Involvement of ITF2 in the transcriptional regulation of melanogenic genes.
In response to agouti signal protein, melanocytes switch from producing eumelanin to pheomelanin concomitant with the down-regulation of melanogenic gene transcription. We previously reported that a ubiquitous basic helix-loop-helix transcription factor, known as ITF2, is up-regulated during this switch, and we now report that treatment of melanocytes with melanocyte-stimulating hormone down-regulates expression of ITF2. To more fully characterize the involvement of ITF2 in regulating melanogenic gene transcription, ITF2 sense or antisense constructs were introduced into melan-a melanocytes. Gene and protein expression analyses and luciferase reporter assays using promoters from melanogenic genes showed that up-regulation of ITF2 suppressed melanogenic gene expression as well as the expression of Mitf, a melanocyte-specific transcription factor. In addition, stable ITF2 sense transfectants had significant reductions in pigmentation and a less dendritic phenotype compared with mock transfectants. In contrast, ITF2 antisense-transfected melanocytes were more pigmented and more dendritic. These results demonstrate that up-regulation of ITF2 during the pheomelanin switch is functionally significant and reveal that differential expression of a ubiquitous basic helix-loop-helix transcription factor can modulate expression of melanogenic genes and the differentiation of melanocytes.
Furumura
M
M
Pigment Cell Biology Section, Laboratory of Cell Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Potterf
S B
SB
Toyofuku
K
K
Matsunaga
J
J
Muller
J
J
Hearing
V J
VJ
D000818:Animals; D000951:Antigens, Neoplasm; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D015152:Blotting, Northern; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D003713:Dendritic Cells / Q000378:metabolism; D015536:Down-Regulation; D017930:Genes, Reporter; D018257:Helix-Loop-Helix Motifs; D008156:Luciferases / Q000378:metabolism; D058965:MART-1 Antigen; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D051820:TCF Transcription Factors; D015534:Trans-Activators / Q000737:chemistry / Q000502:physiology*; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation
D000951:Antigens, Neoplasm; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D058965:MART-1 Antigen; D008543:Melanins; C548668:Mlana protein, mouse; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D012333:RNA, Messenger; D051820:TCF Transcription Factors; C090743:Tcf4 protein, mouse; D015534:Trans-Activators; D000073940:Transcription Factor 4; D014157:Transcription Factors; C018362:pheomelanin; D000242:Cyclic AMP; D008156:Luciferases; D012260:Ribonucleases