Transcriptional activation of a subset of hair keratin genes by the NF-kappaB effector p65/RelA.
The hair follicle is an intricate miniature organ dedicated to the production of the structural hair fiber, which is largely composed of hair keratin (HK) proteins. Many developmental pathways contribute to hair follicle development; however, the molecular control of HK genes is still far from being resolved. Because the nuclear factor (NF)-kappaB pathway is known to be involved in the morphogenesis of the hair follicle, we explored the possibility that it may also regulate HK expression. To this end, we analyzed the effect of p65/RelA, an NF-kappaB effector, on HK regulatory regions using transient transfections into tissue culture cells. Reporter assays on cells transfected with HK promoter constructs and real-time polymerase chain reaction analysis of endogenous HK gene activity demonstrated that p65 induces transcriptional activation of several HK genes of human and mouse origin, primarily that of acidic hair keratin 5 (Ha5). Focusing on the highly responsive human Ha5 gene, we defined the major NF-kappaB/RelA binding sites in its regulatory region and showed the direct binding of p65 to these sites using gel shift assays. We further show, using immunohistochemistry on human hair follicle sections, that p65 is co-expressed with HKs in the hair shaft compartment and may thus be the effector that mediates the NF-kappaB pathway's activity, which recently was genetically demonstrated to be active in the same region. Thus, we provide evidence for a previously unknown function of NF-kappaB in hair formation-direct activation of HK target genes-a function that may shed light on some of the symptoms of ectodermal dysplasias.
Gilon
Michal
M
Department of Cell and Animal Biology, Silberman Life Sciences Institute Edmond Safra Campus at Givat-Ram The Hebrew University Jerusalem 91904, Israel.
Sher
Noa
N
Cohen
Shulamit
S
Gat
Uri
U
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D018859:Hair Follicle / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D053564:Keratins, Hair-Specific / Q000096:biosynthesis / Q000235:genetics*; D053530:Keratins, Type I / Q000096:biosynthesis / Q000235:genetics*; D053531:Keratins, Type II / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D016328:NF-kappa B / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D025941:Protein Interaction Mapping; D011993:Recombinant Fusion Proteins / Q000502:physiology; D051996:Transcription Factor RelA / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation
C507597:KRT35 protein, human; C507600:KRT81 protein, human; C507604:KRT85 protein, human; D053564:Keratins, Hair-Specific; D053530:Keratins, Type I; D053531:Keratins, Type II; D016328:NF-kappa B; C498143:RELA protein, human; D011993:Recombinant Fusion Proteins; D051996:Transcription Factor RelA; C531579:keratin 35, mouse; D004247:DNA