title: Transcriptional activation of tyrosinase gene by human placental sphingolipid.
abstract: The sphingolipids, a class of complex bioactive lipids, are involved in diverse cellular functions such as proliferation, differentiation, and apoptosis as well as growth inhibition. Recently sphingosylphosphorylcholine (SPC), sphingosine-1-phosphate (S1P), and C2-ceramide (C2-Cer), sphingolipid containing acetic acid are emerging as melanogenic regulators. A bioactive sphingolipid (PSL) was isolated from hydroalcoholic extract of fresh term human placenta and it induced melanogenesis in an in vitro culture of mouse melanoma B16F10 cells. Tyrosinase, the rate-limiting enzyme for melanogenesis, is required to be upregulated for the increased melanin production. The expression of tyrosinase, both at protein as well as mRNA level, was higher in the PSL treated B16F10 cells as evidenced by Western blot and RT-PCR analysis. Actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, inhibited PSL-induced tyrosinase activity and its protein expression showing decrease in melanogenesis, correspondingly. The activity of GFP coupled tyrosinase promoter was upregulated in transfected B16F10 cells after treating with PSL as determined by fluorescence microscopy, fluorometric analysis, and Western blot. These results, thus, suggested that PSL upregulated tyrosinase gene expression at transcription level through promoter activation to show increased melanogenesis. Therefore, PSL as an inducer of melanogenesis might account for the recovery of pigment in depigmentation disorder.
authors.affiliation: Cellular Biochemistry Laboratory, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata, 700 032, India.
authors.forename: Bidisha
authors.initials: B
authors.lastname: Saha
authors.forename: Suman Kumar
authors.initials: SK
authors.lastname: Singh
authors.forename: Chinmoy
authors.initials: C
authors.lastname: Sarkar
authors.forename: Shampa
authors.initials: S
authors.lastname: Mallick
authors.forename: Rabindranath
authors.initials: R
authors.lastname: Bera
authors.forename: Ranjan
authors.initials: R
authors.lastname: Bhadra
mesh_terms: D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008544:Melanocytes / Q000187:drug effects / Q000502:physiology; D008545:Melanoma / Q000473:pathology; D051379:Mice; D014442:Monophenol Monooxygenase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D010920:Placenta / Q000737:chemistry* / Q000378:metabolism; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000187:drug effects; D013107:Sphingolipids / Q000378:metabolism* / Q000494:pharmacology; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D013107:Sphingolipids; D003609:Dactinomycin; D003513:Cycloheximide; D014442:Monophenol Monooxygenase