| The two closely relative members of phospholipase C- Y family, y \ and Y 2, are the key enzymes in the extracellular signal transduction pathway, which have 50.8% homology and similar enzymolysis to produce two second messengers, inositol 1,4,5-trisphosphate (IPs) which releases Ca2+from the intracellular stores and rises the cytosolic-free Ca2+ level and diacylglycerol (DAG) which activates PKC leading to protein phosphorylation, granule secretion and fibrinogen-receptor expression, by hydrolysis phosphatidylinositol. It is deemed that phospholipase C- Y i and Y 2 are able to transduct some growth factoral signals resulting in migration, growth, differentiation, apoptosis and trigger of certain biological events in some terminal differentiation cells such as development and respiratory burst of polymorphonuclear leukocytes and so on. However, we have not still known well the roles that phospholipase C- Y i and Y 2 respectively play in the complex signal network.In order to observe and compare the roles of phospholipase C- Y i and Y 2 in the platelet -derived growth factor signal transduction in fibroblast, we overexpress phospholipase C- Y 2 on the fibroblast cell line which has been defected phospholipase C- Y i gene to exclude the disruption of phospholipase C- Y i by homologous recombination and simultaneous establish several wild type and vector transfected control cell lines, which all are used to study the effection of phospholipase C- Y i and Y 2 on growth, proliferation, migration and clonogenicity and transcription of c-myc, c-jun, egr-1, pi6 and p27 genes under the induction of PDGRBy statistically analyses of the detected indices, we reveale that phospholipase C- y \ and phospholipase C- Y 2 both show a positive but not essential regulator effect on the migration and proliferation signal of fibroblast induced by PDGF, the effect of the former one is significantly stronger and earlier than the later and phospholipase C- Y 2 can cooperate a?little with phospholipase C- Y i- Although phospholipase C- Y 2 is demonstrated greatly dispensable for clonogenicity, Y i fails to have any difference. The disruption of phospholipase C- Y i gene leads to an important increase of DNA synthesis and a short of G\ and S phases in fibroblast cell, whilst phospholipase C- Y 2 affects DNA synthesis little and extends S phases relatively by proceeding S phases earlier.Phospholipase C- Y i and Y 2 both are involve in the regulation in transcription of five detected early response genes. Phospholipase C- Y i is not essential for cell survival on serum-deprived condition and capable of contributing to increase in transcription of c-jun, c-myc and egr-1 genes and a decline in pi6 upon stimulation with PDGF, which all lead cells to entering into cell cycle. As for transcription of c-jun, c-myc and egr-1 genes in the phospholipase C- Y i gene-defected cell line, there might be other additional compensation pathways.In the present study, we conclude that no compensation for phospholipase C- Y 2 expresses in phospholipase C- Y i gene knocked out cell line, the distinct functional modes between phospholipase C- Y i and Y 2 on growth, proliferation, migration and clonogenicity and transcription patterns of c-myc > c-jun> egr-K pi6 and p27 genes are also carried out in fibrablast cell, which indicats both these the two enzymes are linked to independent functions and can not substitute for each other.
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