OSTEOBLAST NUCLEAR MATRIX REGULATION OF COLLAGEN

甲状旁腺激素（PTH）的间歇剂量通过选择性刺激骨形成来增加骨量。 调节这种合成代谢作用的分子机制尚不清楚。使用体外模型证明这种现象是有问题的，因为PTH减弱成骨细胞培养中的胶原蛋白合成。 细胞结构影响胶原蛋白的合成，并可能导致骨和培养的成骨细胞对PTH的相反反应。 我们认为胶原蛋白的表达通过组织基质、细胞外基质、细胞骨架和核基质的相互连接蛋白与细胞结构偶联。 此外，我们提出，这种结构途径最终与核基质结构转录因子，蛋白质，改变基因活性的弯曲启动子DNA在组织基质组织的变化。因此，PTH诱导的组织基质蛋白的变化可能会改变COL 1A 1的表达，通过“牵引”基因和改变启动子的几何形状。我们已经确定了一个新的核基质结构转录因子家族，NP/NMP 4，其以序列特异性结合到I型胶原的大鼠α 1（I）多肽链（COL 1A 1）的启动子。 这些独特的锌指蛋白与COL 1A 1启动子结合，使其弯曲，并含有基础启动子活性。 PTH调节NP/NMP 4-COL 1A 1结合活性和NP/NMP 4 mRNA表达。 激素诱导的NP/NMP 4-COL 1A 1结合改变在骨和培养物之间不同。 我们的目标是研究NP/NMP 4在介导基础和PTH调节的COL 1A 1转录中的功能作用。 第一项研究将测试这一假设，即COL 1A 1启动子NP/NMP 4结合元件有助于成骨细胞基础和PTH调节的转录在体外和体内。 第二项研究将确定NP和NMP 4在介导基础和PTH调节的COL 1A 1转录中的不同功能。 第三项研究将确定NP/NMP 4蛋白的功能结构域。这一信息将确定一个结构通路的PTH行动在成骨细胞，并进一步澄清细胞基础上的合成代谢作用，这种激素对骨。

Intermittent doses of parathyroid hormone (PTH) increase bone mass by selectively stimulating bone formation. The molecular mechanisms mediating this anabolic effect are unknown. Demonstrating this phenomenon is problematic using in vitro models because PTH attenuates collagen synthesis in osteoblast culture. Cell structure influences collagen synthesis and likely contributes to the opposing responses of bone and cultured osteoblasts to PTH. We propose that collagen expression is coupled to cell structure via the tissue matrix, the interlinking proteins of the extracellular matrix, cytoskeleton, and nuclear matrix. Furthermore, we propose that this structural pathway culminates with nuclear matrix architectural transcription factors, proteins that alter gene activity by bending promoter DNA in response to changes in tissue matrix organization. Therefore, PTH-induced changes in tissue matrix proteins may alter COL1A1 expression by "tugging" at the gene and altering promoter geometry. We have identified a novel family of nuclear matrix architectural transcription factors, NP/NMP4, that bind with sequence specificity to the promoter of the rat alpha1 (I) polypeptide chain (COL1A1) of type I collagen. These unique zinc finger proteins bind to the COL1A1 promoter, bend it, and contain basal promoter activity. PTH regulates NP/NMP4-COL1A1 binding activity and NP/NMP4 mRNA expression. Hormone-induced alterations in NP/NMP4-COL1A1 binding differ between bone and culture. Our goal is to investigate the functional role of NP/NMP4 in mediating basal and PTH-regulated COL1A1 transcription. The first study will test the hypothesis that the COL1A1 promoter NP/NMP4 binding elements contribute to osteoblast basal and PTH-modulated transcription in vitro and in vivo. The second study will determine the distinct functions of NP and NMP4 in mediating basal and PTH-regulated COL1A1 transcription. The third study will determine the functional domains of the NP/NMP4 proteins. This information will define a structural pathway for PTH action in osteoblasts and further clarify the cellular basis for the anabolic action of this hormone on bone.