A zebrafish model to investigate beta-cell functional maturation and heterogeneity

β细胞是胰腺中一小群高度特化的内分泌细胞，它们产生胰岛素，这是一种生存所需的激素，对能量稳态的适当调节至关重要。虽然人们越来越认识到β细胞存在相当大的异质性，但我们对这种异质性的基础和意义，以及指导β细胞成熟的因素的理解仍然很少。******斑马鱼提供了一个很好的模型来阐明β细胞发育和成熟的分子机制。从遗传和生理的角度来看，斑马鱼与人类惊人地相似。事实上，所有控制哺乳动物新陈代谢的器官和细胞都存在于这些鱼身上。它们也很容易接受基因工程，以产生新的鱼类品种，以便对基因、蛋白质和细胞的功能进行复杂的探测。使用斑马鱼作为模式生物的一个特别有用的方面是它们发育得非常快。此外，胚胎非常透明，这一特性使它们成为研究脊椎动物发育的理想选择。因此，通过斑马鱼，我们可以看到β细胞发育的整个过程，并实时监测β细胞的功能成熟。******我们的总体目标是描述胰岛素分泌细胞成熟的分子途径，并从发育和生理的角度研究β细胞的异质性。这将通过以下三个特定目标来实现：******目标1：描述斑马鱼β细胞功能成熟。我们将使用一种新的斑马鱼转基因系，它允许在体内可视化β-细胞刺激-分泌偶联。******目的2：确定胰腺发育过程中产生的β细胞的不同谱系是否导致了成年斑马鱼胰腺中β细胞的异质性。我们的主要假设之一是β细胞由不同的亚群组成，这些亚群专门用于分泌胰岛素以响应营养或在组织损伤发生时增殖。为了研究这方面的问题，我们将使用一种新的斑马鱼转基因系，在那里我们可以标记不同的β细胞群，并在鱼的整个生命周期中跟踪它们，以评估它们特定的遗传特征和功能。******目的3：描述营养感知对β细胞功能成熟的贡献。斑马鱼β细胞如何感知营养物质和协调对刺激的反应尚未被研究。我们将使用遗传工具结合实时成像方法来探测适当的营养传感所必需的关键成分。******总的来说，这种前所未有的β细胞表征深度将提供对β细胞生物学和控制β细胞发育、成熟和功能的分子机制的更深层次的理解。

β-cells are a small population of highly specialized endocrine cells in the pancreas that produce insulin, a hormone required for survival and key to the proper regulation of energy homeostasis. While there is an increasing appreciation that there exists considerable β-cell heterogeneity, our understanding of the basis and significance of this heterogeneity, along with the factors guiding β-cell maturation, remain poorly understood. ******Zebrafish provide an excellent model to elucidate the molecular mechanisms underlying the development and maturation of β-cells. From a genetic and physiological perspective, zebrafish are surprisingly similar to humans. Indeed, all organs and cells involved in controlling mammalian metabolism are present in these fish. They are also readily amenable to genetic engineering to generate novel lines of fish to permit sophisticated probing of the function of genes, proteins and cells. A particularly useful aspect of using zebrafish as a model organism is the fact that they develop very rapidly. Moreover, the embryos are remarkably transparent, a characteristic that makes them ideal to study vertebrate development. Therefore, with zebrafish we can visualize the entire process of β-cell development, as well as monitor β-cell functional maturation, in real time in a living organism. ******Our overall goal is to delineate the molecular pathways underlying the maturation of insulin-secreting cells, and to investigate β-cell heterogeneity from a developmental and physiological perspective. This will be achieved by the following three specific objectives:******Objective 1: To delineate β-cell functional maturation in zebrafish. We will use a novel zebrafish transgenic line which allows visualization of β-cell stimulus-secretion coupling in vivo. ******Objective 2: To determine whether the different lineages of β-cells arising during pancreas development contribute to β-cell heterogeneity in the adult zebrafish pancreas. One of our main hypotheses is that β-cells are composed of different sub-populations which are specialized either to secrete insulin in response to nutrients or proliferate when tissue damage occurs. To investigate this aspect, we will use a novel zebrafish transgenic line where we can label different β-cell populations and follow them through the entire life of the fish to assess their specific genetic profile and function.******Objective 3: To delineate the contribution of nutrient sensing to β-cell functional maturation. How zebrafish β-cells sense nutrients and coordinate responses to stimuli has not been investigated. We will use genetic tools combined with live imaging approaches to probe the key components essential to proper nutrient sensing.******Collectively, this unprecedented depth of β-cell characterization will provide a deeper understanding of β-cell biology and the molecular mechanisms that control β-cell development, maturation and function.