ZO-1/ZONAB信号通路与细胞的增殖分化

闭合小带蛋白-1(zonula occludens-1,ZO-1)相关性核酸结合蛋白(ZO-1-associated nucleic acid binding protein,ZONAB)是一种Y-box转录抑制因子。ZONAB结合于ZO-1的SH3(Src homology 3)结构域,并与多种调控细胞周期的基因、蛋白质、酶、转录因子等相互作用,共同构成ZO-1/ZONAB信号通路。研究证实,ZO-1/ZONAB信号通路参与多种细胞的增殖与分化、基因表达及器官发生等过程的调控,主要涉及肾小管、视网膜、角膜、肺泡上皮、神经胶质细胞及肿瘤等组织细胞。ZO-1/ZONAB信号通路调控细胞增殖分化的具体机制尚未完全阐明,但已在细胞再生、干细胞医学及肿瘤学等领域显示出潜在而巨大的研究价值。该文主要针对ZO-1/ZONAB信号通路与细胞增殖分化的最新研究进行综述。     

缺氧诱导因子经典通路的拓展与干细胞调控

缺氧诱导因子是在缺氧条件下被激活参与机体低氧适应性反应的一类核因子,对于低氧条件下维持机体生命活动起着不可或缺的作用,且与肿瘤的发生发展以及干细胞调控关系密切,本文综述缺氧诱导因子经典氧感通路信号轴和非经典信号通路以及其对干细胞调控的作用,讨论了非经典通路中沉默信息调节因子家族尤其是去乙酰化酶sirtuin-3(SIRT3)对HIFα的负性调控作用,以及M2型丙酮酸激酶(PKM2)对HIFα的激活作用。探讨了HIF1α对多种干细胞生物学的调控,发现HIF1α可抑制胚胎干细胞-外胚层干细胞(ESC-Epi SC)过渡期线粒体呼吸,从而驱使其向糖酵解代谢的转变,继而维持ESC的多能性;且HIF1α可介导间充质干细胞的定向分化,如向成骨细胞,软骨细胞,神经细胞,脂肪细胞,肌细胞等细胞的定向分化;并可促进神经干细胞增殖与迁移以及参与肿瘤干细胞的干性维持。目的阐明缺氧诱导因子经典与非经典信号通路轴及其对干细胞生物学的调控,为临床组织损伤修复组织工程乃至肿瘤的诊疗预防提供新的靶点。     

Hippo-YAP/TAZ信号通路在干细胞增殖、分化及器官再生中的研究进展

Hippo-YAP/TAZ信号通路最初在果蝇中被发现,是器官发育和肿瘤生长过程中重要的调节者。通过调控细胞增殖、凋亡和分化等过程影响器官再生。近年来,对于Hippo-YAP/ TAZ信号通路在调节干细胞 (SC)增殖、自我更新及分化过程中的相关机制有了较大进展。本综述拟通过介绍Hippo-YAP/TAZ信号通路在SC增殖及多向分化过程中的作用、调控机制及器官再生方面的研究进展,为应用SC治疗疾病提供相关理论基础。     

调控纤连蛋白表达的信号通路

纤连蛋白(fibronectin,Fn)作为细胞外基质(extracellular matrix,ECM)中重要的黏附分子之一,通过与细胞膜上的整合素受体结合,在调节细胞黏附、迁移、增殖等过程中发挥着重要作用。Fn的异常表达与伤口愈合、肿瘤转移、组织器官纤维化等密切相关。Fn的表达受到复杂的细胞信号通路网络调控,其中包括MAPK、TGF-β1/Smad、PKC、JAK/STAT及JNK/NF-κB/NADPH/ROS等。该文对调控Fn表达的信号通路及分子作一综述,旨在全面了解Fn参与机体对环境变化的适应机制及与Fn表达异常相关疾病的分子机理。     

Wnt信号通路调控干细胞成软骨分化

Wnt信号通路调控细胞增殖、再生、分化等多种细胞生物学过程。近年来研究表明,Wnt信号通路参与干细胞成软骨分化的起始、间充质的凝集、分化和肥大等一系列阶段。阐明其具体机制对软骨损伤修复及软骨功能的维持十分重要。该文就经典和非经典Wnt信号通路调控干细胞成软骨分化的研究进展进行综述。     

肝细胞生长因子及受体传递的调节与内吞作用

肝细胞生长因子(HGF)是一种具有多重功能的细胞调控因子。HGF与其受体Met酪氨酸激酶(c-Met)的结合可激发多种生物学反应,从而调节细胞的增殖、分化、形态发生和侵袭运动等。有多种因素参与了HGF/c-Met信号传导的调控,从而防止信号的过度放大,其中Cbl1、Rab、泛素化激酶和HGF/c-Met的内吞等发挥了重要的作用。因此,对HGF/c-Met内吞过程的研究,了解内吞对于HGF/c-Met的信号传导及其调控的影响,探讨HGF/c-Met信号传导通路的调控机理和相互作用模式,可进一步阐明HGF/c-Met信号传导的调控机制,从而验证肝细胞中内吞作用直接调节HGF/c-Met信号通路的作用机制。     

PI3K/Akt信号通路调控胚胎干细胞的自我更新和多向分化潜能的研究进展

磷脂酰肌醇3-激酶(phosphatidylinositol 3-kinase,PI3K)及其下游靶点蛋白激酶B(protein kinase B,Akt/PKB)可被细胞内外一系列信号所激活,在增殖、分化、凋亡等多种细胞生物学功能的调节过程中,起着非常重要的关键信号分子的作用。近年来研究显示,I型PI3K和其下游分子Akt/PKB所组成的信号通路与胚胎干细胞(embryonic stem cells,ES细胞)自我更新和多向分化潜能的维持密切相关。深入研究ES细胞自我更新和多向分化潜能的维持及其分子机制,是其应用于细胞替代治疗、再生医学和组织工程的基础。本文着重对PI3K/Akt信号通路调控ES细胞自我更新和多向分化潜能的研究进展进行综述。     

间充质干细胞抑制肿瘤细胞增殖机制的研究进展

间充质干细胞(mesenchymal stem cells,MSCs)是能够从多种组织来源的基质细胞分离出来的一种具有分化潜能的干细胞,能够分化为脂肪、成骨和软骨细胞等多种组织细胞。研究表明,MSCs对肿瘤细胞具有抑制作用,其作用机制体现在两方面:一方面是通过直接分泌蛋白和微泡来调节肿瘤细胞信号通路和生长所需的因子的表达;另一方面是作为肿瘤靶向药物运输载体,向肿瘤组织输送多种能够抑制肿瘤生长、促进肿瘤细胞凋亡的基因或药物。该文针对MSCs对肿瘤细胞的直接和间接抑制机制进行了综述。     

机械力及力学信号转导影响干细胞命运的研究进展

干细胞作为一种未分化的祖细胞,目前已被广泛应用于开展组织损伤修复、再生以及干细胞特异谱系分化的研究.大量研究表明,干细胞所处的微环境对调控干细胞的生长和分化具有重要作用,多种溶液介质、细胞外基质和信号通路等参与了干细胞命运的调控.尽管已有大量研究证明,溶液介质(如激素和生长因子)在干细胞的生长和分化中发挥重要作用,但近年来越来越多的研究表明,机械力及力学信号转导同样在干细胞自我更新、分化、衰老和凋亡等细胞生理过程中起到重要的作用.本文将对机械应力响应的细胞基础、生物力学及力学信号调控干细胞自我更新和分化,以及生物力学调控干细胞命运可能的作用机制几个方面加以综述.     

肿瘤坏死因子样弱凋亡诱导因子对人肝星状细胞生物学行为的影响

目的:观察肿瘤坏死因子样弱凋亡诱导因子(TWEAK)对人肝星状细胞(HSCs)株LX-2增殖、细胞周期、细胞凋亡、迁移及粘附能力的影响。方法:用不同浓度TWEAK培养LX-2细胞24或48 h,采用CCK-8法检测TWEAK对LX-2细胞增殖的影响,流式细胞术检测TWEAK对LX-2细胞周期和凋亡的影响,Transwell小室检测TWEAK对LX-2细胞迁移能力的影响,Matrigel基质胶检测TWEAK对LX-2细胞的粘附能力的影响。结果:与对照组相比,40 ng/m L和100 ng/m L TWEAK都能使LX-2细胞的迁移能力增强(P0.05),且100 ng/m L较40 ng/m L作用更强(P0.01);100 ng/m L TWEAK能够明显抑制LX-2细胞的粘附能力(P0.0001);40 ng/m L、100 ng/m L TWEAK对LX-2细胞的增殖、周期及凋亡无明显影响(P0.05)。结论:TWEAK能够增强LX-2细胞迁移能力,抑制其粘附能力。     

TWEAK, via its receptor Fn14, is a novel regulator of mesenchymal progenitor cells and skeletal muscle regeneration

Inflammation participates in tissue repair through multiple mechanisms including directly regulating the cell fate of resident progenitor cells critical for successful regeneration. Upon surveying target cell types of the TNF ligand TWEAK, we observed that TWEAK binds to all progenitor cells of the mesenchymal lineage and induces NF-kappaB activation and the expression of pro-survival, pro-proliferative and homing receptor genes in the mesenchymal stem cells, suggesting that this pro-inflammatory cytokine may play an important role in controlling progenitor cell biology. We explored this potential using both the established C2C12 cell line and primary mouse muscle myoblasts, and demonstrated that TWEAK promoted their proliferation and inhibited their terminal differentiation. By generating mice deficient in the TWEAK receptor Fn14, we further showed that Fn14-deficient primary myoblasts displayed significantly reduced proliferative capacity and altered myotube formation. Following cardiotoxin injection, a known trigger for satellite cell-driven skeletal muscle regeneration, Fn14-deficient mice exhibited reduced inflammatory response and delayed muscle fiber regeneration compared with wild-type mice. These results indicate that the TWEAK/Fn14 pathway is a novel regulator of skeletal muscle precursor cells and illustrate an important mechanism by which inflammatory cytokines influence tissue regeneration and repair. Coupled with our recent demonstration that TWEAK potentiates liver progenitor cell proliferation, the expression of Fn14 on all mesenchymal lineage progenitor cells supports a broad involvement of this pathway in other tissue injury and disease settings.     

Considering TWEAK as a target for therapy in renal and vascular injury

TWEAK is a cytokine of the TNF superfamily that activates the Fn14 receptor. TWEAK may regulate cell proliferation, cell death, cell differentiation, angiogenesis and inflammation. The expression of TWEAK and Fn14 is increased during vascular and renal injury. Inflammatory cytokines increase Fn14 receptor expression in tubular and vascular smooth muscle cells. Moreover, TWEAK induces tubular cell apoptosis under proinflammatory conditions. TWEAK itself contributes to renal and vascular inflammation by promoting chemokine and inflammatory cytokine secretion. Confirmation of its role in acute kidney injury and atherosclerotic lesions formation came from functional studies in experimental animal models. The available evidence suggests that TWEAK might be a target for therapeutic intervention in renal and vascular injury and its role in different forms of tissue damage should be further explored.     

A Further TWEAK to Multiple Sclerosis Pathophysiology

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a member of the TNF super family that controls many cellular activities including proliferation, migration, differentiation, apoptosis, and inflammation by binding to fibroblast growth factor-inducible 14 (Fn14), a highly inducible cell surface receptor. Recent studies have indicated that TWEAK–Fn14 axis signaling may contribute to chronic autoimmune diseases. TWEAK expression via microglia in cortical lesions, presence of TWEAK⁺ macrophages in inflamed leptomeninges, and absence of TWEAK/Fn14 expression in healthy brain implicates importance of this pathway in pathogenesis of multiple sclerosis lesions. TWEAK–Fn14 axis blockade has also shown promise in various multiple sclerosis animal models. Stimulation of the TWEAK/Fn14 pathway can result in activation of both canonical and noncanonical NF-κB signaling and could also stimulate mitogen-activated protein kinase (MAPK) signaling pathways. Here, we have reviewed evidence of the possible role of TWEAK–Fn14 axis in pathophysiology of multiple sclerosis and experimental autoimmune encephalomyelitis (EAE) via neuroinflammation, tissue remodeling, blood–brain barrier (BBB) disruption, neurodegeneration, and astrogliosis.     

Multiple members of the TNF superfamily contribute to IFN-gamma-mediated inhibition of erythropoiesis

IFN-gamma inhibits the growth and differentiation of erythroid precursor cells and mediates hemopoietic suppression through mechanisms that are not completely understood. We found that treatment of human erythroid precursor cells with IFN-gamma up-regulates the expression of multiple members of the TNF family, including TRAIL and the recently characterized protein TWEAK. TWEAK and its receptor fibroblast growth factor-inducible 14 (Fn14) were expressed by purified erythroblasts at all the stages of maturation. Exposure to recombinant TWEAK or agonist anti-Fn14 Abs was able to inhibit erythroid cell growth and differentiation through caspase activation. Because other members of the TNF family such as TRAIL and CD95 ligand (CD95L) are known to interfere with erythroblast growth and differentiation, we investigated the role of different TNF/TNFR family proteins as potential effectors of IFN-gamma in the immature hemopoietic compartment. Treatment of erythroid precursor cells with agents that blocked either TRAIL, CD95L, or TWEAK activity was partially able to revert the effect of IFN-gamma on erythroid proliferation and differentiation. However, the simultaneous inhibition of TRAIL, TWEAK, and CD95L resulted in a complete abrogation of IFN-gamma inhibitory effects, indicating the requirement of different receptor-mediated signals in IFN-gamma-mediated hemopoietic suppression. These results establish a new role for TWEAK and its receptor in normal and IFN-gamma-mediated regulation of hematopoiesis and show that the effects of IFN-gamma on immature erythroid cells depend on multiple interactions between TNF family members and their receptors.     

Pro-inflammatory effect of TWEAK/Fn14 interaction on human umbilical vein endothelial cells

TWEAK, a member of the TNF family, induces cell death in some tumor cell lines, but also induces proliferation of endothelial cells and angiogenesis. Recently, fibroblast growth factor-inducible 14 (Fn14) has been identified to be a TWEAK receptor, which may be responsible for the proliferation of endothelial cells and angiogenesis. In this study, we investigated the pro-inflammatory effect of TWEAK on human umbilical vein endothelial cells (HUVEC). We demonstrated that TWEAK could not only induce the proliferation and migration but also upregulate the cell surface expression of adhesion molecules such as ICAM-1 and E-selectin, and induce the secretion of chemokines such as IL-8 and MCP-1 in HUVEC. Moreover, by using an anti-Fn14 mAb that blocks the TWEAK/Fn14 interaction, we demonstrated that Fn14 was constitutively expressed on HUVEC and totally mediated the biological effects of TWEAK on HUVEC. These results indicated that TWEAK could induce pro-inflammatory reactions via Fn14 on HUVEC.     

TWEAK/Fn14 interaction regulates RANTES production, BMP-2-induced differentiation, and RANKL expression in mouse osteoblastic MC3T3-E1 cells

Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of the TNF family, is a multifunctional cytokine that regulates cell growth, migration, and survival principally through a TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14). However, its physiological roles in bone are largely unknown. We herein report various effects of TWEAK on mouse osteoblastic MC3T3-E1 cells. MC3T3-E1 cells expressed Fn14 and produced RANTES (regulated upon activation, healthy T cell expressed and secreted) upon TWEAK stimulation through PI3K-Akt, but not nuclear factor-kappaB (NF-kappaB), pathway. In addition, TWEAK inhibited bone morphogenetic protein (BMP)-2-induced expression of osteoblast differentiation markers such as alkaline phosphatase through mitogen-activated protein kinase (MAPK) Erk pathway. Furthermore, TWEAK upregulated RANKL (receptor activation of NF-kappaB ligand) expression through MAPK Erk pathway in MC3T3-E1 cells. All these effects of TWEAK on MC3T3-E1 cells were abolished by mouse Fn14-Fc chimera. We also found significant TWEAK mRNA or protein expression in osteoblast- and osteoclast-lineage cell lines or the mouse bone tissue, respectively. Finally, we showed that human osteoblasts expressed Fn14 and induced RANTES and RANKL upon TWEAK stimulation. Collectively, TWEAK/Fn14 interaction regulates RANTES production, BMP-2-induced differentiation, and RANKL expression in MC3T3-E1 cells. TWEAK may thus be a novel cytokine that regulates several aspects of osteoblast function.     

TWEAKing tissue remodeling by a multifunctional cytokine: role of TWEAK/Fn14 pathway in health and disease

First described as a weak apoptosis inducer, the TNF superfamily ligand TWEAK has since emerged as a cytokine that regulates multiple cellular responses, including proinflammatory activity, angiogenesis and cell proliferation, suggesting roles in inflammation and cancer. More recently TWEAK's ability to regulate progenitor cell fate was elucidated. Experiments using genetic overexpression and pathway inhibition or deficiency in mice indicate that TWEAK coordinates inflammatory and progenitor cell responses in settings of acute injury through its highly inducible receptor, FGF-inducible molecule 14 (Fn14), establishing the pathway's physiological role in facilitating acute tissue repair. In contrast, in chronic inflammatory disease models characterized by persistent TWEAK/Fn14 activation, TWEAK functions as a novel pathogenic mediator by amplifying inflammation, promoting tissue damage and potentially impeding endogenous repair mechanisms. Herein we aim not only to review the multifaceted functions of this emerging pathway, but also propose a conceptual framework for TWEAK/Fn14 pathway function in health and disease, supported by studies employing TWEAK and Fn14 deficient mice and anti-TWEAK blocking mAbs in acute injury and inflammatory disease settings. In addition to a perspective of the biology, we discuss potential therapeutic strategies targeting this pathway for the treatment of tissue injury, chronic inflammatory diseases and cancer.     

Functional Expression of TWEAK and the Receptor Fn14 in Human Malignant Ovarian Tumors: Possible Implication for Ovarian Tumor Intervention

The aim of this current study was to investigate the expression of the tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its receptor fibroblast growth factor-inducible 14 (Fn14) in human malignant ovarian tumors, and test TWEAK’s potential role on tumor progression in cell models in-vitro. Using immunohistochemistry (IHC), we found that TWEAK and its receptor Fn14 were expressed in human malignant ovarian tumors, but not in normal ovarian tissues or in borderline/benign epithelial ovarian tumors. High levels of TWEAK expression was detected in the majority of malignant tumors (36 out of 41, 87.80%). Similarly, 35 out of 41 (85.37%) malignant ovarian tumors were Fn14 positive. In these malignant ovarian tumors, however, TWEAK/Fn14 expression was not corrected with patients’ clinical subtype/stages or pathological features. In vitro, we demonstrated that TWEAK only inhibited ovarian cancer HO-8910PM cell proliferation in combination with tumor necrosis factor-α (TNF-α), whereas either TWEAK or TNF-α alone didn’t affect HO-8910PM cell growth. TWEAK promoted TNF-α production in cultured THP-1 macrophages. Meanwhile, conditioned media from TWEAK-activated macrophages inhibited cultured HO-8910PM cell proliferation and invasion. Further, TWEAK increased monocyte chemoattractant protein-1 (MCP-1) production in cultured HO-8910PM cells to possibly recruit macrophages. Our results suggest that TWEAK/Fn14, by activating macrophages, could be ovarian tumor suppressors. The unique expression of TWEAK/Fn14 in malignant tumors indicates that it might be detected as a malignant ovarian tumor marker.     

TWEAK/Fn14 interaction stimulates human bronchial epithelial cells to produce IL-8 and GM-CSF

TNF-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor (TNF) family, is a multifunctional cytokine that regulates cellular proliferation, angiogenesis, inflammation, and apoptosis. In this study, we investigated the effect of TWEAK on human bronchial epithelial cells. A human bronchial epithelial cell line, BEAS2B, expressed a TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14), and produced IL-8 and GM-CSF upon TWEAK stimulation in a dose-dependent manner, which was abrogated by anti-Fn14 blocking antibody. TWEAK induced phosphorylation of IkappaBalpha and BAY11-7082, a selective inhibitor of IkappaBalpha phosphorylation, inhibited the TWEAK-induced IL-8 and GM-CSF production by BEAS2B cells. Moreover, primary cultured human bronchial epithelial cells also expressed Fn14 and produced IL-8 and GM-CSF upon TWEAK stimulation. Collectively, TWEAK stimulated human bronchial epithelial cells to produce IL-8 and GM-CSF through Fn14. Because IL-8 and GM-CSF are associated with inflammatory conditions, these results suggest that TWEAK/Fn14 interaction may play some roles in airway inflammatory responses.     

TWEAK-Independent Fn14 Self-Association and NF-κB Activation Is Mediated by the C-Terminal Region of the Fn14 Cytoplasmic Domain

The tumor necrosis factor (TNF) superfamily member TNF-like weak inducer of apoptosis (TWEAK) is a pro-inflammatory and pro-angiogenic cytokine implicated in physiological tissue regeneration and wound repair. TWEAK binds to a 102-amino acid type I transmembrane cell surface receptor named fibroblast growth factor-inducible 14 (Fn14). TWEAK:Fn14 engagement activates several intracellular signaling cascades, including the NF-κB pathway, and sustained Fn14 signaling has been implicated in the pathogenesis of chronic inflammatory diseases and cancer. Although several groups are developing TWEAK- or Fn14-targeted agents for therapeutic use, much more basic science research is required before we fully understand the TWEAK/Fn14 signaling axis. For example, we and others have proposed that TWEAK-independent Fn14 signaling may occur in cells when Fn14 levels are highly elevated, but this idea has never been tested directly. In this report, we first demonstrate TWEAK-independent Fn14 signaling by showing that an Fn14 deletion mutant that is unable to bind TWEAK can activate the NF-κB pathway in transfected cells. We then show that ectopically-expressed, cell surface-localized Fn14 can self-associate into Fn14 dimers, and we show that Fn14 self-association is mediated by an 18-aa region within the Fn14 cytoplasmic domain. Endogenously-expressed Fn14 as well as ectopically-overexpressed Fn14 could also be detected in dimeric form when cell lysates were subjected to SDS-PAGE under non-reducing conditions. Additional experiments revealed that Fn14 dimerization occurs during cell lysis via formation of an intermolecular disulfide bond at cysteine residue 122. These findings provide insight into the Fn14 signaling mechanism and may aid current studies to develop therapeutic agents targeting this small cell surface receptor.