Mouse Models to Delineate a Unique Metabolic and Skeletal Network

描绘独特代谢和骨骼网络的小鼠模型

• 批准号: 7842876
• 负责人: CLIFFORD JAMES ROSEN
• 金额: $ 81.24万
• 依托单位: MAINEHEALTH
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-23 至 2011-09-22
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7842876
• 关键词: 2,4-thiazolidinedione; 3' Untranslated Regions; Address; Adipocytes; Affect; Aftercare; Age; Biochemical Pathway; Bone Density; Bone Marrow; Bone Resorption; Cell Differentiation process; Characteristics; Chromosomes, Human, Pair 6; Clinical; Coculture Techniques; Collaborations; Complex; Data; Diet; Enzymes; Fatty acid glycerol esters; Female; Fracture; Gender; Gene Expression; Genes; Genetic Determinism; Genetic Models; Genetic Polymorphism; Genomics; Grant; Hematopoietic; Histology; Homeostasis; In Vitro; Inbred Strains Mice; Insulin Resistance; Insulin-Like Growth Factor I; Knockout Mice; Laboratories; Ligands; Location; Magnetic Resonance Imaging; Maintenance; Marrow; Mediator of activation protein; Mesenchymal; Metabolic; Metabolism; Modeling; Molecular; Mus; Nuclear Receptors; Obesity; Osteoblasts; Osteoclasts; Osteogenesis; PPAR gamma; Parents; Pathway interactions; Peroxisome Proliferator-Activated Receptors; Pharmaceutical Preparations; Phase; Phenocopy; Phenotype; Play; RXR; RalDH1; Regulation; Regulon; Reporting; Resistance; Retina; Retinaldehyde; Retinoids; Role; Series; Serum; Serum Markers; Signal Pathway; Signal Transduction; Stromal Cell-Derived Factor 1; Stromal Cells; Sum; Testing; Thiazolidinediones; Thinness; Tretinoin; Work; X-Ray Computed Tomography; atherogenesis; bone; bone cell; bone loss; bone mass; bone turnover; congenic; design; gain of function; in vivo; indexing; insight; insulin sensitivity; lipid biosynthesis; mouse model; novel; osteoblast differentiation; osteoclastogenesis; progenitor; programs; public health relevance; research study; response; retinaldehyde dehydrogenase; rosiglitazone; skeletal

DESCRIPTION (provided by applicant): In the current RO1 AR54604, we are studying the interaction between skeletal acquisition and bone marrow adiposity, and testing the hypothesis that there are shared skeletal and metabolic networks controlled by a series of genes situated on mouse chromosome 6. This competitive revision expands our ongoing work by building on the recent identification by our collaborator, Jorge Plutzky, that the retinoic acid (RA) precursor, retinaldehyde (Rald), functions as a novel biologically active mediator in fat where it determines metabolic phenotypes by repressing PPAR3. The Rosen/Horowitz laboratories have been characterizing congenic (e.g. B6.C3H-6T) and inbred strains of mice (C57BL6 and C3H/HeJ) and identifying genetic determinants of bone mass and IGF-I. We found genes in the mid region of mouse Chr6 that function together as a regulatory unit to determine a skeletal phenotype in 6T mice of low bone mass, impaired osteoblast (OB) differentiation, low circulating IGF-I, and enhanced bone marrow adiposity. Although 6T mice lose bone after a high fat diet (HFD) challenge, their metabolic profile is characterized by protection from diet-induced insulin resistance and obesity. Remarkably, the location of this small genomic cluster (4Mb) on mouse Chr 6 includes 4 genes important in adipogenesis: peroxisome proliferator-activated receptor-gamma (PPAR3), Alox5, SDF-1, and FSP 27. Recently we identified several polymorphisms within the 3'UTR of the PPAR3 gene, and examined the downstream effects of this 'gain of function' on targets such as IGF-I. These data provided an important rationale for studying the mechanisms of adipogenic differentiation in marrow stromal cells. After the Plutzky group reported that Rald, which previously had no documented role outside of the retina, inhibited PPAR3-RXR and repressed adipogenesis in vivo, we began a collaboration to determine Rald's mechanism of action in bone. We analyzed skeletal phenotypes from retinaldehyde dehydrogenase null (Raldh1-/-) mice and found markedly increased femoral areal bone mineral density in 12 week Raldh1-/- mice vs B6. In addition, there was more than twice the femoral bone volume fraction in the null mice compared to controls. These lines of evidence now permit us to test how Rald, either through the RXR- PPAR complex, or independently, has a critical regulatory role in stromal cell fate, and ultimately in bone acquisition. We will accomplish this by fully characterizing the skeletal phenotype of the Raldh1-/- mice on regular and high fat diets as well as with and without rosiglitazone. We will interrogate the molecular mechanisms in osteoblasts and osteoclasts to determine the presence of Rald and Raldh1 and the effects of the retinoid axis on bone marrow stromal cell allocation and osteoclastogenesis. PUBLIC HEALTH RELEVANCE: The importance of nuclear receptor networks in bone marrow differentiation programs has been firmly established and in our ongoing grant, AR54604, we identified several genetic polymorphisms in the PPAR3 gene which we identified as a key determinant of adipocyte and bone cell fate. We now propose to study retinaldehyde and its effect on RXR which partners with PPAR3, to form an activated transcriptional complex to regulate gene expression and ultimately to influence bone mass acquisition. A more comprehensive understanding of the regulatory inputs that determine PPAR3 responses in bone has important clinical implications, particularly after the discovery that the thiazolidinediones, drugs that enhance insulin sensitivity and are exogenous ligands for PPAR3, cause bone loss and fractures.

描述（由申请人提供）：在当前的 RO1 AR54604 中，我们正在研究骨骼获取与骨髓肥胖之间的相互作用，并测试以下假设：存在由位于小鼠 6 号染色体上的一系列基因控制的共享骨骼和代谢网络。这一竞争性修订以我们的合作者 Jorge Plutzky 最近的鉴定为基础，扩展了我们正在进行的工作，即视黄酸 (RA) 前体视黄醛 (Rald) 在脂肪中充当一种新型生物活性介质，通过抑制 PPAR3 来决定代谢表型。 Rosen/Horowitz 实验室一直在鉴定同系小鼠（例如 B6.C3H-6T）和近交系小鼠（C57BL6 和 C3H/HeJ）的特征，并确定骨量和 IGF-I 的遗传决定因素。我们在小鼠 Chr6 的中部区域发现了一些基因，这些基因共同作为调节单元发挥作用，以确定低骨量、受损的成骨细胞 (OB) 分化、低循环 IGF-I 和增强的骨髓肥胖的 6T 小鼠的骨骼表型。尽管 6T 小鼠在高脂肪饮食 (HFD) 挑战后骨质流失，但其代谢特征的特点是可以防止饮食引起的胰岛素抵抗和肥胖。值得注意的是，小鼠 Chr 6 上这个小基因组簇 (4Mb) 的位置包括 4 个在脂肪形成中重要的基因：过氧化物酶体增殖物激活受体-γ (PPAR3)、Alox5、SDF-1 和 FSP 27。最近，我们在 PPAR3 基因的 3'UTR 内发现了几个多态性，并检查了这种“功能获得”对靶标的下游影响，例如 IGF-I。这些数据为研究骨髓基质细胞脂肪形成分化机制提供了重要依据。在 Plutzky 小组报道 Rald（之前在视网膜之外没有任何作用记录）可抑制 PPAR3-RXR 并抑制体内脂肪生成后，我们开始合作以确定 Rald 在骨骼中的作用机制。我们分析了视黄醛脱氢酶缺失 (Raldh1-/-) 小鼠的骨骼表型，发现 12 周 Raldh1-/- 小鼠与 B6 小鼠相比，股骨区域骨矿物质密度显着增加。此外，与对照组相比，无效小鼠的股骨体积分数增加了一倍多。这些证据现在使我们能够测试 Rald 如何通过 RXR-PPAR 复合物或独立地在基质细胞命运以及最终骨获得中发挥关键的调节作用。我们将通过全面表征常规饮食和高脂肪饮食以及使用和不使用罗格列酮的 Raldh1-/- 小鼠的骨骼表型来实现这一目标。我们将探究成骨细胞和破骨细胞的分子机制，以确定 Rald 和 Raldh1 的存在以及类视黄醇轴对骨髓基质细胞分配和破骨细胞生成的影响。 公共健康相关性：核受体网络在骨髓分化计划中的重要性已得到牢固确立，并且在我们正在进行的 AR54604 资助中，我们鉴定了 PPAR3 基因中的几种遗传多态性，我们将其确定为脂肪细胞和骨细胞命运的关键决定因素。我们现在建议研究视黄醛及其对 RXR 的影响，RXR 与 PPAR3 合作，形成激活的转录复合物来调节基因表达并最终影响骨量获得。更全面地了解决定骨骼中 PPAR3 反应的调节输入具有重要的临床意义，特别是在发现噻唑烷二酮类药物（增强胰岛素敏感性且是 PPAR3 的外源配体）会导致骨质流失和骨折之后。