内质网硒蛋白的研究进展

硒是哺乳动物必需的一种微量营养元素,主要以硒代半胱氨酸的形式存在于各种硒蛋白中,硒的主要生物功能通过硒蛋白实现.在25种哺乳动物硒蛋白中,有7种硒蛋白位于内质网,分别为2型脱碘酶、15-kDa硒蛋白、硒蛋白M、硒蛋白T、硒蛋白K、硒蛋白S和硒蛋白N.除了2型脱碘酶外,对其余内质网硒蛋白知之甚少.最近一些研究显示,一些内质网硒蛋白在氧化还原平衡调节、蛋白质折叠质量控制、错误折叠蛋白从内质网逆向转运至胞质、Ca2+稳态调节、内质网应激调节及炎症调节等过程中发挥作用.本文介绍了每种内质网硒蛋白的结构、功能及其生理和病理作用的一些最新研究进展,并对未来需要研究的内容进行了展望.     

硒蛋白S的结构、功能及与疾病的关系

硒是一种人体必需的微量营养元素,其主要生物功能是通过硒蛋白实现。硒蛋白S （SELENOS）是一种主要存在于内质网膜的硒蛋白,参与了内质网相关蛋白降解过程。SELENOS主要是通过胞质中的卷曲螺旋结构域和C-端含硒代半胱氨酸残基的无规结构区发挥生物功能的。大量体外研究结果显示,SELENOS有调节氧化应激、内质网应激、炎症等功能,进而可能影响心血管疾病、2型糖尿病、阿尔茨海默症等疾病的发生发展。此外,流行病学观察研究发现SELENOS基因的多种单核苷酸多态性与心血管疾病、癌症等疾病密切相关。本文综述了SELENOS结构、功能及与疾病的关系,总结了SELENOS研究中尚待解决的问题,并对其未来的发展方向进行了展望。     

人肝中硒蛋白K相互作用蛋白的筛选与验证

以硒蛋白K(SelK)突变体为"诱饵", 采用酵母双杂交系统对人肝cDNA文库进行筛选, 得到一个与SelK相互作用的蛋白──环腺苷酸应答元件结合蛋白3(CREB3). 将SelK与CREB3共同转染酵母细胞, 验证了SelK与CREB3的相互作用; 并采用受体漂白、敏化发射和荧光寿命3种荧光共振能量转移方法进一步验证了二者间的相互作用, 发现其不受SelK中硒代半胱氨酸(Sec)的影响. 推测SelK可能通过其Sec之前的区域与CREB3发生作用, 参与CREB3介导的内质网相关降解过程, 影响相关癌症的转移和发展.     

硒蛋白M及其与重大疾病的关系

硒蛋白M(SelM)是2002年应用生物信息学方法发现的一种内质网硒蛋白,其二级结构中含有一个氧化还原调节基序CXXU,且该蛋白在脑中大量表达。SelM因具有维持机体氧化还原水平、保护神经细胞和调节钙稳态平衡等重要作用,近年成为研究热点。本文结合本课题组的研究结果,对硒蛋白M的最新研究进展、生物功能、与重大疾病的关系及今后研究方向等方面进行了综述和展望。     

硒蛋白与糖尿病——硒的两面性

糖尿病是危害人类健康的全球性重大疾病,胰岛素抵抗是诱发2型糖尿病的重要因素。微量必需元素硒与人体健康密切相关,通过硒蛋白发挥多种重要生物学功能。近年来硒与糖尿病的关系引人关注,早期研究表明硒具有类胰岛素作用,可望用于防治糖尿病,但近来的人群试验和动物研究却表明硒在糖尿病发生发展中的作用具有两面性,长期补充一定剂量的硒反而增加了胰岛素抵抗和2型糖尿病的发病率。而且,硒在糖尿病发生发展中的两面性被证实与几种硒蛋白密切相关,包括谷胱甘肽过氧化物酶1(GPx1)、硒蛋白S(SelS)和硒蛋白P(SelP)等。本文结合本课题组的工作介绍了硒在糖尿病中的两面性以及硒蛋白在糖尿病发生发展中的作用,并对未来的研究方向进行了展望。     

基因组中硒蛋白的信息学

人类已经步入"后基因组"时代,基因组研究的重心将由测定基因的DNA序列转移到解释生命的所有遗传信息,从分子整体水平对生物学功能的研究,在分子层面上探索人类健康和疾病的奥秘.硒蛋白基因是各种基因组中一类重要的蛋白质基因,从基因组中寻找新的硒蛋白基因,对于硒蛋白生物功能的探索具有十分重要的意义.本文就硒代半胱氨酸插入元件(SECIS)结构特征、从基因组中寻找硒蛋白的生物信息学方法及其研究进展作了简要介绍,并对未来的发展趋势进行了展望.     

硒蛋白的抗氧化性研究与第21个氨基酸的发现

硒是人体必需的微量元素,以硒代半胱氨酸(Sec)的形式存在于蛋白质中作为硒酶的活性中心发挥作用,其生物功能主要是抗氧化。由于硒与人体健康具有十分密切的关系,所以硒蛋白的研究有着重要的理论和实际意义。本文以第一个硒蛋白细胞谷胱甘肽过氧化物酶为例,结合作者自己的工作,重点对该硒酶的结构、催化机制和模拟进行了综述,并就TGA编码Sec致第21个氨基酸的发现以及基于硒代半胱氨酸插入元件(SECIS)的特征寻找新硒蛋白的研究进展进行了介绍。     

梅花鹿茸快速生长及骨化期相关差异表达蛋白分析

采用同位素标记相对定量(iTRAQ)技术、超高效液相色谱-质谱联用技术和生物信息学分析方法对东北梅花鹿快速生长期(60 d)与骨化期鹿茸(90 d)进行比较蛋白质组学研究,共鉴定出127种差异蛋白。与骨化期鹿茸比较,快速生长期鹿茸中显著上调的差异蛋白80种,显著下调差异蛋白47种,这些差异表达蛋白主要分布在细胞外基质、核小体、珠蛋白-血红蛋白复合物、肌动蛋白丝、内质网-高尔基中隔室、内质网官腔及核内膜等部位。快速生长期鹿茸显著上调的差异蛋白主要是参与血氧运输、神经生长和再生、软骨和骨组织发育及ATP合成的功能蛋白,而显著下调的差异蛋白主要为参与软骨内骨化过程的功能蛋白,这些蛋白在鹿茸不同生长时期表达量的变化与鹿茸的快速生长和骨化进程密切相关。本研究为系统揭示鹿茸快速生长及骨化的分子机制提供了基础数据,同时对研究鹿茸的药效物质基础及临床应用具有重要的指导意义。     

内质网荧光探针研究进展

内质网作为亚细胞器在哺乳细胞生命活动中发挥重要作用.将内质网可视化,进一步检测其活性物质、微环境及生理过程,对于疾病的诊治具有重要的指导价值.近年来,内质网靶向荧光探针的设计与合成受到了越来越多的关注.当前已报道的内质网靶向荧光探针涵盖了单纯内质网成像、金属离子、小分子物质、大分子物质、微环境等.总结并介绍了近期报道的内质网靶向荧光探针的设计与合成工作,分析了内质网荧光探针在研究细胞生理过程中的应用,并展望了内质网靶向荧光探针的发展趋势.     

纳米材料诱导内质网应激途径的研究进展

随着纳米技术的蓬勃发展,纳米材料已被广泛用于化妆品、医药卫生、国防科技等领域.由于纳米材料的特殊物理化学性质,在其生产、加工、运输以及应用的过程中增加了人类的暴露风险及潜在的健康危害.研究显示,纳米材料能够在动物、细胞、分子及基因水平对生物体造成毒性损害,而活性氧的生成和氧化应激的产生则是这种毒性损害的重要机制.内质网作为细胞内蛋白质合成、加工及储存Ca~(2+)的重要场所,对细胞内稳态的变化十分敏感,细胞的氧化应激损伤及细胞内Ca~(2+)平衡的紊乱都会诱发内质网应激,继而通过内质网应激途径导致细胞凋亡.本文对纳米材料与内质网应激及相关细胞功能的影响进行了综述.     

gp78: a Multifaceted Ubiquitin Ligase that Integrates a Unique Protein Degradation Pathway from the Endoplasmic Reticulum

The endoplasmic reticulum (ER) is the site for maturation of proteins destined for the secretory pathway. Failure in maturation leads to production of misfolded proteins that are eliminated through the ER-associated degradation (ERAD) pathway. ERAD is a complex process that includes misfolded protein recognition, retrotranslocation to the cytosol, ubiquitination and proteasomal degradation. gp78 is an E3 ubiquitin ligase that integrates these ERAD steps by nucleating a unique degradation machine, which uses the p97/VCP-Npl4 complex for retrotranslocation instead of the wellknown p97/VCP-Ufd1-Npl4 complex. A growing list of substrates have been identified for gp78, which highlights the importance of gp78-mediated ERAD in essential physiological pathways and pathological processes.     

BODIPY/Nile‐Red‐Based Efficient FRET Pair: Selective Assay of Endoplasmic Reticulum Membrane Fluidity

We synthesized a boron‐dipyrromethene (BODIPY)/Nile Red hybrid probe capable of selectively recognizing fluidity changes in the endoplasmic reticulum (ER) membrane due to its preferential localization to the ER and strong energy transfer from BODIPY to the Nile Red moiety, emitting only in nonaqueous environments. ER membrane fluidity in HepG2 cells was markedly reduced by a cell model of metabolic syndrome.     

Roles of Ubiquitin in Endoplasmic Reticulum-Associated Protein Degradation (ERAD)

In the secretory pathway, quality control for the correct folding of proteins is largely occurring in the endoplasmic reticulum (ER), at the earliest possible stage and in an environment where early folding intermediates mix with terminally misfolded species. An elaborate cellular mechanism aims at dividing the former from the latter and promotes the selective transport of misfolded species back into the cytosol, a step called retrotranslocation. During retrotranslocation proteins will become ubiquitinated on the cytosolic side of the ER membrane by dedicated machineries and will be targeted to the proteasome for degradation. The entire process, from protein recognition to final degradation, has been named ER-associated protein degradation, or simply ERAD. Ubiquitin has well known functions in aiding late steps of substrate retrotranslocation and in targeting substrates to the proteasome. Recent results show that several cytosolic machineries allow ubiquitinated substrates to undergo extensive remodeling, or processing, on their poly-ubiquitin chains (PUCs). Although still ill-defined, PUC processing might have a unique function for ERAD in that it might provide a mechanism to generate optimal PUCs for recognition by proteasomal ubiquitin receptors. Ubiquitination might also have a previously unanticipated role in quality control of ER membrane proteins. This review recapitulates the current knowledge and recent findings about ERAD-specific roles of ubiquitin.     

Upregulation of the SERCA-type Ca2+ pump activity in response to endoplasmic reticulum stress in PC12 cells

Background  

Ca²⁺-ATPases of endoplasmic reticulum (SERCAs) are responsible for maintenance of the micro- to millimolar Ca²⁺ ion concentrations within the endoplasmic reticulum (ER) of eukaryotic cells. This intralumenal Ca²⁺ storage is important for the generation of Ca²⁺ signals as well as for the correct folding and posttranslational processing of proteins entering ER after synthesis. ER perturbations such as depletion of Ca²⁺ or abolishing the oxidative potential, inhibition of glycosylation, or block of secretory pathway, activate the Unfolded Protein Response, consisting of an upregulation of a number of ER-resident chaperones/stress proteins in an effort to boost the impaired folding capacity.     

An aggregation-induced emission platform for efficient Golgi apparatus and endoplasmic reticulum specific imaging

As two important subcellular organelles in eukaryotic cells, the Golgi apparatus (GA) and endoplasmic reticulum (ER) have recently captivated much interest due to their considerable importance in many biofunctions and role as critical biomarkers for various diseases. The development of efficient GA- and ER-specific probes is of great significance, but remains an appealing yet significantly challenging task. Herein, we reported for the first time the construction of an aggregation-induced emission (AIE) platform for GA and ER fluorescent probes, termed as AIE-GA and AIE-ER, by facile synthesis and simple functionalization. Their excellent targeting specificity to GA or ER, remarkable photostability, high brightness, and low working concentration make AIE-GA and AIE-ER significantly impressive and superior to commercially available probes. Moreover, molecular docking calculations are performed to validate the targeting mechanism of the two AIE probes.

As two important subcellular organelles in eukaryotic cells, the Golgi apparatus (GA) and endoplasmic reticulum (ER) have recently captivated much interest due to their considerable importance in many biofunctions and role as critical biomarkers for various diseases.     

The role of the UPS in cystic fibrosis

CF is an inherited autosomal recessive disease whose lethality arises from malfunction of CFTR, a single chloride (Cl-) ion channel protein. CF patients harbor mutations in the CFTR gene that lead to misfolding of the resulting CFTR protein, rendering it inactive and mislocalized. Hundreds of CF-related mutations have been identified, many of which abrogate CFTR folding in the endoplasmic reticulum (ER). More than 70% of patients harbor the DeltaF508 CFTR mutation that causes misfolding of the CFTR proteins. Consequently, mutant CFTR is unable to reach the apical plasma membrane of epithelial cells that line the lungs and gut, and is instead targeted for degradation by the UPS. Proteins located in both the cytoplasm and ER membrane are believed to identify misfolded CFTR for UPS-mediated degradation. The aberrantly folded CFTR protein then undergoes polyubiquitylation, carried out by an E1-E2-E3 ubiquitin ligase system, leading to degradation by the 26S proteasome. This ubiquitin-dependent loss of misfolded CFTR protein can be inhibited by the application of 'corrector' drugs that aid CFTR folding, shielding it from the UPS machinery. Corrector molecules elevate cellular CFTR protein levels by protecting the protein from degradation and aiding folding, promoting its maturation and localization to the apical plasma membrane. Combinatory application of corrector drugs with activator molecules that enhance CFTR Cl- ion channel activity offers significant potential for treatment of CF patients. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).     

Role of autophagy in diabetes and endoplasmic reticulum stress of pancreatic β-cells

Type 2 diabetes mellitus is characterized by insulin resistance and failure of pancreatic β-cells producing insulin. Autophagy plays a crucial role in cellular homeostasis through degradation and recycling of organelles such as mitochondria or endoplasmic reticulum (ER). Here we discussed the role of β-cell autophagy in development of diabetes, based on our own studies using mice with β-cell-specific deletion of Atg7 (autophagy-related 7 ), an important autophagy gene, and studies by others. β-cell-specific Atg7-null mice showed reduction in β-cell mass and pancreatic insulin content. Insulin secretory function ex vivo was also impaired, which might be related to organelle dysfunction associated with autophagy deficiency. As a result, β-cell-specific Atg7-null mice showed hypoinsulinemia and hyperglycemia. However, diabetes never developed in those mice. Obesity and/or lipid are physiological ER stresses that can precipitate β-cell dysfunction. Our recent studies showed that β-cellspecific Atg7-null mice, when bred with ob/ob mice, indeed become diabetic. Thus, autophagy deficiency in β-cells could be a precipitating factor in the progression from obesity to diabetes due to inappropriate response to obesity-induced ER stress.     

Revealing HOCl burst from endoplasmic reticulum in cisplatin-treated cells via a ratiometric fluorescent probe

The reactive oxygen species (ROS) are tightly associated with endoplasmic reticulum (ER) stress. Thus, the deep and visual insight of aberrant ROS fluctuations in the ER can help us better investigate the ER stress-associated pathology. In this work, a fluorescent probe ERC for HOCl detection in the ER based on phenothiazine-derived coumarin platform was developed. In the presence of HOCl, ERC exhibited an emission change from 609 nm to 503 nm within seconds. It also showed high sensitivity (0.44 μmol/L) and superb photostability. Significantly, ERC displayed low cytotoxicity, good cell membrane permeability, and appreciable ER-targetability. Ultimately, the probe was successfully utilized to image exogenous and endogenous HOCl in living cells and reveal the HOCl burst in cisplatin-treated cancer cells.     

A dual cytotoxic and anti-angiogenic water-soluble gold(III) complex induces endoplasmic reticulum damage in HeLa cells

The water-soluble gold(III) complex [Au(III)(butyl-C^N)biguanide]Cl (butyl-HC^N = 2-(4-n-butylphenyl)pyridine, BCN) displays cytotoxicity through S-phase cell cycle arrest and endoplasmic reticulum (ER) damage in HeLa cells, and shows a promising anti-angiogenic effect at sub-cytotoxic concentrations.     

A ratiometric fluorescent sensor for tracking Cu(I) fluctuation in endoplasmic reticulum

Science China Chemistry - A two-photon ratiometric fluorescent sensor for Cu+ in endoplasmic reticulum (ER), CNSB, was developed via coumarin/ASBD integration based on FRET mechanism. In solution,...