Affiliations: [a] Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal | [b] Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
Correspondence:
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Correspondence to: Cecília MP Rodrigues, iMed.UL, Faculty of Pharmacy, University of Lisbon, 1649-003 Lisbon, Portugal. Tel.: +351 21 794 6490; Fax: +351 21 794 6491; E-mail: cmprodrigues@ff.ul.pt.
Abstract: p63, the structural and functional homologue of p53, is expressed either as a full-length isoform, containing a transactivation (TA) domain (TAp63), or as a truncated isoform, which lacks TA (ΔNp63). Amyloid-β (Aβ) incubation of neuronal cells results in stress-induced cell death through poorly understood mechanisms. We investigated the role of p63 in Aβ-induced stress. Our results show that Aβ-induced apoptosis of rat PC12 neuronal-like cells and primary cortical neurons was associated with stabilization of pro-apoptotic TAp63 and, most importantly, degradation of anti-apoptotic ΔNp63 through a MAPK- and proteasome-dependent mechanism. This was associated with increased c-Jun, and partially modulated by tauroursodeoxycholic acid. As expected, classic genotoxic insults resulted in c-Jun upregulation and concomitant ΔNp63 reduction. Endogenous and ectopic ΔNp63 expression was also markedly reduced by c-Jun overexpression. Further, Aβ-mediated ΔNp63 degradation occurred in a c-Jun-dependent manner. Downregulation of c-Jun expression by specific c-Jun siRNA abrogated the reduction of ΔNp63 levels following Aβ insult, whereas overexpression of c-Jun led to its degradation. c-Jun significantly decreased ΔNp63 half-life. Together, these findings demonstrate that the abundance of anti-apoptotic ΔNp63 in response to Aβ-induced cell stress is regulated by a c-Jun-dependent mechanism, and highlight the importance of finding novel targets for potential therapeutic intervention.
