REGULATORY MECHANISMS OF PLATELET-DERIVED GROWTH FACTOR BETARECEPTOR GENE EXPRESSION VIA CCAAT-BINDING PROTEINS.

血小板衍生生长因子（platelet derived growth factor， PDGF）是血管平滑肌细胞（vascular smooth muscle cells， VSMC）发育或肥大的主要生长因子之一。已知PDGF在与特定受体结合时具有生理活性。-本研究的主要目的是阐明PDGF n受体（PDGFRB）基因在VSMC中的表达调控机制。PDGFRB基因启动子的功能分析表明，PDGFRB基因转录主要受位于-150 ~ -121 （R30）和-67 ~ -61 （CCAAT box, C67）的两个重要顺式元件调控。dna结合研究表明，属于ccaat结合蛋白家族之一的NF-Y家族（尤其是NF-YC）与C67序列特异性相互作用，正调控PDGFRB基因的转录活性。另一方面，含有负调控元件（NRE）的R30以组织特异性的方式负向控制基因的表达。此外，为了获得这些顺式元件在VSMC中具有功能活性的直接证据，我们还研究了序列特异性“诱饵”寡脱氧核苷酸（OUN）对这两个序列内在PDGFPB mRNA表达的影响。R30或C67的“诱饵”ODN均可显著抑制VSMC中PDGFRB mRNA的内在表达，这表明这两个元件可以作为PDGFRB基因转录的功能性启动子和/或上游控制元件。之前，我们还确定了另一个CCAAT结合家族，CCAAT/增强子结合蛋白（C/FBP）家族在VSMC中PDGF α受体（PDGFRA）基因转录活性中的重要性。从这两项研究中，我们强烈假设包括NF-Y和C/EBP在内的ccaat结合蛋白在体内血管发育或重塑相关基因的转录调控中起关键作用。此外，CCAAT盒及其结合因子家族可能成为血管壁动脉粥样硬化和再狭窄病变基因治疗的有用候选者。少

Platelet-derived growth factor (PDGF) is one of major growth factors on cellular development or hypertrophy in vascular smooth muscle cells (VSMC). PDGF is known to become physiologically active when it binds to its specific receptor, alpha or beta. -Main purpose of this study is to elucidate regulatory mechanisms of PDGF n-receptor (PDGFRB) gene expression in VSMC.Functional analyses of PDGFRB gene promoter revealed that PDGFRB gene transcription is mainly regulated by two important cis-elements located at -150 through -121 (designated R30) and at -67 through -61 (CCAAT box, designated C67). DNA-binding studies indicated that NF-Y family (especially NF-YC), which belongs to one of CCAAT-binding protein families, is specifically interacted with the C67 sequence and positively regulates the transcriptional activity of the PDGFRB gene. On the other hand, R30, which contains a negative regulatory element (NRE), negatively control the gene expression under a tissue-specific manner. Further … More more, to gain a direct evidence that these cis-elements are functional active in VSMC, effects of sequence-specific "decoy" oligodeoxynucleotide (OUN) for these two sequences on intrinsic PDGFPB mRNA expression were also investigated. Either 'decoy' ODN for R30 or C67 significantly suppressed intrinsic PDGFRB mRNA expression in VSMC indicating that these two elements can act as a functional promoter and/or an upstream control element of PDGFRB gene transcription. Previously, we have also determined the importance of another CCAAT-binding family, CCAAT/enhancer-binding proteins (C/FBP) family, on the transcriptional activity of the PDGF alpha-receptor (PDGFRA) gene in VSMC.From these two studies, we strongly postulate the hypothesis that CCAAT-binding proteins including NF-Y and C/EBP play a pivotal role in the transcriptional regulation of the genes related to the vascular development or remodeling in vivo. Furthermore, CCAAT boxs and their binding factor families may become useful candidates for the gene therapy of atherosclerotic and restenotic lesions in the vessel wall. Less