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LXR? is required for glucocorticoid-induced hyperglycemia and hepatosteatosis in mice.

ABSTRACT: Although widely prescribed for their potent antiinflammatory actions, glucocorticoid drugs (e.g., dexamethasone) cause undesirable side effects that are features of the metabolic syndrome, including hyperglycemia, fatty liver, insulin resistance, and type II diabetes. Liver x receptors (LXRs) are nuclear receptors that respond to cholesterol metabolites and regulate the expression of a subset of glucocorticoid target genes. Here, we show LXR? is required to mediate many of the negative side effects of glucocorticoids. Mice lacking LXR? (but not LXR?) were resistant to dexamethasone-induced hyperglycemia, hyperinsulinemia, and hepatic steatosis, but remained sensitive to dexamethasone-dependent repression of the immune system. In vivo, LXR?/? knockout mice demonstrated reduced dexamethasone-induced expression of the key hepatic gluconeogenic gene, phosphoenolpyruvate carboxykinase (PEPCK). In perfused liver and primary mouse hepatocytes, LXR? was required for glucocorticoid-induced recruitment of the glucocorticoid receptor to the PEPCK promoter. These findings suggest a new avenue for the design of safer glucocorticoid drugs through a mechanism of selective glucocorticoid receptor transactivation.

SUBMITTER: Patel R

PROVIDER: S-EPMC3007136 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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LXRβ is required for glucocorticoid-induced hyperglycemia and hepatosteatosis in mice.

Patel Rucha R Patel Monika M Tsai Ricky R Lin Vicky V Bookout Angie L AL Zhang Yuan Y Magomedova Lilia L Li Tingting T Chan Jessica F JF Budd Conrad C Mangelsdorf David J DJ Cummins Carolyn L CL

The Journal of clinical investigation 20101201 1

Although widely prescribed for their potent antiinflammatory actions, glucocorticoid drugs (e.g., dexamethasone) cause undesirable side effects that are features of the metabolic syndrome, including hyperglycemia, fatty liver, insulin resistance, and type II diabetes. Liver x receptors (LXRs) are nuclear receptors that respond to cholesterol metabolites and regulate the expression of a subset of glucocorticoid target genes. Here, we show LXRβ is required to mediate many of the negative side effe ...[more]

PMID: 21123945

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Project description:BACKGROUND & AIMS:The paradox of selective hepatic insulin resistance, wherein the insulin-resistant liver fails to suppress glucose production but continues to produce lipids, has been central to the pathophysiology of hepatosteatosis and hyperglycemia. Our study was designed to investigate the mechanism(s) by which microRNA-206 alleviates the pathogenesis of hepatosteatosis and hyperglycemia. METHODS:Dietary obese mice induced by a high fat diet were used to study the role of microRNA-206 in the pathogenesis of hepatosteatosis and hyperglycemia. A mini-circle vector was used to deliver microRNA-206 into the livers of mice. RESULTS:Lipid accumulation impaired biogenesis of microRNA-206 in fatty livers of dietary obese mice and human hepatocytes (p<0.01). Delivery of microRNA-206 into the livers of dietary obese mice resulted in the strong therapeutic effects on hepatosteatosis and hyperglycemia. Mechanistically, miR-206 interacted with the 3' untranslated region of PTPN1 (protein tyrosine phosphatase, non-receptor type 1) and induced its degradation. By inhibiting PTPN1 expression, microRNA-206 facilitated insulin signaling by promoting phosphorylation of INSR (insulin receptor) and impaired hepatic lipogenesis by inhibiting Srebp1c transcription. By simultaneously modulating lipogenesis and insulin signaling, microRNA-206 reduced lipid (p=0.006) and glucose (p=0.018) production in human hepatocytes and livers of dietary obese mice (p<0.001 and p<0.01 respectively). Re-introduction of Ptpn1 into livers offset the inhibitory effects of microRNA-206, indicating that PTPN1 mediates the inhibitory effects of microRNA-206 on both hepatosteatosis and hyperglycemia. CONCLUSIONS:MicroRNA-206 is a potent inhibitor of lipid and glucose production by simultaneously facilitating insulin signaling and impairing hepatic lipogenesis. Our findings potentially provide a novel therapeutic agent for both hepatosteatosis and hyperglycemia. LAY SUMMARY:The epidemic of obesity is causing a sharp rise in the incidence of insulin resistance and its major complications, type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). However, there are no effective treatments because the mechanisms underlying both disorders are not well described. We identified microRNA-206 as a novel and effective inhibitor for both glucose and lipid production in liver and potentially provide a unique therapeutic drug for both hepatosteatosis and hyperglycemia.

Project description:BACKGROUND:Glucocorticoid (GC)-induced hyperglycemia is characterized by elevated postprandial blood glucose, which commonly requires multiple insulin injections. We investigated whether a long-acting glucagon-like peptide-1 receptor agonist, dulaglutide (Dula), safely improved GC-induced hyperglycemia in inpatients, to reduce insulin injection frequency. METHODS:The data of hospitalized patients with GC-induced hyperglycemia treated with Dula (Dula group, n?=?38) or without (non-Dula group, n?=?38) were retrospectively evaluated. Baseline data were collected at the beginning of GC treatment. The primary outcome in this study was glycemic control, which was compared between the groups using the six-point blood glucose (before and 2?h after each meal) profiles at discharge. The daily injection frequency of injectable drugs at discharge were also compared between groups. RESULTS:No specific trend of underlying diseases was observed between the non-Dula and Dula groups. The proportion of patients previously administered with GC pulse therapy was comparable between the two groups. No significant differences were observed between groups, in the starting maintenance GC dose, GC dose at pretreatment of Dula and discharge, and cumulative GC dose during the observation. Six-point blood glucose levels at pretreatment and discharge were comparable between the two groups. However, daily injection frequency of injectable drugs and insulin dose were significantly lower in the Dula group than that in the non-Dula group. No differences were observed in the number of hypoglycemic events, the elevation of serum pancreatic enzyme levels, or gastrointestinal adverse events. CONCLUSION:These findings suggest that Dula could provide glycemic control while reducing the insulin dose and injection frequency in inpatients with GC-induced hyperglycemia. The occurrence of adverse events such as gastrointestinal symptoms and hypoglycemia did not increase in the Dula-treated patients compared to those not treated, suggesting its safety.

Dataset Information

LXR? is required for glucocorticoid-induced hyperglycemia and hepatosteatosis in mice.

Publications

LXRβ is required for glucocorticoid-induced hyperglycemia and hepatosteatosis in mice.

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