NUCLEAR EVENTS IN PTH ACTION ON BONE CELLS

PTH 对骨细胞作用中的核事件

• 批准号: 7850402
• 负责人: Nicola C Partridge
• 金额: $ 3.1万
• 依托单位: UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-12-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7850402
• 关键词: Accounting; Acetylation; Binding; Binding Sites; Bone Resorption; CREB-binding protein; Calcium; Calcium Metabolism Disorders; Cell Line; Cell Nucleus; Cell surface; Cells; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Data; Dissociation; EP300 gene; Enzymes; Event; Formaldehyde; G-Protein-Coupled Receptors; Genes; Genetic Transcription; Goals; Histone H3; Histone H4; Histones; Homeostasis; Hormones; Hypercalcemia; Immunoprecipitation; Investigation; Kinetics; Knowledge; Lead; Matrix Metalloproteinases; Modification; Nuclear; Nucleic Acid Regulatory Sequences; Nucleosomes; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Parathyroid Hormones; Pathway interactions; Peptide Hydrolases; Peptides; Pharmaceutical Preparations; Phosphorylation; Play; Post-Translational Protein Processing; Production; Protein Biosynthesis; Protein Kinase Inhibitors; Protein Synthesis Inhibitors; Proteins; Rattus; Recruitment Activity; Regulation; Relaxation; Repressor Proteins; Research; Research Personnel; Role; Runx2 protein; Series; Serum Calcium Level; Signal Transduction; Site; Structure; TATA Box; Time; Transcription Factor AP-1; Transcriptional Regulation; Western Blotting; Work; activating transcription factor 4; bone; calcium metabolism; chromatin immunoprecipitation; chromatin modification; collagenase 3; crosslink; histone acetyltransferase; hormone regulation; hormone response element; human CREBBP protein; human PTH protein; parathyroid hormone-related protein; programs; promoter; protein kinase inhibitor; research study; response

Parathyroid hormone (PTH) is an essential regulator of calcium homeostasis and also has a role as an anabolic hormone for bone. PTH induces matrix metalloproteinase-13 (MMP-13) gene transcription in osteoblastic cells through a cAMP-dependent pathway requiring de novo protein synthesis, i.e., this is a secondary event. We have identified the PTH-response elements as being the runt domain and the activator protein-1 binding sites in the MMP-13 promoter. We have demonstrated a PTH-dependent cooperative interaction between the sites and the proteins (Runx2 and Fos/Jun) binding to them. We have now established that these two sites in the MMP-13 promoter are in a single nucleosome close to the TATA box and PTH relaxes and modifies this nucleosome but does not cause its dissociation. The relaxation is the product of several steps which occur as early and late events: In the early events, first, PTH stimulates p300 (a histone acetyltransferase, HAT) activity, causes the phosphorylation of Runx2, and p300 is recruited to the promoter resulting in early site-specific acetylation of histone H4; in the late events, newly synthesized Fos/Jun associate with the promoter and then appear to interact with Runx2 followed by recruitment of CBP (CREB binding protein), another HAT, to the entire proximal promoter and acetylation of histone H3 resulting in loosening of the nucleosome. Maximal transcription of the MMP-13 gene then ensues. Our hypothesis is that the gene is in a repressed state and PTH causes the stepwise modification of the chromatin though dissociation of histone deacetylases and co-repressor proteins and association of HATs and activator proteins. The long-term goals of this work are to delineate the mechanisms conveying PTH action to regulation of transcription of the MMP-13 gene in osteoblasts. Consequently, the specific aims of this competing continuation proposal are to, 1) investigate the early events at the RD site of the MMP-13 promoter, and, 2) investigate the late events at the AP-1 site and the interaction of Fos/Jun with other proteins on the MMP-13 promoter. The results of this work will make major contributions to our knowledge of how PTH exerts its nuclear effects on osteoblast function. In so doing, the data will also provide new perspectives into treatment of disorders of calcium metabolism. This research will investigate how a protein hormone (parathyroid hormone, PTH) is able to interact with a cell's surface and transmit signals to the nucleus to cause the DMAand associated proteins to change their structure and cause expression of an enzyme involved in bone breakdown. PTH is essential for regulating serum calcium levels, and is also being used to treat osteoporosis. The results of our research could lead to new drugs being developed, in place of PTH, to treat osteoporosis.

甲状旁腺激素（PTH）是钙稳态的重要调节剂，也具有作为钙稳态调节剂的作用。 骨合成激素甲状旁腺素诱导基质金属蛋白酶-13（MMP-13）基因转录 成骨细胞通过需要从头蛋白质合成的cAMP依赖性途径，即，这是一 次要事件。我们已经确定了PTH反应元件作为runt结构域和激活剂 MMP-13启动子中的蛋白-1结合位点。我们已经证明了PTH依赖的合作 这些位点和与它们结合的蛋白质（Runx 2和Fos/Jun）之间的相互作用。我们现在已经 确定MMP-13启动子中的这两个位点位于靠近TATA盒的单个核小体中 而PTH松弛并修饰该核小体，但不引起其解离。放松是 作为早期和晚期事件发生的几个步骤的产物：在早期事件中，首先，PTH刺激p300 （一种组蛋白乙酰转移酶，HAT）活性，导致Runx 2的磷酸化，p300被募集， 该启动子导致组蛋白H4的早期位点特异性乙酰化;在晚期事件中，新合成 Fos/Jun与启动子结合，然后似乎与Runx 2相互作用，随后募集CBP (CREB结合蛋白），另一种HAT，与整个近端启动子和组蛋白H3的乙酰化， 核小体的松动。MMP-13基因的最大转录然后增强。我们的假设是 该基因处于抑制状态，PTH导致染色质的逐步修饰， 组蛋白去乙酰化酶和辅阻遏蛋白的解离以及HAT和激活剂的缔合 proteins.这项工作的长期目标是阐明传递PTH作用的机制， 成骨细胞中MMP-13基因转录的调节。因此，这一具体目标 相互竞争的延续方案是，1）调查MMP-13研发中心的早期事件 2）研究AP-1位点的晚期事件以及Fos/Jun与其他启动子的相互作用 MMP-13启动子上的蛋白质。这项工作的结果将对我们了解 甲状旁腺激素如何发挥其对成骨细胞功能的核效应。在这样做的过程中，数据还将提供新的 钙代谢紊乱的治疗前景。 本研究将探讨蛋白质激素（甲状旁腺激素，PTH）如何能够与 细胞的表面和传输信号到细胞核，使DMA和相关蛋白质改变其 结构并引起与骨分解有关的酶的表达。PTH对于调节 血清钙水平，也被用于治疗骨质疏松症。我们的研究结果可能会导致 正在开发新的药物来代替PTH来治疗骨质疏松症。