dysfunction and left ventricular dilatation. CA was most severe at the aortic sinus level to an extent that no dKO mice survived to 20 weeks on the modified diet. None of control mice, however, developed CA or IHD.Conclusions: SR-BI deletion led to CA and IHD in LDL-R KO mice when fed the modified western-type diet. We established SR-BI/LDL-R dKO mice as a diet-induced murine model of human IHD and developed detection methods, using a combination of SPECT and Echo, for effective in vivo evaluation of cardiac functions.

The hamster has been shown to share a variety of metabolic similarities with humans. To replicate human acute pancreatitis with hamsters, we comparatively studied the efficacy of common methods, such as the peritoneal injections of caerulein, L-arginine, the retrograde infusion of sodium taurocholate, and another novel model with concomitant administration of ethanol and fatty acid. The severity of pancreatitis was evaluated by serum amylase activity, pathological scores, myeloperoxidase activity, and the expression of inflammation factors in pancreas. The results support that the severity of pathological injury is consistent with the pancreatitis induced in mice and rat using the same methods. Specifically, caerulein induced mild edematous pancreatitis accompanied by minimal lung injury, while L-arginine induced extremely severe pancreatic injury including necrosis and neutrophil infiltration. Infusion of Na-taurocholate into the pancreatic duct induced necrotizing pancreatitis in the head of pancreas and lighter inflammation in the distal region. The severity of acute pancreatitis induced by combination of ethanol and fatty acids was between the extent of caerulein and L-arginine induction, with obvious inflammatory cells infiltration. In view of the advantages in lipid metabolism features, hamster models are ideally suited for the studies of pancreatitis associated with altered metabolism in humans.

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Seipin deficiency is responsible for type 2 congenital generalized lipodystrophy with severe loss of adipose tissue and can lead to hepatic steatosis, insulin resistance (IR), and dyslipidemia in humans. Adipose tissue secretes many adipokines that are central to the regulation of metabolism. In this study, we investigated whether transplantation of normal adipose tissue could ameliorate severe hepatic steatosis, IR, and dyslipidemia in lipoatrophic seipin knockout (SKO) mice. Normal adipose tissue from wild-type mice was transplanted into 6-wk-old SKO mice. At 4 mo after adipose tissue transplantation (AT), the transplanted fat survived with detectable blood vessels, and the reduced levels of plasma leptin, a major adipokine, were dramatically increased. Severe hepatic steatosis, IR, and dyslipidemia in SKO mice were ameliorated after AT. In addition, abnormal hepatic lipogenesis and β-oxidation gene expression in SKO mice were improved after AT. Our results suggest that AT may be an effective treatment to improve lipodystrophy-associated metabolic disorders.