PMID:16411896

Citation	Park, HY, Wu, C, Yonemoto, L, Murphy-Smith, M, Wu, H, Stachur, CM and Gilchrest, BA (2006) MITF mediates cAMP-induced protein kinase C-beta expression in human melanocytes. Biochem. J. 395:571-8
Abstract	The cAMP-dependent pathway up-regulates MITF (microphthalmia-associated transcription factor), important for key melanogenic proteins such as tyrosinase, TRP-1 (tyrosinase-related protein 1) and TRP-2. We asked whether MITF is also a key transcription factor for PKC-beta (protein kinase C-beta), required to phosphorylate otherwise inactive tyrosinase. When paired cultures of human melanocytes were treated with isobutylmethylxanthine, known to increase intracellular cAMP, both protein and mRNA levels of PKC-beta were induced by 24 h. To determine whether MITF modulates PKC-beta expression, paired cultures of human melanocytes were transfected with dn-MITF (dominant-negative MITF) or empty control vector. By immunoblotting, PKC-beta protein was reduced by 63+/-3.7% within 48 h. Co-transfection of an expression vector for MITF-M, the MITF isoform specific for pigment cells, or empty control vector with a full-length PKC-beta promoter-CAT (chloramphenicol acetyltransferase) reporter construct (PKC-beta/CAT) into Cos-7 cells showed >60-fold increase in CAT activity. Melanocytes abundantly also expressed MITF-A, as well as the MITF-B and MITF-H isoforms. However, in contrast with MITF-M, MITF-A failed to transactivate co-expressed PKC-beta/CAT or CAT constructs under the control of a full-length tyrosinase promoter. Together, these results demonstrate that MITF, specifically MITF-M, is a key transcription factor for PKC-beta, linking the PKC- and cAMP-dependent pathways in regulation of melanogenesis.
Links	PubMed PMC1462691 Online version:10.1042/BJ20051388
Keywords	1-Methyl-3-isobutylxanthine/pharmacology; Cells, Cultured; Cyclic AMP/metabolism; Cyclic AMP/pharmacology; Enzyme Induction/drug effects; Humans; Melanocytes/drug effects; Melanocytes/enzymology; Microphthalmia-Associated Transcription Factor/genetics; Microphthalmia-Associated Transcription Factor/metabolism; Monophenol Monooxygenase/genetics; Monophenol Monooxygenase/metabolism; Promoter Regions, Genetic/genetics; Protein Isoforms/genetics; Protein Isoforms/metabolism; Protein Kinase C/genetics; Protein Kinase C/metabolism; RNA, Messenger/genetics; Transcription, Genetic/genetics; Up-Regulation/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:MITF		GO:2001141: regulation of RNA biosynthetic process	ECO:0000314:		P		figure 5b1 and 5b2 show that MITF-M transfection upregulates PKC-beta promoter activity approximately 60-fold over control vector transfection.	complete CACAO 3536
HUMAN:MITF	involved_in	GO:2001141: regulation of RNA biosynthetic process	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

References

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