Barbara Marinari

The p63 transcription factor, homolog to the p53 tumor suppressor gene, plays a crucial role in epidermal and limb development, as its mutations are associated to human congenital syndromes characterized by skin, craniofacial and limb defects. While limb and skin-specific p63 transcriptional targets are being discovered, little is known of the post-translation modifications controlling ΔNp63α functions. Here we show that the p300 acetyl-transferase physically interacts in vivo with ΔNp63α and catalyzes its acetylation on lysine 193 (K193) inducing ΔNp63α stabilization and activating specific transcriptional functions. Furthermore we show that FGF8, a morphogenetic signaling molecule essential for embryonic limb development, increases the binding of ΔNp63α to the tyrosine kinase c-Abl as well as the levels of ΔNp63α acetylation. Notably, the natural mutant ΔNp63α-K193E, associated to the Split-Hand/Foot Malformation-IV syndrome, cannot be acetylated by this pathway. This mutant ΔNp63...

Psoriasis (Ps) is a common and stigmatizing chronic inflammatory skin disease that may cause other chronic inflammatory conditions with overlapping pathology, such as rheumatoid arthritis (RA). Tumor necrosis factor (TNF) is a proinflammatory cytokine that plays a pivotal role in chronic inflammatory and autoimmune diseases such as uveitis, multiple sclerosis, systemic lupus, arthritis, Ps, and Crohn's disease. The TNF superfamily and receptors represent active targets for drug development. Anti-TNF biological therapies, such as infliximab, adalimumab (ADL), and etanercept, are effective in treating RA, spondyloarthritis, Ps, and inflammatory bowel diseases, but long-term treatment can induce anti-drug antibody (ADA) formation associated with lower drug levels and clinical nonresponse. An investigation of the relationship between serum ADL/anti-adalimumab antibody (AAA) concentration, and clinical response in moderate to severe Ps, confirmed an association between ADL and AAA le...

The p53 protein plays a pivotal role in determining the quality of the response to DNA damage through its transcriptional activity. Upon DNA damage, p53 is activated by post-translational modifications, binds its cognate sequences on the promoters of its target genes and stimulates transcription. In proliferating keratinocytes, the activity of p53 is blunted by its inhibitor DeltaNp63alpha. Here, we describe a novel mechanism through which DeltaNp63 functions in order to prevent the survival and propagation of ultraviolet (UV)-damaged keratinocytes. We found that UVB stimulation induces the rapid phosphorylation of DeltaNp63, which precedes DeltaNp63 transcriptional downregulation and protein degradation, which is mediated by the p38 MAPK. Phosphorylated DeltaNp63 has a lower affinity for p53REs and detaches from cell cycle arrest and apoptotic promoters, thus allowing the rapid activation of p53-dependent transcriptional apoptotic program.

CD28-delivered costimulatory signals are required to induce NF-kappaB activation in response to TCR stimulation. We have recently demonstrated that the mitogen-activated kinase kinase 1 (MEKK1), a kinase known to regulate the c-jun N-terminal kinase (JNK) pathway, is also involved in the CD28- and TCR-induced inhibitor of kappaB factor (IkappaB) kinases (IKK) and NF-kappaB activation. Searching for molecules that couple TCR and CD28 to MEKK1, we found that the guanine nucleotide exchange factor Vav synergized with CD28 stimulation in Jurkat cells to induce NF-kappaB transcriptional activity through the activation of IKKalpha and IKKbeta. Dominant negative mutants of Vav inhibited TCR- and CD28-NF-kappaB-dependent transcription by interfering with the activation of the IKK complex. Blocking Rac signaling downstream of Vav by dominant negative RacN17 exerts similar effects on IKK and NF-kappaB activation after TCR/CD28 stimulation. Finally, Vav-induced NF-kappaB activation in CD28 cos...

Psoriasis is a common T-cell-mediated skin disease with 2-3% prevalence worldwide. Psoriasis is considered to be an autoimmune disease, but the precise nature of the autoantigens triggering T-cell activation remains poorly understood. Here we find that two-thirds of patients with moderate-to-severe plaque psoriasis harbour CD4(+) and/or CD8(+) T cells specific for LL37, an antimicrobial peptide (AMP) overexpressed in psoriatic skin and reported to trigger activation of innate immune cells. LL37-specific T cells produce IFN-γ, and CD4(+) T cells also produce Th17 cytokines. LL37-specific T cells can infiltrate lesional skin and may be tracked in patients blood by tetramers staining. Presence of circulating LL37-specific T cells correlates significantly with disease activity, suggesting a contribution to disease pathogenesis. Thus, we uncover a role of LL37 as a T-cell autoantigen in psoriasis and provide evidence for a role of AMPs in both innate and adaptive immune cell activation.

Tazarotene, a member of the new class of acetylenic retinoids, has been shown to be effective in the treatment of several hyperproliferative skin diseases, including non-melanoma skin cancer. Its effectiveness is thought to rely on the ability to activate retinoic acid receptors beta and gamma and to induce a number of downstream anti-proliferative genes. Here, we show that the p53-related gene p73 is a target of tazarotene. Indeed, tazarotene modulates the expression of the p73 gene in immortalized keratinocyte cell lines by inducing the pro-apoptotic and anti-proliferative TAp73 isoforms and by repressing the anti-apoptotic and pro-proliferative DeltaNp73 isoforms. This occurs at the transcriptional level through a coordinated action on P1p73 and P2p73 promoters that control the expression of TA and DeltaN isoforms, respectively. The selective downregulation of DeltaNp73 expression by small interfering RNA led to an enhancement of tazarotene-induced bax activation and apoptosis, whereas the downregulation of both TA and DeltaN isoforms impairs tazarotene-mediated apoptosis. These results indicate the relevance of p73 gene products in tazarotene-induced growth inhibition and effectiveness in the treatment of skin tumors.

The p53 protein plays a pivotal role in determining the quality of the response to DNA damage through its transcriptional activity. Upon DNA damage, p53 is activated by post-translational modifications, binds its cognate sequences on the promoters of its target genes and stimulates transcription. In proliferating keratinocytes, the activity of p53 is blunted by its inhibitor ΔNp63α. Here, we describe