The role of phosphatidylinositol turnover in nuclei

1.多聚磷脂酰肌醇对基因转录的调控我们首次利用抗4，5-二磷酸磷脂酰肌醇(PIP2)抗体筛选出新的PIP2结合蛋白。PIP2-Western印迹结果表明，组蛋白是PIP2结合蛋白，组蛋白具有抑制基因转录的作用。然后我们检测了磷脂如PIP2、PIP、PI、PC等对组蛋白H1转录抑制的影响。PIP2能显著拮抗这种抑制作用。2.与有丝分裂信号相关的一种新的磷脂酶Cdelta4(PLCdelta4)出现在细胞核内，血清可显著诱导瑞士3T3细胞中PLCdelta4的表达。对不同细胞中表达差异的检测表明，PLCdelta4蛋白在大鼠肝癌AH7974细胞和C6大鼠胶质瘤细胞中大量存在。3.小鼠PLCdelta4基因启动子区域的分析。我们发现剪接异构体对Delta型PLC有负调控作用。接下来，我们确定了120个碱基为转录的最小必需区域。利用这个区域，我们通过检测荧光素酶活性和凝胶移动实验来研究诱导机制。我们发现溶血磷脂酸或缓激肽抑制了PLCdelta4的转录。

1.Regulation of gene transcription by polyphosphoinositides.We have first screened new phosphatidylinositol 4,5-bisphosphate (PIP2)-binding proteins by using anti-PIP2 antibody. PIP2-western blot revealed that histones as PIP2-binding proteins.Histones are konwn to inhibit gene transcription. Then we examined the effect of phospholipids such as PIP2, PIP, PI, PC etc.on the transcriptional inhibition by histone Hl. PIP2 was found to antagonize the inhibition, remarkably. On the other hand, PC or PS didn't affect at all.2.A novel phospholipase Cdelta4 (PLCdelta4) appears in nuclei in correlation to mitogenic signal.Expression of PLCdelta4 was remarkably induced in Swiss 3T3 cells by treatment of serum. Examination of the diffence of expression in various cells revealed that PLCdelta4 protein exists much in oncogenic cells such as rat hepatoma AH7974 cells and C6 rat glioma cells.3.Analysis of promoter region of mouse PLCdelta4 gene.We have isolated mouse PLCdelta4 gene and analized promoter region of mouse PLCdelta4 gene. We found splicing isoforms which were found to regulate delta type of PLC negatively. Next we determined the 120 bp as minimam essential region for the transcription. Using this region, we examined the induction mechanism by measuringluciferase activity and gel shift assay. We found lysophosphatidic acid or bradykinin induded the transcription of PLCdelta4.