RESUMEN
SignificanceΔNp63 is a master regulator of skin homeostasis since it finely controls keratinocyte differentiation and proliferation. Here, we provide cellular and molecular evidence demonstrating the functional role of a ΔNp63 interactor, the R-loop-resolving enzyme Senataxin (SETX), in fine-tuning keratinocyte differentiation. We found that SETX physically binds the p63 DNA-binding motif present in two early epidermal differentiation genes, Keratin 1 (KRT1) and ZNF750, facilitating R-loop removal over their 3' ends and thus allowing efficient transcriptional termination and gene expression. These molecular events translate into the inability of SETX-depleted keratinocytes to undergo the correct epidermal differentiation program. Remarkably, SETX is dysregulated in cutaneous squamous cell carcinoma, suggesting its potential involvement in the pathogenesis of skin disorders.
Asunto(s)
Diferenciación Celular , ADN Helicasas/metabolismo , Epidermis/metabolismo , Queratinocitos/metabolismo , Enzimas Multifuncionales/metabolismo , ARN Helicasas/metabolismo , Factores de Transcripción/metabolismo , Terminación de la Transcripción Genética , Proteínas Supresoras de Tumor/metabolismo , ADN Helicasas/genética , Humanos , Queratina-1/biosíntesis , Queratina-1/genética , Células MCF-7 , Enzimas Multifuncionales/genética , ARN Helicasas/genética , Factores de Transcripción/biosíntesis , Factores de Transcripción/genética , Proteínas Supresoras de Tumor/biosíntesis , Proteínas Supresoras de Tumor/genéticaRESUMEN
The transcription factor ΔNp63 plays a pivotal role in maintaining the integrity of stratified epithelial tissues by regulating the expression of distinct target genes involved in lineage specification, cell stemness, cell proliferation and differentiation. Here, we identified the ABC transporter subfamily member ABCC1 as a novel ΔNp63 target gene. We found that in immortalized human keratinocytes and in squamous cell carcinoma (SCC) cells, ∆Np63 induces the expression of ABCC1 by physically occupying a p63-binding site (p63 BS) located in the first intron of the ABCC1 gene locus. In cutaneous SCC and during the activation of the keratinocyte differentiation program, ∆Np63 and ABCC1 levels are positively correlated raising the possibility that ABCC1 might be involved in the regulation of the proliferative/differentiative capabilities of squamous tissue. However, we did not find any gross alteration in the structure and morphology of the epidermis in humanized hABCC1 knock-out mice. Conversely, we found that the genetic ablation of ABCC1 led to a marked reduction in inflammation-mediated proliferation of keratinocytes, suggesting that ABCC1 might be involved in the regulation of keratinocyte proliferation upon inflammatory/proliferative signals. In line with these observations, we found a significant increase in ABCC1 expression in squamous cell carcinomas (SCCs), a tumor type characterized by keratinocyte hyper-proliferation and a pro-inflammatory tumor microenvironment. Collectively, these data uncover ABCC1 as an additional ∆Np63 target gene potentially involved in those skin diseases characterized by dysregulation of proliferation/differentiation balance.
Asunto(s)
Carcinoma de Células Escamosas , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Queratinocitos , Proteínas Asociadas a Resistencia a Múltiples Medicamentos , Neoplasias Cutáneas , Factores de Transcripción , Proteínas Supresoras de Tumor , Humanos , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patología , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/metabolismo , Animales , Queratinocitos/metabolismo , Queratinocitos/patología , Ratones , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/metabolismo , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Proliferación Celular/genética , Diferenciación Celular/genética , Ratones Noqueados , Transactivadores/genética , Transactivadores/metabolismo , Línea Celular TumoralRESUMEN
The transcription factor ΔNp63 regulates epithelial stem cell function and maintains the integrity of stratified epithelial tissues by acting as transcriptional repressor or activator towards a distinct subset of protein-coding genes and microRNAs. However, our knowledge of the functional link between ∆Np63 transcriptional activity and long non-coding RNAs (lncRNAs) expression is quite limited. Here, we show that in proliferating human keratinocytes ∆Np63 represses the expression of the lncRNA NEAT1 by recruiting the histone deacetylase HDAC1 to the proximal promoter of NEAT1 genomic locus. Upon induction of differentiation, ∆Np63 down-regulation is associated by a marked increase of NEAT1 RNA levels, resulting in an increased assembly of paraspeckles foci both in vitro and in human skin tissues. RNA-seq analysis associated with global DNA binding profile (ChIRP-seq) revealed that NEAT1 associates with the promoter of key epithelial transcription factors sustaining their expression during epidermal differentiation. These molecular events might explain the inability of NEAT1-depleted keratinocytes to undergo the proper formation of epidermal layers. Collectively, these data uncover the lncRNA NEAT1 as an additional player of the intricate network orchestrating epidermal morphogenesis.