Adaptive Thermogenesis in Mice Is Enhanced by Opsin 3-Dependent Adipocyte Light Sensing

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Recombinant GST-human osteopontin fusion protein is functional in RGD-dependent cell adhesion

Osteopontin (OPN) is a secreted phosphoprotein expressed by many tumor cells, as well as a limited set of normal cells. Native OPN has been shown to support cell adhesion in an RGD-peptide-inhibitable fashion. Here we expressed human OPN in E. coli as a recombinant fusion protein with glutathione-S-transferase (GST). We report that the GST-OPN fusion protein has functional activity. PAP2 (ras-transformed, metastatic murine NIH 3T3) and MDA-MB-435 human mammary carcinoma cells bound to GST-OPN in an in vitro cell adhesion assay nearly as well as to native bovine OPN. Adhesion to the recombinant fusion protein was blocked by addition of GRGDS peptide, suggesting that the cells adhere to the recombinant and native OPN proteins by similar, integrin-mediated mechanisms. Adhesion to both sources of OPN also was inhibited by thrombin treatment of the protein. Thrombin cleaves GST from OPN in the fusion protein, and also cleaves internally in OPN, adjacent to the RGD sequence of the protein. Our results suggest that (a) thrombin cleavage of native OPN may be a natural regulator of OPN function, and (b) the majority of OPN cell binding activity is mediated by the RGD sequence in the protein backbone, with little or no requirement for post-translational modifications that occur in native OPN for adhesive function as measured here.     

Osteoclast migration on phosphorylated osteopontin is regulated by endogenous tartrate-resistant acid phosphatase

Osteopontin (OPN) is a multifunctional protein implicated in cellular adhesion and migration. Phosphorylation has emerged as a post-translational modification important for certain biological activities of OPN. This study demonstrates that adhesion of isolated neonatal rat osteoclasts in vitro was augmented on bovine milk osteopontin (bmOPN) with post-translational modifications (PTMs) compared to human Escherichia-coli-derived recombinant OPN (hrOPN) without PTMs. The difference in adhesiveness between these OPN variants was more pronounced at low coating concentrations (≤ 10 μg/ml). Both OPN forms adhered exclusively using a β₃-integrin. Partial (≤50%) dephosphorylation by tartrate-resistant acid phosphatase (TRAP) in vitro reduced osteoclast attachment to bmOPN to the same level as to hrOPN, demonstrating the importance of specific phosphorylations in OPN-dependent osteoclast adhesion.The involvement of PTMs of OPN in migration of primary rat and mouse osteoclasts was assessed on culture dishes coated with the different OPN forms and then overlaid with gold particles. Here, osteoclasts exhibited haptotactic migration on bmOPN but did not migrate on hrOPN. The presence of neutralizing antibodies to TRAP inhibited migration on bmOPN. Moreover, migration of osteoclasts isolated from TRAP-overexpressing transgenic mice was augmented on bmOPN, but not on hrOPN or type I collagen.These data collectively provide evidence in favor of a role for endogenous TRAP in regulating osteoclast migration on post-translationally modified OPN. In a tissue context, modulation of the phosphorylation level of OPN by extracellular phosphatases, e.g., TRAP, could regulate the extent of degradation such as depth and area at each bone resorption site by triggering osteoclast detachment and facilitate subsequent migration on the bone surface.     

上调OPN和TIP30表达对口腔鳞癌cal-27细胞的影响

目的:探讨上调骨桥蛋白(OPN)和TIP30表达对口腔鳞状细胞癌cal-27细胞增殖和迁移能力的影响。方法:采用过表达OPN载体病毒和过表达TIP30质粒分别感染或转染cal-27细胞株后,通过实时荧光定量PCR法和蛋白印迹western blot法检测OPN和TIP30的表达,CCK-8法检测细胞增殖能力,细胞划痕实验检测细胞的迁移能力。结果:过表达OPN载体病毒感染的cal-27-sh OPN细胞株OPN m RNA和蛋白的表达均明显高于cal-27-sh N细胞株(P0.001,P=0.002),且细胞的增殖能力和迁移能力强(P0.001,P=0.002)。过表达TIP30质粒转染的cal-27-p TIP30细胞株TIP30 m RNA和蛋白的表达均明显高于cal-27-pc3.0细胞株(P=0.001,P=0.003),且细胞的增殖能力和迁移能力弱(P0.001,P=0.005)。结论:OPN能促进cal-27细胞的增殖和迁移,TIP30抑制cal-27细胞的增殖和迁移。     

血清CA125 和OPN 联检在卵巢癌患者中的诊断价值

目的:探讨CA125和OPN联检在卵巢癌诊断中的应用价值。方法:以50例正常健康人为对照,对经组织病理学确诊的69例卵巢癌患者和54例卵巢良性肿瘤患者术前行血清CA125(放免法)和OPN(ELISA法)测定。比较二种血清标志物在正常人、卵巢良性肿瘤和卵巢癌病例中的表达水平。以正常人血清OPN均值±1.96S作为上下界,计算OPN临界值,大于临界值即为OPN阳性。血清CA125≥35 U/mL为阳性。比较三组病例中血清CA125和OPN单检及联检的灵敏度及特异性。比较二种血清标志物在卵巢癌及卵巢良性肿瘤的不同组织分型中的灵敏度。结果:卵巢癌组血清CA125和OPN的水平均显著高于正常对照组和卵巢良性肿瘤组(P<0.01),OPN临界值为27 ng/mL。在卵巢癌诊断中CA125、OPN检测的敏感度分别为66.7%和85.5%,二者联检的敏感度为95.7%。同时二者联检对浆液性囊腺癌、粘液性囊腺癌和子宫内膜样腺癌的敏感度分别为91.7%、70.0%和66.7%。结论:血清CA125和OPN是卵巢癌诊断的敏感性指标,二者联检可提高卵巢癌、特别是粘液性卵巢癌诊断的敏感度。     

野猪骨桥蛋白基因表达及与家猪的对比分析

采用RT-PCR法克隆野猪(Sus scrofa)OPN基因,构建其进化树,半定量RT-PCR法结合Western-blot法对其表达进行研究.结果表明,野猪的OPN基因CDS全长909 bp,编码303个氨基酸.特征基序包括(1)第86个氨基酸处有8个连续的天冬氨酸;(2)第153～157氨基酸处有一个与细胞黏附有关的Gly-Arg-Gly-Asp-Ser(GRGDS)序列;(3)第163～164氨基酸处有一个凝血酶酶切位点RS.分子进化树表明,野猪与家猪的亲缘关系最近,与石斑鱼(Danio,rerio)的亲缘关系最远,OPN基因在进化过程中发生过一次大的变异.OPN mRNA在心、胃、肾、卵巢的表达水平较高,在肝、脾、肺、小肠、肌肉、子宫内的表达水平较低.不同组织表达的OPN蛋白大小不同,存在70 ku、70 ku+45 ku和70 ku+45 ku+24 ku这三种模式.     

Remarkable similarities between the hemichordate (Saccoglossus kowalevskii) and vertebrate GPCR repertoire

Saccoglossus kowalevskii (the acorn worm) is a hemichordate belonging to the superphylum of deuterostome bilateral animals. Hemichordates are sister group to echinoderms, and closely related to chordates. S. kowalevskii has chordate like morphological traits and serves as an important model organism, helping developmental biologists to understand the evolution of the central nervous system (CNS). Despite being such an important model organism, the signalling system repertoire of the largest family of integral transmembrane receptor proteins, G protein-coupled receptors (GPCRs) is largely unknown in S. kowalevskii. Here, we identified 260 unique GPCRs and classified as many as 257 of them into five main mammalian GPCR families; Glutamate (23), Rhodopsin (212), Adhesion (18), Frizzled (3) and Secretin (1). Despite having a diffuse nervous system, the acorn worm contains well conserved orthologues for human Adhesion and Glutamate family members, with a similar N-terminal domain architecture. This is particularly true for genes involved in CNS development and regulation in vertebrates. The average sequence identity between the GPCR orthologues in human and S. kowalevskii is around 47%, and this is same as observed in couple of the closest vertebrate relatives, Ciona intestinalis (41%) and Branchiostoma floridae (~ 47%). The Rhodopsin family has fewer members than vertebrates and lacks clear homologues for 6 of the 13 subgroups, including olfactory, chemokine, prostaglandin, purine, melanocyte concentrating hormone receptors and MAS-related receptors. However, the peptide and somatostatin binding receptors have expanded locally in the acorn worm. Overall, this study is the first large scale analysis of a major signalling gene superfamily in the hemichordate lineage. The establishment of orthologue relationships with genes involved in neurotransmission and development of the CNS in vertebrates provides a foundation for understanding the evolution of signal transduction and allows for further investigation of the hemichordate neurobiology.