Biological Roles of Galectins

描述（由申请人提供）：半乳糖凝集素是可溶性2-半乳糖苷结合蛋白家族。几种凝集素类型已经被描述（原型、嵌合体和串联重复），每一种都具有独特的分子结构、生化特性和分类分布。胚胎表达模式和对细胞外基质糖蛋白的亲和力表明，半凝集素介导发育过程，而它们在巨噬细胞、嗜酸性粒细胞和嗜碱性粒细胞中的表达，以及它们最近建立的对微生物的识别特性，表明它们在免疫中的功能。斑马鱼具有体外受精发育、胚胎透明、世代时间短、遗传系统强大、基因组资源丰富等特点，是开展体内发育和免疫学研究的有效模型。我们在斑马鱼中凝集素的生化、结构和进化特征方面做出了重大贡献：我们鉴定了原型、嵌合体、串联重复和嵌合串联重复凝集素，并表征了它们的发育表达和组织分布。我们进行了初步的功能分析：低敲集集素原型胚胎表现出肌肉纤维组织破坏、视网膜再生和心脏发育不全，而嵌合体、串联重复和嵌合串联重复集集素在免疫攻击下上调。我们假设：(1)原始凝集素Drgal1-L2和Drgal1-L4在脊索发育中起关键作用，并通过来自脊索或神经管的信号间接参与成肌细胞分化和心脏发育。(2)原凝集素DrGRIFIN在晶状体发育中起重要作用。最后，（III）嵌合和串联重复半乳糖凝集素（Drgal3-L1、Drgal9-L3和Drgal9-L4）通过与潜在病原体相互作用和/或招募吞噬细胞到急性炎症部位直接参与先天免疫反应，和/或间接地通过与表面受体相互作用，诱导其在感染攻击时激活。拟议的研究将产生(a)关于聚集素在斑马鱼模型的发育和免疫中的生物学作用的新信息；(b)关于细胞-细胞、细胞- ecm和细胞-病原体相互作用的分子机制的新信息，这些相互作用调节了硬骨鱼和包括人类在内的高等脊椎动物的胚胎发育和免疫功能；(c)斑马鱼模型中凝集素功能分析的分子工具和资源将与科学界共享。

DESCRIPTION (provided by applicant): Galectins are a family of soluble 2-galactoside-binding proteins. Several galectin types have been described (proto, chimera, and tandem-repeat), each endowed with a unique molecular structure, biochemical properties, and taxonomic distribution. Embryonic expression patterns and affinity for extracellular matrix glycoproteins have led to propose that galectins mediate developmental processes, whereas their expression in macrophages, eosinophils and basophils suggests, and their recently established recognition properties for microbes, suggest their functions in immunity. Because of its external fertilization and development, transparent embryos, short generation time, powerful genetic systems, and extensive genomic resources, the zebrafish (Danio rerio) is a useful model for in vivo studies of development and immunology. We have made substantial contributions to the biochemical, structural, and evolutionary characterization of galectins in zebrafish: we identified proto, chimera, tandem-repeat, and chimeric tandem-repeat galectins, and characterized their developmental expression and tissue distribution. We performed preliminary functional analyses: knockdown embryos for proto type galectins exhibit disrupted muscle fiber organization, retinal regeneration, and an underdeveloped heart, while chimera, tandem-repeat, and chimeric tandem-repeat galectins are up-regulated upon immune challenge. We hypothesize that (I) the proto galectins Drgal1-L2 and Drgal1-L4 play a critical role in notochord development, and are indirectly involved in myoblast differentiation and heart development through signals from the notochord or neural tube. Further, (II) the proto galectin DrGRIFIN plays an important role in eye lens development. Finally, (III) the chimeric and tandem-repeat galectins (Drgal3-L1, Drgal9-L3, and Drgal9-L4) are directly involved in innate immune responses by interacting with potential pathogens and/or by recruiting phagocytic cells to sites of acute inflammation, and/or indirectly, by interacting with receptors on their surface, inducing their activation upon infectious challenge. The proposed studies will yield (a) novel information on the biological role(s) of galectins in development and immunity in the zebrafish model; (b) novel information concerning the molecular mechanisms of cell-cell, cell-ECM, and cell-pathogen interactions that modulate embryonic development and immune functions shared between teleost fish and higher vertebrates, including man, and (c) molecular tools and resources for functional analysis of galectins in the zebrafish model that will be shared with the scientific community. PUBLIC HEALTH RELEVANCE: The goal of the proposed studies is to gain further insight into the biological functions of galectins (2- galactoside-binding proteins) using zebrafish (Danio rerio) as a model organism. Results will yield fundamental knowledge concerning their roles in embryonic development and immune functions in higher vertebrates, including man, and useful molecular tools/resources for the scientific community.