Genetic predisposition to leprosy: A major gene reveals novel pathways of immunity to Mycobacterium leprae

The elucidation of the genetic control of susceptibility to common infectious diseases is expected to provide new and more effective tools for prevention and control of some of the most pressings health needs on a global scale. A major advantage of whole genome based genetic approaches is that no a priori assumptions about mechanisms of pathogenesis need to be made in these studies. Hence, genetic studies can identify previously unrecognized pathways of disease susceptibility and tag critical pathogenic events for further biochemical, immunological or physiological analysis. We have applied this strategy to leprosy, a disease that still claims 400,000 new cases each year. We identified genetic variants in the shared promoter region of the PARK2 and PACRG genes as major risk factors of leprosy susceptibility. Both encoded proteins are part of the cellular ubiquitination system. Specifically, PARK2, the cause of early onset Parkinson's disease, is an E3 ligase that likely is involved in controlled proteolysis, the cellular anti-oxidants response and the regulation of innate immune responsiveness. In addition, numerous E3 ligases have recently been shown to be critical regulators of immunity. While the specific role of PARK2/PACRG in leprosy pathogenesis remains unknown, a number of experimentally testable scenarios can be developed to further explore the role of these proteins in anti-Mycobacterium leprae host responsiveness.     

宫颈癌细胞株Hela中CSN6对E6-AP及p53的调节及其分子机制

目的:探讨宫颈癌细胞株Hela中组成型光形态发生因子9信号复合体6(CSN6)对E6-AP及其目标蛋白p53的调节及其分子机制。方法:重组慢病毒干扰载体质粒转染Hela细胞,降调CSN6表达。Western blot法检测E6-AP表达,实时荧光定量PCR检测p53下游基因表达变化。分别将蛋白酶抑制剂MG132、真核生物蛋白合成抑制剂放线菌酮(CHX)和高表达CSN6的Flag-CSN6质粒分别作用于Hela细胞,Western blot法检测E6-AP蛋白表达。将重组慢病毒质粒shRAN CSN6转染Hela细胞48h后,泛素化检测分析CSN6调节E6-AP蛋白表达的分子机制。试验组裸鼠皮下接种shRNA-CSN6细胞株,对照组接种shRNA-vector细胞株,观察肿瘤体积变化。结果:放线菌酮(CHX)可下调E6AP表达,抑制CSN6表达后E6-AP下调更显著;MG132可使E6AP表达增加,CSN6可加强该作用;抑制CSN6表达后,Hela细胞和裸鼠肿瘤组织中p53下游相关基因表达增加,裸鼠肿瘤生长缓慢。泛素化检测提示,CSN6可抑制E6-AP蛋白的泛素化水解,并呈剂量依赖性。结论:宫颈癌细胞株Hela中CSN6上调E6AP是通过抑制E6-AP蛋白的泛素化水解,稳定其在细胞中的表达,实现对p53的持续降解。     

干扰素调节因子4在风湿性心脏病中去泛素化作用的研究

目的 探究风湿性心脏病病人干扰素调节因子4(IRF4)去泛素化与去泛素化酶USP4互相作用的分子机制,为风湿性心脏病提供新的治疗策略。方法 来自安徽医科大学第一附属医院2015年7月至2016年1月20例风湿性心脏病病人,均行体外循环下瓣膜置换手术,均顺利出院。10例健康对照来自于健康志愿者。分别抽取以上参与实验人员5 mL的外周血,经过细胞培养与转染;通过免疫共沉淀实验观察IRF4的DNA结合结构域以及和配体结合结构域是否可以和USP4互相结合;通过NI-NTA镍螯合树脂纯化实验观察IRF4蛋白针对48位和63位赖氨酸相关的去泛素化是否可以被USP4介导;应用荧光素酶检测技术观察白细胞介素(IL)-4是否可以在IRF4、活化T细胞核因子(NFATC2)和USP4共同促进下表达;利用基因沉默方法在人源Th2细胞中下调USP4。结果 下调USP4后Th2细胞相关细胞因子的转录水平也明显减少;利用流式细胞术检测经USP4抑制剂处理后的Th2细胞表达的IRF4和IL-4均减少;以流式细胞技术测得风湿性心脏病中IL-4表达增高,IRF4表达也增高。结论 风湿性心脏病病人血中IRF4的蛋白稳定表达可以通过USP4去泛素化的作用而实现;IL-4在IRF4表达增加协同NFATC2的情况下可增加表达。     

The NEDD4-1 E3 ubiquitin ligase: A potential molecular target for bortezomib sensitivity in multiple myeloma

E3 ubiquitin ligases primarily determine the substrate specificity of the ubiquitin-proteasome system and play an essential role in the resistance to bortezomib in multiple myeloma (MM). Neural precursor cell-expressed developmentally downregulated gene 4-1 (NEDD4-1, also known as NEDD4) is a founding member of the NEDD4 family of E3 ligases and is involved in the proliferation, migration, invasion and drug sensitivity of cancer cells. In the present study, we investigated the role of NEDD4-1 in MM cells and explored its underlying mechanism. Clinically, low NEDD4-1 expression has been linked to poor prognosis in patients with MM. Functionally, NEDD4-1 knockdown (KD) resulted in bortezomib resistance in MM cells in vitro and in vivo. The overexpression (OE) of NEDD4-1, but not an enzyme-dead NEDD4-1-C867S mutant, had the opposite effect. Furthermore, the overexpression of NEDD4-1 in NEDD4-1 KD cells resensitized the cells to bortezomib in an add-back rescue experiment. Mechanistically, pAkt-Ser473 levels and Akt signaling were elevated and decreased by NEDD4-1 KD and OE, respectively. NEDD4-1 ubiquitinated Akt and targeted pAkt-Ser473 for proteasomal degradation. More importantly, the NEDD4-1 KD-induced upregulation of Akt expression sensitized MM cells to growth inhibition after treatment with an Akt inhibitor. Collectively, our results suggest that high NEDD4-1 levels may be a potential new therapeutic target in MM.     

泛素连接酶在皮肤黑素瘤的研究进展

皮肤黑素瘤是一种起源于皮肤黑素细胞的恶性肿瘤,具有高度增殖性和侵袭性,并常发生转移.尽管近年来皮肤恶性黑素瘤的治疗取得很大进展,但晚期黑素瘤患者预后依然很差.泛素蛋白酶体系统可通过调节细胞内蛋白对各种生理过程进行调控,泛素连接酶是泛素化过程中识别底物特异性的酶,可作为癌基因或抑癌基因参与黑素瘤发病机制,能够调节各种不同的信号通路和多种在黑素瘤发展中起重要作用的蛋白.因此,针对泛素连接酶的分子靶向治疗是目前研究黑素瘤的热点之一.     

Chronic lithium treatment decreases tau lesions by promoting ubiquitination in a mouse model of tauopathies

Lithium, a widely used drug for treating affective disorders, is known to inhibit glycogen synthase kinase-3 (GSK-3), which is one of the major tau kinases. Thus, lithium could have therapeutic benefit in neurodegenerative tauopathies by reducing tau hyperphosphorylation. We tested this hypothesis and showed that long-term administration of lithium at relatively low therapeutic concentrations to transgenic mice that recapitulate Alzheimers disease (AD)-like tau pathologies reduces tau lesions, primarily by promoting their ubiquitination rather than by inhibiting tau phosphorylation. These findings suggest novel mechanisms whereby lithium treatment could ameliorate tauopathies including AD. Because lithium also has been shown to reduce the burden of amyloid- pathologies, it is plausible that lithium could reduce the formation of both amyloid plaques and tau tangles, the two pathological hallmarks of AD, and thereby ameliorate the behavioral deficits in AD.     

The Sts proteins target tyrosine phosphorylated, ubiquitinated proteins within TCR signaling pathways

The T cell receptor (TCR) detects the presence of infectious pathogens and activates numerous intracellular signaling pathways. Protein tyrosine phosphorylation and ubiquitination serve as key regulatory mechanisms downstream of the TCR. Negative regulation of TCR signaling pathways is important in controlling the immune response, and the Suppressor of TCR Signaling proteins (Sts-1 and Sts-2) have been shown to function as critical negative regulators of TCR signaling. Although their mechanism of action has yet to be fully uncovered, it is known that the Sts proteins possess intrinsic phosphatase activity. Here, we demonstrate that Sts-1 and Sts-2 are instrumental in down-modulating proteins that are dually modified by both protein tyrosine phosphorylation and ubiquitination. Specifically, both naïve and activated T cells derived from genetically engineered mice that lack the Sts proteins display strikingly elevated levels of tyrosine phosphorylated, ubiquitinated proteins following TCR stimulation. The accumulation of the dually modified proteins is transient, and in activated T cells but not naïve T cells is significantly enhanced by co-receptor engagement. Our observations hint at a novel regulatory mechanism downstream of the T cell receptor.     

泛素特异性蛋白酶9X与肿瘤

泛素特异性蛋白酶(USP)在调节蛋白酶体的活性、器官的发生、肿瘤的形成以及转录调控等方面都具有重要的作用.其中,USP9X通过去泛素化底物蛋白,影响肿瘤细胞增殖、黏附和信号转导,是肿瘤演进的重要因素之一.