Inhibition of mitochondrial complex I improves glucose metabolism independently of AMPK activation

Accumulating evidences showed metformin and berberine, well‐known glucose‐lowering agents, were able to inhibit mitochondrial electron transport chain at complex I. In this study, we aimed to explore the antihyperglycaemic effect of complex I inhibition. Rotenone, amobarbital and gene silence of NDUFA13 were used to inhibit complex I. Intraperitoneal glucose tolerance test and insulin tolerance test were performed in db/db mice. Lactate release and glucose consumption were measured to investigate glucose metabolism in HepG2 hepatocytes and C2C12 myotubes. Glucose output was measured in primary hepatocytes. Compound C and adenoviruses expressing dominant negative AMP‐activated protein kinase (AMPK) α1/2 were exploited to inactivate AMPK pathway. Cellular NAD⁺/NADH ratio was assayed to evaluate energy transforming and redox state. Rotenone ameliorated hyperglycaemia and insulin resistance in db/db mice. It induced glucose consumption and glycolysis and reduced hepatic glucose output. Rotenone also activated AMPK. Furthermore, it remained effective with AMPK inactivation. The enhanced glycolysis and repressed gluconeogenesis correlated with a reduction in cellular NAD⁺/NADH ratio, which resulted from complex I suppression. Amobarbital, another representative complex I inhibitor, stimulated glucose consumption and decreased hepatic glucose output in vitro, too. Similar changes were observed while expression of NDUFA13, a subunit of complex I, was knocked down with gene silencing. These findings reveal mitochondrial complex I emerges as a key drug target for diabetes treatment. Inhibition of complex I improves glucose homoeostasis via non‐AMPK pathway, which may relate to the suppression of the cellular NAD⁺/NADH ratio.     

嘌呤拟似物对豚鼠胃窦环行肌自发性收缩及电活动的影响

为探讨非肾上腺素能非胆碱能神经递质对胃窦环行肌功能的调节作用,在离体胃平滑肌上观察了嘌呤拟似物对胃窦环行肌自发性收缩活动和电活动的影响。电活动用传统的细胞内微电极记录,并和收缩活动同步描记于多道生理记录仪。结果表明,嘌呤能P2Y受体激动剂,三磷酸腺苷(ATP)和2-methylthio ATP(2-MeSATP)均增强胃窦平滑肌的收缩活动,但不影响电活动,而且ATP和2-MeSATP对胃平滑肌收缩活动的增强作用可被嘌呤能P2Y受体阻断剂,reactive blue-2和苏拉明(suramin)所阻断。用100μmol／L α,β-MeATP引起的脱敏感使P2X受体被阻断,ATP增强胃窦平滑肌收缩活动的效应不受影响。嘌呤能P2X受体激动剂,α,β-MeATP明显抑制胃窦环行肌自发性收缩活动,同时使膜电位明显超极化。ATP对胃窦平滑肌的收缩作用不被L型钙通道阻断剂尼卡地平(nicardipine)阻断,但细胞外用无钙液灌流时这种效应则完全被阻断。用前列腺素合成抑制剂消炎痛预先处理20min后,ATP和2-MeSATP仍能增强胃窦平滑肌的自发性收缩活动。以上结果提示：(1)ATP和2-MeSATP通过嘌呤能P2Y受体增强胃窦平滑肌的自发性收缩活动,而α,β-MeATP或β,γ-MeATP通过嘌呤能P2X受体使膜电位超极化,引起胃窦平滑肌的舒张;(2)ATP和2-MeSATP增强胃窦平滑肌自发性收缩活动的效应依赖于细胞外钙,但钙离子进入细胞的途径并不是电压依赖性钙通道;(3)ATP和2-MeSATP增强胃窦平滑肌自发性收缩活动的效应不通过前列腺素介导。     

HIV-protease inhibitors induce expression of suppressor of cytokine signaling-1 in insulin-sensitive tissues and promote insulin resistance and type 2 diabetes mellitus

Insulin resistance, hyperglycemia, and type 2 diabetes are among the sequelae of metabolic syndromes that occur in 60-80% of human immunodeficiency virus (HIV)-positive patients treated with HIV-protease inhibitors (PIs). Studies to elucidate the molecular mechanism(s) contributing to these changes, however, have mainly focused on acute, in vitro actions of PIs. Here, we examined the chronic (7 wk) in vivo effects of the PI indinavir (IDV) in male Zucker diabetic fatty (fa/fa) (ZDF) rats. IDV exposure accelerated the diabetic state and dramatically exacerbated hyperglycemia and oral glucose intolerance in the ZDF rats, compared with vehicle-treated ZDF rats. Oligonucleotide gene array analyses revealed upregulation of suppressor of cytokine signaling-1 (SOCS-1) expression in insulin-sensitive tissues of IDV rats. SOCS-1 is a known inducer of insulin resistance and diabetes, and immunoblotting analyses revealed increases in SOCS-1 protein expression in adipose, skeletal muscle, and liver tissues of IDV-administered ZDF rats. This was associated with increases in the upstream regulator TNF-alpha and downstream effector sterol regulatory element-binding protein-1 and a decrease in IRS-2. IDV and other PIs currently in clinical use induced the SOCS-1 signaling cascade also in L6 myotubes and 3T3-L1 adipocytes exposed acutely to PIs under normal culturing conditions and in tissues from Zucker wild-type lean control rats administered PIs for 3 wk, suggesting an effect of these drugs even in the absence of background hyperglycemia/hyperlipidemia. Our findings therefore indicate that induction of the SOCS-1 signaling cascade by PIs could be an important contributing factor in the development of metabolic dysregulation associated with long-term exposures to HIV-PIs.     

cⅠ857基因的体外定位同义突变

 ｃⅠ８５７基因的体外定位同义突变陈南春,高辉,陈苏民,杨萍,刘新平（西安第四军医大学分子生物学研究所,西安７１００３２）外源基因要在大肠杆菌中获得高表达,需要合适的ＳＤ序列和可调控的强启动子［１］。ＰＬ启动子在原核启动子中属强启动子,它受ｃⅠ基因产物...     

鲍肽素对血管性痴呆大鼠学习与记忆能力的干预及机制研究

目的：观察鲍肤索对血管性痴呆大鼠学习与记忆能力的干预及机制。方法：制备生物鲍肤索,分剂量喂饲血管性痴呆大鼠,测试学习与记忆能力、红细胞和血红蛋白。结果：鲍肤素提高大鼠Y型迷宫测试的分值和红细胞、血红蛋白水平。结论：鲍肤素能提高血管性痴呆大鼠的学习与记忆能力和红细胞、血红蛋白水平。     

Targeting NADPH Oxidase and Phospholipases A2 in Alzheimer’s Disease

Alzheimer’s disease (AD) is marked by an increase in the production of extracellular beta amyloid plaques and intracellular neurofibrillary tangles associated with a decline in brain function. Increases in oxidative stress are regarded as an early sign of AD pathophysiology, although the source of reactive oxygen species (ROS) and the mechanism(s) whereby beta amyloid peptides (Aβ) impact oxidative stress have not been adequately investigated. Recent studies provide strong evidence for the involvement of NADPH oxidase and its downstream oxidative signaling pathways in the toxic effects elicited by Aβ. ROS produced by NADPH oxidase activate multiple signaling pathways leading to neuronal excitotoxicity and glial cell-mediated inflammation. This review describes recent studies demonstrating the neurotoxic effects of Aβ in conjunction with ROS produced by NADPH oxidase and the downstream pathways leading to activation of cytosolic phospholipase A₂ (PLA₂) and secretory PLA₂. In addition, this review also describes recent studies using botanical antioxidants to protect against oxidative damage associated with AD. Investigating the metabolic and signaling pathways involving Aβ NADPH oxidase and PLA₂ can help understand the mechanisms underlying the neurodegenerative effects of oxidative stress in AD. This information should provide new therapeutic approaches for prevention of this debilitating disease.     

Soil Diversity and Land Use in the United States

Soils are dynamic components of terrestrial ecosystems that historically have been viewed as economic resources by government and private interests. The large-scale conversion of many sections of the United States to agriculture and urban land uses, combined with the growing awareness of the role of soils in global biogeochemistry and ecology, ultimately requires an assessment of the remaining distribution of undisturbed soils in the country. Here we conduct the first quantitative analysis of disturbed and undisturbed soil distribution in the USA using a GIS-based approach. We find that a sizable fraction (4.5%) of the nation's soils are in danger of substantial loss, or complete extinction, due to agriculture and urbanization. In the agricultural belt of the country, up to 80% of the soils that were naturally of low abundance are now severely impacted (greater than 50% conversion to agricultural/urban uses). Undisturbed soils provide ecosystem services that warrant their preservation, including a somewhat complex relationship with rare or endangered plants. The known and unknown attributes of undisturbed soils suggests the need for an integrated biogeodiversity perspective in landscape preservation efforts.     

Successive chromosome walking by compatible ends ligation inverse PCR

Here we describe an advanced polymerase chain reaction (PCR) technique, the compatible ends ligation inverse PCR (CELI-PCR) for chromosome walking. In CELI-PCR, several restriction enzymes, which produce compatible cohesive ends, were used to digest target DNA simultaneously or sequentially to produce DNA fragments of suitable size. DNA fragments were then easily circularized and PCR amplification could be carried out efficiently. The previous limitations of inverse PCR were overcome, such as unavailable restriction sites, poor template DNA circularization, and low amplification efficiency. Therefore, successive chromosome walking was performed successfully. Our work, isolating a 11,395-bp fragment from Gossypium hirsutum, was presented as an example to describe how CELI-PCR was carried out.