title: Deciphering the calcitriol-induced transcriptomic response in keratinocytes: presentation of novel target genes.
abstract: Numerous studies to date have been aimed at unraveling the large suite of calcitriol (1α,25-dihydroxyvitamin D(3)) response genes in diverse tissues including skin, where this hormone is involved in regulating keratinocyte proliferation, differentiation, permeability barrier formation, innate immunity promotion, antimicrobial peptide production, and wound healing. However, the various approaches differ considerably in probed cell types, scale, throughput, and statistical reliability and do, of note, not reveal much overlap. To further expand our knowledge on presently elusive targets and characterize the extent of fragmentation of existing datasets, we have performed whole-transcriptome microarray examinations of calcitriol-treated human primary keratinocytes. Out of 28,869 genes investigated, we uncovered 86 differentially expressed (67 upregulated and 19 downregulated) candidates that were functionally clustered into five annotation categories: response to wounding, protease inhibition, secondary metabolite biosynthesis, cellular migration, and amine biosynthetic processes. A complementary RTq-PCR study of 78 nominees selected thereof demonstrated significant differential expression of 55 genes (48 upregulated and seven downregulated) within biological replicates. Our hit list contains nine previously authenticated targets (16.36%, proof of concept) and 46 novel genes (83.6%) that have not yet been explicitly described as being differentially regulated within human primary keratinocytes. Direct vitamin D receptor response element predictions within the regulatory promoter regions of 50 of the RTq-PCR-validated targets agreed with known biological functionality and corroborated our stringent data validation pipeline. Altogether, our results indicate the value of continuing these kinds of gene expression studies, which contribute to an enhanced comprehension of calcitriol-mediated processes that may be dysregulated in human skin pathophysiology.
authors.affiliation: Division of Molecular Dermatology, Department of Dermatology, Paracelsus Private Medical University Salzburg, Salzburg, Austria.
authors.forename: Raphaela
authors.initials: R
authors.lastname: Rid
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.forename: Christina J
authors.initials: CJ
authors.lastname: Maier
authors.forename: Harald
authors.initials: H
authors.lastname: Hundsberger
authors.forename: Helmut
authors.initials: H
authors.lastname: Hintner
authors.forename: Johann W
authors.initials: JW
authors.lastname: Bauer
authors.forename: Kamil
authors.initials: K
authors.lastname: Onder
mesh_terms: D001665:Binding Sites; D002117:Calcitriol / Q000494:pharmacology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D058977:Molecular Sequence Annotation; D061251:Primary Cell Culture; D015203:Reproducibility of Results; D059467:Transcriptome; D030181:Vitamin D Response Element
chemical_list: D002117:Calcitriol