Alcoholism and acquired immune deficiency syndrome are associated with severe muscle wasting.This impairment in nitrogen balance arises from increased protein degradation and a decreased rate of protein synthesis.The ...Alcoholism and acquired immune deficiency syndrome are associated with severe muscle wasting.This impairment in nitrogen balance arises from increased protein degradation and a decreased rate of protein synthesis.The regulation of protein synthesis is a complex process involving alterations in the phosphorylation state and protein-protein interaction of various components of the translation machinery and mammalian target of rapamycin(mTOR) complexes.This review describes mechanisms that regulate protein synthesis in cultured C2C12 myocytes following exposure to either alcohol or human immunodeficiency virus antiretroviral drugs.Particular attention is given to the upstream regulators of mTOR complexes and the downstream targets which play an important role in translation.Gaining a better understanding of these molecular mechanisms could have important implications for preventing changes in lean body mass in patients with catabolic conditions or illnesses.展开更多
Heat shock proteins (HSPs) serve to correct proteins’ conformation, send the damaged proteins for degradation (quality control function). Heat shock factors (HSFs) are their transcription factors. The protein complex...Heat shock proteins (HSPs) serve to correct proteins’ conformation, send the damaged proteins for degradation (quality control function). Heat shock factors (HSFs) are their transcription factors. The protein complexes mTOR1 and 2 (with the same core mTOR), the phosphoinositide-dependent protein kinase-1 (PDK1), the seine/threonine-specific protein kinase (Akt), HSF1, plus their associated proteins form a network participating in protein synthesis, bio-energy generation, signaling for apoptosis with the help of HSPs. A cancer cell synthesizes proteins at fast rate and needs more HSPs to work on quality control. Shutting down this network would lead to cell death. Thus inhibitors of mTOR (mTORI) and inhibitors of HSPs (HSPI) could drive cancer cell to apoptosis—a “passive approach”. On the other hand, HSPs form complexes with polypeptides characteristic of the cancer cells;on excretion from the cell, they becomes antigens for the immunity cells, eventually leading to maturation of the cytotoxic T cells, forming the basic principle of preparing cancer-specific, person-specific vaccine. Recent finding shows that HSP70 can penetrate cancer cell and expel its analog to extracellular region, giving the hope to prepare a non-person-specific vaccine covering a variety of cancers. Activation of anti-cancer immunity is the “active approach”. On the other hand, mild hyperthermia, with increase of intracellular HSPs, has been found to activate the immunity response, and demonstrate anti-cancer effects. There are certain “mysteries” behind the mechanisms of the active and passive approaches. We analyze the mechanisms involved and provide explanations to some mysteries. We also suggest future research to improve our understanding of these two approaches, in which HSPs play many roles.展开更多
Background: We investigated the immunohistochemical expression of Arp2/3 complex in 88 oral squamous cell carcinomas (OSCCs) and correlated it with the tumor type and grade. Materials and methods: This is a retrospect...Background: We investigated the immunohistochemical expression of Arp2/3 complex in 88 oral squamous cell carcinomas (OSCCs) and correlated it with the tumor type and grade. Materials and methods: This is a retrospective study of 88 cases of OSCCs (9 verrucous carcinomas, 4 carcinomas in situ, 37 well differentiated OSCCs, 32 moderately differentiated OSCCs, and 6 poorly differentiated OSCCs), stained with mouse monoclonal antibodies for Arp2 and Arp3. Staining was graded according to the extent of positivity by two observers. Results: Arp2 positivity was seen in 79 (89.77%) cases and Arp3 positivity in 78 (88.63%) cases. In positive cases, Arp2 expression was graded as (+) in 12.5%, (++) in 28.4% and (+++) in 48.86% of the cases;Arp3 was graded as (+) in 36.36%, (++) in 30.68% and (+++) in 21.59% of the cases. Conclusion: Expression of Arp2 and Arp3, indicative of the formation of the Arp2/3 complex, was seen in most OSCCs examined. Although no statistically significant correlation was found between the immunohistochemical expression of Arp2/Arp3 and tumor type or grade, the more common expression in invasive OSCCs than in non-invasive verrucous carcinomas and carcinomas in situ is indicative of its involvement in the biological behaviour of the lesions. The availability of Arp2/3 inhibitors that could be used in clinical practice warrants further study of the expression of Arp2/3 in OSCC.展开更多
背景与目的:肌动蛋白相关蛋白2/3复合体5(actin related protein 2/3 complex subunit5,ARPC5)参与肌动蛋白的组装,影响细胞的运动能力,在形成癌细胞侵袭性伪足的过程中起到重要作用。本研究通过基因沉默手段,探讨下调ARPC5基因表达对...背景与目的:肌动蛋白相关蛋白2/3复合体5(actin related protein 2/3 complex subunit5,ARPC5)参与肌动蛋白的组装,影响细胞的运动能力,在形成癌细胞侵袭性伪足的过程中起到重要作用。本研究通过基因沉默手段,探讨下调ARPC5基因表达对肺鳞癌细胞株SK-MES-1增殖、侵袭和转移能力的影响。方法:应用阳离子脂质体转染法构建ARPC5基因沉默(si-ARPC5)的SK-MES-1肺鳞癌细胞株,qRT-PCR和蛋白质印迹法(Western blot)鉴定转染效率和表达情况。实验设置si-ARPC5实验组、空白对照组(mock组)及阴性对照组(NC组)。采用细胞技术试剂盒(cell couiting kit-8,CCK-8)法测定si-ARPC5对SK-MES-1细胞的增殖的影响;划痕修复实验测定si-ARPC5对SK-MES-1细胞迁移能力的影响;Transwell小室体外侵袭实验测定siARPC5对SK-MES-1细胞的侵袭能力的影响。结果:转染si-ARPC5后的SK-MES-1细胞在mRNA和蛋白水平上均下调ARPC5的表达。与mock组及NC组比较,si-ARPC5实验组SK-MES-1细胞增殖能力明显下降(t=7.993,t=8.681,P<0.05)。si-ARPC5实验组划痕修复率(43.32±0.23)%,而mock组和NC组划痕修复率分别为(73.11±0.43)%和(76.58±0.88)%,差异有统计学意义(t=7.348,t=10.614,P<0.05)。si-ARPC5组的SK-MES-1细胞穿膜数为(27±6)个,mock组为(101±11)个,NC组为(92±9)个。si-ARPC5组穿膜细胞数明显少于其他2组,差异有统计学意义(t=10.229,t=8.391,P<0.05)。结论:下调ARPC5基因的表达能够显著抑制肺鳞癌细胞株SK-MES-1的增殖、侵袭和转移能力。展开更多
The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EM...The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EMC6 is one of the core members of EMC and forms an enclosed hydrophilic vestibule in cooperation with EMC3.Despite studies demonstrating that deletion of EMC3 led to rhodopsin mislocalization in rod photoreceptors of mice,the precise mechanism leading to the failure of rhodopsin trafficking remains unclear.Here,we generated the first rod photoreceptor-specific knockout of Emc6(RKO)and cone photoreceptor-specific knockout of Emc6(CKO)mouse models.Deficiency of Emc6 in rod photoreceptors led to progressive shortening of outer segments(OS),impaired visual function,mislocalization and reduced expression of rhodopsin,and increased gliosis in rod photoreceptors.In addition,CKO mice displayed the progressive death of cone photoreceptors and abnormal localization of cone opsin protein.Subsequently,proteomics analysis of the RKO mouse retina illustrated that several cilium-related proteins,particularly anoctamin-2(ANO2)and transmembrane protein 67(TMEM67),were significantly down-regulated prior to OS degeneration.Detrimental rod photoreceptor cilia and mislocalized membrane disc proteins were evident in RKO mice.Our data revealed that in addition to monitoring the synthesis of rhodopsin-dominated membrane disc proteins,EMC6 also impacted rod photoreceptors'ciliogenesis by regulating the synthesis of membrane proteins associated with cilia,contributing to the mislocalization of membrane disc proteins.展开更多
基金Supported by National Institute of Health Grants R37 AA-011290and DK-072909
文摘Alcoholism and acquired immune deficiency syndrome are associated with severe muscle wasting.This impairment in nitrogen balance arises from increased protein degradation and a decreased rate of protein synthesis.The regulation of protein synthesis is a complex process involving alterations in the phosphorylation state and protein-protein interaction of various components of the translation machinery and mammalian target of rapamycin(mTOR) complexes.This review describes mechanisms that regulate protein synthesis in cultured C2C12 myocytes following exposure to either alcohol or human immunodeficiency virus antiretroviral drugs.Particular attention is given to the upstream regulators of mTOR complexes and the downstream targets which play an important role in translation.Gaining a better understanding of these molecular mechanisms could have important implications for preventing changes in lean body mass in patients with catabolic conditions or illnesses.
文摘Heat shock proteins (HSPs) serve to correct proteins’ conformation, send the damaged proteins for degradation (quality control function). Heat shock factors (HSFs) are their transcription factors. The protein complexes mTOR1 and 2 (with the same core mTOR), the phosphoinositide-dependent protein kinase-1 (PDK1), the seine/threonine-specific protein kinase (Akt), HSF1, plus their associated proteins form a network participating in protein synthesis, bio-energy generation, signaling for apoptosis with the help of HSPs. A cancer cell synthesizes proteins at fast rate and needs more HSPs to work on quality control. Shutting down this network would lead to cell death. Thus inhibitors of mTOR (mTORI) and inhibitors of HSPs (HSPI) could drive cancer cell to apoptosis—a “passive approach”. On the other hand, HSPs form complexes with polypeptides characteristic of the cancer cells;on excretion from the cell, they becomes antigens for the immunity cells, eventually leading to maturation of the cytotoxic T cells, forming the basic principle of preparing cancer-specific, person-specific vaccine. Recent finding shows that HSP70 can penetrate cancer cell and expel its analog to extracellular region, giving the hope to prepare a non-person-specific vaccine covering a variety of cancers. Activation of anti-cancer immunity is the “active approach”. On the other hand, mild hyperthermia, with increase of intracellular HSPs, has been found to activate the immunity response, and demonstrate anti-cancer effects. There are certain “mysteries” behind the mechanisms of the active and passive approaches. We analyze the mechanisms involved and provide explanations to some mysteries. We also suggest future research to improve our understanding of these two approaches, in which HSPs play many roles.
文摘Background: We investigated the immunohistochemical expression of Arp2/3 complex in 88 oral squamous cell carcinomas (OSCCs) and correlated it with the tumor type and grade. Materials and methods: This is a retrospective study of 88 cases of OSCCs (9 verrucous carcinomas, 4 carcinomas in situ, 37 well differentiated OSCCs, 32 moderately differentiated OSCCs, and 6 poorly differentiated OSCCs), stained with mouse monoclonal antibodies for Arp2 and Arp3. Staining was graded according to the extent of positivity by two observers. Results: Arp2 positivity was seen in 79 (89.77%) cases and Arp3 positivity in 78 (88.63%) cases. In positive cases, Arp2 expression was graded as (+) in 12.5%, (++) in 28.4% and (+++) in 48.86% of the cases;Arp3 was graded as (+) in 36.36%, (++) in 30.68% and (+++) in 21.59% of the cases. Conclusion: Expression of Arp2 and Arp3, indicative of the formation of the Arp2/3 complex, was seen in most OSCCs examined. Although no statistically significant correlation was found between the immunohistochemical expression of Arp2/Arp3 and tumor type or grade, the more common expression in invasive OSCCs than in non-invasive verrucous carcinomas and carcinomas in situ is indicative of its involvement in the biological behaviour of the lesions. The availability of Arp2/3 inhibitors that could be used in clinical practice warrants further study of the expression of Arp2/3 in OSCC.
文摘背景与目的:肌动蛋白相关蛋白2/3复合体5(actin related protein 2/3 complex subunit5,ARPC5)参与肌动蛋白的组装,影响细胞的运动能力,在形成癌细胞侵袭性伪足的过程中起到重要作用。本研究通过基因沉默手段,探讨下调ARPC5基因表达对肺鳞癌细胞株SK-MES-1增殖、侵袭和转移能力的影响。方法:应用阳离子脂质体转染法构建ARPC5基因沉默(si-ARPC5)的SK-MES-1肺鳞癌细胞株,qRT-PCR和蛋白质印迹法(Western blot)鉴定转染效率和表达情况。实验设置si-ARPC5实验组、空白对照组(mock组)及阴性对照组(NC组)。采用细胞技术试剂盒(cell couiting kit-8,CCK-8)法测定si-ARPC5对SK-MES-1细胞的增殖的影响;划痕修复实验测定si-ARPC5对SK-MES-1细胞迁移能力的影响;Transwell小室体外侵袭实验测定siARPC5对SK-MES-1细胞的侵袭能力的影响。结果:转染si-ARPC5后的SK-MES-1细胞在mRNA和蛋白水平上均下调ARPC5的表达。与mock组及NC组比较,si-ARPC5实验组SK-MES-1细胞增殖能力明显下降(t=7.993,t=8.681,P<0.05)。si-ARPC5实验组划痕修复率(43.32±0.23)%,而mock组和NC组划痕修复率分别为(73.11±0.43)%和(76.58±0.88)%,差异有统计学意义(t=7.348,t=10.614,P<0.05)。si-ARPC5组的SK-MES-1细胞穿膜数为(27±6)个,mock组为(101±11)个,NC组为(92±9)个。si-ARPC5组穿膜细胞数明显少于其他2组,差异有统计学意义(t=10.229,t=8.391,P<0.05)。结论:下调ARPC5基因的表达能够显著抑制肺鳞癌细胞株SK-MES-1的增殖、侵袭和转移能力。
基金supported by The National Natural Science Foundation of China(No.82121003,81970841,82101160)the program of Science and Technology International Cooperation Project of Qinghai province(China)(No.2022-HZ-814)+2 种基金the CAMS Innovation Fund for Medical Sciences(No.2019-12M-5-032)Sichuan Intellectual Property Office(China)(No.2022-ZS-0070)the Department of Chengdu Science and Technology(Sichuan,China)(No.2021-YF05-01316-SN).
文摘The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EMC6 is one of the core members of EMC and forms an enclosed hydrophilic vestibule in cooperation with EMC3.Despite studies demonstrating that deletion of EMC3 led to rhodopsin mislocalization in rod photoreceptors of mice,the precise mechanism leading to the failure of rhodopsin trafficking remains unclear.Here,we generated the first rod photoreceptor-specific knockout of Emc6(RKO)and cone photoreceptor-specific knockout of Emc6(CKO)mouse models.Deficiency of Emc6 in rod photoreceptors led to progressive shortening of outer segments(OS),impaired visual function,mislocalization and reduced expression of rhodopsin,and increased gliosis in rod photoreceptors.In addition,CKO mice displayed the progressive death of cone photoreceptors and abnormal localization of cone opsin protein.Subsequently,proteomics analysis of the RKO mouse retina illustrated that several cilium-related proteins,particularly anoctamin-2(ANO2)and transmembrane protein 67(TMEM67),were significantly down-regulated prior to OS degeneration.Detrimental rod photoreceptor cilia and mislocalized membrane disc proteins were evident in RKO mice.Our data revealed that in addition to monitoring the synthesis of rhodopsin-dominated membrane disc proteins,EMC6 also impacted rod photoreceptors'ciliogenesis by regulating the synthesis of membrane proteins associated with cilia,contributing to the mislocalization of membrane disc proteins.
