ROLE OF CAMKII IN HEPATIC GLUCONEOGENESIS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 糖异生（GNG）在禁食期间被强烈刺激，在糖尿病中被异常激活。一些转录因子和辅激活因子已被证明可以调节这一过程，然而，其潜在的机制尚未完全阐明。 我们最近发现，钙响应激酶钙/钙调蛋白依赖性蛋白激酶II（CaMKII）在瘦素缺乏（ob/ob）小鼠（严重胰岛素抵抗和糖尿病的模型）的肝脏中被激活。用特异性CaMKII抑制剂治疗ob/ob小鼠，可降低肝脏CaMKII活性，降低空腹血糖，并降低促凋亡基因G6 β和PEPCK的表达。我们接下来探索了来自WT与Camk 2g-/-小鼠的表达CaMKIIg的原代肝细胞中的GNG。我们证明了CaMKII在调节空腹胰岛素生成中起着重要作用。我们发现，CaMKIIg缺陷的肝细胞有一个显着的减少，G6 β和PEPCK的表达诱导毛喉素，胰高血糖素模拟物和cAMP激活剂，和较低水平的核FoxO 1，转录诱导GNG基因。此外，与对照组相比，用含有组成型活性CaMKII的腺病毒转导的原代肝细胞具有增加的G6 β和PEPCK mRNA表达水平。为了支持CaMKIIg在体内禁食GNG中的作用，我们发现禁食的Camk 2g-/-小鼠具有较低的血糖水平;丙酮酸转化为葡萄糖的较低转化率;肝GNG基因的钝化诱导;以及与WT小鼠相比肝细胞核中FoxO 1水平较低。这些数据表明，ER应激诱导的激活CaMKIIg在肝脏中肥胖和禁食有助于增加肝葡萄糖的生产和高血糖症。这一概念提出了肝CaMKIIg的治疗靶向可能对胰岛素抵抗受试者的葡萄糖稳态具有特别益处的可能性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Gluconeogenesis (GNG) is strongly stimulated during fasting and is aberrantly activated in diabetes mellitus. Several transcription factors and coactivators have been shown to regulate this process, however, the underlying mechanisms have not been fully elucidated. We recently found that a calcium-responsive kinase calcium/calmodulin-dependent protein kinase II (CaMKII) is activated in the liver of leptin-deficient (ob/ob) mice, a model of severe insulin resistance and diabetes. Treatment of ob/ob mice with a specific CaMKII inhibitor decreased hepatic CaMKII activity, lowered fasting blood glucose, and decreased the expression of the gluconeogenic genes, G6Pase and PEPCK. We next explored GNG in primary hepatocytes, which express CaMKIIg, from WT vs. Camk2g-/- mice. We demonstrated that CaMKII plays an essential role in the regulation of fasting gluconeogenesis. We found that the CaMKIIg-deficient hepatocytes have a marked decrease in the expression of G6Pase and PEPCK induced by forskolin, a glucagon mimetic and cAMP activator, and lower levels of nuclear FoxO1, which transcriptionally induces GNG genes. Moreover, primary hepatocytes transduced with adenovirus containing constitutively active CaMKII have increased expression levels of G6Pase and PEPCK mRNA compared with controls. In support of a role for CaMKIIg in fasting GNG in vivo, we found that fasted Camk2g-/- mice had lower blood glucose levels; lower conversion of pyruvate to glucose; blunted induction of hepatic GNG genes; and lower levels of FoxO1 in hepatic nuclei compared with WT mice. These data suggest that ER stress-induced activation of CaMKIIg in liver during obesity and fasting contributes to increased hepatic glucose production and hyperglycemia. This concept raises the possibility that therapeutic targeting of hepatic CaMKIIg may have particular benefit in glucose homeostasis in insulin-resistant subjects.