scholarly journals The co-mitogenic combination of transforming growth factor β1 and bombesin protects protein kinase C-δ from late-phase down-regulation, despite synergy in diacylglycerol accumulation

1996 ◽  
Vol 318 (2) ◽  
pp. 519-525 ◽  
Author(s):  
Andrée R. OLIVIER ◽  
Gurdip HANSRA ◽  
Trevor R. PETTITT ◽  
Michael J. O. WAKELAM ◽  
Peter J. PARKER
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Transforming Growth Factor ◽  
Late Phase ◽  
Flow Cytometric Analysis ◽  
Transforming Growth Factor Β1 ◽  
Mrna Levels ◽  
Down Regulation ◽  
Kinase C

Bombesin induces the down-regulation of protein kinase C-Δ (PKC-Δ) and PKC-ϵ in Swiss 3T3 cells. Simultaneous addition of transforming growth factor β1 (TGFβ1) selectively blocks PKC-Δ down-regulation at mid-S-phase, whereas PKC-ϵ levels continue to decline. Northern blot analysis shows that PKC-ϵ levels could be controlled in part at the level of transcription; PKC-Δ mRNA levels remained constant at these later times. Bombesin induces a sustained elevation of some species of diacylglycerol (DAG), consistent with the observed loss of PKC-Δ and PKC-ϵ. Interestingly, the combination of bombesin and TGF-β1 produces an even greater DAG response. Flow cytometric analysis demonstrates that bombesin induces only 15% of the cells to enter the cell cycle, in contrast to the combination of TGFβ1 plus bombesin which induces 75–80% of the cells to progress through the cycle. The protection of PKC-Δ from down-regulation under conditions of sustained DAG elevation correlates with the mitogenic response and implies that the down-regulation process itself is regulated. Consistent with this, it is demonstrated that bombesin plus TGFβ1 protects PKC-Δ from phorbol ester-induced down-regulation.

scholarly journals Thrombin increases clusterin mRNA in glomerular epithelial and mesangial cells.

1997 ◽  
Vol 8 (6) ◽  
pp. 906-914 ◽  
Author(s):  
N J Laping ◽  
B A Olson ◽  
B Short ◽  
C R Albrightson
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Transforming Growth Factor ◽  
Specific Effect ◽  
Receptor Activation ◽  
Thrombin Receptor ◽  
Mrna Levels ◽  
Kinase C

Clusterin, a multifunctional protein with complement blocking activity, and fibrin, a product of thrombin's enzymatic activity, are present in the kidney during acute and chronic renal failure. The role of thrombin in regulating clusterin mRNA in the kidney is not known. The effect of thrombin on clusterin mRNA expression was examined in rat glomerular mesangial and glomerular epithelial cells, and cultured human renal proximal tubular epithelial cells by northern blot. Thrombin (10(-8) M) increased clusterin mRNA levels two- to fourfold in glomerular mesangial, glomerular epithelial, and proximal tubule epithelial cells. This was a specific effect of thrombin receptor activation because peptides corresponding to the tethered ligand of the thrombin receptor were also able to increase clusterin mRNA levels. Epidermal growth factor, insulin-like growth factor-1, and transforming growth factor-beta 1 had little or no effect on clusterin mRNA levels. The protein kinase C inhibitor RO-32-0432 (1 microM) inhibited the thrombin-induced increase in clusterin mRNA, suggesting that thrombin receptor activation may regulate renal clusterin mRNA levels through protein kinase C.

scholarly journals Stimulation of hyaluronan biosynthesis by platelet-derived growth factor-BB and transforming growth factor-β1 involves activation of protein kinase C

1995 ◽  
Vol 307 (3) ◽  
pp. 817-821 ◽  
Author(s):  
M Suzuki ◽  
T Asplund ◽  
H Yamashita ◽  
C H Heldin ◽  
P Heldin
Keyword(s):  
Protein Kinase C ◽  
Growth Factors ◽  
Growth Factor ◽  
Protein Kinase ◽  
Transforming Growth Factor ◽  
Human Fibroblasts ◽  
Transforming Growth Factor Β1 ◽  
Platelet Derived Growth Factor ◽  
Tgf Beta ◽  
Kinase C

The intracellular signal transduction pathways that mediate the stimulatory effects of platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-beta on hyaluronan biosynthesis in human fibroblasts were investigated. The stimulatory effects of both PDGF-BB and TGF-beta 1 were dependent on protein kinase C (PKC), since the PKC inhibitor calphostin C inhibited the stimulation by the growth factors. Direct activation of PKC by phorbol 12-myristate 13-acetate (PMA) also stimulated hyaluronan production, and the combination of either PDGF-BB or TGF-beta 1 and PMA gave an increased effect. One possible mechanism for activation of PKC is via induction of phospholipase C (PLC) activity; U-17322, an inhibitor of PLC-gamma, was found to inhibit partially PDGF-BB-stimulated hyaluronan synthesis. PDGF-BB is known to activate PLC-gamma through tyrosine phosphorylation; however, a PDGF beta-receptor mutant unable to interact with and activate PLC-gamma was still able to mediate induction of hyaluronan biosynthesis, indicating that PDGF-mediated stimulation is not entirely dependent on PLC-gamma. The stimulations by PDGF-BB and TGF-beta 1 were partly dependent on protein synthesis, since parts of the effects were inhibited by cycloheximide; in contrast, the effects mediated by PMA were not. Our results indicate that PKC is involved in the transduction of the effects of growth factors on hyaluronan biosynthesis, and that the effects involve direct or indirect activation of existing hyaluronan synthetase molecules, as well as induction of new enzyme molecules.

scholarly journals Mechanisms of protein kinase C epsilon down-regulation by transforming growth factor-beta in lung cancer cells

2020 ◽  
Author(s):  
Victoria Casado-Medrano ◽  
Martin J. Baker ◽  
Mariana Cooke ◽  
Marcelo G. Kazanietz
Keyword(s):  
Lung Cancer ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Transforming Growth Factor ◽  
Mrna Levels ◽  
Down Regulation ◽  
Mesenchymal Transition ◽  
Kinase C ◽  
Protein Kinase C Epsilon

ABSTRACTProtein kinase C epsilon (PKCε), a diacylglycerol (DAG)/phorbol ester-regulated PKC isoform, has been widely linked to oncogenesis and metastasis. PKCε plays important roles in the regulation of motility and invasiveness in non-small cell lung cancer (NSCLC). We previously reported that this kinase becomes prominently down-regulated upon TGF-β-induced epithelial-to-mesenchymal transition (EMT), which leads to prominent phenotypic changes. While the phorbol ester PMA causes down-regulation of PKCα, δ and ε within hours, TGF-β requires at least 4 days to reduce the expression levels of PKCε without affecting the expression of other PKCs, an effect that parallels the acquisition of a mesenchymal phenotype. Despite the prominent transcriptional component involved in EMT, we found that PKCε down-regulation does not involve changes in PKCε mRNA levels and was entirely independent of transcriptional activation of the PRKCE gene. Further mechanistic analysis revealed that the reduction in PKCε expression is dependent on proteasomal and endolysosomal pathways, but independent of autophagy processing mechanisms. Site-directed mutagenesis of Lys312 and Lys321 in PKCε prevented its down-regulation in response to either TGF-β or the phorbol ester PMA. The shift in PKCε isozyme levels depending on cell plasticity underscores relevant functional consequences by modulating the expression of this oncogenic/metastatic kinase and highlights key roles of protein stability mechanisms in the control of PKCε phenotypic outcomes.

Sign in / Sign up

Export Citation Format

Share Document