Overexpression Of Phospholipase Research Articles

Neoplastic transformation and tumorigenesis associated with overexpression of phospholipase D isozymes in cultured murine fibroblasts.

Phospholipase D (PLD) has been suggested to play an important role in a variety of cellular functions. PLD activity has been shown to be significantly elevated in many tumours and transformed cells, suggesting the possibility that PLD might be involved in tumorigenesis. In this study, we have established stable cell lines overexpressing PLD1 and PLD2 from fibroblast cells. These cells, but not control cells, showed altered growth properties and anchorage-independent growth in soft agar. Both PLD1 and PLD2 also induced an up-regulation of the activity of matrix metalloprotease-9 as detected by zymograms. Furthermore, both PLD1 and PLD2 transformants, but not vector-transfectants, induced undifferentiated sarcoma when transplanted into nude mice. Both PLD1- and PLD2-mediated cell cycle distributions in stable cell lines revealed an increased fraction of cells in the S phase compared with control cells. Interestingly, the level of cyclin D3 protein, known as an activator of G(1) to S phase transition in the cell cycle, was aberrantly high in cells overexpressing PLD1 and PLD2 compared with control cells. These results suggest that overexpression of PLD isozymes may play an important role in neoplastic transformation.

Transformation of rat fibroblasts by phospholipase C-γ1 overexpression is accompanied by tyrosine dephosphorylation of paxillin

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465–5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion.

Overexpression of phospholipase C-γ1 suppresses UVC-induced apoptosis through inhibition of c- fos accumulation and c-Jun N-terminal kinase activation in PC12 cells

Ultraviolet-C (UVC) irradiation induces DNA damage and UVC-irradiated cells undergo cell growth arrest to repair the damaged DNA or the induction of apoptosis to prevent the risk of neoplastic transformation. Phospholipase C-γ1 (PLC-γ1) is a mediator of growth factor induced-signal cascade, catalyzing the hydrolysis of phosphatidyl 4,5-bisphosphate to generate second messengers, diacylglycerol and inositol 1,4,5-trisphosphate (IP 3). PLC-γ1 is activated by phosphorylation of tyrosine residues upon occupation of cell surface receptors by growth factors and plays an important role in controlling cellular proliferation and differentiation. In this study, we found that PLC-γ1 was tyrosine phosphorylated within 2.5 min after UVC irradiation. To investigate the role of UVC-induced tyrosine phosphorylation of PLC-γ1, we compared the effect of UVC between PLC-γ1 overexpressing cells and empty vector transfected cells. Overexpression of PLC-γ1 inhibited UVC-induced sub-diploid peak and DNA fragmentation. Northern blot analysis revealed that UVC-induced c- fos mRNA accumulation was inhibited in PLC-γ1 overexpressing cells, while c- jun expression was not affected. In addition, UVC-induced activation of c-Jun N-terminal kinase (JNK) was significantly suppressed in PLC-γ1 overexpressing cells. These results suggest that PLC-γ1 may associate with the protective function against the UVC-induced cell death progression via the inhibition of accumulation of c- fos mRNA and the inhibition of JNK kinase activity.

Signal transduction pathway in human middle ear cholesteatoma

Phospholipase C-γ1 plays a central role in signal transduction, and it is important in cellular growth, differentiation, and proliferation. Human cholesteatoma in the middle ear is characterized by the presence of a keratinizing epithelium that is believed to have hyperproliferative properties. The purpose of this study is to elucidate the distribution of phospholipase C-γ1 in cholesteatoma matrix and deep meatal skin with Western blot analysis and immunohistochemistry. In conclusion, overexpression of phospholipase C-γ1 in cholesteatoma matrix suggests a possible derangement of enhanced growth signal transduction in keratinocytes. (Otolaryngol Head Neck Surg 1999;120:899-904.)

Rapid and Long Term Effects of Protein Kinase C on Receptor Tyrosine Kinase Phosphorylation and Degradation

Rapid and long term effects of protein kinase C alpha activation on receptor tyrosine kinase signaling parameters were investigated in human 293 embryonic fibroblasts and mouse NIH 3T3 cells. Within minutes of phorbol 12-myristate 13-acetate treatment, epidermal growth factor receptor and HER2 tyrosine phosphorylation was decreased, while platelet-derived growth factor receptor and insulin receptor autophosphorylation was upregulated. These effects are not mediated by protein kinase C-dependent receptor tyrosine kinase phosphorylation but apparently by activation or inactivation of receptor tyrosine kinase-specific phosphatases, as indicated by neutralization of these phenomena upon treatment of cells with sodium orthovanadate. In contrast to these short term effects, sustained activation of protein kinase C alpha by phorbol 12-myristate 13-acetate results in translocation of protein kinase C from the cytosol to the membrane fraction where it forms stable complexes with all receptor tyrosine kinases investigated. Ligand-induced receptor tyrosine kinase/protein kinase C association in NIH 3T3 fibroblasts is accompanied by a mobility shift of the receptor, indicating phosphorylation by activated protein kinase C. This phenomenon correlates with the disappearance of receptor tyrosine kinases from the cell surface, implying that this interaction plays a role in the process of receptor internalization and degradation. Interestingly, ligand-stimulated receptor down-regulation is also enhanced by overexpression of phospholipase C gamma, which strongly indicates a role for this common receptor tyrosine kinase substrate in negative regulation of growth factor signals.

Over-expression of human phospholipase C-γ2 enhances platelet-derived growth factor-induced mobilization of intracellular Ca 2+ and the release of arachidonic acid and prostaglandins in NIH 3T3 fibroblasts

Over-expression of human phospholipase C-γ2 in murine NIH 3T3 fibroblasis has been shown to result in an increased platelet-derived growth factor-mediated formation of inositol phosphates. Here we show that phospholipase C-γ2 over-expression is associated with an increased platelet-derived growth factor-mediated release of arachidonic acid, prostaglandin E 2, 6-keto prostaglandin F 10 and prostaglandin F 20. The phorbol ester, calcium ionophore- and fluoride-induced release of arachidonate and its metabolites is not affected by phospholipase C-γ2 over-expression. Over-expression of phospholipase C-γ2 is also associated with an enhancement of platelet-derived growth factor-induced change in intracellular Ca 2+. These results demonstrate that stimulation of recombinant human phospholipase C-γ2 induces a change in the intracellular Ca 2+ concentration, a release of arachidonic acid and formation of prostaglandins in NIH 3T3 cells. In control cells platelet-derived growth factor-induced activation of arachidonic acid cascade is rate-limited by the endogenous phospholipase C.

A new wide-range B-A gauge from uhv to 10 −1 torr : N Ohsaka, J Vac Sci Technol, 20 (4), 1982, 1153–1155

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465–5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion.

Electrochromism of WO 3/LiAlF 4/LiIn thin-film overlayers : Tetsu Oi et al, J Appl Phys, 53 (3), 1982, 1823–1824

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465–5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion.

Microprocessor controlled quadrupole mass spectrometer: S. Burzynski, Vacuum, 32 (3), 1982, 163–168

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465–5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion.

A evaporation-field formula including the repulsive ion-surface interaction: Richard G Forbes, J Phys D: Appl Phys, 15 (7), 1982, L75–L77

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465–5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion.