模拟海拔5000米低氧环境下大鼠甲状腺轴与CRH家族的相关性研究

目的研究SD大鼠HPT轴激素及蛋白在低氧环境下的病理生理变化机制及与促肾上腺皮质激素释放激素(Corticotropin releasing hormone,CRH)家族相关蛋白及激素的相互作用。方法用低压低氧舱模拟海拔5 000 m高原低氧环境复制SD大鼠动物模型,采用ELISA法检测大鼠血清中HPT轴激素水平,包括游离三碘甲腺原氨酸(Free triido-thyronine,FT3)、游离四碘甲腺原氨酸(Free tetraiodo-thyronine,FT4)、总三碘甲腺原氨酸(Total triido-thyronine,TT3)、总四碘甲腺原氨酸(Total tetraiodo-thyronine,TT4)、反三碘甲腺原氨酸(3,5,3’-L-triiodo-thyronine,r T3)、促甲状腺激素(Thyrotropin stimulating hormone,TSH)、促甲状腺激素释放激素(Thyrotropin releasing hormone,TRH),以及CRH家族激素CRH、尿皮素2(Urocortin II,Ucn2)、Ucn3、皮质酮(Corticosterone,CORT)在血清中的水平,通过Western blot检测低氧诱导因子-1α(Hypoxia-inducible factor 1α,HIF-1α),HPT轴的TSHR、TRHR1及CRH家族受体CRHR1、CRHR2的表达。采用免疫荧光双染检测CRHR1、CRHR2与TSHR在甲状腺滤泡细胞的表达。通过Pearson相关分析探讨CRH家族CRH、Ucn2、Ucn3、CORT和HPT轴激素FT3、FT4、TT3、TT4、TSH、TRH、r T3相关性。结果低氧组大鼠TRH、TT3、TT4、FT3、FT4和TSH血清水平均下降(P0.05),r T3、CRH、Ucn2、Ucn3和CORT血清浓度上升(P0.05)。相关性统计表明低氧各组大鼠血清CRH与TRH激素水平负相关(r=-0.80),Ucn2与FT3、TT3分别呈负相关(r=-0.796,-0.798)。免疫荧光双标显示CRHR1与TSHR、CRHR2与TSHR在甲状腺滤泡细胞存在共表达。结论结果表明模拟5000米海拔低氧环境使大鼠HPT轴功能受到抑制,可能与CRH家族基因激活有关,这对进一步研究HPT轴与CRH家族相互作用机制提供一定的线索。     

组蛋白去乙酰化酶SIRT1调控肿瘤微环境的研究进展

SIRT1是烟酰胺腺嘌呤二核苷酸(NAD+)依赖的去乙酰化酶家族(即Sirtuins家族)中的明星成员,因为其在衰老、免疫以及炎症方面的功能而与肿瘤高度相关.研究表明,SIRT1能够通过调节肿瘤微环境中的免疫细胞功能、各种细胞因子的分泌、调节肿瘤细胞的分泌行为以及肿瘤细胞的黏附功能,重塑肿瘤微环境,进而影响肿瘤的发展和...     

Fosl2与免疫系统和自身免疫性疾病关系的研究进展

Fosl2属于转录因子AP-1(activator protein 1)家族中Fos亚家族中的一个成员。Fos亚家族蛋白的成员有c-Fos、Fosl1、Fosl2及FosB。Fos家族蛋白与Jun家族成员蛋白以同源或异源二聚体的形式结合DNA靶序列后被称为转录因子AP-1,参与靶基因调节。Fosl2参与恒定NK细胞分化、巨噬细胞极化、B细胞发育、炎性因子分泌和骨稳态调控。研究表明其可诱导表皮分化、保持皮肤屏障功能从而防止银屑病的发生,并且与TGF-β1相互调节而参与硬皮病等疾病,另外,Fosl2可能参与到酚类抗氧化剂预防肿瘤的机制中。随着研究的开展,Fosl2在更多不同疾病中的作用也逐渐被揭示,如乳腺癌的发生发展及转移、炎症所致的纤维化等。因此,调控Fosl2活性或功能或可成为未来开发自身免疫性疾病药物的靶点之一。     

CRH通过CRHR1激活cAMP/PKA通路调节宫颈癌细胞的免疫逃逸和促进宫颈癌生长

目的 探讨促肾上腺皮质激素释放激素(corticotropin-releasing hormone,CRH)及其受体(corticotropin-releasing hormone receptor 1,CRHR1)影响宫颈癌免疫逃逸和生长的途径.方法 采用实时荧光定量聚合酶链反应(quantitative real-...     

IL-25与免疫相关疾病关系的研究进展

IL-25又称为IL-17E,是细胞因子IL-17家族的成员之一,主要由活化的Th细胞和肥大细胞所分泌。与其他家族成员不同,IL-25能够诱导Th2型细胞因子如IL-4、IL-5和IL-13的产生,介导Th2类免疫应答,还能够影响Th17细胞的分化并调节自身免疫性疾病的发生发展。总之,IL-25在多种免疫性疾病的发生发展中都发挥着重要的作用。     

IL-12家族新成员及其在免疫应答中的重要调节作用

白细胞介素-12(Interleukin-12, IL-12)家族成员IL-12、 IL-23、 IL-27三者及其各自受体在结构上的相似性, 使得它们在发挥调节NK细胞活性、 T细胞增殖和细胞因子产生以及抗体类别转换等方面的功能相互重叠但又不完全相同.而2007年发现的该家族的另一新成员IL-35, 结构上虽与其他3个成员同源, 但却具有独特的生物学功能, 是一种主要由调节性T细胞(Treg)分泌的抑制性细胞因子.IL-12家族各成员以及同其他细胞因子之间存在着相互协同、相互拮抗的网络, 不仅在细胞内感染及炎症过程中起着重要的调节作用, 而且与银屑病、多发性硬化症、 Crohn' s病等多种临床疾病的发病密切相关.IL-12家族相关生物制品在自身免疫性疾病、感染性疾病以及肿瘤的治疗中有着广阔的应用前景.     

半乳糖凝集素3对树突状细胞及T淋巴细胞功能影响的研究进展

半乳糖凝集素3(Gal-3)是半乳糖凝集素家族成员之一,它是半乳糖凝集素家族中唯一的嵌合型凝集素,存在于正常细胞和肿瘤细胞的胞核、胞质和细胞外基质中,能调节树突状细胞(DC)和T淋巴细胞的免疫功能,调节机体免疫应答和炎症反应。研究发现DC分泌Gal-3具有抑制自身凋亡、调节细胞因子生成以及调节T细胞应答等多种功能。同时Gal-3位于胞外和胞内对T淋巴细胞分别具有相反作用,胞外Gal-3诱导T细胞凋亡,胞内Gal-3抑制其凋亡。此外Gal-3在调节炎症反应中的起重要作用。     

B7家族PD-L1和B7-H4的研究进展

“协同刺激信号”的提出很好地解释了免疫系统对自身和外源性抗原的不同调节机制.B7家族作为唯一能从抗原提呈细胞传递信号给T细胞的共刺激分子,其与相应配体结合在调节免疫反应、炎症及癌症中都起着重要作用.对于B7家族成员在免疫反应中的调节机制仍然不甚清楚,本文综述了程序性死亡配体1(PD-L1)、B7-H4的生物学功能及其与疾病的关系.     

肠免疫组织对肠上皮细胞生长的影响

肠粘膜免疫组织除了发挥免疫功能外,还能通过分泌多种细胞因子调节肠上皮细胞受损后的再生和修复.其中,在二者间起重要交流作用的细胞因子是IFN-γ,此外IL-2和IL-4也对维持正常的粘膜免疫和肠上皮细胞发挥重要调节作用.这些细胞因子调节上皮细胞增殖和分化的机制之一通过上皮细胞表面受体激活JAKs激酶,随后激活包括转录蛋白STAT家族在内的各种不同的信号蛋白,从而表达细胞因子功能.     

受体活性修饰蛋白的研究进展

受体活性修饰蛋白(RAMPs)与不同的G蛋白偶联受体 (GPCRs)相互作用可形成稳定的异二聚体在细胞膜表达并决定受体表型。RAMPs与降钙素基因相关肽家族(CGRP)受体、降钙素受体 (CTR)及降钙素受体样受体(CRLR)相互作用,可使CTR和CRLR表现为不同的CGRP家族成员受体表型。此外,RAMPs还能与其他Ⅱ型GPCRs相互作用,显示RAMPs在G蛋白偶联受体功能调节中具有更为广泛的作用。RAMPs对GPCRs的调节依赖于它的分子基础。RAMPs的发现为G蛋白偶联受体功能及细胞信号转导的研究提供了新思路。     

EGFR enhances Survivin expression through the phosphoinositide 3 (PI-3) kinase signaling pathway

The ErbB family of receptor tyrosine kinases includes the epidermal growth factor receptor (EGFR), p185/neu/c-erbB2, ErbB3, and ErbB4. Many of these receptors are overexpressed or amplified in various forms of cancers. Previous studies have indicated that activation of erbB molecules contributes to malignant transformation both by promoting cell proliferation through the mitogen-activated protein kinase (MAP kinase) signaling pathway and by preventing apoptosis through the Phosphoinositide 3 kinase (PI-3 kinase) pathway. Disabling erbB receptors converts malignant cells that were resistant to cell death caused by irradiation to cells that are sensitive to apoptosis. Here, we report that an activated form of EGFR can elevate the levels of Survivin, a member of the Inhibitor of Apoptosis Protein (IAP) family implicated in mitotic checkpoint control. Conversely, inactivation of the ErbB receptors reduces the expression levels of Survivin. Furthermore, we found that upregulation of Survivin by EGFR is dependent on the PI-3 kinase pathway but not on the MAP kinase pathway. Indeed, inhibition of PI-3 kinase can diminish Survivin at both the mRNA and the protein levels. Combined with previous findings that Survivin plays a role in control of chromosome segregation and that it is overexpressed in various cancers, our results suggest that EGFR may cause transformation by directly affecting mitosis and increasing chromosome instability.     

Corticotropin-releasing hormone potentiates neural injury induced by oxygen-glucose deprivation: a possible involvement of microglia

While corticotropin-releasing hormone (CRH) has been implicated in a variety of brain disorders such as ischemic injury, the molecular mechanism by which CRH elicits its activities is largely unclear. In the present study, we have determined the effect of CRH on oxygen-glucose deprivation (OGD) induced apoptosis in fetal hippocampal neurons. CRH alone at concentrations of 10-200 nM had no effect on neuronal apoptosis. However, when neurons were co-cultured with microglia, CRH alone at concentrations greater than 100 nM induced neuronal apoptosis and CRH potentiated significant neuronal apoptosis following exposure to OGD. The effect of CRH on neuronal apoptosis was inhibited in the presence of the CRH antagonist astressin. Real-time RT-PCR revealed an increase in mRNA levels of Fas ligand (Fas-L), a membrane protein related to the TNF family, in cultured microglia following OGD exposure. In the presence of CRH, OGD-induced Fas-L expression was significantly increased. The effect of CRH on Fas-L expression was inhibited by specific inhibitors of the extracellular signal-regulated protein kinase (PD98059) and p38 mitogen-activated protein kinase (SB203580). These results suggest that CRH potentiates neuronal apoptosis induced by OGD in the presence of microglia and that this effect may be mediated through the induction of proinflammatory mediators in microglia.     

Worldwide haplotype diversity and coding sequence variation at human bitter taste receptor loci

Bitter taste perception in humans is mediated by receptors encoded by 25 genes that together comprise the TAS2R (or T2R) gene family. The ability to identify the ligand(s) for each of these receptors is dependent on understanding allelic variation in TAS2R genes, which may have a significant effect on ligand recognition. To investigate the extent of coding variation among TAS2R alleles, we performed a comprehensive evaluation of sequence and haplotype variation in the human bitter taste receptor gene repertoire. We found that these genes exhibit substantial coding sequence diversity. In a worldwide population sample of 55 individuals, we found an average of 4.2 variant amino acid positions per gene. In aggregate, the 24 genes analyzed here, along with the phenylthiocarbamide (PTC) receptor gene analyzed previously, specify 151 different protein coding haplotypes. Analyses of the ratio of synonymous and nonsynonymous nucleotide substitutions using the Ka/Ks ratio revealed an excess of amino acid substitutions relative to most other genes examined to date (Ka/Ks = 0.94). In addition, comparisons with more than 1,500 other genes revealed that levels of diversity in the TAS2R genes were significantly greater than expected (pi = 0.11%; p < 0.01), as were levels of differentiation among continental populations (FST = 0.22; p < 0.05). These diversity patterns indicate that unusually high levels of allelic variation are found within TAS2R loci and that human populations differ appreciably with respect to TAS2R allele frequencies. Diversity in the TAS2R genes may be accounted for by natural selection, which may have favored alleles responsive to toxic, bitter compounds found in plants. These findings are consistent with the view that different alleles of the TAS2R genes encode receptors that recognize different ligands, and suggest that the haplotypes we have identified will be important in studies of receptor-ligand recognition.     

Nogo-B受体在恶性实体肿瘤发病中的抑制和促进作用

Nogo-B是网状蛋白家族4的重要成员,广泛表达于中枢神经系统及外周组织。研究显示,Nogo-B能与Nogo受体1（NgR1）、Nogo-B特异性受体（NgBR）和配对免疫球蛋白样受体B（PirB）3种不同的受体结合,受体通过RhoA/Rho相关蛋白激酶（ROCK）、磷脂酰肌醇-3激酶/蛋白激酶B（PI3K/Akt）、磷酸腺苷活化激酶α/肝X受α（AMPAα/LXRα）、细胞外信号调节激酶（ERK）、上皮-间质转化（EMT）以及未折叠蛋白反应（UPR）等多个信号通路,在血管生成、增殖和凋亡以及侵袭和迁移等肿瘤发生和发展过程中发挥抑制和促进的双重作用。了解Nogo-B受体参与肿瘤发病的机制将会为治疗药物的开发提供新的思路。我们将对Nogo-B及其受体的基本结构和表达以及Nogo-B受体信号通路在恶性实体肿瘤发生和发展中的抑制和促进作用等方面的最新研究进展做一简要综述。     

AKRL1 and AKRL2 activate the JNK pathway

BACKGROUND: c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, is activated by specific cytokines and various environmental stresses. MKK4 and MKK7 are shown to be direct activators of JNK. Although several upstream components of the JNK pathway, including members of the MAPKKK family have been described, the components lying between the receptors or sensors and JNK have not been fully characterized. RESULTS: We have identified AKRL1 and AKRL2 (Akr1p-like 1 and 2) as novel activators of the JNK pathway. AKRL1 and AKRL2 proteins have a considerable sequence similarity to Akr1p, a protein essential for endocytosis in Saccharomyces cerevisiae. Expression of AKRL1 or AKRL2 activates JNK and its activators MKK4 and MKK7. This AKRL1/2-induced JNK activation is significantly suppressed by the expression of a kinase-negative mutant of TAK1, a member of the MAPKKK family. AKRL1 and AKRL2 localize to the Golgi. Both the N-terminal half and the C-terminal transmembrane domain of AKRL1/2 are required for the JNK activation. The C-terminal transmembrane domain of AKRL1/2 is required for localization to the Golgi. CONCLUSION: AKRL1 and AKRL2 are localized to Golgi and the novel activators of the JNK pathway.     

Corticotropin releasing hormone and proopiomelanocortin involvement in the cutaneous response to stress

The skin is a known target organ for the proopiomelanocortin (POMC)-derived neuropeptides alpha-melanocyte stimulating hormone (alpha-MSH), beta-endorphin, and ACTH and also a source of these peptides. Skin expression levels of the POMC gene and POMC/corticotropin releasing hormone (CRH) peptides are not static but are determined by such factors as the physiological changes associated with hair cycle (highest in anagen phase), ultraviolet radiation (UVR) exposure, immune cytokine release, or the presence of cutaneous pathology. Among the cytokines, the proinflammatory interleukin-1 produces important upregulation of cutaneous levels of POMC mRNA, POMC peptides, and MSH receptors; UVR also stimulates expression of all the components of the CRH/POMC system including expression of the corresponding receptors. Molecular characterization of the cutaneous POMC gene shows mRNA forms similar to those found in the pituitary, which are expressed together with shorter variants. The receptors for POMC peptides expressed in the skin are functional and include MC1, MC5 and mu-opiate, although most predominant are those of the MC1 class recognizing MSH and ACTH. Receptors for CRH are also present in the skin. Because expression of, for example, the MC1 receptor is stimulated in a similar dose-dependent manner by UVR, cytokines, MSH peptides or melanin precursors, actions of the ligand peptides represent a stochastic (predictable) nonspecific response to environmental/endogenous stresses. The powerful effects of POMC peptides and probably CRH on the skin pigmentary, immune, and adnexal systems are consistent with stress-neutralizing activity addressed at maintaining skin integrity to restrict disruptions of internal homeostasis. Hence, cutaneous expression of the CRH/POMC system is highly organized, encoding mediators and receptors similar to the hypothalamic-pituitary-adrenal (HPA) axis. This CRH/POMC skin system appears to generate a function analogous to the HPA axis, that in the skin is expressed as a highly localized response which neutralizes noxious stimuli and attendant immune reactions.     

Signaling pathways involved in the A and B receptor-mediated cortisol secretagogue effect of endothelins in the human adrenal cortex

Endothelins (ETs) are a family of 21-amino acid hypertensive peptides, which together with their receptors ETA and ETB are expressed in human adrenal cortex. Evidence has been provided that ETs exert a potent secretagogue effect on human adrenocortical cells, acting through both ETA and ETB receptors. Therefore, it seemed worthwhile to study the signaling cascades mediating the cortisol secretagogue effect of the two receptor subtypes. Normal adrenal glands were obtained from consenting patients undergoing unilateral nephrectomy with ipsilateral adrenalectomy for renal cancer. Dispersed zona fasciculata-reticularis (ZF/R) cells were obtained by collagenase digestion and mechanical disaggregation. The selective activation of ETA and ETB receptors was obtained by exposing dispersed cells to ET-1 plus the ETB receptor antagonist BQ-788 and to the selective ETB receptor agonist BQ-3020, respectively. ETA and ETB receptors about equally contributed to the cortisol response of dispersed ZF/R cells to ETs. The phospholipase (PL) C inhibitor U-73122 abolished ETA-mediated secretory response, but only partially prevented the ETB-mediated one. The phosphatidylinositol 3-kinase inhibitor wortmannin and the protein kinase (PK) C inhibitor calphostin-C significantly blunted the secretory responses ensuing from the activation of both receptor subtypes, while the Ca(2+)-channel blocker nifedipine was ineffective. The ETB receptor-, but not the ETA receptor-mediated cortisol response was partially reversed by the cyclooxygenase (COX) inhibitor indomethacin, which when added together with U-73122 abolished it. The inhibitors of adenylate cyclase, PKA, tyrosine kinase and lipoxygenase did not affect the secretory response to the activation of either receptor subtype. ETA-receptor activation raised inositol triphosphate (IP3) production from dispersed ZF/R cells, while ETB-receptor stimulation enhanced both IP3 and prostaglandin-E(2) production. Collectively, our findings indicate that ETs stimulate cortisol secretion from human ZF/R cells, acting through ETA receptors exclusively coupled with PLC/PKC-dependent pathway and ETB receptors coupled with both PLC/PKC- and COX-dependent cascades.     

Detection and characterization of the protein encoded by the v-rel oncogene

To identify the protein encoded by v-rel, the oncogene of reticuloendotheliosis virus (REV-T), antisera have been raised to three synthetic peptides derived from the translation of our previously published v-rel DNA sequence [R.M. Stephens, N.R. Rice, R.R. Hiebsch, H.R. Bose, Jr., and R.V. Gilden, Proc. Natl. Acad. Sci. USA 80, 6229-6233 (1983)]. Sera to all three peptides precipitate a 59,000 Da protein from REV-T-transformed chicken lymphoid cells. This protein is not detectable in uninfected chick embryo fibroblasts, and its observed size is in good agreement with the 56,000 Da predicted by the DNA sequence. We conclude that this protein is the v-rel product and designate it p59rel. To search for evidence of post-translational processing of this protein, cells were grown in the presence of glycosylation inhibitors. These resulted in no detectable difference in the size of p59rel. Nor was its size detectably altered during the course of a pulse-chase experiment. Growth of cells in the presence of [32P] orthophosphate, however, revealed that p59rel is a phosphoprotein. It is also closely associated with a protein kinase activity, for precipitation with one of the peptide antisera (but not the other two) resulted in strong kinase activity in the immune complex pellet. During this reaction, p59rel itself becomes phosphorylated. Kinase activity was retained in the immune complex following detergent and high salt washes, leaving open the possibility that p59rel is itself a kinase.