Role of p62/SQSTM1 beyond autophagy: a lesson learned from drug-induced toxicity in vitro

Autor: Alegre F, Moragrega ÁB, Polo M, Marti-Rodrigo A, Esplugues JV, Blas-Garcia A, Apostolova N
Rok vydání: 2018
Zdroj: BRITISH JOURNAL OF PHARMACOLOGY
r-FISABIO. Repositorio Institucional de Producción Científica
instname
r-INCLIVA. Repositorio Institucional de Producción Científica de INCLIVA
r-FISABIO: Repositorio Institucional de Producción Científica
Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana (FISABIO)
ISSN: 0007-1188
Popis: BACKGROUND AND PURPOSE SQSTM1/p62 is a multifunctional, stress-induced, scaffold protein involved in multiple cellular processes including autophagic clearance, regulation of inflammatory responses and redox homeostasis. Its altered function has been associated with different human pathologies, such as neurodegenerative, metabolic and bone diseases (down-regulation), and cancerogenesis (up-regulation). However, its role in the off-target effects of clinically used drugs is still not understood. EXPERIMENTAL APPROACH We evaluated the expression of p62 in cultured Hep3B cells and their derived rho degrees cells (lacking mitochondria), along with markers of autophagy and mitochondrial dysfunction. The effects of efavirenz were compared with those of known pharmacological stressors, rotenone, thapsigargin and CCCP, and we also used transient silencing with siRNA and p62 overexpression. Western blotting, quantRT-PCR and fluorescence microscopy were used to assay these effects and their underlying mechanisms. KEY RESULTS In Hep3B cells, efavirenz augmented p62 protein content, an effect not observed in the corresponding rho degrees cells. p62 up-regulation followed enhanced SQSTM1 expression mediated through the transcription factor CHOP/DDIT3, while other well-known regulators (NF-kB and Nrf2) were not involved. Inhibition of autophagy with 3MA or with transient silencing of Atg5 did not affect SQSTM1 expression in efavirenz-treated cells while p62 overexpression ameliorated the deleterious effect of efavirenz on cell viability. CONCLUSION AND IMPLICATIONS In our model, p62 exerted a specific, autophagy-independent role and protected against efavirenz-induced mitochondrial ROS generation and activation of the NLRP3 inflammasome. These findings add to the multifunctional nature of p62 and may help to understand the off-target effects of clinically useful drugs.
Databáze: OpenAIRE
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