整合素及其相关miRNA在肝纤维化中作用的研究进展

整合素家族是一类拥有细胞黏附、信号通路传导枢纽和机械力信号传感功能的跨膜二聚体蛋白.整合素广泛分布于肝星状细胞和其他多种类型的肝内细胞中,其中,含有αⅤ亚基的整合素αⅤβ3和αⅤβ5,以及含β1亚基的整合素α4β1、α5β1、α8β1、α9β1和α11β1能促进肝纤维化.miR-125b通过靶向下调整合素α8β1中α8...     

整合素激活FAK介导的信号传导途径研究进展

整合素是一类重要的细胞表面受体家族,主要介导细胞与细胞外基质的粘附。整合素在胞内外信号传导中起重要作用。FAK是整合素信号传导途径中的关键酪氨酸激酶,整合素、FAK及细胞骨架蛋白共聚于焦点粘附物上,使FAK自身磷酸化而激活,FAK激活后,其磷酸化的Tyr397与Src家族激酶结合,通过形成FAK/Src复合物而引起Paxillin和Cas磷酸化,后二者通过接头蛋白Crk和Grb2激活Ras途径的下游激酶MAPK,通过MAPK改变细胞行为。本文综述了FAK在整合素信号传导中的生物学作用,即介导细胞在ECM上的粘附和迁移,调节细胞增殖和存活等。     

RGD三肽的临床应用进展

整合素是一个异源二聚体组成的膜受体蛋白家族,能特异性识别精氨酸-甘氨酸-天冬氨酸(RGD)序列。整合素在肿瘤细胞和新生血管高表达。利用它们3者之间特殊关系,将RGD作为载体,与放射性示踪剂、抗肿瘤药物以及其他物质结合,使其具有亲肿瘤显像、靶向抗肿瘤治疗、抗感染、抗抑郁和骨骼及神经修复等作用。     

整合素激活FAK介导的信号传导途径研究进展

整合素量类重要的细胞表面受体家族，主要介导细胞与细胞上基质的粘附。整合素在胞内外信号传导中起重要作用。ＦＡＫ是整合素信号传导途径的关键酪氨酸激酶，整合素、ＦＡＫ及细胞骨架蛋白共聚于焦点粘附物上，使ＦＡＫ自身磷酸化而激活，ＦＡＫ激活后，其磷酸化的Ｔｙｒ３９７与Ｓｒｃ家族激酶结合，通过形成ＦＡＫ／Ｓｒｃ复合物而引起Ｐａｘｉｌｉｎ和Ｃａｓ磷酸化，后二者通过接头蛋白Ｃｒｋ和Ｇｒｂ２激活Ｒａｓ途径的下游激酶     

腺病毒受体及其介导基因转导的分子机制研究

腺病毒载体 (AdV)是一种重要的基因转导系统。腺病毒依两种不同的受体侵入靶细胞 :Ad纤维蛋白与CAR作用 ,介导病毒黏附细胞 ;Ad五邻体基底蛋白与整合素αvβ3 及αvβ5结合 ,促进病毒内化。靶细胞的CAR和整合素αvβ3 及αvβ5表达水平与AdV介导的基因转导效率直接相关 ,受体低表达限制AdV的转导率。动力蛋白调节Ad进入靶细胞 ,整合素聚集与肌动蛋白相关。Ad侵入靶细胞需要的信号通路包括GTP酶Pho家族成员P13K和肌动蛋白单纤维聚合。     

整合素在烧伤创面愈合中的作用研究进展

整合素家族为跨膜糖蛋白受体家族,其作用是介导细胞与细胞外基质之间的相互作用,参与细胞相互之间的黏附功能。整合素通过双向信号转导,影响细胞的分化、增生与凋亡;整合素信号系统还可以通过调控细胞周期,产生细胞凋亡,影响瘢痕的形成。本文就整合素家族参与烧伤创面成纤维细胞分化、促进创面收缩,增强细胞外基质的收缩能力以及整合素连接激酶与创面愈合之间的关系作一综述。     

压力诱导血管平滑肌细胞整合素β3、桩蛋白和纽蛋白的变化

目的 研究压力对大鼠颈总动脉血管平滑肌细胞整合素β3、桩蛋白和纽蛋白的分布与表达的影响，探讨它们在血管平滑肌细胞的机械应力信号转导中的作用。方法 不同压力(160mmHg和80mmHg)灌流大鼠颈总动脉30min，免疫组织化学和免疫电镜观察整合素β3、桩蛋白和纽蛋白在血管平滑肌细胞上的表达和分布变化。结果 高压和常压灌流对大鼠颈总动脉平滑肌细胞的整合素β3、桩蛋白和纽蛋白的表达无明显影响，但高压使整合素β3、桩蛋白和纽蛋白在平滑肌细胞膜上的分布发生改变，向离管腔面的平滑肌细胞膜聚集。结论 高压诱导了整合素β3、桩蛋白和纽蛋白向离管腔面的平滑肌细胞膜聚集。提示整合素β3、桩蛋白和纽蛋白可能在血管平滑肌细胞的机械应力信号转导中发挥作用。     

整合素调节Fak/SFKs与生长因子受体信号传导的研究进展

在胚胎发育和组织修复过程中,整合素介导的信号传导起着重要作用.整合素与细胞外配体结合,引发的细胞内信号可以产生两种主要作用,即肌动蛋白细胞骨架重构和调节细胞行为,如细胞存活、分化和生长.整合素也可以通过与细胞内衔接蛋白、胞质酪氨酸激酶、生长因子/细胞因子受体直接结合或功能联合,进入信号传导过程.了解有关整合素信号的最新实验和理论进展,尤其着重于整合素调节Fak/Src家族激酶（SFKs）活化和整合素与可溶性生长因子/细胞因子受体相互作用很有必要.     

整合素:一类介导细胞信号转导的膜分子

整合素形成了一个大的蛋白家族 ,主要介导细胞 -基质之间的相互作用。整合素除了熟知的参与粘附功能外 ,还可通过独特的信号转导途径 ,影响细胞的增殖、凋亡、分化以及运动。而细胞生理过程的失调常常导致恶性肿瘤的发生。     

整合素及其信号传递在肝纤维化中的作用

整合素 (Integrin)是一种分布在细胞表面的跨膜糖蛋白 ,属粘附分子家族 ,为细胞外基质 (ECM)主要的受体 ,通过粘附蛋白配体介导细胞 ECM或细胞 细胞间粘附及细胞内外信号传递。在肝脏中可被诱导表达。整合素介导的肝脏星状细胞 (HSC) ECM间相互作用对HSC激活过程及HSC功能起重要作用。整合素参与肝纤维化的病理过程 ,已成为干预肝纤维化中的靶位点。     

RhoA activation by CNFy restores cell–cell adhesion in kindlin‐2‐deficient keratinocytes

Kindlins are a family of integrin adapter and cell–matrix adhesion proteins causally linked to human genetic disorders. Kindlin‐2 is a ubiquitously expressed protein with manifold functions and interactions. The contribution of kindlin‐2 to integrin‐based cell–matrix adhesions has been extensively explored, while other integrin‐independent roles emerge. Because of the early involvement of kindlin‐2 in development, no viable animal models with its constitutional knockout are available to study its physiological functions in adult skin. Here, we uncovered a critical physiological role of kindlin‐2 in the epidermis by using a skin‐equivalent model with shRNA‐mediated knock‐down of kindlin‐2 in keratinocytes. Kindlin‐2‐deficient keratinocytes built stratified epidermal layers, but displayed impaired dermal–epidermal and intra‐epidermal adhesion and barrier function. Co‐immunoprecipitation studies demonstrated that kindlin‐2 interacts with both integrin‐ and cadherin‐based adhesions. In kindlin‐2‐deficient keratinocytes, reduced cell–cell adhesion was associated with abnormal cytoplasmic distribution of adherens junctions and desmosomal proteins, which was dependent on RhoA activation. Direct activation of RhoA with recombinant bacterial cytotoxic necrotizing factor y (CNFy) reverted the abnormal phenotype and barrier function of kindlin‐2‐deficient keratinocytes and skin equivalents. These findings have physiological and pathological significance, since kindlin‐2 expression modulates the phenotype in Kindler syndrome, a skin fragility disorder caused by kindlin‐1 deficiency. Our results suggest that pharmacological regulation of RhoGTPase activity may represent a therapeutic option for skin fragility. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd     

Kindlin-1 and -2 have overlapping functions in epithelial cells implications for phenotype modification

Kindlins are a novel family of intracellular adaptor proteins in integrin-containing focal adhesions. Kindlin-1 and -2 are expressed in the skin, but whether and how they cooperate in adult epithelial cells have remained elusive. We uncovered the overlapping roles of kindlin-1 and -2 in maintaining epithelial integrity and show that the phenotype of kindlin-1-deficient cells can be modulated by regulating kindlin-2 gene expression and vice versa. The experimental evidence is provided by use of human keratinocyte cell lines that express both kindlins, just kindlin-1 or kindlin-2, or none of them. Double deficiency of kindlin-1 and -2 had significant negative effects on focal adhesion formation and actin cytoskeleton organization, cell adhesion, survival, directional migration, and activation of β(1) integrin, whereas deficiency of one kindlin only showed variable perturbation of these functions. Cell motility and formation of cell-cell contacts were particularly affected by lack of kindlin-2. These results predict that kindlin-1 and -2 can functionally compensate for each other, at least in part. The high physiologic and pathologic significance of the compensation was emphasized by the discovery of environmental regulation of kindlin-2 expression. UV-B irradiation induced loss of kindlin-2 in keratinocytes. This first example of environmental regulation of kindlin expression has implications for phenotype modulation in Kindler syndrome, a skin disorder caused by kindlin-1 deficiency.     

Increased cytoplasmic level of migfilin is associated with higher grades of human leiomyosarcoma

AIMS: Leiomyosarcomas (LMS) are malignant neoplasms composed of cells that exhibit distinct smooth muscle differentiation. The molecular and cytogenetic features of LMS are complex and no consistent aberrations have been reported to date. Mitogen inducible gene-2 (Mig-2), kindlin and migfilin are recently identified cell-matrix adhesion proteins. The aim was to determine the expression and distribution of these proteins in human smooth muscle tumours of somatic soft tissue. METHODS AND RESULTS: Immunohistochemistry was performed on a human LMS tissue microarray and on sections of human leiomyomas (LM) and normal smooth muscle. Migfilin was barely detectable in normal smooth muscle cells, whereas increased levels of migfilin were observed in the majority of LM and LMS. Furthermore, the cytoplasmic level of migfilin was strongly associated with higher tumour grades. Additionally, the cytoplasmic levels of migfilin and Mig-2 were correlated with each other, suggesting an association between the two in the cytoplasm. Kindlin was expressed in normal smooth muscle, LM and LMS, and its level did not correlate with tumour grade. CONCLUSIONS: Our results suggest a role for cytoplasmic migfilin in the progression of LMS and identify cytoplasmic migfilin as a potentially important biological marker for human LMS progression.     

Kindlin-2 controls bidirectional signaling of integrins

Control of integrin activation is required for cell adhesion and ligand-induced signaling. Here we report that loss of the focal adhesion protein Kindlin-2 in mice results in peri-implantation lethality caused by severe detachment of the endoderm and epiblast from the basement membrane. We found that Kindlin-2-deficient cells were unable to activate their integrins and that Kindlin-2 is required for talin-induced integrin activation. Furthermore, we demonstrate that Kindlin-2 is required for integrin outside-in signaling to enable firm adhesion and spreading. Our findings provide evidence that Kindlin-2 is a novel and essential element of bidirectional integrin signaling.     

粘着斑相关蛋白Kindlin-1在血管内皮细胞的表达及功能研究

目的 探索Kindin-1蛋白在健康骨关节组织及关节炎模型骨关节组织中的表达模式及相关功能.方法 分离健康小鼠、经内侧半月板失稳定术(DMM)诱导关节炎小鼠以及经胶原诱导关节炎(CIA)小鼠的骨关节组织,通过抗体免疫荧光标记分析Kindlin-1蛋白在骨关节组织内的表达情况.筛选针对Kindlin-1的siRNA序列并...     

Developmental expression of the fermitin/kindlin gene family in Xenopus laevis embryos

Fermitin genes are highly conserved and encode cytocortex proteins that mediate integrin signalling. Fermitin 1 (Kindlin1) is implicated in Kindler syndrome, a human skin blistering disorder. We report the isolation of the three Fermitin orthologs from Xenopus laevis embryos and describe their developmental expression patterns. Fermitin 1 is expressed in the skin, otic and olfactory placodes, pharyngeal arches, pronephric duct, and heart. Fermitin 2 is restricted to the somites and neural crest. Fermitin 3 is expressed in the notochord, central nervous system, cement gland, ventral blood islands, vitelline veins, and myeloid cells. Our findings are consistent with the view that Fermitin 1 is generally expressed in the skin, Fermitin 2 in muscle, and Fermitin 3 in hematopoietic lineages. Moreover, we describe novel sites of Fermitin gene expression that extend our knowledge of this family. Our data provide a basis for further functional analysis of the Fermitin family in Xenopus laevis. Developmental Dynamics 240:1958–1963, 2011. © 2011 Wiley‐Liss, Inc.     

Chronic colitis due to an epithelial barrier defect: the role of kindlin-1 isoforms

Kindlin-1 is an epithelium-specific phosphoprotein and focal adhesion adaptor component. Mutations in the corresponding gene (KIND1) cause Kindler syndrome (KS), which is manifested by skin blistering, poikiloderma, photosensitivity and carcinogenesis. Some patients also exhibit gastrointestinal symptoms, but it has remained unclear whether these represent a feature of Kindler syndrome or a coincidence. We examined kindlin-1 in human gastrointestinal epithelia and showed that it is involved in the aetiopathology of Kindler syndrome-associated colitis. Kindlin-1 expression was assessed by indirect immunofluorescence, western blot and RT-PCR. Kindlin-1 is expressed in oral mucosa, colon and rectum. Both the full-length 74 kDa kindlin-1 protein and a 43 kDa isoform were detected in CaCo2 cells, the latter resulting from alternative splicing. In the first months of life, patients (homozygous for null mutations) had severe intestinal involvement with haemorrhagic diarrhoea and showed morphological features of severe ulcerative colitis. Later in childhood, histopathology demonstrated focal detachment of the epithelium in all segments of the colon, chronic inflammation and mucosal atrophy. These findings define an intestinal phenotype for Kindler syndrome as a consequence of a primary epithelial barrier defect. The different clinical intestinal manifestations in Kindler syndrome patients may be explained by partial functional compensation of kindlin-1 deficiency by the intestinal isoform or by the presence of truncated mutant kindlin-1.     

Induction of phenotype modifying cytokines by FERMT1 mutations

Kindler syndrome (KS) is a progressive skin disorder caused by FERMT1 mutations. Early in life, KS manifests as a mechanobullous disease reflecting diminished cell adhesion, but the mechanisms of its later phenotypic features, progressive poikiloderma, and mucocutaneous fibrosis, remain elusive. The FERMT1 gene product and KS protein, kindlin-1, is an epithelial-specific phosphoprotein involved in integrin beta-1 activation, without an obvious link to dermal connective tissue. Here we show how lack of intracellular kindlin-1 in epidermal keratinocytes leads to profound changes in another skin compartment, the dermis. Kindlin-1-deficient keratinocytes respond to cell stress by upregulating the expression of cytokines such as IL-20, IL-24, TGF-β2, IL1F5, PDGFB, and CTGF. These launch-via paracrine communication-an inflammatory response in the dermis, accompanied by the presence of TGF-β, IL-6, and CTGF, activation of fibroblasts and their differentiation to myofibroblasts, which secrete and deposit increased amounts of extracellular matrix proteins. These data are concordant with a model wherein repeated cycles of epidermal cell stress, cytokine secretion, dermal inflammation, and profibrotic processes underlie mucocutaneous fibrosis in KS.     

Integrin signalling and function in immune cells

Integrins not only mediate cell-cell and cell-extracellular matrix adhesion, but also affect the multitude of signal transduction cascades in control of cell survival, proliferation, differentiation and organ development. Mutations in integrins or the major effectors of integrin signalling pathways cause defective organ development, immunodeficiency, cancer or autoimmune disease. Understanding of the signalling events that drive integrin activation and signalling is therefore crucial to uncover the molecular mechanisms of these diseases. This review discusses the key signalling complexes regulating integrin activation and function in both 'inside-out' and 'outside-in' pathways in T lymphocytes, including kinases, SLP-76, VAV1, ADAP, SKAP-55, RapL, RIAM, Rap1, Talin and Kindlin.     

Partial loss of epithelial phenotype in kindlin-1-deficient keratinocytes

Kindlin-1 is an adaptor protein that is expressed by most epithelial cells and has been implicated in integrin bidirectional signaling. Mutations in the gene encoding kindlin-1 are associated with Kindler syndrome, a recessively inherited disorder that is characterized by fragile skin. Functionally, a loss of kindlin-1 impairs the adhesion of basal keratinocytes to the extracellular matrix both in vivo and in vitro. In this study, we show that the phenotype of mutant keratinocytes deficient in kindlin-1 is characterized by the modification of the cortical actin network and increased plasticity of the plasma membrane. At the molecular level, expression of several proteins associated with an epithelial phenotype, such as α6β4 integrin, collagen XVII, E-cadherin, and desmoglein-3, is strongly reduced, whereas, surprisingly, laminin 332 is synthesized in larger amounts than in control keratinocytes. In contrast, mesenchymal markers such as vimentin and fibronectin are increased in keratinocytes lacking kindlin-1. The switch in cell plasticity and protein expression was confirmed by siRNA-mediated down-regulation of kindlin-1 in HaCaT epithelial cells. Furthermore, there was up-regulation of matrix metalloproteinases and pro-inflammatory cytokines in kindlin-1-deficient keratinocytes. These results provide new insights into the pathogenic mechanisms that take place in Kindler syndrome. Moreover, the constellation of molecular defects associated with the loss of kindlin-1 may explain the higher incidence of skin cancer observed in patients affected with this disorder.