Ligand independent signaling by VDR in Keratinocytes

角质形成细胞中 VDR 的配体独立信号传导

基本信息

批准号：
7880089
负责人：
PAUL N MACDONALD
金额：
$ 20.98万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-07-01 至 2012-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7880089
关键词：
Ablation Alopecia Binding Biological Models Biology CYP27B1 gene Calcitriol Calcium Cell Proliferation Cell model Cells Cyst DNA Damage Data Dermal Dietary Calcium EGF gene Endocrine system Endocrinology Ensure Environmental Carcinogens Enzymes Fibroblasts Gene Expression Gene Expression Profile Gene Targeting Genes Genetic Genetic Models Goals Growth Hair follicle structure Heterodimerization Homeostasis Hormonal Human In Vitro Intestinal Absorption Kidney Knock-out Knockout Mice Laboratories Ligands Malignant Neoplasms Mediating Mixed Function Oxygenases Modeling Molecular Molecular Profiling Mus Nuclear Receptors Organ Osteoblasts Osteoclasts Pathology Pathway interactions Pharmacologic Substance Phenotype Physiological Process Property Proteins Psoriasis Publishing RXR Regulation Research Research Proposals Resistance Role Signal Transduction Skin Skin Neoplasms Skin Tissue Source Stem cells System Transactivation Tumor Suppressor Proteins UV induced Vitamin D Vitamin D3 Receptor Work analog base cell type clinically relevant cohort in vivo keratinocyte keratinocyte differentiation knowledge base monocyte mouse model mutant novel public health relevance receptor skin disorder tool tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): The classic physiological role for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is to maintain appropriate calcium homeostasis by ensuring adequate intestinal absorption of dietary calcium. However, 1,25(OH)2D3 and its cognate receptor, the vitamin D receptor (VDR), also have critical roles in the skin and in keratinocyte biology. In fact, VDR is a clinically relevant target for the use of 1,25(OH)2D3 analogs in the treatment of psoriasis, a hyperproliferative disorder of the skin. The focus of this research proposal is on the vitamin D endocrine system in epidermal keratinocytes and, specifically, on the use of murine models of the vitamin D endocrine system as tools to explore the in vivo role and identify potential mechanisms of vitamin D action in the skin. In particular, the VDR knockout mouse (VDRKO) is highly susceptible to chemically-induced skin tumorigenesis. In contrast, our preliminary data show that genetic ablation of CYP27B1, the gene encoding the renal 1alpha- hydroxylase (1aOHase), the enzyme that generates the bioactive 1,25(OH)2D3 hormonal ligand, is completely resistant to chemically-induced skin tumorigenesis. These data as well as published data on hair follicle cycling in these mouse models and in humans, point to a novel ligand-independent role for VDR in keratinocytes. The molecular details involved in the tumor suppressor role for unliganded VDR in the skin are completely unknown. Our preliminary in vivo and in vitro data support a model in which the VDR-RXR heterodimer is activated by EGF in the absence of its 1,25(OH)2D3 ligand selectively in keratinocytes. EGF treatment drives heterodimerization of VDR and RXR in the absence of the 1,25(OH)2D3 ligand and this in turn promotes heterodimer binding to select keratinocyte genes involved in diverse processes such as hair follicle cycling and in protecting skin tissue from tumorigenesis initiated by DNA-damaging agents. Importantly, this mechanism exists for select target genes, i.e., not all established VDR target genes are regulated by unliganded VDR. It is this class of undefined genes whose expression is controlled by unliganded VDR-RXR that need to be defined in order to understand the in vivo biologies of the VDRKO and 11OHaseKO mice. In order to define the genes that are direct targets for unliganded VDR-RXR in keratinocytes, we will use gene expression array analysis of mouse keratinocytes and purified bulge stem cells from WT, VDRKO, and 1aOHaseKO mice. PUBLIC HEALTH RELEVANCE: The molecular details involved in the tumor suppressor role for unliganded VDR in the skin are completely unknown. Our working hypothesis states that EGF signaling in keratinocytes impinges on VDR to promote VDR-RXR heterodimerization and transactivation of select target genes in the absence of the 1,25(OH)2D3 ligand. The main goal of this proposal is to define target genes for unliganded VDR-RXR heterodimers in keratinocytes.

描述（由申请人提供）：1,25-二羟基维生素D3（1,25（OH）2d3）的经典生理作用是通过确保足够的饮食钙吸收来维持适当的钙稳态。然而，1,25（OH）2d3及其同源受体维生素D受体（VDR）在皮肤和角质形成细胞生物学中也具有关键作用。实际上，VDR是使用1,25（OH）2d3类似物在牛皮癣治疗中使用1,25（OH）2d3的临床目标，这是皮肤的过度增殖性疾病。该研究建议的重点是表皮角质形成细胞中的维生素D内分泌系统，特别是在使用维生素D内分泌系统的鼠模型作为探索体内作用并识别皮肤中维生素D作用的潜在机制的工具。特别是，VDR基因敲除小鼠（VDRKO）非常容易受到化学诱导的皮肤肿瘤发生的影响。相反，我们的初步数据表明，编码肾脏1alpha-羟化酶（1AOHASE）CYP27B1的遗传消融，该酶是生物活性1,25（OH）2d3激素配体的酶，完全抵抗化学上对化学诱发的皮肤化学剂。这些数据以及在这些小鼠模型和人类中发表的有关毛囊循环的数据，指出了VDR在角质形成细胞中的新型配体无依赖性作用。抑制肿瘤抑制作用的分子细节完全未知。我们的初步体内和体外数据支持了一个模型，其中VDR-RXR异二聚体在没有其1,25（OH）2d3配体中在角质形成细胞中选择性地被EGF激活。在没有1,25（OH）2D3配体的情况下，EGF处理可驱动VDR和RXR的异二二聚化，这反过来又促进了异二聚体与选择的角质细胞基因的结合，其中涉及各种过程，例如卵泡循环和保护皮肤组织免受肿瘤组织的影响，从而促进了由DNA-DNA-DNA-DNA-Agents进行肿瘤组织。重要的是，对于某些靶基因而言，这种机制存在，即，并非所有已建立的VDR靶基因均由无配合的VDR调节。正是这类未定义的基因由非配合的VDR-RXR控制，需要定义，以了解VDRKO和11ohaseko小鼠的体内生物学。为了定义角质形成细胞中无配合的VDR-RXR的直接靶标的基因，我们将使用来自WT，VDRKO和1aohaseko小鼠的小鼠角质形成细胞的基因表达阵列分析和纯化的凸起干细胞。公共卫生相关性：抑制肿瘤抑制作用的分子细节是在皮肤中无配合的VDR的，这是完全未知的。我们的工作假设指出，在没有1,25（OH）2d3配体的情况下，角质形成细胞中的EGF信号会影响VDR上的VDR上的EGF信号，以促进VDR-RXR异二聚化和选择靶基因的反式激活。该提案的主要目标是定义角质形成细胞中无配合的VDR-RXR异二聚体的靶基因。