BACKGROUND: Cardiac hypertrophy is an adaptive mechanisms in response to an increased cardiac work load. Alterations in gene expression play an important role in this adaptive process. Recent investigations have indicated that the alpha-1 adrenergic stimulation in vitro induces hypertrophic change of neonatal cardiomyocytes. The signalling mechanisms of this alpha-1 agonist induced cardiomyocyte hypertrophy are largely unknown. however, recent evidence favors an effector pathway that involves phospholipase C(PLC) mediated hydrolysis of phosphatidylinositol 4,50 bisphosphate. It should be recognized that the demonstration of enhanced phosphoinositol turnover in the presence of alpha-1 adrenergic agonist in vitro does not necessarily imply that a similar response is operative in vivo. Furthermore, the role of subtypes of phospholipase C in this system should be determined. In this context, we produced in vivo cardiac hypertrophy by repeated injection of alpha-1 adrenergic agonist, phenylephrine, and tried to evaluate any change of phospholipase C subtypes by immunohistochemistry and immunoblotting technique and also measured the phosphatidylinositol hydrolyzing activity of the enzyme. METHOD: To produce cardiac hypertrophy, we injected phenylephrine 12mg/kg i.p. to the 28 female S-D rats weighing 150-250g daily for 5 days. This measures produced 22% increase of heart weight/body weight ratio. After 5 days. rats were sacrificed and hearts were rapid excised and freezed for next procedure. The immunohistochemical stainings of myocardium were carried out using monoclonal antibodies against PLC-beta1,-gamma1,-delta1 with Avidine-Biotin Complex method. Immunoblotting was done with monoclonal anti-PLC-gamma1 antibody after immnoprecipitation. The activity of PLC-gamma1 was determined in the assay mixture containing [3H] phosphatidylinositol of 20,000 cpm. The reaction was performed by incubating with resuspended immunoprecipttol of 20,000 cpm. The reaction was performed by incubating with resuspended immunoprecipitate for 10 min and supernatant was collected for -scintillation counting. RESULTS: Immunohistochemical staining demonstrated increased staining of PLC-gamma1 in the phenylephrine induced hypertrophied heart as compared with normal control heart. PLC-beta1 and-o1 did not showed any change. Elghteen out of 20 hypertrophied cardiac tissue(90%) demonstrated increased expression of the PLC-gamma1 compared with control heart tissue in immunoblotting. [3H] PI hydrolyzing activity of PLC-gamma1 in the immunoprecipitates of the hypertrophied hearts(4650+/-614 cpm) were increased consistently in 6 samples as compared with control normal hearts (2387+/-651 cpm). CONCLUSION: In the present experiments we demonstrated that Phospholipase C-gamma1 was overexpressed compared with control normal heart of rat by immunohistochemistry and immunoblotting technique and showed that the activity of this isoenzyme was elevated. Our findings of increased PLC-gamma1 expression in the alpha1-adrenergic agonist induced cardiac hypertrophy tissue suggest that the phosphatidylinositol signalling pathway is important in the genesis of cardiac hypertrophy and the isoenzyme of PLC-gamma1 may play a central role in this mechanism.
Adrenergic Agonists ; Animals ; Antibodies, Monoclonal ; Cardiomegaly* ; Female ; Gene Expression ; Heart ; Humans ; Hydrolysis ; Hypertrophy ; Immunoblotting ; Immunohistochemistry ; Myocardium ; Myocytes, Cardiac ; Phenylephrine* ; Phosphatidylinositols ; Phospholipases* ; Rats* ; Signal Transduction ; Type C Phospholipases

Phosphoinositide-specific phospholipase C(PLC) is known as a key enzyme which produces two major second messengers: diacylglycerol and inositol 1,4,5 trisphosphate. Although it has been suggested that PLC beta isozymes have important roles in nervous system, less is known about the function of PLC beta in development of nervous system. We have localized the mRNA expressions of PLC beta isozymes in the postnatal rat brains by id firm hybridization histochemistry. In the postnatal rat brains, each isozyme of PLC beta showed differential expression pattern. The expression of PLC beta1 mRNA was found in various areas including olfactory bulb, cerebral cortex, caudate putamen, hippocampus, dentate gyrus, and cerebellum. In general, the expression in these areas was gradually increased after birth (PO) until postnatal day 21 (P2l) and slightly decreased to adult level. The expression of PLC beta2 mRNA was not found in postnatal rat brains. The expression of PLC beta3 mRNA was found from P0, peaked at Pl4, and decreased to adult level in the purkinje cells of cerebellum. PLC beta4 mRNA was strongly expressed in the thalamus, cerebellum, cerebral cortex, and olfactory bulb. In these areas, the expression was gradually increased after birth, peaked at P2l, and decreased to adult level. In whole body parasagittal sections of 18 day old rat embryo, PLC betal mRNA was exclusively expressed in nervous tissue, PLC beta3 and PLC beta4 were expressed in various tissues, and the expression of PLC beta2 was not found in any kind of rat tissues. From the different spatiotemporal mRNA expression patterns of PLC beta isozymes in the postnatal rat brains, it is suspected that each PLC beta isozyme may have specific role in signal transduction for postnatal development of rat brain.
Adult ; Animals ; Brain* ; Cerebellum ; Cerebral Cortex ; Dentate Gyrus ; Embryonic Structures ; Hippocampus ; Humans ; Inositol ; Isoenzymes* ; Nervous System ; Olfactory Bulb ; Parturition ; Phospholipase C beta* ; Phospholipases* ; Purkinje Cells ; Putamen ; Rats* ; RNA, Messenger* ; Second Messenger Systems ; Signal Transduction ; Thalamus

Phospholipase C (PLC) plays a pivotal role in transmembrane signal transduction pathway for cellular proliferation differentiation and growth. Thus far, there have been few reports in which PLC activity was investigated in human malignant neoplastic tissues. In the present study, we evaluated PLC activity in 23 human gastric cancer tissues and normal mucosal tissues to investigate whether alteration of PLC activity is associated with gastric cancer. The amount of [14C] diacylglycerol, one of the earliest products of inositol phospholipid hydrolysis by PLC, was measured by thin layer chromatography. Also, expression of PLC-gamma1, which is one of the most important PLC isozymes,was examined by immunohistochemistry using specific monoclonal antibody directed against PLC-gamma1. The results are summarized as follows. PLC activity in all 23 gastric cancer tissues (1.35+/-1.04 units/mg of protein) was significantly higher than normal mucosal tissues (0.28+/-0.21 units/mg of protein) (P<0.001). PLC activity in gastric cancer tissues was not correlated with histologic grade (P>0.05). PLC-gamma1 immunoreactivity was detected in all of 23 cases studied. The intensity and extent of PLC-gamma1 immunoreactivity was not correlated with PLC enzyme activity, although stronger intensity was demonstrated in malignant cells in comparison to normal gland epithelial cells. The present study provides the first evidence of significant elevation of PLC activity in human stomach cancer tissues. Our results strongly suggest that PLC might be involved in tumorigenesis and/or progression(uncontrolled continuous cycling of cells) of human gastric cancer. Further studies are needed to elucidate the role of elevated PLC activity in cancer tissues.
Humans ; Cell Transformation, Neoplastic ; Stomach Neoplasms

Phospholipase C (PLC) plays a role in ligand-mediated signal transduction for cellular activity such as proliferation and differentiation. A recent observation that PLC- gamma1 is highly expressed in some kinds of human cancer tissue supports the view that PLC-gamma1 may be involved in proliferation and carcinogenesis. PLC-gamma2 is known to be involved in B cell differentiation and maturation. However, there have been few studies about the expressions of PLC-gamma1 and gamma2 in human lymphoid malignancy. In the present study, we examined the contents of PLC-gamma1 and gamma2 in 10 cases of B cell, 10 cases of T cell non-Hodgkin's lymphoma and 5 cases of Hodgkin's lymphoma to find out whether these enzymes play any role in the carcinogenesis by immunohistochemistry and immunoprecipitation. Immunoprecipitation analysis revealed that in contrast to increased expression of PLC-gamma2 only in B cell lymphoma, a considerably higher level of PLC-gamma1 was detected in both B and T cell lymphoma. Immunohistochemical finding confirmed this observation. PLC-gamma1 and PLC-gamma2 were expressed in the cytoplasm of most tumor cells. PLC-gamma2 was also expressed in mature B cells, while PLC-gamma1 was not expressed in reactive non-tumor cells. These results suggest that PLC-gamma1 mediated signal transduction implicates a significant role in the carcinogenesis of all types of lymphoid tissue, and PLC-gamma2 may play a role in the carcinogenesis of B cell lymphoma as well as B cell differentiation.
B-Lymphocytes ; Carcinogenesis ; Cell Differentiation ; Cytoplasm ; Hodgkin Disease* ; Humans ; Immunohistochemistry ; Immunoprecipitation ; Lymphoid Tissue ; Lymphoma, B-Cell ; Lymphoma, Non-Hodgkin ; Lymphoma, T-Cell ; Phospholipases* ; Signal Transduction ; Type C Phospholipases

5'-upstream region of the phospholipase C-beta2 gene, 810 bp, was cloned and characterized. S1 nuclease mapping and primer extension analyses revealed that a single transcriptional start site locates at 284 nucleotides upstream from the beginning of translation. The 5-upstream region lacks both TATA motif and typical initiator sequence, but retains GC-rich segment. Two putative regulatory regions, a negative region (-636/-588) and a positive region (-98/ -13) were identified in the upstream region of PLC-beta2 gene. We suggest that the transcription of PLC-beta2 may be regulated by binding of regulatory proteins to the negative and/or positive regulatory regions located in the upstream of the gene.
Aspergillus Nuclease S1/metabolism ; Base Sequence ; Cells, Cultured ; Chloramphenicol O-Acetyltransferase/metabolism ; Cloning, Molecular ; Conserved Sequence ; Gene Deletion ; Isoenzymes/*chemistry/*genetics ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Phospholipase C/*chemistry/*genetics ; Promoter Regions (Genetics) ; Protein Binding ; Support, Non-U.S. Gov't ; Transcription, Genetic ; Transfection

His-Phe-Tyr-Leu-Pro-Met (HFYLPM) is a synthetic peptide that stimulates Jurkat T cells resulting in intracellular calcium ([Ca2+]i) increase in a pertussis toxin (PTX)-sensitive manner. We have examined the physiological role of the peptide in T cell activity by comparative investigation of intracellular signaling pathways accompanied with HFYLPM-induced T cell chemotaxis with a well-known chemokine, stromal cell-derived factor-1 (SDF-1)-induced signalings. Wortmannin and genistein inhibited both of HFYLPM- and SDF-1-induced Jurkat T cell chemotaxis indicating that phosphoinositide-3-kinase and tyrosine kinase activity were required for the processes. However, U-73122 and BAPTA/AM preferentially blocked HFYLPM- but not SDF-1-induced T cell chemotaxis. It indicates that phospholipase C/calcium signaling is necessary for only chemotaxis by HFYLPM. One of the well-known cellular molecules involving chemotaxis, extracellular signal-regulated protein kinase (ERK), was activated by SDF-1 but not by HFYLPM ruling out a possible role of ERK on the peptide-mediated chemotaxis. These results indicate that the synthetic peptide, HFYLPM, stimulates T cell chemotaxis showing unique signaling and provide a useful tool for the study of T cell activation mechanism.
1-Phosphatidylinositol 3-Kinase/metabolism ; Androstadienes/pharmacology ; Calcium/metabolism ; Cell Line ; Chemokines, CXC/*pharmacology ; Chemotaxis, Leukocyte/drug effects/*physiology ; Dose-Response Relationship, Drug ; Genistein/pharmacology ; Human ; Jurkat Cells ; Oligopeptides ; Peptide Fragments/chemical synthesis/metabolism/*physiology ; Pertussis Toxin ; Phospholipase C/metabolism ; Protein-Tyrosine Kinase/metabolism ; Signal Transduction/drug effects ; T-Lymphocytes/*drug effects ; Virulence Factors, Bordetella/pharmacology

His-Phe-Tyr-Leu-Pro-Met (HFYLPM) is a synthetic peptide that stimulates Jurkat T cells resulting in intracellular calcium ([Ca2+]i) increase in a pertussis toxin (PTX)-sensitive manner. We have examined the physiological role of the peptide in T cell activity by comparative investigation of intracellular signaling pathways accompanied with HFYLPM-induced T cell chemotaxis with a well-known chemokine, stromal cell-derived factor-1 (SDF-1)-induced signalings. Wortmannin and genistein inhibited both of HFYLPM- and SDF-1-induced Jurkat T cell chemotaxis indicating that phosphoinositide-3-kinase and tyrosine kinase activity were required for the processes. However, U-73122 and BAPTA/AM preferentially blocked HFYLPM- but not SDF-1-induced T cell chemotaxis. It indicates that phospholipase C/calcium signaling is necessary for only chemotaxis by HFYLPM. One of the well-known cellular molecules involving chemotaxis, extracellular signal-regulated protein kinase (ERK), was activated by SDF-1 but not by HFYLPM ruling out a possible role of ERK on the peptide-mediated chemotaxis. These results indicate that the synthetic peptide, HFYLPM, stimulates T cell chemotaxis showing unique signaling and provide a useful tool for the study of T cell activation mechanism.
1-Phosphatidylinositol 3-Kinase/metabolism ; Androstadienes/pharmacology ; Calcium/metabolism ; Cell Line ; Chemokines, CXC/*pharmacology ; Chemotaxis, Leukocyte/drug effects/*physiology ; Dose-Response Relationship, Drug ; Genistein/pharmacology ; Human ; Jurkat Cells ; Oligopeptides ; Peptide Fragments/chemical synthesis/metabolism/*physiology ; Pertussis Toxin ; Phospholipase C/metabolism ; Protein-Tyrosine Kinase/metabolism ; Signal Transduction/drug effects ; T-Lymphocytes/*drug effects ; Virulence Factors, Bordetella/pharmacology

Phosphatidylinositol phosphates (PtdInsPs) are ubiquitous membrane phospholipids that play diverse roles in cell growth and differentiation. To clarify the regulation mechanism acting on neurofilament light chain (NF-L) self assembly, we examined the effects of various PtdInsPs on this process. We found that PtdInsPs, including PI(4,5)P2, directly bind to the positively charged Arg54 of murine NF-L, and this binding promotes NF-L self assembly in vitro. Mutant NF-L (R53A/R54A) proteins lacking binding affinity to PtdInsPs did not have the same effect, but the mutant NF-L proteins showed greater self assembly than the wild-type in the absence of any PtdInsP. These results collectively suggest that Arg54 plays a pivotal role in NF-L self assembly by binding with PtdInsPs.
Animals ; Fluorescent Antibody Technique ; Mice ; Mutation/genetics ; Neurofilament Proteins/genetics/*metabolism ; Phosphatidylinositol Phosphates/*metabolism ; Phospholipase C gamma/metabolism ; *Protein Multimerization

The possible involvement of phospholipase C (PLC) in the regulation of insulin secretion is not clearly understood and neither its isozymes expressed nor cellular localization in the pancreatic islets is known. By using specific monoclonal antibodies, we have investigated the expression and localization of eight different PLC isozymes, beta1, beta2, beta3, beta4, gamma1, gamma2, delta1, and delta2, in the pancreatic islets of adult mice. Immunohistochemical analysis carried out on paraffin embedded sections showed a distinct pattern of expression for each of the PLC isozymes. In the central part of the islets containing beta cells, a high level of beta4 and moderate levels of beta3 and gamma1 were expressed, whereas PLC-beta1 and -gamma1 were abundantly expressed in the exocrine pancreas. These results demonstrated the heterogeneity in expression of the phospholipase C isozymes in pancreatic islets. It is conceivable that these isozymes are coupled to different receptors and perform selective tasks in the regulation of insulin secretion for glucose homeostasis.
Animal ; Antibodies, Monoclonal ; Glucagon/analysis ; Insulin/analysis ; Islets of Langerhans/cytology/*enzymology ; Isoenzymes/analysis/immunology ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Phospholipase C/*analysis/immunology

Phospholipase C (PLC)1 hydrolyzes phosphatidylinositol 4,5-bisphosphate to generate the second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 induces a transient increase in intracellular free Ca2+, while DAG directly activates protein kinase C. Upon stimulation of cells with growth factors, PLC-gamma1 is activated upon their association with and phosphorylation by receptor and non-receptor tyrosine kinases. In this review, we will focus on the activation mechanism and regulatory function of PLC-gamma1.
Cell Division ; Enzyme Activation ; Isoenzymes/metabolism* ; Phospholipase C/metabolism* ; Second Messenger Systems ; T-Lymphocytes