JunB control of keratinocyte-mediated inflammation [RNA-seq]

To determne JunB target gene in human keratincoytes Mice with epidermal deletion of JunB transcription factor displayed a psoriasis-like inflammation. The relevance of these findings to humans and the mechanisms mediating JunB function are not fully understood. Here, we demonstrate that impaired JunB function via gene silencing or overexpression of a dominant negative mutant increased human keratinocyte cell proliferation but decreased cell barrier function. RNA-seq revealed over 500 genes affected by JunB loss-of-function which included an upregulation of an array of proinflammatory molecules relevant to psoriasis. Among these were TNFa, CCL2, CXCL10, IL6R and SQSTM1, an adaptor protein involved in NF-kB activation. ChIP-Seq and gene reporter analyses showed that JunB directly suppressed SQSTM1 through binding to a consensus AP-1 cis-element located around 2 Kb upstream of SQSTM1-trasncription start site. Similar to JunB loss-of-function, SQSTM1-overexpression induced TNFa, CCL2 and CXCL10. Conversely, NF-kB-inhibition genetically with a mutant IkBa or pharmacologically with PDTC prevented cytokine, but not IL6R, induction by JunB-deficiency. Taken together, our findings indicate that JunB controls epidermal growth, barrier formation and proinflammatory responses through direct and indirect mechanisms, pinpointing SQSTM1 as a key mediator of JunB-suppression of NF-kB-dependent inflammation. Overall design: 3 indepdent set of priamry human keratinocytes isolated from foreskin skin samples were transfected with nonsilencing control or siRNA oligonucleotides targeting JunB. mRNA was then isolated and used for cDNA library construction followed by RNA-sequencing.

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Zhang X, Jin JY, Wu J, Qin X, Streilein R, Hall RP, Zhang JY