BMP1基因在动物卵泡发生和胚胎发育中的表达规律及调控机制的研究进展

骨形态发生蛋白1(BMP1)是一类属于虾红素家族的金属蛋白酶,它在细胞外基质的形成以及调控TGFβ信号通路的过程中发挥重要作用。BMP1基因在动物卵泡发育过程中具有不同程度表达,并以某种形式参与了动物胚胎的发生和发育过程。开展对BMP1基因的研究将有助于人们从基因角度进一步阐明动物卵泡的形成和胚胎发育的机制,对医学和畜牧业等领域将产生积极的影响。着重从BMP1基因在动物胚胎发育过程中的表达定位、功能及其机制进行综述。     

皮层蛋白介导斑马鱼(Danio rerio)原肠化细胞运动

在胚胎发育过程中, 细胞运动对指导原肠期胚胎细胞的时空定位并决定其发育命运具有核心作用, 然而活体状态下原肠化过程中细胞运动的调控机制目前并不清楚. 微丝结合蛋白皮层蛋白(cortactin)是微丝核化过程的重要调控分子, 它通过激活微丝相关蛋白2/3复合物(Arp2/3 complex)促进微丝在细胞前导缘区域迅速组装, 从而直接作用于细胞运动. 为阐明斑马鱼(Danio rerio)原肠化细胞运动的分子调控机制, 本研究首先检测了皮层蛋白在斑马鱼胚胎发育过程的表达水平. Western blotting分析证明皮层蛋白在斑马鱼原肠期胚胎中大量表达; 整装胚胎抗体染色结果表明在斑马鱼原肠化过程中, 皮层蛋白主要分布于胚胎背侧胚盾区域的细胞中, 在发生活跃运动的上皮层细胞和下皮层细胞中含量较高;在亚细胞水平, 皮层蛋白和Arp2/3复合物共同定位于运动的皮层区域, 并在细胞连接处也有大量分布. 此外, 研究还发现皮层蛋白在发育中的中枢神经系统中表达量较高. 本研究结果首次表明皮层蛋白和Arp2/3复合物介导的微丝聚合参予了斑马鱼原肠化细胞运动, 并在中枢神经系统发育中扮演重要角色.     

斑马鱼胚胎发育过程中FGF3基因的表达

为了解斑马鱼胚胎发育过程中FGF3基因的时空性表达情况,并探讨其对胚胎发育的调控作用,该研究分别提取2,4,8,12,24,36,48,72hpf斑马鱼胚胎的总RNA,经逆转录成cDNA,实时荧光定量PcR检测FGF3基因mRNA表达量;扩增FGF3基因特异片段,构建pGEM-T／FGF3基因片段重组质粒,经克隆及测序验证后,合成地高辛标记的反义RNA探针,以整体原位杂交法检测斑马鱼胚胎FGF3基因的空间性表达。结果显示：FGF3P基因在2hp胚胎就有表达,并持续至胚胎孵化,12hpf胚胎FGF3表达量达到高峰（P〈0．01）;胚胎发育过程中心表达部位以头、尾、咽弓为主。由此得出结论,FGF3主要在胚胎发育早期表达,其表达可能与胚胎脑、眼、耳、咽弓及尾部器官的发育调控有关。     

斑马鱼早期内胚层发育及其分子调控机制

斑马鱼已成为研究脊椎动物胚胎发育的理想模式生物,它具有体外受精、发育周期快、胚体透明等优点,此外其胚胎发育过程中的信号通路与哺乳动物有很高的同源性。该文阐述了斑马鱼早期内胚层发育的过程及其分子调控机制。     

斑马鱼胚胎发育过程中TGF-1基因的表达特征分析

为研究转化生长因子 (Transforming growth factor , TGF)1对斑马鱼胚胎发育的调控作用, 通过NCBI获得TGF-1基因序列, TGF-1 cDNA全长1571 bp, 编码377个氨基酸。系统进化树分析发现, TGF-蛋白按照不同的类型严格聚类, 斑马鱼TGF-1与其他鱼类的TGF-1聚集到一个分支, 在进化中非常保守。对斑马鱼胚胎进行RT-PCR和Real-Time PCR检测显示, TGF-1基因为母源表达基因, 在分节期之前的表达水平比较低, 而从咽囊期开始持续高水平的表达。胚胎整体原位杂交发现, TGF-1基因在斑马鱼24 hpf 胚胎中开始有特异信号出现, TGF-1基因的表达主要分布在腮弓、侧线原基、耳囊、嗅觉基板、心脏和前肾等处, 表明TGF-1基因可能参与斑马鱼胚胎免疫调节、循环系统发育和侧线形成。用低氧处理斑马鱼胚胎, 发现低氧处理24h后斑马鱼胚胎发育延迟。利用Real-Time PCR和胚胎整体原位杂交检测发现, 低氧处理后发育延迟的斑马鱼胚胎中TGF-1 mRNA表达量较常氧组显著降低。以上结果表明, TGF-1基因参与斑马鱼胚胎发育调控, 并且可能与低氧处理后斑马鱼胚胎发育延迟有关。研究结果将为深入研究斑马鱼TGF-1基因的功能奠定基础。       

斑马鱼胚胎背腹轴建立的分子机制

脊椎动物胚胎发育起始于体轴的建立,是胚胎早期发育过程中最重要的事件之一。Wnt、BMP、Nodal和FGF等多个信号通路协同调控细胞分化和细胞运动,促进胚胎胚层的形成和空间上的分离,调控胚胎背腹轴、前后轴和左右轴线的分化,为胚胎进一步发育勾勒出蓝图。本文主要综述斑马鱼胚胎背腹轴建立的分子机制,包括背部组织中心简介;母源Wnt/β-catenin信号调控背部组织中心形成的分子机制;BMP信号调控背腹轴建立的分子机制。     

反义抑制和过表达miR-219引起斑马鱼胚胎发育异常

业已表明,miRNA在转录后水平对基因表达起调控作用,参与诸多重要的生理、病理过程。本研究利用整体原位杂交和Northern杂交技术发现miR-219主要从16体节期开始在中后脑和脊髓表达。在此基础上,采用基因沉默和过表达技术观察到斑马鱼受精卵在显微注射miR-219和反义miR-219后均导致其胚胎发育缺陷。进一步研究表明,miR-219过表达可以诱导胚胎细胞凋亡。我们的初步结果为深入研究miR-219在胚胎发育过程中的调控机制提供了基础。     

DNA甲基化与脊椎动物胚胎发育

DNA甲基化是指DNA甲基转移酶(DNMT)将DNA序列中的5′胞嘧啶转变为5′甲基胞嘧啶的化学修饰, 可以调控基因的时空特异性表达, 从而影响细胞命运决定和分化等生物学过程。近年来研究发现, DNA甲基化在脊椎动物胚胎早期发育中有重要作用, Dnmt基因的缺失会影响胚胎早期发育和多个器官的形成及分化, 如胚胎早期致死、内脏器官和神经系统终末分化缺陷以及血液发生紊乱等。文章总结了DNA甲基化转移酶在小鼠和斑马鱼发育过程中的动态变化, 并系统阐述了DNA甲基化在胚胎早期发育和器官发生中的作用, 重点揭示DNA 甲基化转移酶与组蛋白甲基化转移酶如何协同调控DNA甲基化从而影响基因转录的分子机理。DNA甲基化作为一种关键的表观遗传学因素, 全面系统地理解其在胚胎发育过程中的作用机制对靶向治疗人类相关疾病有一定的理论指导意义。     

Dkk1在器官发育及肿瘤发生中的调控作用

Wnt信号通路在脊椎动物的胚胎发育过程中发挥重要作用. Dkk1(Dickkopf1)是Dkk基因家族的成员之一,通过编码一种分泌型的糖蛋白与Wnt信号蛋白竞争细胞表面受体,来维持Wnt信号通路的稳态,从而调控胚胎器官的正常发育. 同时,在人类成体中,Dkk1基因活性的改变与肿瘤、代谢性骨病和骨关节炎等疾病的发生密切相关. 本文对Dkk1在头部、肢、眼和牙齿等器官的胚胎发育过程中的相关分子调控机制以及Dkk1与肿瘤发生的关系进行综述.     

胚胎发育过程中的DNA甲基化作用

哺乳动物的正常发育取决于表观遗传学调控机制准确无误地运行.其中尤为重要的是发生在原生殖细胞和胚胎中的基因组范围内的DNA甲基化模式重排等表观遗传学修饰.胚胎发育过程中的DNA甲基化作用与基因印记的建立、基因表达的调控以及细胞和胚胎的形态建成都密切相关.DNA甲基化发生机制和功能的阐明将对哺乳动物个体发育与人类疾病研究有重要意义.     

The zebrafish as a model organism for the study of apoptosis

Apoptosis plays important roles in embryogenesis, tissue homeostasis, and immune system regulation. The zebrafish (Danio rerio) is a powerful vertebrate model organism that has been extensively used to study apoptotic cell death during normal development and under conditions of cellular stress. In the past 5 years, a detailed picture has begun to emerge of the molecular underpinnings of the cell-intrinsic and the cell-extrinsic apoptosis signaling pathways in zebrafish. We begin this review with an introduction to the techniques and experimental approaches that are used to study apoptosis in zebrafish. We follow with a general overview of developmental apoptosis during zebrafish embryogenesis. Finally, we present a comprehensive review of the intrinsic and extrinsic apoptosis pathways in zebrafish, focusing on the high degree of conservation with humans and other mammals. Recent publications that draw upon the unique advantages of the zebrafish system to study novel aspects of apoptosis regulation and function are highlighted throughout.     

Apoptosis in zebrafish development

Apoptosis (programmed cell death) is important in normal biological processes and in pathogenesis in vertebrates. This review focuses on some of the prominent features of apoptosis during fish development. Caspases and other apoptosis-regulating genes have been cloned from zebrafish (Danio rerio) and other fish species. Elucidation of in vivo functions of apoptosis is focused on development, morphogenesis and sex differentiation. In an attempt to elucidate cause and effect relationships between caspase and development, transgenic zebrafish overexpressing procaspase-3 were generated. Stress-induced apoptosis in zebrafish embryos can be monitored by whole mount TUNEL staining and caspase assay. Thus, zebrafish is a useful experimental model animal for investigation of apoptosis in vivo.     

Different cell cycle modifications repress apoptosis at different steps independent of developmental signaling in Drosophila

Apoptotic cell death is important for the normal development of a variety of organisms. Apoptosis is also a response to DNA damage and an important barrier to oncogenesis. The apoptotic response to DNA damage is dampened in specific cell types during development. Developmental signaling pathways can repress apoptosis, and reduced cell proliferation also correlates with a lower apoptotic response. However, because developmental signaling regulates both cell proliferation and apoptosis, the relative contribution of cell division to the apoptotic response has been hard to discern in vivo. Here we use Drosophila oogenesis as an in vivo model system to determine the extent to which cell proliferation influences the apoptotic response to DNA damage. We find that different types of cell cycle modifications are sufficient to repress the apoptotic response to ionizing radiation independent of developmental signaling. The step(s) at which the apoptosis pathway was repressed depended on the type of cell cycle modification—either upstream or downstream of expression of the p53-regulated proapoptotic genes. Our findings have important implications for understanding the coordination of cell proliferation with the apoptotic response in development and disease, including cancer and the tissue-specific responses to radiation therapy.     

Zebrafish Models of p53 Functions

Zebrafish models have significantly contributed to our understanding of vertebrate development and, more recently, human disease. The growing number of genetic tools available in zebrafish research has resulted in the identification of many genes involved in developmental and disease processes. In particular, studies in the zebrafish have clarified roles of the p53 tumor suppressor in the formation of specific tumor types, as well as roles of p53 family members during embryonic development. The zebrafish has also been instrumental in identifying novel mechanisms of p53 regulation and highlighting the importance of these mechanisms in vivo. This article will summarize how zebrafish models have been used to reveal numerous, important aspects of p53 function.The zebrafish, Danio rerio, is a small model organism that has long been used to study vertebrate development. Zebrafish embryos are optically clear and develop externally to the mother, facilitating the study of early developmental processes. In addition, zebrafish have increasingly been used in modeling human diseases, including a number of cancers. The availability of forward and reverse genetic tools in the zebrafish has resulted in the identification and characterization of many genes involved in development and disease. One gene that has been extensively studied is the p53 tumor suppressor gene, which is structurally and functionally conserved in the zebrafish. This article will discuss how studies in the zebrafish have increased our understanding of how p53 contributes to the formation of specific tumor types, resulted in the identification of novel mechanisms of p53 regulation, and showed how p53 and p53 family members are involved in embryonic development.     

Identification and expression analysis of mical family genes in zebrafish

Mical(molecule interacting with CasL)represent a conserved family of cytosolic multidomain proteins that has been shown to be associated with a variety of cellular processes,including axon guidance,cell movement,cell-cell junction formation,vesicle trafficking and cancer cell metastasis.However,the expression and function of these genes during embryonic development have not been comprehensively characterized,especially in vertebrate species,although some limited in vivo studies have been carried out in neural and musculature systems of Drosophila and in neural systems of vertebrates.So far,no mica/family homologs have been reported in zebrafish,an ideal vertebrate model for the study of developmental processes.Here we report eight homologs of m/ca/family genes in zebrafish and their expression profiles during embryonic development.Consistent with the findings in Drosophila and mammals,most zebrafish mical family genes display expression in neural and musculature systems.In addition,five mica/homologs are detected in heart,and one,micall2a,in blood vessels.Our data established an important basis for further functional studies of mica/family genes in zebrafish,and suggest a possible role for mica/genes in cardiovascular development.     

Identification of differentially expressed genes in the zebrafish hypothalamic–pituitary axis

The vertebrate hypothalamic–pituitary axis (HP) is the main link between the central nervous system and endocrine system. Although several signal pathways and regulatory genes have been implicated in adenohypophysis ontogenesis, little is known about hypothalamic–neurohypophysial development or when the HP matures and becomes functional. To identify markers of the HP, we constructed subtractive cDNA libraries between adult zebrafish hypothalamus and pituitary. We identified previously published genes, ESTs and novel zebrafish genes, some of which were predicted by genomic database analysis. We also analyzed expression patterns of these genes and found that several are expressed in the embryonic and larval hypothalamus, neurohypophysis, and/or adenohypophysis. Expression at these stages makes these genes useful markers to study HP maturation and function.