TRANSGENIC EXPRESSION OF 11B-HSD2 IN BONE

11B-HSD2 在骨中的转基因表达

• 批准号: 7002749
• 负责人: BARBARA E KREAM
• 金额: $ 24.92万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2008-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7002749
• 关键词: aromatase; biological signal transduction; bone development; bone marrow; cell differentiation; chimeric proteins; gender difference; gene expression; genetic promoter element; genetically modified animals; glucocorticoids; green fluorescent proteins; hormone regulation /control mechanism; hydroxysteroid dehydrogenases; intracellular transport; laboratory mouse; microarray technology; microinjections; osteoblasts; osteoclasts; osteogenesis; physiologic bone resorption; protein transport; recombinase; tamoxifen; tissue /cell culture

DESCRIPTION (provided by applicant): This proposal builds on our current research efforts to understand the role of glucocorticoids in bone development and remodeling using novel genetic strategies. A long-standing paradox in bone biology has been the seemingly disparate effects of glucocorticoids on osteogenesis in vivo and in vitro. Published literature shows that glucocorticoids can promote osteoblast differentiation and bone formation in a variety of in vitro models, even though high levels of glucocorticoids typically decrease bone mass and inhibit markers of bone formation in humans and mice. The significance of the osteogenic effect of glucocorticoids seen in vitro remains unclear, although this may reflect a permissive role in the maintenance of the osteoblast phenotype. We have recently generated transgenic mice with osteoblast-targeted expression of 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD2), a metabolic enzyme that disrupts glucocorticoid signaling by converting bioactive glucocorticoids to their inactive 11-keto-metabolites. This approach will allow us to block all known glucocorticoid signaling pathways in bone and assess the physiological role of glucocorticoids on bone development and remodeling in vivo. Thus far, transgenic expression of 11beta-HSD2 in mature osteoblasts results in a fascinating sex- and skeletal-site dependent bone phenotype in which there is reduction of bone volume in vertebrae of female mice. The experiments in this proposal are designed extend our preliminary studies and test the hypothesis that endogenous glucocorticoids are key regulators of osteoblast differentiation, osteoblast function and bone remodeling in vivo. To this end, the specific aims are: 1) To determine the cellular and molecular mechanisms by which endogenous glucocorticoids affect osteoblast function and bone remodeling using the Col2.3-HSD2 transgenic mouse model in which 11beta-HSD2 is expressed in mature osteoblasts; and 2) To determine the role of endogenous glucocorticoids in osteoblast differentiation and function using a constitutively active and temporally inducible Col3.6-HSD2 transgenic models in which 11beta-HSD2 is targeted more broadly to mature osteoblasts and their progenitors.

描述（由申请人提供）：该提案建立在我们目前的研究工作基础上，旨在了解糖皮质激素在骨发育和重塑中的作用，使用新的遗传策略。骨生物学中一个长期存在的悖论是糖皮质激素在体内和体外对骨生成的作用似乎完全不同。已发表的文献表明，糖皮质激素可在多种体外模型中促进成骨细胞分化和骨形成，尽管高水平的糖皮质激素通常会降低人和小鼠的骨量并抑制骨形成标志物。糖皮质激素在体外的成骨作用的意义尚不清楚，虽然这可能反映了在维持成骨细胞表型的许可作用。我们最近产生了成骨细胞靶向表达11 β-羟基类固醇脱氢酶-2（11 β-HSD 2）的转基因小鼠，11 β-HSD 2是一种代谢酶，通过将生物活性糖皮质激素转化为无活性的11-酮代谢物来破坏糖皮质激素信号传导。这种方法将使我们能够阻断骨中所有已知的糖皮质激素信号通路，并评估糖皮质激素对体内骨发育和重塑的生理作用。到目前为止，11 β-HSD 2在成熟成骨细胞中的转基因表达导致了一种迷人的性别和脊椎部位依赖性骨表型，其中雌性小鼠椎骨中的骨体积减少。本实验的设计扩展了我们的初步研究，并验证了内源性糖皮质激素是体内成骨细胞分化、成骨细胞功能和骨重建的关键调节因子的假设。为此，本研究的具体目标是：1）利用11 β-HSD 2在成熟成骨细胞中表达的Col2.3-HSD 2转基因小鼠模型，确定内源性糖皮质激素影响成骨细胞功能和骨重建的细胞和分子机制;和2）使用组成性活性和时间诱导的Col3.6-β-CD来确定内源性糖皮质激素在成骨细胞分化和功能中的作用。HSD 2转基因模型，其中11 β-HSD 2更广泛地靶向成熟成骨细胞及其祖细胞。