Islet amyloid polypeptide in the islets of Langerhans: friend or foe?

Islet amyloid polypeptide (IAPP), or amylin, was originally discovered as the constituent peptide in amyloid occurring in human insulinomas and in pancreatic islets in human subjects with Type II (non-insulin-dependent) diabetes mellitus. Its normal expression in beta cells and its co-secretion with insulin in response to nutrient stimuli, suggest a metabolic function for the peptide. Specifically, IAPP has most frequently been shown to inhibit insulin secretion, implying that IAPP has a role in the regulation of islet hormone homeostasis. The physiological significance of IAPP in islets has been difficult to assess; very high IAPP concentrations are required to alter insulin secretion. Moreover, until recently, IAPP receptors have not been characterised at the molecular level, thus leaving the actual target cells for IAPP unidentified. Furthermore, in experimental diabetes in rodents, the ratio of IAPP expression to that of insulin invariably is increased. In view of the pleiotropic effects attributed to IAPP, such regulation could be both adverse and beneficial in diabetes. Metabolic characterisation of mice carrying a null mutation in the IAPP gene or which overexpress IAPP in beta cells have recently confirmed that IAPP is a physiological inhibitor of insulin secretion. Based on experiments in which IAPP-deficient mice develop a more severe form of alloxan-induced diabetes, we argue that the action of IAPP in the islets normally is beneficial for beta-cell function and survival; thus, the established up regulation of IAPP expression compared with that of insulin in experimental rodent diabetes could serve to protect islets under metabolically challenging circumstances. [Diabetologia (2000) 43: 687–695]     

益心解毒方对Nox2和Nox4亚基过表达的心肌细胞NADPH氧化酶活性的影响

目的通过观察益心解毒方含药血清对Nox2、Nox4亚基过表达的H9c2心肌细胞NADPH氧化酶活性的影响,揭示其作用环节是否与干预相应亚型的NADPH氧化酶调控环节有关。方法采用PCR方法扩增Nox2、Nox4基因全长序列,经双酶切、连接载体和转化后提取重组质粒,经酶切鉴定的阳性质粒进行DNA测序,测序正确后按照lipofectamine 2000试剂的说明书瞬时转染H9c2细胞,转染后的心肌细胞分组给予不同的药物干预,24 h后检测NADPH氧化酶活性。结果 1含有Nox2/Nox4亚基的重组质粒载体通过测序鉴定,结果与Gen Bank报道的完全一致。2通过荧光显微镜下观察转染72 h后的H9c2细胞,可见大量发绿色荧光的细胞,流式细胞术计数结果显示转染率均在60%左右,符合实验要求。3空质粒载体组、模型组、益心解毒方组的NADPH氧化酶活性表达明显高于正常组(P<0.01,P<0.05);模型组和益心解毒方组的NADPH氧化酶活性表达高于空载体组(P<0.01);模型组NADPH氧化酶活性表达均明显高于其他各组,而益心解毒方各组的NADPH氧化酶活性表达均明显低于模型组(P<0.01,P<0.05)。结论成功构建大鼠心肌细胞Nox2、Nox4亚基的重组质粒载体,该重组质粒载体可以在心肌细胞中过表达,益心解毒方可以有效地降低NADPH氧化酶活性的表达。提示此复方治疗心衰的机制可能是抑制了Nox2和Nox4型NADPH氧化酶的表达。     

Prohibitin: a potential biomarker for tissue-based detection of gastric cancer

BACKGROUND: Prohibitin (PHB) was found to be overexpressed in breast cancer and thus is suggested as a biomarker in that disease. A few studies have investigated the PHB expression pattern in gastric cancer by two-dimensional gel electrophoresis. Uncertainties still existed on whether PHB expression could indicate the differentiation and apoptosis degree of gastric cancer and whether PHB protein as well as anti-PHB antibody could be a biomarker in the serum of the gastric cancer patient. In this study, the expression levels of PHB protein and mRNA of the tissues as well as PHB antigen and anti-PHB antibody in serum of patients with gastric cancer were systemically examined. METHODS: Immunohistochemistry and real-time PCR were used to detect expression levels of PHB protein and mRNA in gastric cancer tissues. Recombinant PHB antigen was identified by Western blotting. The expression of PHB antigen and anti-PHB antibody was investigated by ELISA and TRFIA. Bcl-2 expression was examined by immunohistochemistry. RESULTS: By immunohistochemistry and real-time PCR analyses, PHB protein and mRNA were both overexpressed in gastric cancer tissues compared to adjacent normal gastric tissues (P < 0.01). Moreover, an elevated PHB expression pattern paralleled the differentiation degree and Bcl-2 protein expression in gastric cancer. However, no significant differences of PHB protein and anti-PHB antibody expression were detected in serum of gastric cancer patients and that of healthy volunteers. CONCLUSIONS: These results indicated that PHB could be a potential diagnostic and differentiation biomarker of gastric cancer for tissue-based detection by immunohistochemistry and real-time PCR, but not for serum-based detection.     

Molecular characterization of a new D‐ ‐ haplotype in a Comorian man

The D‐ ‐ phenotype is a genetic variant of the Rh blood group system. It expresses D antigen but lacks C, c, E and e antigens. In D‐ ‐ phenotype, the RHCE coding region is extensively modified by RHD sequence replacement, nucleotide deletion or splice‐site changes. This article reports the identification of a new D‐ ‐ haplotype in a Comorian man. It exhibits a hybrid gene in which RHCE gene exons 3–8 have been replaced by RHD sequences on the RHCE * C allele background. This allele is associated with no expression of c/C and e/E antigens and overexpression of RhD antigen.     

FER overexpression is associated with poor postoperative prognosis and cancer-cell survival in non-small cell lung cancer

Here, we show that overexpression of fer tyrosine kinase (FER), a non-receptor tyrosine kinase, predicts poor postoperative outcome and might be involved in cancer-cell survival in non-small cell lung cancer (NSCLC). Systematic screening using in silico analyses and quantitative RT-PCR revealed that FER was overexpressed in about 10% of NSCLC patients. Evaluation of FER expression using immunohistochemistry (IHC) on tissue microarrays was consistent with the mRNA level detected using quantitative RT-PCR. In analyses of 135 NSCLC patients who had undergone potential curative resection, we found that FER overexpression detected using IHC had no association with clinicopathological features such as age, sex, smoking history, histological type, disease stage, T factor, N factor, adjuvant chemotherapy history, or EGFR mutation, but was correlated with poor postoperative survival periods. A multivariate Cox regression analysis showed that this prognostic impact was independent of other clinicopathological features. In functional analyses of FER in vitro, FER exhibited a transforming activity, suggesting that it possesses oncogenic functions. We also found that human lung cancer NCI-H661 cells, which exhibited FER-outlier expression, were led to apoptosis by the knockdown of FER using RNA interference. FER overexpression might serve as a prognostic biomarker and be involved in cancer-cell survival in NSCLC.     

The overexpression of SIRT1 inhibited osteoarthritic gene expression changes induced by interleukin‐1β in human chondrocytes

In this study, we examined the effects of overexpression of SIRT1 on IL‐1β‐induced gene expression changes in human chondrocytes to explore a protective role of SIRT1 in human chondrocytes. SIRT1 was overexpressed in human chondrocytes by expression plasmid under stimulation with IL‐1β. SIRT1 was also inhibited by siRNA under stimulation with IL‐1β. Gene expression changes were examined by real‐time PCR. The interaction of SIRT1 and p65 (NF‐κB) were examined by Western blotting. SIRT1, MMP‐13, and ADAMTS‐5 expressions in human cartilage were examined by immunohistochemistry. IL‐1β stimulation significantly up‐regulated MMP‐1, 2, 9, and 13 and ADAMTS‐5. Overexpression of SIRT1 significantly inhibited the up‐regulation of those genes caused by IL‐1β while the inhibition of SIRT1 further increased them. In addition, the overexpression of SIRT1 markedly reduced the IL‐1β‐induced acetylation of p65. SIRT1 expression was clearly detected in the non‐OA cartilage while MMP‐13 and ADAMTS‐5 were undetectable. In contrast, in the OA cartilage, SIRT1 expression was decreased while MMP‐13 and ADAMTS‐5 were increased. Our observations suggested that SIRT1 can play a protective role by suppressing IL‐1β‐induced expressions of cartilage‐degrading enzymes partially through the modulation of the NF‐κB pathway. SIRT1 overexpression might be a new therapeutic approach for OA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 531–537, 2013     

Interleukin-12p40 overexpression promotes interleukin-12p70 and interleukin-23 formation but does not affect bacille Calmette-Guérin and Mycobacterium tuberculosis clearance

Interleukin (IL)-12p40, a subunit of IL-12p70 and IL-23, has previously been shown to inhibit IL-12p70 activity and interferon-gamma (IFN-gamma) production. However, recent evidence has suggested that the role of IL-12p40 is more complex. To study the contribution of IL-12p40 to immune responses against mycobacterial infections, we have used transgenic (tg) mice overexpressing IL-12p40 under the control of a major histocompatibility complex-II promoter. The IL-12p40 transgene was expressed during steady state at concentrations of 129 +/- 25 ng/ml of serum and 75 +/- 13 ng per spleen, while endogenous IL-12p40 was hardly detectable in control littermates. Bacille Calmette-Guérin (BCG) infection strongly induced the expression of IL-12p40 transgene in infected organs, and IL-12p40 monomeric and dimeric forms were identified in spleen of IL-12p40 tg mice. Excessive production of IL-12p40 resulted in a 14-fold increase in IL-12p70 serum levels in tg mice versus non-transgenic mice. IL-23 was also strongly elevated in the serum and spleens of IL-12p40 tg mice through BCG infection. While IFN-gamma and tumour necrosis factor protein levels were similar in IL-12p40 tg and non-transgenic mice, Th2 type immune responses were reduced in IL-12p40 tg mice. The number of BCG granulomas and macrophage expressing inducible nitric oxide synthase were similar in IL-12p40 tg and non-transgenic mice. IL-12p40 tg mice were as resistant as non-transgenic mice to BCG and Mycobacterium tuberculosis infections as they could efficiently control bacillary growth. These data show that high amounts of IL-12p40 promotes IL-12p70 and IL-23 formation, but that does not affect T helper 1 type immune responses and granuloma function, thus leading to normal mycobacterial clearance in infected organs.     

过表达TrxR1重组HEK293细胞株的构建和鉴定

目的 构建稳定过表达硫氧还蛋白还原酶1（TrxR1）的HEK293细胞株,为TrxR1的功能研究以及靶向TrxR1药物筛选提供细胞模型。方法 通过PCR扩增,连接转化以及Sanger双脱氧测序构建并筛选出TrxR1的重组慢病毒表达载体pLVX-PuroTXNRD1,转染HEK293细胞,经嘌呤霉素筛选获得稳定转染细胞株。后续研究分为3组进行：①TrxR1过表达HEK293细胞：pLVX-Puro-TXNRD1载体稳定转染细胞;②对照HEK293细胞：pLVX-Puro空载病毒载体稳定转染细胞;③正常HEK293细胞;通过RT-qPCR、Western blot实验检测上述3组细胞中TrxR1的mRNA以及蛋白表达情况;通过胰岛素终点法以及TRFS-green探针成像检测上述3种细胞内TrxR1的酶活力;通过CCK8实验检测上述3种细胞对TrxR1特异性抑制剂auranofin的敏感性。结果 构建载体经DNA测序,成功获得插入TrxR1的重组慢病毒表达载体pLVX-Puro-TXNRD1。与HEK293以及HEK293-NC细胞相比,HEK293-TrxR1-OE细胞中TrxR1的mRNA和蛋白高表达,且酶活力也同样显著上升（P<0.005）;而与HEK293以及HEK293-NC细胞相比,auranofin对HEK293-TrxR1-OE细胞中TrxR1酶活力以及细胞增殖的抑制效率均显著下降（P<0.005）。结论 通过构建pLVX-Puro-TXNRD1慢病毒载体,成功获得过表达TrxR1酶的HEK293细胞株,该细胞对特异性靶向TrxR1的抑制剂的抗增殖作用具有抵抗,因而可用于靶向TrxR1药物的筛选。     

Beclin 1 基因对恶性胶质瘤细胞 U87 自噬活性和增殖的影响简

目的研究BeclinJ基因对U87胶质瘤细胞自噬和增殖的影响。方法实验分5组：空白对照组．pSUPER—Bec组（表达BeclinsiRNA）与其阴性对照组（pSUPER—non组）,pcDNA3．1-Bec组（表达BeclinJ基因质粒）与其阴性对照组（pcDNA3．1-non组）。分别转染U87细胞,采用免疫印迹检测Beclin1、LC3和p62蛋白在各组的表达;用氚标胸腺嘧啶脱氧核苷（3H-TdR）检测各组细胞增殖率。结果转染后48h,pSUPER—Bec组Beclin1、LC3B—11蛋白表达下降,p62蛋白表达升高。pcDNA3．1-Bec组Beclin1、LC3B-Ⅱ蛋白表达升高,p62蛋白表达下降。与空白对照组或pcDNA3．1-non组相比．pcDNA3．1-Bec组细胞增殖速度降低（P〈0．05）,其他各组细胞增殖速度无明显差异。结论恶性胶质瘤细胞中自噬相关基因Beclinj表达下降,过表达Beclinl蛋白能增强细胞的自噬活性,抑制细胞的增殖活性。