低氧诱导因子1α与血管钙化关系的研究进展

低氧诱导因子1α(HIF-1α)是细胞在低氧环境下产生的高度特异性核转录因子,在骨形成及骨再生修复中发挥重要作用。血管钙化是一个与骨形成类似、主动调节的复杂生物学过程,是心血管死亡率增加的主要危险因素,但其发生机制尚未完全阐明。新近的研究表明HIF-1α可通过调节血管平滑肌细胞(VSMC)成骨样分化、糖代谢途径、炎症、Notch信号通路等机制参与血管钙化。本文就HIF-1α与血管钙化的关系作一综述。     

Notch信号通路在血管生成中的作用研究进展

血管生成存在于机体生长发育的各个阶段.Notch信号是细胞间相互作用的重要信使,大量的研究发现Notch信号在细胞分化及血管生成方面发挥重要的调控作用.Notch信号参与生理性血管生成可能与以下机制有关:调节尖细胞与茎细胞的分化,调节动静脉分化、内皮祖细胞、血管壁细胞、血管内皮生长因子、一氧化氮以及与其他信号通路相互作用.此外,Notch信号在肿瘤以及损伤后组织修复等病理性血管生成中亦发挥重要作用.明确Notch信号的作用机制对疾病的治疗有重要意义.     

血管新生与骨形成耦联、骨骼疾病发生及治疗中H型血管的作用机制研究进展

在哺乳动物骨骼系统的生长发育及修复重建过程中,血管新生与骨形成之间高度耦联.H型血管(CD31hiEmcnhi)是一种特殊的骨组织毛细血管亚型,其在血管新生与骨形成的耦联过程中发挥重要作用,其中涉及多种细胞因子及信号通路,包括缺氧诱导因子-1信号通路、Notch信号通路、血小板源性生长因子-BB、SLIT3和γ-干扰素...     

Dll4/Notch1在消化道血管发育不良出血患者中的表达以及沙利度胺的干预机制

背景:Dll4/Notch1信号通路是肿瘤血管形成、血管发育等领域的研究热点,然而其在消化道血管发育不良(AGD)中的作用机制尚未阐明。沙利度胺常用于治疗AGD所致的消化道出血。目的:探讨Dll4/Notch1信号通路在消化道AGD形成中的作用以及沙利度胺的干预机制。方法:收集不明原因反复消化道出血、经胶囊内镜和(或)小肠镜检查确诊为AGD的患者25例和因AGD致消化道出血接受沙利度胺(100 mg/d,疗程4个月)治疗者10例,1 8名健康志愿者作为正常对照。以ELISA法检测血清Dll4、Notch1浓度。结果:AGD组血清Dll4、Notch1浓度显著高于正常对照组(P0.01),且Dll4与Notch1间呈正相关(r=0.900,P0.01)。沙利度胺治疗前后,AGD患者的血清Dll4、Notch1浓度无明显改变;根据性别和疗效进行分层分析,差异亦无统计学意义。结论:Dll4/Notch1信号通路可能参与了消化道AGD的形成,沙利度胺对该信号通路的调节作用不明显。     

血管钙化中成骨样细胞来源及其转化的研究进展

血管钙化是一种多因素介导、主动、可逆的调节过程,涉及多种细胞因子及信号通路。血管钙化的本质是多种血管细胞成分向成骨样细胞表型转化,最终导致管壁增厚、管腔狭窄和血管硬化重塑。目前研究表明,血管平滑肌细胞、钙化血管细胞、周细胞以及血管壁内的间充质干细胞都具有向成骨样细胞表型转化的潜能。成骨样细胞的来源及其转化和促血管钙化机制已成为这一领域的重大研究课题。     

Notch信号转导通路在缺血性心脏病中的作用

Notch是一种结构及功能在进化上高度保守的跨膜受体蛋白家族,广泛表达于果蝇、脊椎动物、哺乳动物等多个物种.目前在哺乳动物中发现4种受体Notch 1～4,以及Jagged 1、Jagged 2、Delta-like 1(Dll 1)、Delta-like 3(Dll 3)和Delta-like 4(Dll4)五种配体.Notch信号通路受细胞间多种网络信号的调控,由两个邻近细胞的Notch受体与配体结合而激活,介导下游信号元件、靶基因及各种辅助蛋白相互作用,从而调节细胞的增殖、分化、迁移及凋亡[1].在胚胎发育及出生早期,Notch受体和配体均有不同程度的表达,Notch信号参与了心肌细胞的分化、房室管和瓣膜的发育、心室小梁的形成以及心室流出道的重塑[2].研究发现[3],心脏缺血改变激活了许多胚胎基因程序.在梗死初期,Notch信号活化,其下游基因表达量升高,这为心肌梗死的研究提供了新的方向.本文就Notch信号通路及其介导的细胞间通讯对缺血性心脏病的影响做以综述.     

DLL4/NOTCH通路与肿瘤血管生成关系研究进展

Notch信号通路是进化保守的影响胚胎和出生后发育分化进程和细胞命运的细胞间信号通路[1].许多研究证明其对血管的发生发展有重要的调控功能,其在脉管系统不同发育阶段均有表达.研究发现Notch信号通路配体Dll4在人类许多肿瘤血管中呈现高表达.因此对Dll4深入研究可为肿瘤新生血管分子靶向治疗提供新的策略和靶标.现就Notch 信号通路组成,传导,调控与肿瘤血管生成关系做一综述.     

Notch信号通路与血管生成

Notch通路为细胞发育的重要信号传导通路。研究显示在血管内皮、平滑肌细胞均存在不同程度的Notch家族基因表达，其成员相互作用，在细胞增殖、分化等诸多方面起重要调控作用。本文对Notch信号通路的组成及其与血管生成的关系作一综述，以进一步了解血管生成的机制。     

DII4／Notch1在消化道血管发育不良出血患者中的表达以及沙利度胺的干预机制

DII4／Notch1信号通路是肿瘤血管形成、血管发育等领域的研究热点．然而其在消化道血管发育不良（AGD）中的作用机制尚未阐明。沙利度胺常用于治疗AGD所致的消化道出血。目的：探讨DII4／Notch1信号通路在消化道AGD形成中的作用以及沙利度胺的干预机制。方法：收集不明原因反复消化道出血、经胶囊内镜和（或）小肠镜检查确诊为AGD的患者25例和因AGD致消化道出血接受沙利度胺（100mg／d．疗程4个月）治疗者10例,18名健康志愿者作为正常对照。以ELISA法检测血清DII4、Notchl浓度。结果：AGD组血清DII4、Notch1浓度显著高于正常对照组（P〈0．01）,且DII4与Notch1间呈正相关（r=0．900,P〈0．01）。沙利度胺治疗前后,AGD患者的血清DII4、Notch1浓度无明显改变;根据性别和疗效进行分层分析,差异亦无统计学意义。结论：DII4／Notch1信号通路可能参与了消化道AGD的形成．沙利度胺对该信号通路的调节作用不明显．     

Jagged1/Notch在消化道肿瘤及其血管形成中的作用

Jagged1是哺乳动物细胞膜上Notch受体的主要配体之一,其介导的Notch信号通路的活化和抑制参与多种消化道肿瘤的发生、发展.最新研究发现,Jagged1在肿瘤血管形成中起着重要作用,为肿瘤治疗提供了潜在的靶点.     

Notch Signaling in Cardiovascular Disease and Calcification

Recent increase in human lifespan has shifted the spectrum of aging-related disorders to an unprecedented upsurge in cardiovascular diseases, especially calcific aortic valve stenosis, which has an 80% risk of progression to heart failure and death. A current therapeutic option for calcified valves is surgical replacement, which provides only temporary relief. Recent progress in cardiovascular research has suggested that arterial and valve calcification are the result of an active process of osteogenic differentiation, induced by a pro-atherogenic inflammatory response. At molecular level, the calcification process is regulated by a network of signaling pathways, including Notch, Wnt and TGFbeta/BMP pathways, which control the master regulator of osteogenesis Cbfa1/Runx2. Genetic and in vitro studies have implicated Notch signaling in the regulation of macrophage activation and cardiovascular calcification. Individuals with inactivating Notch1 mutations have a high rate of cardiovascular disorders, including valve stenosis and calcification. This article reviews recent progress in the mechanism of cardiovascular calcification and discusses potential molecular mechanisms involved, focusing on Notch receptors. We propose a calcification model where extreme increases in vascular wall cell density due to inflammation-induced cell proliferation can trigger an osteogenic differentiation program mediated by Notch receptors. Key Words: Calcification, cardiac valve, inflammation, Notch signaling, mesenchymal stem cells, atherosclerosis.     

Notch1 represses osteogenic pathways in aortic valve cells

Calcific aortic stenosis is the third leading cause of adult heart disease and the most common form of acquired valvular disease in developed countries. However, the molecular pathways leading to calcification are poorly understood. We reported two families in which heterozygous mutations in NOTCH1 caused bicuspid aortic valve and severe aortic valve calcification. NOTCH1 is part of a highly conserved signaling pathway involved in cell fate decisions, cell differentiation, and cardiac valve formation. In this study, we examined the mechanism by which NOTCH1 represses aortic valve calcification. Heterozygous Notch1-null (Notch1^+/-) mice had greater than fivefold more aortic valve calcification than age- and sex-matched wildtype littermates. Inhibition of Notch signaling in cultured sheep aortic valve interstitial cells (AVICs) also increased calcification more than fivefold and resulted in gene expression typical of osteoblasts. We found that Notch1 normally represses the gene encoding bone morphogenic protein 2 (Bmp2) in murine aortic valves in vivo and in aortic valve cells in vitro. siRNA-mediated knockdown of Bmp2 blocked the calcification induced by Notch inhibition in AVICs. These findings suggest that Notch1 signaling in aortic valve cells represses osteoblast-like calcification pathways mediated by Bmp2.     

Notch1 represses osteogenic pathways in aortic valve cells

Calcific aortic stenosis is the third leading cause of adult heart disease and the most common form of acquired valvular disease in developed countries. However, the molecular pathways leading to calcification are poorly understood. We reported two families in which heterozygous mutations in NOTCH1 caused bicuspid aortic valve and severe aortic valve calcification. NOTCH1 is part of a highly conserved signaling pathway involved in cell fate decisions, cell differentiation, and cardiac valve formation. In this study, we examined the mechanism by which NOTCH1 represses aortic valve calcification. Heterozygous Notch1-null (Notch1^+/-) mice had greater than fivefold more aortic valve calcification than age- and sex-matched wildtype littermates. Inhibition of Notch signaling in cultured sheep aortic valve interstitial cells (AVICs) also increased calcification more than fivefold and resulted in gene expression typical of osteoblasts. We found that Notch1 normally represses the gene encoding bone morphogenic protein 2 (Bmp2) in murine aortic valves in vivo and in aortic valve cells in vitro. siRNA-mediated knockdown of Bmp2 blocked the calcification induced by Notch inhibition in AVICs. These findings suggest that Notch1 signaling in aortic valve cells represses osteoblast-like calcification pathways mediated by Bmp2.     

Notch signaling in vascular morphogenesis

PURPOSE OF REVIEW: This review highlights recent developments in the role of the Notch signaling pathway during vascular morphogenesis, angiogenesis, and vessel homeostasis. RECENT FINDINGS: Studies conducted over the past 4 years have significantly advanced the understanding of the effect of Notch signaling on vascular development. Major breakthroughs have elucidated the role of Notch in arterial versus venular specification and have placed this pathway downstream of vascular endothelial growth factor. SUMMARY: An emerging hallmark of the Notch signaling pathway is its nearly ubiquitous participation in cell fate decisions that affect several tissues, including epithelial, neuronal, hematopoietic, and muscle. The vascular compartment has been the latest addition to the list of tissues known to be regulated by Notch. Unraveling the contribution of Notch signaling to blood vessel formation has resulted principally from gain-of-function and loss-of-function experiments in mouse and zebrafish. During the past 4 years, these mechanistic studies have revealed that Notch is required for the successful completion of several steps during vascular morphogenesis and differentiation. In addition, the findings that Notch mutations are linked to some late-onset hereditary vascular pathologic conditions suggest the added contribution of this signaling pathway to vascular homeostasis.     

Notch signaling in blood vessels: who is talking to whom about what?

It has become increasingly clear that the Notch signaling pathway plays a critical role in the development and homeostasis of the cardiovascular system. This notion has emerged from loss- and gain-of-function analysis and from the realization that several hereditary cardiovascular disorders originate from gene mutations that have a direct impact on Notch signaling. Current research efforts are focused on determining the specific cellular and molecular effects of Notch signaling. The rationale for this has stemmed from the clinical importance and therapeutic potential of modulating vascular formation during various disease states. A more complete appreciation of Notch signaling, as it relates to vascular morphogenesis, requires an in-depth knowledge of expression patterns of the various signaling components and a comprehensive understanding of downstream targets. The goal of this review is to summarize current knowledge regarding Notch signaling during vascular development and within the adult vascular wall. Our focus is on the genetic analysis and cellular experiments that have been performed with Notch ligands, receptors, and downstream targets. We also highlight questions and controversies regarding the contribution of this pathway to vascular development.     

HGF/c-Met signalling promotes Notch3 activation and human vascular smooth muscle cell osteogenic differentiation in vitro

Objectives

Vascular calcification is a major clinical problem and elucidating the underlying mechanism is important to improve the prognosis of patients with cardiovascular disease. We aimed to elucidate the role and mechanism of action of Hepatocyte Growth Factor (HGF)/c-Met signalling in vascular calcification and establish whether blocking this pathway could prevent mineralisation of vascular smooth muscle cells (VSMCs) in vitro.

Methods and results

We demonstrate increased HGF secretion and c-Met up-regulation and phosphorylation during VSMC osteogenic differentiation. Adenoviral-mediated over-expression of HGF (AdHGF) in VSMCs accelerated mineralisation, shown by alizarin red staining, and significantly increased ⁴⁵Calcium incorporation (1.96 ± 0.54-fold [P < 0.05]) and alkaline phosphatase (ALP) activity (3.01 ± 0.8-fold [P < 0.05]) compared to controls. AdHGF also significantly elevated mRNA expression of bone-related proteins, Runx2, osteocalcin, BMP2 and osterix in VSMCs. AdHGF-accelerated mineralisation correlated with increased Akt phosphorylation, nuclear translocation of Notch3 intracellular domain (N3IC) and up-regulation of the Notch3 target protein, HES1. In contrast, adenoviral-mediated over-expression of the HGF antagonist, NK4, markedly attenuated VSMC mineralisation, and reduced c-Met phosphorylation, Akt activation and HES1 protein expression compared to AdHGF-treated cells. Furthermore, the Notch inhibitor, DAPT, attenuated N3IC nuclear translocation and AdHGF-induced mineralisation.

Conclusion

We demonstrate HGF induces VSMC osteogenic differentiation via c-Met/Akt/Notch3 signalling, highlighting these pathways as potential targets for intervention of vascular calcification.     

Inducible inactivation of Notch1 causes nodular regenerative hyperplasia in mice

The discovery that the human Jagged1 gene (JAG1) is the Alagille syndrome disease gene indicated that Notch signaling has an important role in bile duct homeostasis. The functional study of this signaling pathway has been difficult because mice with targeted mutations in Jagged1, Notch1, or Notch2 have an embryonic lethal phenotype. We have previously generated mice with inducible Notch1 disruption using an interferon-inducible Cre-recombinase transgene in combination with the loxP flanked Notch1 gene. We used this conditional Notch1 knockout mouse model to investigate the role of Notch1 signaling in liver cell proliferation and differentiation. Deletion of Notch1 did not result in bile duct paucity, but, surprisingly, resulted in a continuous proliferation of hepatocytes. In conclusion, within weeks after Notch1 inactivation, the mice developed nodular regenerative hyperplasia without vascular changes in the liver.     

Notch signaling in cardiac development

The Notch signaling pathway has been demonstrated to play a critical role during mammalian cardiac development based on recent findings from gene-targeted mice. In addition, mutations in the Notch signaling pathway have been associated with human congenital heart defects such as Alagille syndrome, bicuspid aortic valve disease, calcification of the heart valves, and ventricular septal defects. Recently, it was demonstrated that Notch activation in the endocardium regulates ventricular myocardial development and that the Notch downstream target genes Hey1 and Hey2 are required for the establishment of the atrioventricular canal myocardial boundary. The Notch pathway has previously been implicated in regulating endothelial-to-mesenchymal transition during development of the heart valves, and recent reports further dissect the role of individual Notch downstream target genes during this process. In addition, a role for the Notch pathway during cardiac neural crest cell development has been identified, which provides a potential mechanism for the findings seen in Alagille syndrome. This review focuses on recently reported findings that elucidate mechanisms regulated by the Notch pathway during ventricular, atrioventricular canal, and outflow tract development.