表皮生长因子受体在肺部疾病中的作用研究进展

表皮生长因子受体(epidermal growth factor receptor, EGFR)是一种受体酪氨酸激酶,属于表皮生长因子受体家族成员之一。EGFR广泛分布于人体的各种组织和器官中,包括皮肤、肺、肝、肾等,它通过激活JAK/STAT、MAPK/ERK以及PI3K/AKT等关键信号通路调控细胞内环境稳态。此外,EGFR可以被生长因子、G蛋白偶联受体等发出的信号激活,参与体内免疫和炎症反应等过程,进而调控多种疾病的病理进程。近年来研究表明EGFR与肺癌、慢性阻塞性肺疾病、支气管哮喘以及肺炎等大部分肺部疾病相关,因此,本文就EGFR在肺部疾病中的作用研究进展做一综述。     

ROR蛋白在癌症中的研究进展

ROR蛋白家族包含受体酪氨酸激酶ROR1和ROR2,作为Wnt受体,它们对于非经典Wnt信号通路至关重要,并与癌细胞增殖存活、侵袭转移和治疗抵抗密切相关。ROR蛋白在大多数成人健康组织中几乎不表达,但在一些癌症中却有较高的表达水平。有趣的是,两种ROR蛋白可能在肿瘤中发挥不同的作用, ROR1主要促进肿瘤发生,而ROR2在不同类型的肿瘤中促进或抑制肿瘤进展。目前这两种受体作为潜在的治疗靶点已经引起了人们的兴趣,该文总结了ROR蛋白的结构学特征及其在不同组织中的表达情况。此外,该文还回顾了ROR蛋白调控的生物学过程和信号通路,解释了其在癌症中发挥的重要作用。最后汇总了目前处于临床试验阶段的靶向ROR蛋白的生物药包括单抗、双抗、抗体偶联药物等。     

Ang-Tie轴在血管和淋巴系统相关疾病中作用的研究进展

形成血管和淋巴管内层的内皮细胞是脉管系统的重要组成部分,并参与血管和淋巴系统疾病的发病机制。内皮细胞上的血管生成素(Angiopoietin,Ang)-具有免疫球蛋白和表皮生长因子同源性结构域的酪氨酸蛋白激酶(Tyrosine kinase receptors with immunoglobulin and EGF homology domains,Tie)轴是除了血管内皮生长因子受体途径外胚胎心血管和淋巴发育所必需的第二种内皮细胞特异性配体-受体信号传导系统。Ang-Tie轴参与调节产后血管生成与重塑、血管通透性和炎症,以维持血管平衡,因此,该系统在许多血管和淋巴系统疾病中发挥重要的作用。针对近年来Ang-Tie轴在血管和淋巴系统相关疾病中作用的研究进展,文中系统论述了Ang-Tie轴在炎症诱导的血管通透性、血管重塑、眼部新生脉管、剪切应力反应、动脉粥样硬化和肿瘤血管生成和转移中的作用,并总结了涉及Ang-Tie轴的相关治疗性抗体、重组蛋白和小分子药物。     

心血管疾病中的蛋白质硝基化

蛋白质硝基化一般是指蛋白质中的酪氨酸硝基化成3-硝基酪氨酸,是与氧化应激密切相关的蛋白质翻译后修饰。蛋白质硝基化现象在心血管疾病中普遍存在,但其对病理生理的确切影响尚不清楚。对它的进一步研究,有待于选择性硝基化方法的发现和更灵敏的检测技术的开发。     

受体酷氨酸激酶—Ras—MPAK信号转导途径研究进展

细胞怎样将外界刺激信息传递到细胞核内,一直是人们十分关心并不断探索的问题。最近,对生长因子影响细胞增殖的信号转导途径有了较明显的认识,它包括生长因子受体、接头蛋白、鸟螵呤核苷酸释放因子、Ｒａｓ蛋白及ＭＡＰ激酶级联系统。对该信号途径中某些成员的性质及作用机理的研究也取得了一定进展。     

酪氨酸磷酸化蛋白质组学技术研究进展及其在生物医学研究中的应用

在酪氨酸磷酸化蛋白质组学的研究过程中,酪氨酸磷酸化位点的富集是最重要的一步。目前常用的富集方法是抗体亲和富集或SH2 superbinder富集。此外,通过质谱与生物信息学等技术,可实现大规模酪氨酸磷酸化位点的鉴定。对酪氨酸磷酸化蛋白质组学进行深度覆盖研究,揭示癌症发生发展过程中失调的激酶,将有助于深入理解癌症的发生发展过程;且由于75%的致癌基因是酪氨酸激酶基因,酪氨酸激酶抑制剂作为抗癌药物受到了越来越多的关注。应用酪氨酸磷酸化蛋白质组学技术,可以鉴定与癌症等重大疾病相关的酪氨酸激酶,从而帮助找到酪氨酸激酶抑制剂。总之,酪氨酸磷酸化蛋白质组学技术可以在酪氨酸激酶鉴定、酪氨酸激酶抑制剂研究及酪氨酸磷酸化信号通路研究等生物医学领域中得到很好的应用。     

酪氨酸激酶膜受体在膀胱癌中的作用机制及临床应用

膀胱癌(bladder cancer,BCa)是泌尿系统常见的恶性肿瘤,发病率在全球范围内逐年上升。近年来,尽管BCa的治疗取得了多项进展,但发病率及病死率仍然较高。酪氨酸激酶膜受体(membrane receptors tyrosine kinase,mRTKs)是目前BCa治疗中备受瞩目的潜力靶点,针对这些受体的靶向疗法正在逐步走向临床。本文综述了BCa中常见的mRTKs的结构、功能及相应细胞内信号传导,并介绍了靶向mRTKs在BCa基础研究与临床研究中的进展,探讨了靶向mRTKs药物在BCa治疗中的潜力。     

FLT3／FLK2：酪氨酸激酶受体家族新成员

属于Ⅲ类酪氨酸激酶受体家族成员的ＦＬＴ３／ＦＬＫ２已分别在人和小鼠得到克隆和表达。该受体在造血早期干祖细胞上表达较丰富,在其他组织也见有表达。小鼠ＦＬＴ３／ＦＬＫ２ｃＤＮＡ长３４５３ｂｐ,编码９９０ａａ的多肽。人与小鼠ＦＬＴ３／ＦＬＫ２的蛋白质序列有８６％同源。     

Axl受体酪氨酸激酶家簇的研究进展

Ａｘｌ家族是一个比较新的受体酪氨酸激酶家族,成员包括Ａｘｌ、Ｍｅｒ及Ｒｓｅ等几个分子、结构很特征;胞浆区与神经细胞粘附分子结构相似,胞膜外区具备酪氨酸激酶活性,这类分子在一此正常组织,恶变组织中都有表达,研究发现它们在组织的成长,发育及恶变中都有一定作用。     

Sprouty2 and Sprouty4 are essential for embryonic morphogenesis and regulation of FGF signaling

Sprouty genes encode cytoplasmic membrane-associated proteins that inhibit receptor tyrosine kinase signaling. Four orthologs of Drosophila Sprouty (dSpry) (Sprouty1-4) have been identified in mammals. Physiological function of Sprouty1 and Sprouty2 has been investigated using gene targeting approaches, however to date detailed examination of Sprouty4 knockout (KO) mice has not been reported. In this study, Sprouty4 KO mice were generated and characterized. Although a significant fraction of Sprouty4 KO mice died shortly after birth due to mandible defects, the remainder were viable and fertile. Growth retardation was observed for most Sprouty4-deficient mice, with nearly all Sprouty4 KO mice having polysyndactyly. ERK activation was sustained in Sprouty4 KO mouse embryonic fibroblasts (MEFs) in response to FGF, but not to EGF. Sprouty2 and Sprouty4 double KO (DKO) mice were embryonic lethal and showed severe defects in craniofacial, limb, and lung morphogenesis. These findings suggest both redundant and non-redundant functions for Sprouty2 and Sprouty4 on embryonic development and FGF signaling.     

Sprouty genes are essential for the normal development of epibranchial ganglia in the mouse embryo

Fibroblast growth factor (FGF) signalling has important roles in the development of the embryonic pharyngeal (branchial) arches, but its effects on innervation of the arches and associated structures have not been studied extensively. We investigated the consequences of deleting two receptor tyrosine kinase (RTK) antagonists of the Sprouty (Spry) gene family on the early development of the branchial nerves. The morphology of the facial, glossopharyngeal and vagus nerves are abnormal in Spry1−/−;Spry2−/− embryos. We identify specific defects in the epibranchial placodes and neural crest, which contribute sensory neurons and glia to these nerves. A dissection of the tissue-specific roles of these genes in branchial nerve development shows that Sprouty gene deletion in the pharyngeal epithelia can affect both placode formation and neural crest fate. However, epithelial-specific gene deletion only results in defects in the facial nerve and not the glossopharyngeal and vagus nerves, suggesting that the facial nerve is most sensitive to perturbations in RTK signalling. Reducing the Fgf8 gene dosage only partially rescued defects in the glossopharyngeal nerve and was not sufficient to rescue facial nerve defects, suggesting that FGF8 is functionally redundant with other RTK ligands during facial nerve development.     

Activation of Ras-ERK pathway by Fgf8 and its downregulation by Sprouty2 for the isthmus organizing activity

In the previous studies, we showed that strong Fgf8 signaling activates the Ras-ERK pathway to induce cerebellum. Here, we show importance of negative regulation following activation of this pathway for proper regionalization of mesencephalon and metencephalon in chick embryos. ‘Prolonged’ activation of ERK by misexpression of Fgf8b and dominant-negative Sprouty2 (dnSprouty2) did not change the fate of the mesencephalic alar plate. Downregulation of ERK activity using an MEK inhibitor, U0126, or by tetracycline-dependent Tet-off system after co-expression of Fgf8b and dnSprouty2 forced the mesencephalic alar plate to differentiate into cerebellum. We then paid attention to Mkp3. After misexpression of dnMkp3 and Fgf8b, slight downregulation of ERK activity occurred, which may be due to Sprouty2, and the mesencephalon transformed to the isthmus-like structure. The results indicate that ERK must be once upregulated and then be downregulated for cerebellar differentiation and that differential ERK activity level established by negative regulators receiving Fgf8 signal may determine regional specificity of mesencephalon and metencephalon.     

Sprouty1 and Sprouty2 limit both the size of the otic placode and hindbrain Wnt8a by antagonizing FGF signaling

Multiple signaling molecules, including Fibroblast Growth Factor (FGF) and Wnt, induce two patches of ectoderm on either side of the hindbrain to form the progenitor cell population for the inner ear, or otic placode. Here we report that in Spry1, Spry2 compound mutant embryos (Spry1^−/−; Spry2^−/− embryos), the otic placode is increased in size. We demonstrate that the otic placode is larger due to the recruitment of cells, normally destined to become cranial epidermis, into the otic domain. The enlargement of the otic placode observed in Spry1^−/−; Spry2^−/− embryos is preceded by an expansion of a Wnt8a expression domain in the adjacent hindbrain. We demonstrate that both the enlargement of the otic placode and the expansion of the Wnt8a expression domain can be rescued in Spry1^−/−; Spry2^−/− embryos by reducing the gene dosage of Fgf10. Our results define a FGF-responsive window during which cells can be continually recruited into the otic domain and uncover SPRY regulation of the size of a putative Wnt inductive center.     

Structure of native oligomeric Sprouty2 by electron microscopy and its property of electroconductivity

Receptor tyrosine kinases (RTKs) regulate many cellular processes, and Sprouty2 (Spry2) is known as an important regulator of RTK signaling pathways. Therefore, it is worth investigating the properties of Spry2 in more detail. In this study, we found that Spry2 is able to self-assemble into oligomers with a high-affinity KD value of approximately 16 nM, as determined through BIAcore surface plasmon resonance analysis. The three-dimensional (3D) structure of Spry2 was resolved using an electron microscopy (EM) single-particle reconstruction approach, which revealed that Spry2 is donut-shaped with two lip-cover domains. Furthermore, the method of energy dispersive spectrum obtained through EM was analyzed to determine the elements carried by Spry2, and the results demonstrated that Spry2 is a silicon- and iron-containing protein. The silicon may contribute to the electroconductivity of Spry2, and this property exhibits a concentration-dependent feature. This study provides the first report of a silicon- and iron-containing protein, and its 3D structure may allow us (1) to study the potential mechanism through the signal transduction is controlled by switching the electronic transfer on or off and (2) to develop a new type of conductor or even semiconductor using biological or half-biological hybrid materials in the future.     

Loss of Sprouty2 partially rescues renal hypoplasia and stomach hypoganglionosis but not intestinal aganglionosis in Ret Y1062F mutant mice

The glial cell line-derived neurotrophic factor (GDNF)/RET tyrosine kinase signaling pathway plays crucial roles in the development of the enteric nervous system (ENS) and the kidney. Tyrosine 1062 (Y1062) in RET is an autophosphorylation residue that is responsible for the activation of the PI3K/AKT and RAS/MAPK signaling pathways. Mice lacking signaling via Ret Y1062 show renal hypoplasia and hypoganglionosis of the ENS although the phenotype is milder than the Gdnf- or Ret-deficient mice. Sprouty2 (Spry2) was found to be an antagonist for fibroblast growth factor receptor (FGFR) and acts as an inhibitory regulator of ERK activation. Spry2-deficient mice exhibit hearing loss and enteric nerve hyperplasia. In the present study, we generated Spry2-deficient and Ret Y1062F knock-in (tyrosine 1062 is replaced with phenylalanine) double mutant mice to see if abnormalities of the ENS and kidney, caused by loss of signaling via Ret Y1062, are rescued by a deficiency of Spry2. Double mutant mice showed significant recovery of ureteric bud branching and ENS development in the stomach. These results indicate that Spry2 regulates downstream signaling mediated by GDNF/RET signaling complex in vivo.     

Sprouty2 controls proliferation of palate mesenchymal cells via fibroblast growth factor signaling

Cleft palate is one of the most common craniofacial deformities. The fibroblast growth factor (FGF) plays a central role in reciprocal interactions between adjacent tissues during palatal development, and the FGF signaling pathway has been shown to be inhibited by members of the Sprouty protein family. In this study, we report the incidence of cleft palate, possibly caused by failure of palatal shelf elevation, in Sprouty2-deficient (KO) mice. Sprouty2-deficient palates fused completely in palatal organ culture. However, palate mesenchymal cell proliferation estimated by Ki-67 staining was increased in Sprouty2 KO mice compared with WT mice. Sprouty2-null palates expressed higher levels of FGF target genes, such as Msx1, Etv5, and Ptx1 than WT controls. Furthermore, proliferation and the extracellular signal-regulated kinase (Erk) activation in response to FGF was enhanced in palate mesenchymal cells transfected with Sprouty2 small interfering RNA. These results suggest that Sprouty2 regulates palate mesenchymal cell proliferation via FGF signaling and is involved in palatal shelf elevation.     

同型半胱氨酸在心血管疾病中的免疫调节作用

高同型半胱氨酸血症是动脉粥样硬化的独立危险因子,但是其致病机制尚未完全阐明。本文将从体液免疫、单核巨噬细胞以及T细胞活性等几方面归纳总结同型半胱氨酸在心血管疾病中的免疫调节作用。同型半胱氨酸可以诱导单核细胞和T细胞分泌趋化因子和细胞因子,还可以直接刺激B细胞增殖及IgG分泌。此外,本文还总结了高同型半胱氨酸致炎作用的细胞内机制。同型半胱氨酸可以直接或间接导致氧化应激或者内质网应激,还可以降低一氧化氮的生物活性,影响包括S-腺苷蛋氨酸和S-腺苷同型半胱氨酸的水平,从而导致心血管疾病的发生。     

松弛素在心血管疾病中的研究进展

松弛素是一类新近发现可作用于心血管的肽类激素,参与心血管系统的生理和病理过程。大量实验研究显示松弛素有扩血管、改善心血管重塑及调节炎症反应的心血管保护作用,也有利于改善高凝状态和胰岛素抵抗。松弛素作用广泛,可与松弛素受体或糖皮质激素受体结合,但其受体后的确切机制以及不同生理和病理状态对松弛素的调控还需进一步基础研究阐明。在从实验室到临床应用转化的初期临床试验中可观察到,人重组松弛素治疗急慢性心力衰竭安全性好,可改善症状、血流动力学指标及近期预后,为Ⅲ期临床试验奠定了基础,其临床应用前景令人期待。     

Regulation of cellular levels of Sprouty2 protein by prolyl hydroxylase domain and von Hippel-Lindau proteins

Sprouty (Spry) proteins modulate the actions of receptor tyrosine kinases during development and tumorigenesis. Decreases in cellular levels of Spry, especially Sprouty2 (Spry2), have been implicated in the growth and progression of tumors of the breast, prostate, lung, and liver. During development and tumor growth, cells experience hypoxia. Therefore, we investigated how hypoxia modulates the levels of Spry proteins. Hypoxia elevated the levels of all four expressed Spry isoforms in HeLa cells. Amounts of endogenous Spry2 in LS147T and HEP3B cells were also elevated by hypoxia. Using Spry2 as a prototype, we demonstrate that silencing and expression of prolyl hydroxylase domain proteins (PHD1-3) increase and decrease, respectively, the cellular content of Spry2. Spry2 also preferentially interacted with PHD1-3 and von Hippel-Lindau protein (pVHL) during normoxia but not in hypoxia. Additionally, Spry2 is hydroxylated on Pro residues 18, 144, and 160, and substitution of these residues with Ala enhanced stability of Spry2 and abrogated its interactions with pVHL. Silencing of pVHL increased levels of Spry2 by decreasing its ubiquitylation and degradation and thereby augmented the ability of Spry2 to inhibit FGF-elicited activation of ERK1/2. Thus, prolyl hydroxylase mediated hydroxylation and subsequent pVHL-elicited ubiquitylation of Spry2 target it for degradation and, consequently, provide a novel mechanism of regulating growth factor signaling.