JAK/STATs信号通路在慢性肾脏病领域作用机制的研究进展

<正>JAK/STATs为酪氨酸蛋白激酶(JAK)/信号转导因子和转录活化因子(STAT)途径缩写。广泛参与细胞多种生理病理过程,介导细胞生殖分化、免疫调节、迁移凋亡等,是维护机体稳态的重要信号通路,与多器官密切相关。就肾脏而言,JAK/STATs在原发性肾脏病、继发性肾损害、慢性肾脏病(chronic kidney disease,CKD)并发症中均发挥重要作用,笔者将近年来相关研究归纳分析,梳理如下。1 JAK/STATs信号通路的结构基础JAK有JAK1、JAK2、JAK3和TYK2,4位家族成员; JAKs下游信号是STAT,STATs家族目前发现共7个成员,包括STAT1、STAT2、STAT3、STAT4、STAT5a、STAT5b、STAT6等。     

瘦素对小鼠脑缺血／再灌注损伤后脑血流和神经营养因子表达的影响

目的：研究瘦素（leptin）对脑缺血／再灌注损伤后血流变化和神经营养因子表达的影响。方法：45只雄性昆明小鼠随机分为假手术组、模型组和leptin治疗组,每组15只。采用大脑中动脉栓塞方法制备小鼠局灶性脑缺血／再灌注损伤模型。leptin治疗组和模型组于动脉栓塞（即缺血0min）的同时分别腹腔注射leptin 1μg／g或等体积磷酸盐缓冲液（PBS）,假手术组未行栓塞。于MCAO前、缺血2h、再灌注5min和24h采用激光多普勒流量仪检测缺血侧脑组织大脑中动脉供血区血流量变化,免疫组化染色观察神经生长因子（NGF）和脑源性神经生长因子（BDNF）的表达。结果：模型建立后,大脑中动脉分支血流速度明显减慢;再灌注24h,leptin治疗组脑组织血流量较模型组明显改善（P〈0．01）。与假手术组相比,模型组缺血半影区NGF表达水平显著升高（P〈0．01）,大部分NGF阳性细胞明显凋亡,而BDNF表达无明显升高（P〉0．05）;leptin治疗组NGF和BDNF表达水平均较假手术组显著升高（P〈0．01）,NGF和BDNF阳性细胞形态接近正常。结论：leptin能够升高神经营养因子NGF、BDNF的表达水平,增加缺血区血流量,从而在脑缺血性损伤中发挥神经保护作用。     

脓毒症大鼠多器官高迁移率族蛋白B1基因表达的信号机制与意义

目的探讨Janus激酶／信号转导和转录激活因子（JAK／STAT）通路对盲肠结扎穿孔术（CLP）所致脓毒症大鼠多器官高迁移率族蛋白B1（HMGBl）基因表达的影响及其意义。方法采用CLP模型,大鼠随机分为正常对照组（10只）、假手术组（10只）、CLP组（60只）、JAK2抑制剂AG490干预组（24只）、STAT抑制剂雷帕霉素（RPM）干预组（24只）。留取肝、肺、肾、肠组织测定HMGB1mRNA表达和STAT1／3的DNA结合活性。结果CLP后,肝、肺、肾、肠组织中STATl在脓毒症早期即迅速活化,6-12h后活化达高峰。肝、肺组织中STAT3的活化特点与STAT1相似,但相对较弱;在肾、肠组织中未探测到STAT3的活化。同时,CLP组除肾组织HMGB1mRNA表达改变不明显外,肝、肺、肠组织其表达均明显增强（P＜0．05或P＜0．01）。AG490早期处理后24—48h,肝、肠组织HMGB1mRNA表达显著低于CLP组（P＜0．05或P＜0．01）;RPM干预组肝、肺、肠组织HMGB1mRNA表达均呈现不同程度地抑制,其中以肺组织下降幅度尤为明显。结论严重腹腔感染可导致机体主要脏器JAK／STAT通路迅速活化,该信号途径参与了HMGB1mRNA的表达调控过程。     

胃转流手术对代谢综合征患者体脂分布改变的影响

目的探讨胃转流术后代谢综合征患者体脂分布的改变情况。方法2009年7月至2010年2月间南京军区福州总院前瞻性入组收治26例胃癌合并代谢综合征病例,行胃转流手术。分别于术前和术后1、4、12、48周,检测体质量指数（BMI）、腰围、臀围和脂肪面积等体脂参数,以及胰岛素抵抗指数（HOMA-IR）等生化指标。结果胃转流术后,26例代谢综合征患者肥胖、高血压、血脂紊乱及高血糖均获得了不同程度的好转。术后48周,26例患者HOMA－IR由术前的5.7±1.5降至3.4±1.0,BMI由术前的（27.1±3.8）kg／m^2降至（22.6±1.4）kg／m^2（P〈0.05）。其中心性肥胖指标腰围由术前的（95.3±2.5）cm降至（75.3±1.1）cm,内脏脂肪面积由术前的（101.7±13.8）cm^2降至（78.7±11.2）cm^2（P〈0.05）;而外周性肥胖指标皮下脂肪面积未见下降（P〉0.05）。结论胃转流术后体脂分布由中心性肥胖向外周性肥胖转变：胰岛素抵抗改善与中心性体脂参数下降有关。     

STATs信号转导通路选择性活化与乳腺浸润性导管癌的研究

乳腺癌是女性常见恶性肿瘤，但是其详细分子生物学机制还有待研究。研究结果显示STATs（STATs）通路在多种人类恶性肿瘤中起重要作用。我们通过本研究检测56例乳腺浸润性导管癌标本中STATs主要成员的表达，探讨STATs通路成员持续活化在乳腺癌发生发展中的作用。[第一段]     

瘦素与女性生殖及胎儿发育

瘦素 ( leptin)是肥胖基因 ( ob)的表达产物 ,是由脂肪细胞分泌的具有重要生物功能的一种激素 ,除调节体重外 ,还与内分泌代谢、生殖密切相关。leptin的分泌水平与性别、肥胖有关 ,肥胖女性 leptin浓度较非肥胖者高 ,但在月经周期中随性激素改变而发生节律性变化的能力较后者差。有研究证明 [1] ,有正常排卵月经周期的女性在黄体期 leptin有明显升高。其中一些女性在排卵前的雌激素高峰时还有一个 leptin升高期。顾卫琼等 [2 ] 对中国人血清 leptin水平与肥胖的研究发现 ,leptin水平性别差异显著 ,女性 leptin水平几乎较男性高 2～ 3倍 ,这…     

乙肝病毒X蛋白通过NF-kB信号能路对Livin基因的表达的影响

目的研究乙肝病毒X蛋白（Hepatitis B virus X protein,HBx）通过核因子-KB（Nuclear factor—kappa B,NF-KB）信号通路对Livin基因表达的影响。方法建立稳定转染HBx基因的L02（L02／HBx）细胞系,用NF-KB信号通路阻断剂吡咯二硫代氨基甲酸酯（pyronidine dithiocarbamate,PDTC）阻断NF—KB信号通路。采用荧光双标激光扫描共聚焦显微镜观察转染前后及PDTC加入前后NF-KB信号通路的激活失活情况,同时用Real-time PCR和Western Blot检测转染前后及PDTC加入前后Livin基因的表达情况。结果转染HBx基因后NF—KB信号通路被激活,Livin基因表达明显上调（P〈0．05）;PDTC加入后NF．KB信号通路被阻断,Livin基因表达明显下调（P〈0．05）。结论NF—KB信号通路可能是HBx上调Livin基因的途径之一。     

细胞因子信号转导抑制分子与肾脏疾病

肾脏疾病的病因及发病机制较为复杂,免疫功能紊乱、感染、炎症信号通路等共同参与其发生、发展过程。近年来研究发现,JAK/STAT途径是人体内生理和病理反应的共同通路之一,与多种肾脏疾病的发病密切相关。而细胞因子信号转导抑制分子（suppressors of cytokine signaling,SOCS）主要通过JAK/STAT信号转导通路的负性调节作用而抑制细胞因子信号转导,从而参与机体多种生理与病理的发生、发展过程。     

肥胖患者瘦素水平与精液指标相关性的初步分析

随着人们生活水平的提高,目前肥胖的发病率呈持续上升趋势,且发病年龄趋于年轻化,我国居民的超重和肥胖人口已接近总人口的1／4,其对女性生育能力的影响已得到公认,但对男性生育能力影响的研究尚处在初期阶段,瘦素（Leptin）是肥胖基因的产物,可作为体脂的重要标记物,许多研究表明,Leptin在控制生殖功能方面可能起着重要作用,本文通过研究肥胖患者的血清Leptin水平与精液指标的相关性,探讨其在男性不育发病中的作用,现报告如下。     

颈椎后纵韧带骨化症肥胖相关基因的筛选及鉴定

目的：探索颈椎后纵韧带骨化症（OPLL）肥胖相关基因及其功能特征。方法：从高通量基因表达（GEO）数据库中下载颈椎OPLL相关的转录组数据集GSE69787,与Gene数据库中肥胖相关基因进行筛选,获得颈椎OPLL肥胖相关差异表达基因（DEGs）。使用DAVID软件和R软件对肥胖相关DEGs进行基因本体（GO）和京都基因与基因组百科全书（KEGG）富集分析,应用Cytoscape软件将数据可视化,并通过cytoHubba工具包计算得到中心基因。采用实时定量PCR(qRT-PCR)检测中心基因在颈椎后纵韧带组织中的表达水平。结果：通过GSE69787数据集与肥胖相关基因筛选得到24个颈椎OPLL肥胖相关DEGs,构建并计算这24个肥胖相关DEGs的蛋白质相互作用网络,最终筛选出10个中心基因。GO/KEGG富集分析结果显示这10个肥胖相关DEGs主要富集于蛋白激酶B信号通路及其调控、骨化、炎症反应调控、骨矿化及PI3K-Akt信号通路、MAPK信号通路等生物学过程和生物信号通路。最后通过qRT-PCR验证发现LEP、IGF2、IL18、BMP2和LOX在颈椎OPLL组韧带组织中高表达（P...     

A common promoter variant of the leptin gene is associated with changes in the relationship between serum leptin and fat mass in obese girls

Mutations in the leptin gene lead to rare obese syndromes of Mendelian inheritance in humans and rodents. However, no relevant mutations are found in the coding region of leptin gene DNA in patients with common multifactorial obesity. These obese patients tend to have an elevation of serum leptin proportional to their adiposity but with a rather wide dispersion of leptin levels for a given body fat content, which in part is attributable to sexual dimorphism. The current study, performed in two independent Caucasian cohorts of obese girls, shows that a frequent promoter variant of the leptin gene is associated with changes in the relationship between serum leptin and body fatness. Girls of comparable adiposity have different circulating leptin levels, depending on their genotype at this locus. Girls with the -/- Lep -2,549 genotype have 25% lower mean leptin levels than the girls with other genotypes, as reflected by differences in the regression slopes of leptin-to-fat mass. Therefore, genetic factors related to the leptin gene may be important in defining the set point of obese individuals (i.e., the circulating leptin level for a given degree of body fatness). This definition may be of both physiological and therapeutic relevance, although a phenotypic association with an individual single-nucleotide polymorphism is not sufficient to assign function to this particular nucleotide site.     

Role of selective leptin resistance in diet-induced obesity hypertension

Leptin is an adipocyte-derived hormone that plays a key role in the regulation of body weight through its actions on appetite and metabolism. Leptin also increases sympathetic nerve activity (SNA) and blood pressure. We tested the hypothesis that diet-induced obesity is associated with resistance to the metabolic actions of leptin but preservation of its renal SNA and arterial pressure effects, leading to hypertension. Mice were fed a high-fat diet for 10 weeks to induce moderate obesity. The decrease in food intake and body weight induced by intraperitoneal or intracerebroventricular leptin was significantly attenuated in the obese mice. Regional SNA responses to leptin were differentially altered in diet-induced obese mice. Renal SNA response to leptin was preserved, whereas lumbar and brown adipose tissue SNA responses were attenuated in obese mice. Radiotelemetric arterial pressure was approximately 10 mmHg higher in obese mice. Furthermore, the increase in arterial pressure in response to long-term (12 days) leptin treatment was preserved in obese mice. Thus, mice with diet-induced obesity exhibit circulating hyperleptinemia and resistance to the metabolic actions of leptin. However, there is preservation of the renal sympathetic and arterial pressure responses to leptin, which represent a potential mechanism for the adverse cardiovascular consequences of obesity.     

The FTO Obesity Gene. Genotyping and Gene Expression Analysis in Morbidly Obese Patients

BACKGROUND: Obesity has emerged as one of the most serious public health concerns in the twenty-first century. the fat mass and obesity associated gene (FTO) has been found to contribute to the risk of obesity in humans. Our aims in this study were to investigate the association of rs9939609 single nucleotide polymorphism (SNP) of the FTO gene with different obesity-related parameters, to assess the FTO gene expression in subcutaneous and visceral adipose tissues from morbidly obese and its correlations with other adipocytokine gene expressions. METHODS: The association between the rs9939609 FTO gene variant and obesity related parameters in 75 obese/morbidly obese adult patients and 180 subjects with body mass index (BMI) < 30 kg/m(2) (control group) was examined. Gene expression analyses: subcutaneous adipose tissue samples were obtained from 52 morbidly obese and five subjects with BMI < 30 kg/m(2). Visceral adipose tissue was also obtained from 35 morbidly obese patients. Weight, height, BMI, SBP, DBP, fasting glucose, lipid profile, proinsulin, insulin, leptin, and adiponectin (RIA) of patients were also obtained. Insulin resistance by HOMA(IR). rs9939609 of FTO genotyping using allele discrimination in real-time PCR. Genomic study of RNA extraction of adipose tissue and real-time PCR (RT-PCR) of adipocytokines and a housekeeping gene were quantified using TaqMan probes. Relative quantification was calculated using the DeltaDelta Ct formula. RESULTS: The minor-(A) allele frequency of rs9939609 FTO gene in the whole population was 0.39. A strong association between this A allele and obesity was found, even after age-sex adjustment (p = 0.013). We found higher levels of FTO mRNA in subcutaneous adipose tissue from morbidly obese than in the control group (p = 0.021). FTO gene expression was lower in visceral than in subcutaneous adipose depot. However, this finding did not reach the level of statistical significance. A negative correlation between subcutaneous FTO gene expression and serum triglyceride levels and a positive correlation with leptin, perilipin, and visfatin gene expressions was found. In the visceral adipose tissue, these positive correlations were statistically significant only for perilipin. CONCLUSIONS: Our results show: (1) A strong association between rs9939609 SNP of the FTO gene variant and obesity in Spanish morbidly obese adult patients; (2) positive correlations between FTO mRNA and leptin, perilipin, and visfatin gene expressions in subcutaneous adipose tissue; (3) FTO and perilipin gene expressions were positively correlated in visceral fat depot. Overall these results may suggest a role of FTO in the regulation of lipolysis as well as in total body fat rather in fat distribution patterns.     

Soluble leptin receptor in serum of subjects with complete resistance to leptin: relation to fat mass

Leptin resistance and obesity have been related to mutations of the leptin receptor gene in rodents and, recently, in a consanguineous family. The latter mutation results in a receptor lacking transmembrane and intracellular domains. Homozygous and heterozygous individuals with this mutation had serum leptin levels higher than expected, given their BMIs: 600, 670, and 526 ng/ml and 145, 362, 294, 240, and 212 ng/ml, respectively. Their serum leptin was fractionated by gel filtration: >80% was present as a high-molecular size complex vs. 7.5% in the nonmutated sister. Western blot analysis showed a band at 146 kDa reacting specifically with an antibody directed against the leptin receptor ectodomain. In 10 obese control subjects, as in the mutated patients, free leptin levels correlated with BMI (r = 0.70, P = 0.0011) and reflected fat mass, regardless of leptin receptor functioning. In the patients, bound leptin levels correlated with BMI (r = 0.99, P = 0.0002) and were related to the number of mutated alleles. These data demonstrate that the truncated receptor is secreted into blood and binds the majority of serum leptin, markedly increasing bound and total leptin. Free serum leptin was similarly correlated with BMI in the mutated and nonmutated obese individuals, providing evidence that the relationship between BMI and circulating free leptin is preserved in this family. This finding suggests that the leptin receptor itself may not be specifically involved in the control of leptin secretion, and it supports the concept of relative resistance to leptin in common obesity.     

The concept of selective leptin resistance: evidence from agouti yellow obese mice.

Leptin, a hormone secreted by adipose tissue, acts to inhibit appetite and promote metabolism, thereby reducing body weight. Leptin also increases sympathetic activity and arterial pressure. Several murine models of obesity, including agouti obese mice, exhibit resistance to the anorexic and weight-reducing effects of leptin. Hypertension in agouti mice has been attributed to hyperleptinemia. These observations pose a seeming paradox. If these mice are leptin-resistant, then how can leptin contribute to hypertension? We tested the novel hypothesis that these mice have selective leptin resistance, with preservation of the sympathoexcitatory action despite resistance to the weight-reducing actions. Leptin-induced decreases in food intake and body weight were less in agouti obese mice than in lean littermates. In contrast, leptin-induced increases in sympathetic nerve activity did not differ in obese and lean mice. These findings support the concept of selective leptin resistance, with resistance to the metabolic actions of leptin but preservation of the sympathoexcitatory actions. This finding may have potential implications for human obesity, which is associated with elevated plasma leptin and is thought to be a leptin-resistant state. If leptin resistance is selective in obese humans, then leptin could contribute to sympathetic overactivity and its adverse consequences in human obesity.     

Leptin promotes aggregation of human platelets via the long form of its receptor.

Plasma leptin levels are elevated in most obese individuals, and obesity is accompanied by a high incidence of cardiovascular disease. Therefore, leptin could be involved in the pathogenesis of cardiovascular disease. In the present study, the role of leptin was explored in the regulation of platelet function. The expression of the long form of the leptin receptor was detected in human platelets. At 50 ng/ml, human leptin induced phosphorylation of several proteins of platelets at the tyrosine residue. Neither leptin at concentrations < or = 100 ng/ml nor ADP at concentrations > or = 1 micromol/l affected platelet aggregation. However, after pretreatment with 100 ng/ml leptin for 5 min, 1 micromol/l ADP caused aggregation. Thus, leptin and ADP acted synergistically. At a concentration of 2 micromol/l, ADP induced platelet aggregation, which was markedly enhanced by 30-100 ng/ml leptin in a concentration-dependent manner. This concentration range corresponds to that of plasma leptin levels in obese individuals. At the lower concentrations (< 10 ng/ml) that are observed in normal individuals, leptin had no effect on platelet aggregation. In conclusion, leptin at high concentrations has the novel function of promoting platelet aggregation, which may be a key coupling factor between obesity and the cardiovascular disease associated with syndrome X and diabetes.     

Association of serum leptin with hypoventilation in human obesity

BACKGROUND: Leptin is a protein hormone produced by fat cells of mammals. It acts within the hypothalamus via a specific receptor to reduce appetite and increase energy expenditure. Plasma leptin levels correlate closely with total body fat mass operating via a central feedback mechanism. In human obesity serum leptin levels are up to four times higher than in lean subjects, indicating a failure of the feedback loop and central leptin resistance. In leptin deficient obese mice (ob/ob mice) leptin infusion reverses hypoventilation. It was hypothesised that a relative deficiency in CNS leptin, indicated by high circulating leptin levels, may be implicated in the pathogenesis of obesity hypoventilation syndrome (OHS). METHODS: Fasting morning leptin levels were measured in obese and non-obese patients with and without daytime hypercapnia (n=56). Sleep studies, anthropometric data, spirometric parameters, and awake arterial blood gas tensions were measured in each patient. RESULTS: In the whole group serum leptin levels correlated closely with % body fat (r=0.77). Obese hypercapnic patients (mean (SD) % body fat 43.8 (6.0)%) had higher fasting serum leptin levels than eucapnic patients (mean % body fat 40.8 (6.2)%), with mean (SD) leptin levels of 39.1 (17.9) and 21.4 (11.4) ng/ml, respectively (p<0.005). Serum leptin (odds ratio (OR) 1.12, 95% CI 1.03 to 1.22) was a better predictor than % body fat (OR 0.92, 95% CI 0.76 to 1.1) for the presence of hypercapnia. CONCLUSIONS: Hyperleptinaemia is associated with hypercapnic respiratory failure in obesity. Treatment with leptin or its analogues may have a role in OHS provided central leptin resistance can be overcome.