Putative conventional protein kinase C inhibitor Gödecke 6976 [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole] stimulates transglutaminase activity in primary mouse epidermal keratinocytes.
Much data in the literature suggest a role for protein kinase C (PKC) in regulating keratinocyte proliferation and differentiation. Nevertheless, the exact role of this family of isoenzymes is unclear, since PKC agonists (e.g., phorbol esters) are known to stimulate expression of both proliferative and differentiative markers in keratinocytes. Similarly, PKC inhibitors have been demonstrated both to inhibit [2-[1-3(aminopropyl)indol-3-yl]-3(1-methyl-1H-indol-3-yl)maleimide, acetate (Ro 31-7549) and 3-[1-[3-(amidinothio)propyl-1H-indol-3-(1-methyl-1H-indol-3yl) maleimide (Ro 31-8220)] and to induce (staurosporine) keratinocyte differentiation. In this study, we examined the role of the PKC inhibitor, Gödecke 6976 (Gö6976) [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo (3,4-c)-carbazole], on keratinocyte proliferation, as measured by DNA synthesis, and differentiation, as monitored by transglutaminase activity. This compound is reported to be selective for the conventional PKC isoforms, of which keratinocytes express only PKCalpha, and for protein kinase D (PKD; also known as PKCmu). We report that Gö6976 stimulated transglutaminase activity. Consistent with this effect, Gö6976 also potently inhibited [(3)H]thymidine incorporation (a half-maximal inhibitory concentration of approximately 0.1 microM). In addition, Gö6976 (1 microM) was able to enhance the stimulation of transglutaminase activity by 1,25-dihydroxyvitamin D(3) but had no effect on D(3)-induced expression of keratin-1. Conversely, Gö6983 [2-[1-(3-dimethylaminopropy)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl)maleimide], a similar compound that also selectively inhibits conventional PKCalpha, but not PKD, had little or no effect on DNA synthesis or transglutaminase activity (up to 1 microM). The effect of Gö6976 was not due to cytotoxicity as its effect on thymidine incorporation was largely reversible, and its stimulation of transglutaminase activity could be inhibited by another general PKC inhibitor, bisindolylmaleimide I. Therefore, our results suggest a proproliferative, antidifferentiative role for PKD in epidermal maturation.
Shapiro
Brian A
BA
Program in Cell Signaling, Department of Medicine, andDepartment of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia.
Ray
Sagarika
S
Jung
EunMi
E
Allred
William T
WT
Bollag
Wendy B
WB
D000818:Animals; D015153:Blotting, Western; D002227:Carbazoles / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects; D015603:Keratinocytes / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008813:Mice, Inbred ICR; D009414:Nerve Growth Factors / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D050637:Receptors, Dopamine D3; D013268:Stimulation, Chemical; D011503:Transglutaminases / Q000096:biosynthesis*
D002227:Carbazoles; C493594:Drd3 protein, mouse; D004791:Enzyme Inhibitors; D009414:Nerve Growth Factors; D019384:Nucleic Acid Synthesis Inhibitors; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C459383:goedecke 6976; D004247:DNA; D011503:Transglutaminases; C089212:protein kinase D; D011493:Protein Kinase C