The role of phosphatidylinositol turnover in nuclei

1.多聚磷酸肌醇对基因转录的调控我们首次利用抗磷脂酰肌醇4，5-二磷酸（PIP 2）抗体筛选了新的PIP 2结合蛋白。PIP 2-western blot显示组蛋白是PIP 2的结合蛋白，组蛋白具有抑制基因转录的作用。然后我们检测了磷脂如PIP 2、PIP、PI、PC等对组蛋白H1转录抑制的影响。发现PIP 2显著地拮抗这种抑制。2.在Swiss 3 T3细胞核中发现一种与促分裂信号相关的磷脂酶Cdelta 4（PLCdelta 4），血清可显著诱导其表达。通过检测不同细胞中的表达差异，发现PLCdelta 4蛋白在大鼠肝癌AH 7974细胞和C6大鼠胶质瘤细胞等致癌细胞中大量存在。3.小鼠PLCdelta 4基因启动子区分析。我们分离了小鼠PLCdelta 4基因，并分析了小鼠PLCdelta 4基因的启动子区。我们发现剪接异构体被发现负调节PLC的δ型。接下来，我们确定了120 bp作为转录的最小必需区。利用该区域，我们通过荧光素酶活性测定和凝胶迁移实验研究了诱导机制。我们发现溶血磷脂酸或缓激肽诱导PLC δ 4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.