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Fedorov YV, Jones NC, Olwin BB. Atypical protein kinase Cs are the Ras effectors that mediate repression of myogenic satellite cell differentiation. Mol Cell Biol 2002; 22:1140-9. [PMID: 11809805 PMCID: PMC134628 DOI: 10.1128/mcb.22.4.1140-1149.2002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2001] [Revised: 07/02/2001] [Accepted: 11/05/2001] [Indexed: 11/20/2022] Open
Abstract
Oncogenic Ha-Ras is a potent inhibitor of skeletal muscle cell differentiation, yet the Ras effector mediating this process remains unidentified. Here we demonstrate that the atypical protein kinases (aPKCs; lambda and/or zeta) are downstream Ras effectors responsible for Ras-dependent inhibition of myogenic differentiation in a satellite cell line. First, ectopic expression of Ha-RasG12V induces translocation of PKClambda from the cytosol to the nucleus, suggesting that aPKCs are activated by Ras in myoblasts. The aPKCs function as downstream Ras effectors since inhibition of aPKCs by expression of a dominant negative PKCzeta mutant or by treatment of cells with an inhibitor, GO6983, promotes myogenesis in skeletal muscle satellite cells expressing oncogenic Ha-Ras. Arresting cell proliferation synergistically enhances myogenic differentiation only when aPKCs are also inhibited. Thus, the repression of myogenic differentiation in a satellite cell line appears to be directly mediated by aPKCs acting as Ras effectors and indirectly mediated via stimulation of cell proliferation.
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Affiliation(s)
- Yuri V Fedorov
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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2
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Cooper DR, Watson JE, Patel N, Illingworth P, Acevedo-Duncan M, Goodnight J, Chalfant CE, Mischak H. Ectopic expression of protein kinase CbetaII, -delta, and -epsilon, but not -betaI or -zeta, provide for insulin stimulation of glucose uptake in NIH-3T3 cells. Arch Biochem Biophys 1999; 372:69-79. [PMID: 10562418 DOI: 10.1006/abbi.1999.1472] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin regulates a diverse array of signaling pathways involved in the control of growth, differentiation, proliferation, and metabolism. Insulin increases in glucose uptake via a protein kinase C-dependent pathway in target tissues such as fat and muscle are well documented. Insulin-regulated events, however, occur in all cells. The utilization of glucose as a preferred energy source is a ubiquitous event in eukaryotic cells. In NIH-3T3 fibroblasts, insulin treatment increased levels of the cPKC and nPKC activator, diacylglycerol. Insulin-responsive 2-[(3)H]deoxyglucose uptake was stimulated in a dose-dependent manner. The overexpression of protein kinase C (PKC)betaI, -betaII, -delta, -epsilon, and -zeta was used to investigate the specificity of PKC isozymes for insulin-sensitive glucose uptake. The stable overexpression of PKCbetaII, -delta, and -epsilon resulted in increases in insulin-stimulated 2-[(3)H]deoxyglucose uptake compared to vector control cells, while basal 2-deoxyglucose uptake levels were not elevated. Overexpression of PKCbetaI and PKCzeta isozymes had no further effect on basal or insulin-stimulated 2-deoxyglucose uptake. The PKC-specific inhibitor, CGP41251, blocked insulin effects on 2-deoxyglucose uptake but not its effects on tyrosine phosphorylation of cellular substrates. Insulin-stimulated 3-O-methylglucose uptake was also greater in cells overexpressing PKCbetaII, -delta, and -epsilon, compared to control cells. The increased responsiveness was not accompanied by conversion of 3T3 cells to the adipocyte phenotype or the increased expression of insulin receptors or glucose transporters (GLUT1-type). Insulin-stimulated recruitment of GLUT1 to plasma membranes of cells overexpressing PKCbetaII, -delta, and -epsilon, was greater than that in control cells. The data suggest that more than one PKC isozyme is involved in insulin signaling pathways in fibroblasts, resulting in increased GLUT1 transporter recruitment to cell membranes.
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Affiliation(s)
- D R Cooper
- James A. Haley Veterans Hospital, University of South Florida College of Medicine, Tampa, Florida, 33612, USA.
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3
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Al-Mazidi HA, Kleine LP, Franks DJ. The presence of an unusual PKC isozyme profile in rat liver cells. Biochem Cell Biol 1998. [DOI: 10.1139/o98-008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have previously shown that protein kinase C (PKC) is involved in the mitogenic response of T51B cells to epidermal growth factor. In fact, epidermal growth factor was an excellent mitogen, even after prolonged pretreatment of cells with TPA, suggesting that the PKC isoform implicated in proliferation is not down-regulated by 12-O-tetradecanoyl phorbol-13-acetate (TPA). We have now determined that the PKC isozymes -α, -βI, -δ, -ε, and -ζ are present in T51B cells. All five isoforms are associated with the plasma membrane and the cytoplasm and are either in or around the nucleus. PKC-βI has a slightly different subcellular profile from that of the other isoforms in that it is clearly and strongly associated with the nuclear membrane. Also, a unique and novel pattern is obtained from immunoblots with anti-PKC-βI. PKC-βI is detected as a single band of 70 kDa in the cytosolic fraction and as a doublet of 65 and 77 kDa in the membrane fraction. PKC-α, -δ, and -ε were down-regulated by pretreatment of cells with TPA, while PKC-ζ was unaffected. Of particular interest was the fact that TPA did not down-regulate PKC-βI. In fact, the amount of this isoform associated with the plasma membrane increased. These findings indicate that it is probably PKC-βI that is involved in the mitogenic response of T51B cells to epidermal growth factor. Since PKC-ζ is also not down-regulated by TPA, the possible involvement of this isoform needs to be resolved.Key words: protein kinase C, intracellular localization, cell proliferation, liver.
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4
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Standaert ML, Avignon A, Arnold T, Saba-Siddique SI, Copper DR, Watson J, Zhou X, Galloway L, Farese RV. Insulin translocates PKC-epsilon and phorbol esters induce and persistently translocate PKC-beta 2 in BC3H-1 myocytes. Cell Signal 1996; 8:313-6. [PMID: 8842533 DOI: 10.1016/0898-6568(96)00043-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Initial studies suggested that insulin increases diacylglycerol and activates protein kinase C (PKC) in BC3H-1 myocytes. In these earlier studies, insulin was found to translocate PKC-beta, but the presence of PKC-epsilon was not appreciated. More recently, the presence of PKC-epsilon was documented, but PKC-beta was not detected, and it was questioned whether insulin activates PKC in BC3H-1 myocytes [Stumpo, D.J., Haupt, D.M. and Blackshear, P.J. (1994) J. Biol. Chem. 269:21184-21190]. We questioned whether insulin translocates PKC-epsilon in BC3H-1 myocytes, and re-evaluated the question of whether myocytes truly contain a PKC-beta isoform whose existence can be verified by its response to phorbol ester treatment. We found that PKC-epsilon was acutely translocated by insulin and phorbol esters from the cytosol to the membrane fraction in BC3H-1 myocytes; in addition, PKC-epsilon, like PKC-alpha, was depleted by chronic phorbol ester treatment. We also found that BC3H-1 myocytes containing a 76,000 Mr PKC-beta isoform that is acutely translocated and subsequently depleted by phorbol esters. Moreover, chronic phorbol ester treatment induced an 84,000 Mr PKC-beta 2 isoform that appeared to be persistently translocated and activated, as suggested by studies of myristoylated arginic-rich C kinase substrate (MARCKS) phosphorylation. We conclude that: (1) insulin acutely translocates PKC-epsilon, as well as PKC-beta, in BC3H-1 myocytes; and (2) PKC-beta is not truly downregulated by phorbol esters in BC3H-1 myocytes.
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5
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Chalfant CE, Mischak H, Watson JE, Winkler BC, Goodnight J, Farese RV, Cooper DR. Regulation of alternative splicing of protein kinase C beta by insulin. J Biol Chem 1995; 270:13326-32. [PMID: 7768933 DOI: 10.1074/jbc.270.22.13326] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Insulin regulates a diverse array of cellular signaling processes involved in the control of growth, differentiation, and cellular metabolism. Insulin increases glucose transport via a protein kinase C (PKC)-dependent pathway in BC3H-1 myocytes, but the function of specific PKC isozymes in insulin action has not been elucidated. Two isoforms of PKC beta result via alternative splicing of precursor mRNA. As now shown, both isoforms are present in BC3H-1 myocytes, and insulin induces alternative splicing of the PKC beta mRNA thereby switching expression from PKC beta I to PKC beta II mRNA. This effect occurs rapidly (15 min after insulin treatment) and is dose-dependent. The switch in mRNA is reflected by increases in the protein levels of PKC beta II. High levels of 12-0-tetradecanoylphorbol-13-acetate, which are commonly used to deplete or down-regulate PKC in cells, also induce the switch to PKC beta II mRNA following overnight treatment, and protein levels of PKC beta II reflected mRNA increases. To investigate the functional importance of the shift in PKC beta isoform expression, stable transfectants of NIH-3T3 fibroblasts overexpressing PKC beta I and PKC beta II were established. The overexpression of PKC beta II but not PKC beta I in NIH-3T3 cells significantly enhanced insulin effects on glucose transport. This suggests that PKC beta II may be more selective than PKC beta I for enhancing the glucose transport effects of insulin in at least certain cells and, furthermore, that insulin can regulate the expression of PKC beta II by alternative mRNA splicing.
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Affiliation(s)
- C E Chalfant
- Department of Biochemistry and Molecular Biology, University of South Florida College of Medicine, Tampa, USA
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6
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Yamaji Y, Moe OW, Miller RT, Alpern RJ. Acid activation of immediate early genes in renal epithelial cells. J Clin Invest 1994; 94:1297-303. [PMID: 8083371 PMCID: PMC295215 DOI: 10.1172/jci117448] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
These studies examined the effect of acidosis on immediate early (IE) gene expression in renal tubule cells. In MCT cells, an SV40 transformed mouse proximal tubule cell line, incubation in acid media led to transient increases in c-fos, c-jun, junB, and egr-1 mRNA abundance, peaking at 30 min to 1 h. In vivo metabolic acidosis caused more prolonged increases in these mRNA species in renal cortex. Nuclear runon studies demonstrated increased rates of transcription for these IE genes. In addition, pretreatment of cells with cycloheximide caused superinduction of these mRNA by acid incubation. These responses are similar to those elicited by growth factors. Inhibition of tyrosine kinase pathways prevented IE gene activation by acid, while inhibition of protein kinase C and/or increases in cell calcium had no effect. In 3T3 cells, acid activated IE genes by a different mechanism in that the increase in mRNA did not include c-jun, was more prolonged, and was blocked by cycloheximide. In summary, incubation of renal cells in acid media leads to activation of IE genes that is similar to growth factor-induced IE gene activation, and is likely mediated by tyrosine kinase pathways.
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Affiliation(s)
- Y Yamaji
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235
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7
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Abstract
Insulin exerts rapid effects on cellular metabolism and can cause morphological changes by inducing rearrangements of cytoskeletal components. The regulation of specific cytoskeletal genes by insulin, however, has not been studied extensively. In the present work insulin was found to rapidly, but transiently, increase transcription of the cytoskeletal gamma-actin gene in rat H4IIE (H4) hepatoma cells. Insulin-induced transcription of the gamma-actin gene was evident within 5 min and was maximal by 15 min at 10-fold above control levels. The stimulation of transcription was transient, with a return towards basal levels by 120 min. Transcription of gamma-actin was increased at insulin concentrations as low as 1 x 10(-11) M and was maximal at 1 x 10(-9) to 1 x 10(-8) M. Transcription of several control genes (skeletal and cardiac alpha-actin and beta-tubulin) were unaltered by insulin administration. Messenger RNA (mRNA) levels for the gamma-actin gene increased, but to a lesser degree than transcription. Since the gamma-actin message is an abundant and stable mRNA, its levels would not be expected to change dramatically from a transient induction of transcription. Like insulin, phorbol esters transiently increased transcription of the gamma-actin gene. In addition, pretreatment of cells with phorbol esters for 24 h reduced the ability of insulin to induce gamma-actin transcription. These data support our hypothesis that insulin and phorbol esters share intracellular signalling pathways in the control of transcription of specific genes.
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Affiliation(s)
- J L Messina
- Department of Physiology, SUNY Health Science Center at Syracuse 13210
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Seckinger P, Milili M, Schiff C, Fougereau M. Interleukin-7 regulates c-myc expression in murine T cells and thymocytes: a role for tyrosine kinase(s) and calcium mobilization. Eur J Immunol 1994; 24:716-22. [PMID: 7510242 DOI: 10.1002/eji.1830240334] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Interleukin-7 (IL-7) was originally identified as a pre-B cell growth factor whose proliferating activity has been extended to numerous target cells including T lymphocytes. We investigated c-myc mRNA expression, an oncogene associated with proliferation, in the murine T cell line D10 G4.1 and freshly isolated thymocytes since both target cells proliferate in response to IL-7. We find that blockade of the tyrosine kinase pathway by genistein, a potent tyrosine kinase inhibitor, inhibits both IL-7-dependent D10 G4.1 cell proliferation and c-myc mRNA expression which appears to involve de novo mRNA synthesis and to be under the control of short-lived protein repressor(s). We have also examined possible signal transduction pathways which might regulate c-myc mRNA expression in the murine T cell line. IL-7 biological activity is not affected by stimulation of the protein kinase C pathway by phorbol esters. Thus, IL-7 regulates c-myc mRNA expression in a protein kinase C-independent manner and these data are strengthened by protein kinase C depletion which does not modify IL-7 c-myc mRNA responsiveness. In contrast and independent of protein kinase C activation, intracellular calcium mobilization by means of ionomycin reduces IL-7 induction of c-myc mRNA expression and may represent a physiological mechanism whereby IL-7 bioactivity is regulated. The activity of IL-7 on c-myc mRNA expression has been extended to freshly isolated thymocytes and we find a synergistic effect of IL-7 with concanavalin A. Taken together our results illuminate the molecular mechanism of IL-7 c-myc induction in the T lineage by ascribing a role for tyrosine kinase and increase in intracellular calcium in both IL-7 induced gene induction and cell proliferation.
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Affiliation(s)
- P Seckinger
- Centre d'Immunologie de Marseille-Luminy, France
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9
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Goodnight J, Mischak H, Mushinski JF. Selective involvement of protein kinase C isozymes in differentiation and neoplastic transformation. Adv Cancer Res 1994; 64:159-209. [PMID: 7879658 DOI: 10.1016/s0065-230x(08)60838-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J Goodnight
- Laboratory of Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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10
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Huwiler A, Pfeilschifter J. A role for protein kinase C-alpha in zymosan-stimulated eicosanoid synthesis in mouse peritoneal macrophages. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:69-75. [PMID: 8223588 DOI: 10.1111/j.1432-1033.1993.tb18219.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A possible regulatory function of protein kinase C (PKC) isoenzymes in zymosan-stimulated eicosanoid synthesis was studied in mouse peritoneal macrophages in culture. The addition of zymosan to intact cells labelled with [3H]arachidonic acid stimulated a time-dependent and concentration-dependent release of the fatty acid. There was a simultaneous marked increase in the synthesis of prostaglandin E2 and leukotriene C4. The protein-kinase inhibitor K-252a and the selective PKC inhibitor CGP41251 completely blocked zymosan-triggered arachidonic acid release as well as prostaglandin E2 and leukotriene C4 synthesis. In contrast, an inactive staurosporine derivative, CGP42700, failed to inhibit any of the zymosan-induced responses. The down-regulation of PKC by long-term treatment with phorbol 12-myristate 13-acetate eliminated zymosan-stimulated arachidonic acid release and eicosanoid synthesis (after 4-6 h treatment). By using specific antibodies it was observed that mouse macrophages express five PKC isoenzymes, PKC-alpha, -beta, -delta, -epsilon and -zeta. No PKC-gamma isoenzyme was detected. After exposure to phorbol 12-myristate 13-acetate, a complete depletion of PKC-beta was observed within 1 h and the complete depletion of PKC-alpha and PKC-delta isotypes was observed within 4 h. In contrast, PKC-epsilon was only partially down-regulated after a 24-h treatment with phorbol 12-myristate 13-acetate and PKC-zeta was not affected at all. These data indicate that PKC-alpha and PKC-delta isoenzymes are candidates for regulating prostaglandin and leukotriene production. From the potent inhibitory activities of K-252a and CGP41251, two compounds that reportedly display a higher selectivity for PKC-alpha compared to PKC-delta, it is suggested that PKC-alpha triggers arachidonic acid mobilization and eicosanoid synthesis in peritoneal macrophages.
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Affiliation(s)
- A Huwiler
- Department of Pharmacology, University of Basel, Switzerland
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11
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Arnold TP, Standaert ML, Hernandez H, Watson J, Mischak H, Kazanietz MG, Zhao L, Cooper DR, Farese RV. Effects of insulin and phorbol esters on MARCKS (myristoylated alanine-rich C-kinase substrate) phosphorylation (and other parameters of protein kinase C activation) in rat adipocytes, rat soleus muscle and BC3H-1 myocytes. Biochem J 1993; 295 ( Pt 1):155-64. [PMID: 8216211 PMCID: PMC1134832 DOI: 10.1042/bj2950155] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To evaluate the question of whether or not insulin activates protein kinase C (PKC), we compared the effects of insulin and phorbol esters on the phosphorylation of the PKC substrate, i.e. myristoylated alanine-rich C-kinase substrate (MARCKS). In rat adipocytes, rat soleus muscle and BC3H-1 myocytes, maximally effective concentrations of insulin and phorbol esters provoked comparable, rapid, 2-fold (on average), non-additive increases in the phosphorylation of immunoprecipitable MARCKS. These effects of insulin and phorbol esters on MARCKS phosphorylation in intact adipocytes and soleus muscles were paralleled by similar increases in the phosphorylation of an exogenous, soluble, 85 kDa PKC substrate (apparently a MARCKS protein) during incubation of post-nuclear membrane fractions in vitro. Increases in the phosphorylation of this 85 kDa PKC substrate in vitro were also observed in assays of both plasma membranes and microsomes obtained from rat adipocytes that had been treated with insulin or phorbol esters. These insulin-induced increases in PKC-dependent phosphorylating activities of adipocyte plasma membrane and microsomes were associated with increases in membrane contents of diacylglycerol, PKC-beta 1 and PKC-beta 2. Our findings suggest that insulin both translocates and activates PKC in rat adipocytes, rat soleus muscles and BC3H-1 myocytes.
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Affiliation(s)
- T P Arnold
- James A. Haley Veterans' Hospital, Department of Internal Medicine, University of South Florida, Tampa 33612
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12
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Rao GN, Lasségue B, Griendling KK, Alexander RW, Berk BC. Hydrogen peroxide-induced c-fos expression is mediated by arachidonic acid release: role of protein kinase C. Nucleic Acids Res 1993; 21:1259-63. [PMID: 8464709 PMCID: PMC309291 DOI: 10.1093/nar/21.5.1259] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We found previously that stimulation of c-fos and c-myc mRNA expression are early events in hydrogen peroxide-induced growth in rat aortic smooth muscle (RASM) cells. In the present study, we investigated the role of phospholipase A2 (PLA2) and protein kinase C (PKC) in mediating hydrogen peroxide-induced c-fos mRNA expression in RASM cells. Mepacrine and p-bromophenacylbromide, potent inhibitors of PLA2 activity, blocked hydrogen peroxide-induced c-fos mRNA expression. Arachidonic acid, a product of PLA2 activity, stimulated the expression of c-fos mRNA with a time course similar to that of hydrogen peroxide. PKC down-regulation attenuated both hydrogen peroxide and arachidonic acid-induced c-fos mRNA expression by 50%. Nordihydroguaiaretic acid (a lipoxygenase-cytochrome P450 monooxygenase inhibitor) significantly inhibited both hydrogen peroxide and arachidonic acid-induced c-fos mRNA expression, whereas indomethacin (a cyclooxygenase inhibitor) had no effect. Together, these findings indicate that 1) hydrogen peroxide-induced c-fos mRNA expression is mediated by PLA2-dependent arachidonic acid release, 2) both PKC-dependent and independent mechanisms are involved in hydrogen peroxide-induced expression of c-fos mRNA and 3) arachidonic acid metabolism via the lipoxygenase-cytochrome P450 monooxygenase pathway appears to be required for hydrogen peroxide-induced expression of c-fos mRNA.
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Affiliation(s)
- G N Rao
- Cardiology Division, Emory University School of Medicine, Atlanta, GA 30322
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13
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Quentmeier A, Daneschmand H, Klein H, Unthan-Fechner K, Probst I. Insulin-mimetic actions of phorbol ester in cultured adult rat hepatocytes. Lack of phorbol-ester-elicited inhibition of the insulin signal. Biochem J 1993; 289 ( Pt 2):549-55. [PMID: 8380998 PMCID: PMC1132203 DOI: 10.1042/bj2890549] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The actions of the phorbol ester phorbol 12-myristate 13-acetate (PMA) on glucose metabolism, amino acid transport and enzyme inductions were studied in primary cultures of adult-rat hepatocytes and compared with the effects of insulin. PMA and insulin stimulated glycolysis 5- and 7-fold respectively. The half-maximal effective dose of PMA was 60 nM. Stimulation of glycolysis was accompanied by an insulin- or PMA-dependent and okadaic acid-sensitive activation of 6-phosphofructo-2-kinase and pyruvate kinase, as well as by an increase in fructose 2,6-bisphosphate. Glucose production from glycogen was decreased to 50% by PMA and to 15% by insulin, whereas glycogen synthesis was stimulated 2- and 7-fold respectively. PMA also increased aminoisobutyrate uptake, induced ornithine decarboxylase and counteracted the glucagon-dependent induction of phosphoenolpyruvate carboxykinase. PMA strongly antagonized the hormonal activation of glycogen synthesis, but all other insulin actions assayed were not decreased by the phorbol ester. Whereas additive effects of PMA and insulin were not detected, PMA and a simultaneous increase in the glucose concentration had additive effects on glycolysis and glycogen metabolism. Cell exposure to insulin resulted in receptor autophosphorylation and a more than 10-fold activation of the receptor tyrosine kinase. PMA did not alter these effects, and also had no effect on the receptor phosphorylation status in the absence of insulin. Long-term (15 h) pretreatment of the cells with PMA abolished all PMA effects, but not the insulin effects. It is concluded that PMA does not generally antagonize the action of insulin in differentiated adult hepatocytes, and that insulin and PMA may use related signal-transduction pathways.
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Affiliation(s)
- A Quentmeier
- Institut für Biochemie, Fachbereich Medizin, Georg-August-Universität Göttingen, Federal Republic of Germany
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14
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Altered Signal Transduction in Carcinogenesis1. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/s1569-2558(08)60235-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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15
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Romero G, Larner J. Insulin mediators and the mechanism of insulin action. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1993; 24:21-50. [PMID: 8504064 DOI: 10.1016/s1054-3589(08)60932-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- G Romero
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania 15261
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16
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17
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Cooper DR, Watson JE, Hernandez H, Yu B, Standaert ML, Ways DK, Arnold TT, Ishizuka T, Farese RV. Direct evidence for protein kinase C involvement in insulin-stimulated hexose uptake. Biochem Biophys Res Commun 1992; 188:142-8. [PMID: 1417838 DOI: 10.1016/0006-291x(92)92361-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Insulin has been reported to translocate protein kinase C (PKC) in rat adipocytes, and activation of PKC by phorbol esters is known to increase hexose uptake in these cells (1.2). To test the hypothesis that PKC may participate in insulin-stimulated hexose uptake, adipocytes were partially depleted of protein kinase C by overnight phorbol ester treatment, thereby impairing insulin effects on hexose uptake. Purified PKC was then introduced into these PKC-depleted adipocytes by electropermeabilization, and this fully restored insulin-stimulated hexose uptake. These findings provide direct evidence that PKC is required for insulin-stimulated hexose uptake.
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Affiliation(s)
- D R Cooper
- Research Service, James A. Haley Veterans Administration Hospital, Tampa, FL 33612
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18
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Borner C, Guadagno S, Fabbro D, Weinstein I. Expression of four protein kinase C isoforms in rat fibroblasts. Distinct subcellular distribution and regulation by calcium and phorbol esters. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42359-9] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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Abstract
Insulin and the phorbol ester, phorbol 12-myristate 13-acetate, induce beta-actin gene transcription in H4 cells. This occurred rapidly, with a maximum 15-fold stimulation following 15 min of insulin (5 x 10(-9) M) or phorbol ester (1 microgram/ml) exposure. The increase in beta-actin transcription was transitory, returning to baseline within 120 min. Pretreatment of cells with phorbol ester for 24 h, reducing functional protein kinase C activity, abolished the ability of phorbol esters to increase beta-actin transcription. When insulin was added to phorbol ester-pretreated cells the insulin-induced increase in beta-actin transcription was reduced by 40-60%. These findings support our hypothesis that a common regulatory signal is utilized by both insulin and phorbol esters for the complete induction of specific genes.
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Affiliation(s)
- J L Messina
- Department of Physiology, SUNY Health Science Center, Syracuse 13210
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20
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Hanania N, Lezenes JR, Castagna M. Tumorigenicity-associated expression of protein kinase C isoforms in rhabdomyosarcoma-derived cells. FEBS Lett 1992; 303:15-8. [PMID: 1592108 DOI: 10.1016/0014-5793(92)80467-u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cell sublines were derived from Ni-induced rat rhabdomyosarcoma which differed in their degree of tumorigenicity. We compared the expression of protein kinase C isoforms alpha, beta, gamma and epsilon in three sublines developing tumors in syngeneic rats (Sy+) and in two sublines devoid of tumorigenicity in these animals (Sy-), with that of normal skeletal muscle. Northern and Western blotting experiments showed that PKC alpha was dramatically overexpressed in Sy- cells whereas it was underexpressed in Sy+ cells. Southern blot analysis provided evidence for a 3-fold increase of PKC alpha-related DNA fragments in Sy- cells. Steady-state levels of the PKC epsilon-related transcript were also markedly decreased in Sy+ cells. However, the expression of PKC beta-related RNA was increased in these cells. Our data support the concept that the differential expression of the PKC isoforms may play a critical role in determining the neoplastic phenotype.
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Affiliation(s)
- N Hanania
- Groupe de laboratoires de l'IRSC, Villejuif, France
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21
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Messina J, Standaert M, Ishizuka T, Weinstock R, Farese R. Role of protein kinase C in insulin's regulation of c-fos transcription. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50411-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Altin JG, Wetts R, Riabowol KT, Bradshaw RA. Testing the in vivo role of protein kinase C and c-fos in neurite outgrowth by microinjection of antibodies into PC12 cells. Mol Biol Cell 1992; 3:323-33. [PMID: 1627832 PMCID: PMC275533 DOI: 10.1091/mbc.3.3.323] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
To define the molecular bases of growth factor-induced signal transduction pathways, antibodies known to block the activity of either protein kinase C (PKC) or the fos protein were introduced into PC12 cells by microinjection. The antibody against PKC significantly inhibited neurite outgrowth when scored 24 h after microinjection and exposure to nerve growth factor (NGF). Microinjection of antibodies to fos significantly increased the percentage of neurite-bearing cells after exposure to either NGF or basic fibroblast growth factor (bFGF) but inhibited the stimulation of DNA synthesis by serum, suggesting that in PC12 cells, fos is involved in cellular proliferation. Thus, activation of PKC is involved in the induction of neurite outgrowth by NGF, but expression of the fos protein, which is induced by both NGF and bFGF, is not necessary and inhibits neurite outgrowth.
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Affiliation(s)
- J G Altin
- Department of Biological Chemistry, College of Medicine, University of California, Irvine
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23
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Farese RV, Standaert ML, Arnold T, Yu B, Ishizuka T, Hoffman J, Vila M, Cooper DR. The role of protein kinase C in insulin action. Cell Signal 1992; 4:133-43. [PMID: 1616820 DOI: 10.1016/0898-6568(92)90077-l] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- R V Farese
- Research Service, J. A. Haley Veterans' Hospital, Tampa, FL 33612
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24
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Hu B, Altschuld RA, Hohl CM. Phorbol esters and cyclic AMP activate AMP deaminase in adult rat cardiac myocytes. Arch Biochem Biophys 1991; 291:100-6. [PMID: 1681786 DOI: 10.1016/0003-9861(91)90110-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using rapid deenergization as a probe for adenylate deaminase activity in intact adult rat cardiac myocytes, we have previously established that IMP formation is enhanced by alpha-adrenergic agonists. In the present study, the effect of adrenergic agents on adenylate deaminase was further characterized. Phenylephrine (PE)3 increased IMP production in a dose-dependent fashion with an EC50 of 8 x 10(-7) M. The response to PE was reversed within 10 min by the alpha 1-antagonist, prazosin. Likewise, adenylate deaminase was also activated in ventricular myocytes challenged with phorbol 12-myristate 13-acetate (PMA, EC50 = 5 nM); cardiac cells presented with 100 nM PMA increased IMP production from 4.4 +/- 0.5 (control) to 15.7 +/- 0.9 nmol/mg protein when subsequently deenergized. The effects of PMA and PE were attenuated 85 +/- 5% and 96 +/- 4%, respectively, by pretreatment of cells with 150 nM staurosporine, an inhibitor of protein kinase C. Furthermore, incubation of cardiac cells with 1 microM PMA for 24 h blunted the response to both PMA and phenylephrine 85-90%. Elevating cyclic AMP (cAMP) content to greater than 15 pmol/mg by treatment with forskolin or isoproterenol plus isobutylmethylxanthine also resulted in enhanced adenylate deaminase activity, but this stimulatory effect was not abolished by 24 h incubation with 5 microM PMA. Forskolin and PMA-induced increases in IMP production appeared to be additive. However, 0.5 microM isoproterenol inhibited the cellular response to phenylephrine by about 30% but did not affect PMA-stimulated adenylate deaminase activity. We conclude that both cAMP and protein kinase C stimulate adenylate deaminase, perhaps through selective activation of different isoforms. However, cAMP also exerts partial inhibition on alpha-adrenoreceptor-mediated increases in IMP production.
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Affiliation(s)
- B Hu
- Department of Medical Biochemistry, Ohio State University, Columbus 43210
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25
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Huwiler A, Fabbro D, Pfeilschifter J. Differential recovery of protein kinase C-alpha and -epsilon isozymes after long-term phorbol ester treatment in rat renal mesangial cells. Biochem Biophys Res Commun 1991; 180:1422-8. [PMID: 1953788 DOI: 10.1016/s0006-291x(05)81355-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Glomerular mesangial cells have been shown to express two protein kinase C (PKC) isozymes, PKC-alpha and PKC-epsilon. Upon long-term treatment with phorbol ester PKC-alpha is depleted faster than PKC-epsilon. Here we demonstrate that removal of phorbol ester results in a differential recovery of PKC-alpha and -epsilon isozymes. Whereas PKC-epsilon starts to recover within 1h, PKC-alpha does not begin to recover before 4 h after removal of phorbol ester. These data suggest a differential rate of protein synthesis of PKC-alpha and -epsilon. In parallel to the recovery of PKC isozymes mesangial cells also regained their functional responsiveness, i.e., stimulation of prostaglandin synthesis and feedback inhibition of angiotensin II-stimulated InsP3 formation.
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Affiliation(s)
- A Huwiler
- Research Department, Ciba-Geigy Ltd, Basel, Switzerland
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26
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Medema R, Burgering B, Bos J. Insulin-induced p21ras activation does not require protein kinase C, but a protein sensitive to phenylarsine oxide. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54838-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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27
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Huwiler A, Fabbro D, Pfeilschifter J. Possible regulatory functions of protein kinase C-alpha and -epsilon isoenzymes in rat renal mesangial cells. Stimulation of prostaglandin synthesis and feedback inhibition of angiotensin II-stimulated phosphoinositide hydrolysis. Biochem J 1991; 279 ( Pt 2):441-5. [PMID: 1659379 PMCID: PMC1151624 DOI: 10.1042/bj2790441] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Short-term treatment of mesangial cells with phorbol 12-myristate 13-acetate (PMA) decreases angiotensin II-induced InsP3 formation, but potentiates hormone-stimulated arachidonic acid release and prostaglandin (PG) E2 synthesis. Long-term treatment with PMA augments hormone-stimulated InsP3 generation (after 8 h treatment), but eliminates angiotensin II-induced arachidonic acid release and PGE2 formation (after 24 h treatment). By using specific antibodies it is observed that mesangial cells express two protein kinase C (PKC) isoenzymes, PKC-alpha and -epsilon. No PKC-beta and -gamma isoenzymes are detected. On exposure to PMA a complete depletion of PKC-alpha is observed within 8 h. In contrast, down-regulation of PKC-epsilon to 10-20% of that found in control cells requires a 24 h treatment with PMA. These results may imply that PKC-alpha mediates feedback inhibition of phosphoinositide hydrolysis, whereas PKC-epsilon is a candidate for regulating PG synthesis in mesangial cells.
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Affiliation(s)
- A Huwiler
- Research Department, Ciba-Geigy Ltd., Basel, Switzerland
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28
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Jelkmann W, Huwiler A, Fandrey J, Pfeilschifter J. Inhibition of erythropoietin production by phorbol ester is associated with down-regulation of protein kinase C-alpha isoenzyme in hepatoma cells. Biochem Biophys Res Commun 1991; 179:1441-8. [PMID: 1656952 DOI: 10.1016/0006-291x(91)91734-t] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The role of protein kinase C (PKC) in the control of erythropoietin (Epo) production was studied using the human hepatoma cell line HepG2. Inhibition of PKC by staurosporine and the selective PKC inhibitor CGP 41251 significantly reduced Epo formation. No inhibition occurred with the inactive staurosporine derivative CGP 42700. Treatment with phorbol 12-myristate 13-acetate (PMA) for 24 h dose-dependently inhibited Epo formation, thus suggesting that down-regulation of PKC might be responsible for this inhibition. Immunoblotting experiments showed that incubation of HepG2 cells with PMA for 24 h resulted in a selective and almost complete down-regulation of PKC-alpha. Thus, PKC-alpha may play a permissive role in Epo synthesis in HepG2 cells.
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Affiliation(s)
- W Jelkmann
- Department of Physiology, University of Bonn, Germany
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29
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Machida CM, Scott JD, Ciment G. NGF-induction of the metalloproteinase-transin/stromelysin in PC12 cells: involvement of multiple protein kinases. J Biophys Biochem Cytol 1991; 114:1037-48. [PMID: 1908468 PMCID: PMC2289118 DOI: 10.1083/jcb.114.5.1037] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In previous work, we found that nerve growth factor (NGF) induced expression of the mRNA transcript encoding the metalloproteinase transin/stromelysin in PC12 cells. Transin was found, moreover, to be a "late" gene product whose expression correlated with neurites extension. In this study, various aspects of the NGF intracellular signaling pathway in PC12 cells are investigated. We show that the protein kinase inhibitor staurosporine, but not various other kinase inhibitors, specifically blocked the NGF induction of transin. Preliminary characterization of this staurosporine-sensitive kinase suggest that it does not correspond to a tyrosine kinase, nor various serine kinases, and that it is involved both at the transcriptional and posttranscriptional levels of transin gene regulation. In contrast to these effects of staurosporine, various activators of protein kinases C and A augmented the NGF induction of transin. Similar effects of these kinase inhibitors and activators were also observed with the expression of various immediate-early genes that have been proposed to mediate the transcriptional effects of NGF, including c-fos and c-jun. These data suggest, therefore, that the NGF induction of transin mRNA expression involves multiple protein kinases acting at a number of postreceptor regulatory steps in the NGF signaling pathway.
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Affiliation(s)
- C M Machida
- Department of Cell Biology and Anatomy, Oregon Health Sciences University, Portland 97201-3098
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30
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Robles-Flores M, Alcántara-Hernández R, García-Sáinz JA. Differences in phorbol ester-induced decrease of the activity of protein kinase C isozymes in rat hepatocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1094:77-84. [PMID: 1653025 DOI: 10.1016/0167-4889(91)90028-v] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Two main forms of protein kinase C (PKC) activity were found in rat hepatocytes using DEAE-cellulose chromatography: PKC 1 and PKC 2. Treatment of cells with 1 microM 12-O-tetradecanoylphorbol 13-acetate (TPA) for 15 min caused a marked loss of PKC 1 activity and only a small loss of PKC 2 activity. Hydroxyapatite column chromatography resolved PKC 1 into three distinct peaks 1a, 1b and 1c, and PKC 2 into four peaks 2a, 2b, 2c and 2d. Immunoblot analysis with isozyme-specific monoclonal antibodies identified peak 1a as PKC-beta and peak 1b as PKC-alpha; the other peaks of activity were not identified. Treatment with TPA provoked a loss of activity of peaks 1b (PKC-alpha) and 1c, whereas peak 1a (PKC-beta) activity was not affected. The peaks of activity corresponding to PCK 2 did not show any major change due to TPA treatment except peak 2d that decreased. The apparent disappearance of PKC histone-kinase activity induced by TPA was also observed using other substrates (protamine or vinculin). The TPA-induced decrease in activity occurs in a time-dependent and dose-dependent fashion. However, the time-courses, the extent of depletion and the potency order of phorbol esters in induction of an activity decrease in the two groups of isoforms exhibited substantial differences.
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Affiliation(s)
- M Robles-Flores
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F
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31
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Vaidya TB, Weyman CM, Teegarden D, Ashendel CL, Taparowsky EJ. Inhibition of myogenesis by the H-ras oncogene: implication of a role for protein kinase C. J Cell Biol 1991; 114:809-20. [PMID: 1714463 PMCID: PMC2289900 DOI: 10.1083/jcb.114.4.809] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Expression of the oncogenic form of H-ras p21 in the mouse myogenic cell line, 23A2, blocks myogenesis and inhibits expression of the myogenic regulatory factor gene, MyoD1. Previous studies from a number of laboratories have demonstrated that the activation of ras p21 is associated with changes in phospholipid metabolism that directly, or indirectly, lead to elevated levels of intracellular diacylglycerol and the subsequent activation of protein kinase C (PKC). To assess the importance of PKC activity to the ras-induced inhibition of skeletal myogenesis, we examined the levels of PKC activity associated with the terminal differentiation of wild-type myoblasts and with the differentiation-defective phenotype of 23A2 ras cells. We demonstrate that there is a 50% reduction in PKC activity during normal myogenesis and that PKC activity is required for myoblast fusion, but not for the transcriptional activation of muscle-specific genes. In contrast, we found that the differentiation-defective 23A2 ras cells possess two- to threefold more PKC activity than wild-type myofibers and that reducing the PKC activity in these cultures does not reverse their non-myogenic phenotype. On the other hand, if PKC activity is downregulated in 23A2 cells before the expression of activated ras p21, myogenesis is not inhibited. These results suggest that activated ras p21 relies on a PKC-dependent signal transduction pathway to initiate, but not to sustain, its negative effects on 23A2 skeletal myogenesis and underscore the potential importance of PKC activity to the proper control of skeletal muscle differentiation.
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Affiliation(s)
- T B Vaidya
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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32
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Sugden D. Down-regulation of pinealocyte protein kinase C: effect on alpha 1-adrenergic potentiation of beta-adrenoceptor stimulation of cyclic AMP accumulation and induction of serotonin N-acetyltransferase activity. J Neurochem 1991; 57:216-21. [PMID: 1675661 DOI: 10.1111/j.1471-4159.1991.tb02118.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Treatment of rat pinealocytes with 4 beta-phorbol 12,13-dibutyrate down-regulated protein kinase C (PKC) activity. Loss of activity was concentration-dependent (50% loss at 8 x 10(-7) M after 18 h of treatment) and time-dependent (50% loss after 2 h with 3 x 10(-6) M). Phenylephrine, an alpha 1-adrenergic agonist, and phorbol esters unable to activate PKC did not down-regulate the enzyme. alpha 1-Adrenergic amplification of beta-adrenergic stimulation of cyclic AMP accumulation, a response previously shown to be mediated by PKC activation, was reduced by only 50% in cells in which PKC activity was down-regulated by approximately 95%. These data suggest that there is not a simple proportional relationship between the degree of activation of pinealocyte PKC and the alpha 1-adrenergic amplification of beta-adrenergic cyclic AMP synthesis. In down-regulated cells, alpha 1-adrenergic amplification of beta-adrenergic induction of serotonin N-acetyltransferase activity, a key cyclic AMP-responsive enzyme involved in the nocturnal synthesis of the pineal hormone melatonin, was unchanged. Thus, even though alpha 1-adrenergic amplification of cyclic AMP synthesis is impaired, sufficient cyclic AMP is generated to allow a full induction of serotonin N-acetyltransferase activity. This finding raises the important question of whether the alpha 1-adrenergic amplification mechanism has a physiological role in regulating melatonin synthesis in vivo.
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Affiliation(s)
- D Sugden
- Biomedical Sciences Division, King's College London, England
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33
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34
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Lassègue B, Alexander RW, Clark M, Griendling KK. Angiotensin II-induced phosphatidylcholine hydrolysis in cultured vascular smooth-muscle cells. Regulation and localization. Biochem J 1991; 276 ( Pt 1):19-25. [PMID: 1903932 PMCID: PMC1151137 DOI: 10.1042/bj2760019] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In cultured vascular smooth-muscle cells (VSMC), angiotensin II (AngII) induces a biphasic, sustained increase in diacylglycerol (DG) of unclear origin. To determine whether hydrolysis of phosphatidylcholine (PC) is a possible source of DG, we labelled cellular PC with [3H]choline, and measured the formation of intra- and extra-cellular [3H]choline and [3H]phosphocholine after stimulation with AngII. AngII induced a concentration-dependent release of choline from VSMC that was significant at 2 min and was sustained over 20 min. In contrast, accumulation of choline inside the cells was very slight. AngII also increased the formation of [3H]myristate-labelled phosphatidic acid, and, in the presence of ethanol, of [3H]phosphatidylethanol, characteristic of a phospholipase D (PLD) activity. Extracellular release of choline was partially inhibited by removal of extracellular Ca2+ (54 +/- 9% inhibition at 10 min) or inhibition of receptor processing by phenylarsine oxide (79 +/- 8% inhibition at 20 min). The protein kinase C activator phorbol myristate acetate also stimulated a large release of choline after a 5 min lag, which was unaffected by the Ca2+ ionophore ionomycin, but was additive with AngII stimulation. Down-regulation of protein kinase C by a 24 h incubation with phorbol dibutyrate (200 nM) decreased basal choline release, but had no effect on AngII stimulation. We conclude that AngII induces a major PC hydrolysis, probably mainly via PLD activation. This reaction is partially dependent on Ca2+ and is independent of protein kinase C, and appears to be mediated by cellular processing of the receptor-agonist complex. Our results are consistent with a preferential hydrolysis of PC from the external leaflet of the plasmalemma, and raise the possibility that PC hydrolysis occurs in specialized 'signalling domains' in VSMC.
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Affiliation(s)
- B Lassègue
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
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35
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Characterization of calcium-independent forms of protein kinase C-beta in phorbol ester-treated rabbit platelets. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)31502-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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36
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Standaert ML, Sasse J, Cooper DR, Farese RV. Protein kinase C(19-31) pseudosubstrate inhibition of insulin action in rat adipocytes. FEBS Lett 1991; 282:139-42. [PMID: 2026249 DOI: 10.1016/0014-5793(91)80463-d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Treatment of intact adipocytes with the autoregulatory PKC pseudosubstrate PKC(19-31) inhibited insulin-stimulated hexose uptake and lipogenesis, with no effect on basal values. The effect was dose-dependent with respective IC50 values of 30 microM and 600 microM for insulin-stimulated hexose uptake in electroporated and intact adipocytes. These studies indicate that PKC may play a role in the mediation of insulin action in adipocytes.
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Affiliation(s)
- M L Standaert
- James A. Haley Veterans' Administration Hospital, Tampa, FL 33612
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37
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Farese RV, Standaert ML, Ishizuka T, Yu B, Hernandez H, Waldron C, Watson J, Farese JP, Cooper DR, Wickstrom E. Antisense DNA downregulates protein kinase C isozymes (beta and alpha) and insulin-stimulated 2-deoxyglucose uptake in rat adipocytes. ANTISENSE RESEARCH AND DEVELOPMENT 1991; 1:35-42. [PMID: 1822247 DOI: 10.1089/ard.1991.1.35] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rat adipocytes were treated with antisense dimethoxytrityl pentadecadeoxynucleotides, complementary to mRNA initiation codon regions for alpha and beta isozymes of protein kinase C (PKC). This antisense treatment provoked 50-70% decreases in PKC and insulin-stimulated 2-deoxyglucose uptake, but did not inhibit insulin-stimulated diacylglycerol synthesis. Sense or nonsense oligodeoxynucleotides were without effect on PKC and 2-deoxyglucose uptake. These results suggest that: (i) PKC-alpha and PKC-beta isozymes can be specifically downregulated in rat adipocytes by antisense oligodeoxynucleotides, and (ii) insulin-stimulated glucose transport requires PKC.
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Affiliation(s)
- R V Farese
- James A. Haley Veterans' Hospital, Department of Internal Medicine, Tampa, FL
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38
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Hocevar BA, Fields AP. Selective translocation of beta II-protein kinase C to the nucleus of human promyelocytic (HL60) leukemia cells. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52396-6] [Citation(s) in RCA: 193] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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39
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Insulin receptor tyrosine residues 1162 and 1163 control insulin stimulation of myristoyl-diacylglycerol generation and subsequent activation of glucose transport. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45354-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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40
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Standaert ML, Buckley DJ, Ishizuka T, Hoffman JM, Cooper DR, Pollet RJ, Farese RV. Protein kinase C inhibitors block insulin and PMA-stimulated hexose transport in isolated rat adipocytes and BC3H-1 myocytes. Metabolism 1990; 39:1170-9. [PMID: 2233279 DOI: 10.1016/0026-0495(90)90090-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Effects of protein kinase C (PKC) inhibitors and "down-regulation" on insulin and PMA-stimulated 2-deoxyglucose transport were determined in isolated rat adipocytes or BC3H-1 myocytes. In both model systems, H-7, sangivamycin, and staurosporine, inhibitors of the catalytic domain of PKC, each effectively blocked insulin and PMA-stimulated hexose uptake at similar concentrations. In the myocytes, staurosporine completely blocked the insulin effect retained post-chronic phorbol myristate acetate (PMA)-induced "down-regulation." These findings indicate (1) that chronic pretreatment with PMA may not lead to a complete loss of PKC activity in the myocyte, and (2) that PKC is involved in insulin-stimulated hexose transport in both isolated rat adipocytes and BC3H-1 myocytes.
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41
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Metz SA, Dunlop M. Stimulation of insulin release by phospholipase D. A potential role for endogenous phosphatidic acid in pancreatic islet function. Biochem J 1990; 270:427-35. [PMID: 2119172 PMCID: PMC1131740 DOI: 10.1042/bj2700427] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Although exogenous phosphatidic acid (PA) has been shown to promote insulin release, the effects of endogenous PA on endocrine function are largely unexplored. In order to generate PA in situ, intact adult-rat islets were treated with exogenous phospholipases of the D type (PLD), and their effects on phospholipid metabolism and on insulin release were studied in parallel. Chromatographically purified PLD from Streptomyces chromofuscus stimulated the accumulation of PA in [14C]arachidonate- or [14C]myristate-prelabelled islets, and also promoted insulin secretion over an identical concentration range. During 30 min incubations, insulin release correlated closely with the accumulation of [14C]arachidonate-labelled PA (r2 = 0.98; P less than 0.01) or [14C]myristate-labelled PA (r2 = 0.97; P less than 0.01). Similar effects were seen both in freshly isolated and in overnight-cultured intact islets. In contrast, PLDs (from cabbage or peanut) which do not support phospholipid hydrolysis at the pH of the extracellular medium also did not promote insulin release. The effects on secretion of the active PLD preparation were inhibited by modest cooling (to 30 degrees C); dantrolene or Co2+ also inhibited PLD-induced secretion without decreasing PLD-induced PA formation. Additionally, the removal of PLD left the subsequent islet responsiveness to glucose intact, further supporting an exocytotic non-toxic mechanism. PLD-induced insulin release did not appear to require influx of extracellular Ca2+, nor could the activation of protein kinase C clearly be implicated. During incubations of 30 min, PLD selectively generated PA; however, more prolonged incubations (60 min) also led to production of some diacyglycerol and free arachidonic acid concomitant with progressive insulin release. These data suggest that PLD activation has both rapid and direct effects (via PA) and more delayed, secondary, effects (via other effects of PA or the generation of other lipid signals). Taken in conjunction with our demonstration that pancreatic islets contain an endogenous PLD which generates PA [Dunlop & Metz (1989) Biochem. Biophys. Res. Commun. 163, 922-928], these studies provide evidence suggesting that PLD activation (and possibly other pathways leading to PA formation) could play a role in stimulus-secretion coupling in pancreatic islets.
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Affiliation(s)
- S A Metz
- Research Service, Denver VA Medical Center, CO 80220
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42
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43
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Godson C, Weiss BA, Insel PA. Differential activation of protein kinase C alpha is associated with arachidonate release in Madin-Darby canine kidney cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38894-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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44
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Cleland PJ, Abel KC, Rattigan S, Clark MG. Long-term treatment of isolated rat soleus muscle with phorbol ester leads to loss of contraction-induced glucose transport. Biochem J 1990; 267:659-63. [PMID: 2187433 PMCID: PMC1131348 DOI: 10.1042/bj2670659] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Muscle contraction involves mobilization of intracellular Ca2+ and is associated with several metabolic adjustments, including increased glucose transport. In the present study isolated rat soleus muscles were exposed to 12-O-tetradecanoylphorbol 13-acetate, and responses to both insulin and contraction in terms of glucose transport were assessed. Muscles treated with this phorbol ester for 12 h showed an increased basal rate of 3-O-methylglucose uptake, and responded partially to insulin but did not respond to contraction. Phorbol-ester-treated and non-treated (vehicle-only) muscles were indistinguishable in terms of pre-contraction content of adenine nucleotide, phosphocreatine, lactate and glycogen, as well as contractile performance and contraction-induced glycogenolysis. Phorbol ester treatment of isolated solei for 12 h resulted in the loss of 90% of protein kinase C activity as determined with histone IIIs as substrate, and 70% as determined by using phorbol ester binding. It is concluded that treatment of solei with phorbol ester gives rise to a marked loss of contraction-induced glucose transport.
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Affiliation(s)
- P J Cleland
- Department of Biochemistry, University of Tasmania, Hobart, Australia
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Farese RV, Cooper DR. Potential role of phospholipid-signaling systems in insulin action and states of clinical insulin resistance. DIABETES/METABOLISM REVIEWS 1989; 5:455-74. [PMID: 2667929 DOI: 10.1002/dmr.5610050504] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R V Farese
- J. A. Haley Veterans' Hospital, Tampa, Florida
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