1,25-Dihydroxyvitamin D and vitamin D Receptor Function in the Zebrafish Skeleton

描述（申请人提供）：本申请的目的是阐明1 α，25-二羟维生素D3的功能（1a，25（OH）2D 3）及其受体1a，25（OH）2D 3受体（VDR）在组织中的作用，在该组织中，其在跨上皮钙（Ca）和磷酸盐（Pi）转运中不起作用（“非经典”效应）使用斑马鱼Danio rerio作为模式生物。我们最近发现VDR在成年和发育中的斑马鱼（Danio rerio）的组织中表达。VDR在受精后早期存在于发育中的软骨、骨、脑、眼和耳中。假设1a，25（OH）2D 3和VDR通过调节骨形态发生蛋白（BMP）和BMP受体的表达来改变斑马鱼软骨的发育和成熟。在目标1中，我们将研究1a，25（OH）2D 3对斑马鱼骨骼发育的影响。我们将给予1a，25（OH）2D 3发育斑马鱼胚胎，以确定是否1a，25（OH）2D 3管理改变BMP和BMP受体的表达，BMP信号和软骨发育和骨骼形态。目的二，我们将用反义寡核苷酸的方法来检测“敲低”VDR在发育中的斑马鱼胚胎中的表达。将评估VDR敲低对斑马鱼胚胎BMP和BMP受体表达、BMP信号传导以及软骨发育和骨骼形态的影响。重要性：1a，25（OH）2D 3及其受体在哺乳动物和人类中对钙转运的影响已被广泛研究。独立的钙运输的影响，但是，没有被详细研究。通过研究1a，25（OH）2D 3和VDR通过BMP途径对斑马鱼胚胎骨骼发育的影响，我们将能够描述1a，25（OH）2D 3和VDR在软骨中的直接和非钙依赖性作用。我们还将建立斑马鱼作为一种新的模式生物，以研究1a，25（OH）2D 3的影响。 公共卫生相关性：维生素D对维持骨骼健康很重要。在这个项目中，我们将研究维生素及其受体如何在骨骼和软骨中发挥作用，通过研究它们在模式生物中的作用，即发育中的斑马鱼。通过研究活性维生素D及其受体对影响骨骼发育的生长因子的影响，我们将深入了解维生素在骨骼中的功能。这一信息将有助于预防随着年龄增长而发生的骨丢失和治疗骨质疏松症。

DESCRIPTION (provided by applicant): The objective of this application is to elucidate the functions of 1a, 25-dihydroxyvitamin D3 (1a,25(OH)2D3) and its receptor, the 1a,25(OH)2D3 receptor (VDR), in tissues in which it does not have a role in trans-epithelial calcium (Ca) and phosphate (Pi) transport ("non-classical" effects) using the zebrafish, Danio rerio as a model organism. We have recently shown that the VDR is expressed in tissues of the adult and developing zebrafish, Danio rerio. The VDR is present in the developing cartilage, bone, brain, eye, and ear of the zebrafish early after fertilization. The hypothesis is that 1a,25(OH)2D3 and the VDR alter cartilage development and maturation in zebrafish by regulating the expression of bone morphogenetic proteins (BMPs) and BMP receptors. In aim 1 we will examine the effects of 1a,25(OH)2D3 on skeletal development in Danio rerio. We will administer 1a,25(OH)2D3 to developing zebrafish embryos to determine whether 1a,25(OH)2D3 administration alters BMP and BMP receptor expression, BMP signaling and cartilage development and skeletal morphology. In aim 2, we will determine the effects of "knocking down" VDR expression in the developing zebrafish embryo with anti-sense morpholino oligonucleotides methods. The effect of VDR knock- down on zebrafish embryo BMP and BMP receptor expression, BMP signaling and cartilage development and skeletal morphology will be assessed. Significance: The effects of 1a,25(OH)2D3 and its receptor have been extensively examined in mammals and humans with respect to their effects on Ca transport. Effects that are independent of Ca transport have not, however, been examined in detail. By examining the effects of 1a,25(OH)2D3 and the VDR on skeletal development in zebrafish embryos through BMP pathways, we will be able to delineate the direct and Ca-independent effects of 1a,25(OH)2D3 and the VDR in cartilage. We will also establish the zebrafish as a new model organism in which to examine the effects of 1a,25(OH)2D3. PUBLIC HEALTH RELEVANCE: Vitamin D is important for the maintenance of bone health. In this project we will examine how the vitamin and its receptor function in bone and cartilage by studying their effects in a model organism, the developing zebrafish. By examining the effects of active vitamin D and its receptor on growth factors that influence skeletal development we will gain insights into how the vitamin functions in bone. This information will be of use in preventing bone loss that occurs with aging and in treating osteoporosis.