Inhibitory G proteins and their receptors: emerging therapeutic targets for obesity and diabetes

The worldwide prevalence of obesity is steadily increasing, nearly doubling between 1980 and 2008. Obesity is often associated with insulin resistance, a major risk factor for type 2 diabetes mellitus (T2DM): a costly chronic disease and serious public health problem. The underlying cause of T2DM is a failure of the beta cells of the pancreas to continue to produce enough insulin to counteract insulin resistance. Most current T2DM therapeutics do not prevent continued loss of insulin secretion capacity, and those that do have the potential to preserve beta cell mass and function are not effective in all patients. Therefore, developing new methods for preventing and treating obesity and T2DM is very timely and of great significance. There is now considerable literature demonstrating a link between inhibitory guanine nucleotide-binding protein (G protein) and G protein-coupled receptor (GPCR) signaling in insulin-responsive tissues and the pathogenesis of obesity and T2DM. These studies are suggesting new and emerging therapeutic targets for these conditions. In this review, we will discuss inhibitory G proteins and GPCRs that have primary actions in the beta cell and other peripheral sites as therapeutic targets for obesity and T2DM, improving satiety, insulin resistance and/or beta cell biology.     

中国梨木虱分泌物中氨基酸的分离与分析

利用离子交换色谱法分离了中国梨木虱分泌物中的氨基酸;利用毛细管气相色谱法对梨木虱分泌物中氨基酸的三氯乙酰了酯衍生物进行了分析。用标准样对照定性,内标法定量。分泌物中共检出13种氨基酸。     

高效液相色谱-电化学(库仑电极)阵列检测技术用于植物内源激素等小分子物质的差异显示

以壳寡糖为诱导物处理烟草植株,利用高效液相色谱-电化学(库仑电极)阵列检测技术检测不同处理时间植物体内内源激素的变化情况及其他小分子物质的差异显示。所用色谱柱为Hypersil BDS C18 柱(4.6 mm i.d.×200 mm, 5 μm),八通道电化学阵列检测器(八个电极)的检测电势依次为-200,300,400,500,600,700,800,850 mV。结果表明,茉莉酸(JA)和赤霉酸(GA)含量在用壳寡糖处理6 h时达到高峰,吲哚乙酸(IAA)含量在处理8 h时达到高峰。处理后烟草植株产     

Fabrication of Xanthan stabilized green gold nanoparticles based tolbutamide delivery system for enhanced insulin secretion in mice pancreatic islets

Abstract

Tolbutamide is an oral anti-diabetic agent for the treatment of type 2 diabetic patients. Its lower absorption results in its inferior therapeutic efficacy. Nano-carrier systems have the subject of greater interests for enhancing efficacy of such drugs. Current study was designed to improve the tolbutamide therapeutic efficacy through its delivery in Gum Xanthan (GX) stabilized green gold nanoparticles (AuNPs). GX stabilized AuNPs were characterized for surface plasmon resonance (SPR), morphology, size, polydisoersity index (PDI) and zeta potential through UV spectrophotometer, atomic force microscope (AFM) and zetasizer respectively. They were used for loading tolbutamide and loaded nanoparticles were investigated for morphology, size, PDI, zeta potential and drug loading efficiency. FT-IR analysis was used for conforming GX functional groups involvement in AuNPs stabilization and drug-excepients interactions. Tolbutamide loaded in the synthesized nanoparticles was investigated for its insulin secretion potentials in isolated mice islets. Synthesized AuNPs were found in nano-size range with spherical morphology, increased surface negativity and loaded increased concentration of drug without changing its chemical nature. They markedly enhanced the tolbutamide insulin secretion potentials as compared to simple drug solution. Results confirm that the developed nano-carrier system is highly efficient in achieving higher therapeutic efficacy of drugs like tolbutamide.     

EXPRESSION OF SYNTHESIZED HIRUDIN GENE IN YEAST

Hirudin is a sort of polypeptides secreted from the salivary gland of medicinal leech. It is of potential importance in medicine. We designed and synthesized the hirudin gene based on the amino acid sequence of hirudin HV2, and expressed it using the yeast alpha factor expression system. The yeast strain stably carrying the hirudin expression plasmid was deduced by mutagenesis. After its cultivation in rich nutritious medium for 36—48 h, the hirudin expression product secreted into the culture fluid was 10—20 ATU/ml. The HPLCpure hirudin product could be obtained through a simpler purification procedure, its N-terminal amino acid sequence was identical with the natural product, and it showed potent anticoagulant and antithrombin activity. About 3000 ATU of pure hirudin witha specific activity of 6600 ATU/mg could be obtained from 500 ml of culture fluid.     

口腔冲洗联合气囊上滞留物冲洗引流对呼吸机相关性肺炎发病的影响研究

目的：探讨口腔冲洗联合气囊上滞留物冲洗引流对呼吸机相关性肺炎（ventilator-associated pneumonia,VAP）发病的影响。方法：选取呼吸重症监护病房（RICU）2009年1月至2011年6月行机械通气的患者120例,随机分为干预组和对照组各印例,干预组给予定时口腔冲洗和气囊上滞留物冲洗引流,对照组行口腔擦拭,未行Vt腔冲洗,未定时冲洗气囊上滞留物。结果：干预组VAP发生率18．3％,对照组VAP发生率38．3％;VAP患者咽拭子、气囊上滞留物和下呼吸道分泌物优势菌符合率为47．1％,气囊上滞留物与下呼吸道分泌物优势菌符合率为61．8％。结论：口腔冲洗联合气囊上滞留物冲洗引流可降低VAP发生率,是预防VAP行之有效的重要方法。     

Dopamine promotes formation and secretion of non-fibrillar alpha-synuclein oligomers

Parkinson's disease (PD) is characterized by selective and progressive degeneration of dopamine (DA)-producing neurons in the substantia nigra pars compacta (SNpc) and by abnormal aggregation of α-synuclein. Previous studies have suggested that DA can interact with α-synuclein, thus modulating the aggregation process of this protein; this interaction may account for the selective vulnerability of DA neurons in patients with PD. However, the relationship between DA and α-synuclein, and the role in progressive degeneration of DA neurons remains elusive. We have shown that in the presence of DA, recombinant human α-synuclein produces non-fibrillar, SDS-resistant oligomers, while β-sheet-rich fibril formation is inhibited. Pharmacologic elevation of the cytoplasmic DA level increased the formation of SDS-resistant oligomers in DA-producing neuronal cells. DA promoted α-synuclein oligomerization in intracellular vesicles, but not in the cytosol. Furthermore, elevation of DA levels increased secretion of α-synuclein oligomers to the extracellular space, but the secretion of monomers was not changed. DA-induced secretion of α-synuclein oligomers may contribute to the progressive loss of the dopaminergic neuronal population and the pronounced neuroinflammation observed in the SNpc in patients with PD.     

Sugar‐Based Synthesis of Tamiflu and Its Inhibitory Effects on Cell Secretion

Tamiflu is currently the most effective drug for the treatment of influenza, but the insufficient supply and side‐effects of this drug demand urgent solutions. We present a practical synthesis of Tamiflu by using novel synthetic routes, cheap reagents, and the abundantly available starting material D ‐glucal. The strategy features a Claisen rearrangement of hexose to obtain the cyclohexene backbone and introduction of diamino groups through tandem intramolecular aziridination and ring opening. In addition, this synthetic protocol allows late‐stage functionalization for the flexible synthesis of Tamiflu analogues. By using the synthesized Tamiflu and its active metabolite (oseltamivir carboxylate), we investigated their influences on neuroendocrine PC12 cells in various aspects. It was discovered that oseltamivir carboxylate significantly inhibits the vesicular exocytosis (regulated secretion) of PC12 cells, and suggests a mechanism underlying the Tamiflu side‐effects, in particular its possible adverse influences on neurotransmitter release in the central nervous system.     

细胞膜锚定DNA四面体传感器实时监测外泌体的分泌

外泌体是细胞主动分泌的一种纳米级双层膜结构的小囊泡,能够直接反映分泌细胞的生理和功能状态,进行细胞间的物质运输和信息通讯,并参与多种生理及病理过程.本文针对细胞分泌外泌体的动态过程,以DNA四面体为基础,结合细胞膜修饰技术和荧光成像技术,构建了一种易操作、高稳定性的细胞膜表面DNA四面体传感器,应用于不同细胞类型分泌外泌体的实时监测. DNA四面体传感器通过脚支链与疏水性胆固醇探针的杂交互补作用锚定于细胞膜表面,利用四跨膜蛋白CD63核酸适配体序列特异性捕获细胞膜表面释放的外泌体,通过监测细胞膜表面荧光的变化,实时测定外泌体的分泌情况.     

Effects of a Shift of the Signal Peptide Cleavage Site in Signal Peptide Variant on the Synthesis and Secretion of SARS-CoV-2 Spike Protein

The COVID-19 pandemic is caused by SARS-CoV-2; the spike protein is a key structural protein that mediates infection of the host by SARS-CoV-2. In this study, we aimed to evaluate the effects of signal peptide on the secretion and release of SARS-CoV-2 spike protein. Therefore, we constructed a signal peptide deletion mutant and three signal peptide site-directed mutants. The (H) region and (C) region in the signal peptide of L5F-S13I mutant have changed significantly, compared with wild type, L5F and S13I. We demonstrated the effects of signal peptide on the secretion and synthesis of RBD protein, finding that mutation of S13 to I13 on the signal peptide is more conducive to the secretion of RBD protein, which was mainly due to the shift of the signal peptide cleavage site in the mutant S13I. Here, we not only investigated the structure of the N-terminal signal peptide of the SARS-CoV-2 spike protein but also considered possible secretory pathways. We suggest that the development of drugs that target the signal peptide of the SARS-CoV-2 spike protein may have potential to treat COVID-19 in the future.