title: Alpha B-crystallin induction in skeletal muscle cells under redox imbalance is mediated by a JNK-dependent regulatory mechanism.
abstract: The small heat shock protein α-B-crystallin (CRYAB) is critically involved in stress-related cellular processes such as differentiation, apoptosis, and redox homeostasis. The up-regulation of CRYAB plays a key role in the cytoprotective and antioxidant response, but the molecular pathway driving its expression in muscle cells during oxidative stress still remains unknown. Here we show that noncytotoxic exposure to sodium meta-arsenite (NaAsO2) inducing redox imbalance is able to increase the CRYAB content of C2C12 myoblasts in a transcription-dependent manner. Our in silico analysis revealed a genomic region upstream of the Cryab promoter containing two putative antioxidant-responsive elements motifs and one AP-1-like binding site. The redox-sensitive transcription factors Nrf2 and the AP-1 component c-Jun were found to be up-regulated in NaAsO2-treated cells, and we demonstrated a specific NaAsO2-mediated increase of c-Jun and Nrf2 binding activity to the genomic region identified, supporting their putative involvement in CRYAB regulation following a shift in redox balance. These changes also correlated with a specific phosphorylation of JNK and p38 MAPK kinases, the well-known molecular mediators of signaling pathways leading to the activation of these transcription factors. Pretreatment of C2C12 cells with the JNK inhibitor SP600125 induced a decrease in c-Jun and Nrf2 content and was able to counteract the NaAsO2-mediated increase in CRYAB expression. Thus these data show a direct role of JNK in CRYAB regulation under redox imbalance and also point to a previously unrecognized link between c-Jun and Nrf2 transcription factors and redox-induced CRYAB expression in muscle cells.
authors.affiliation: Unit of Biology, Genetics and Biochemistry, Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, Rome 00135, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Fittipaldi
authors.affiliation: Unit of Biology, Genetics and Biochemistry, Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, Rome 00135, Italy. Electronic address: neri.mercatelli@uniroma4.it.
authors.forename: Neri
authors.initials: N
authors.lastname: Mercatelli
authors.affiliation: Unit of Biology, Genetics and Biochemistry, Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, Rome 00135, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Dimauro
authors.affiliation: MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal Biology Institute of Ageing and Chronic Disease, University of Liverpool, L69 3GA, Liverpool, UK.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Jackson
authors.affiliation: Unit of Biology, Genetics and Biochemistry, Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, Rome 00135, Italy; Laboratory of Molecular and Cellular Neurobiology, CERC Fondazione Santa Lucia, Rome, Italy.
authors.forename: Maria Paola
authors.initials: MP
authors.lastname: Paronetto
authors.affiliation: Unit of Biology, Genetics and Biochemistry, Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, Rome 00135, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Caporossi
mesh_terms: D000818:Animals; D061745:Antioxidant Response Elements; D001483:Base Sequence; D002460:Cell Line; D020935:MAP Kinase Signaling System; D051379:Mice; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D032448:Myoblasts, Skeletal / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D010084:Oxidation-Reduction; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D024363:Transcription Initiation Site; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D038203:alpha-Crystallin B Chain / Q000235:genetics / Q000378:metabolism*
chemical_list: C525420:Cryab protein, mouse; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D016755:Proto-Oncogene Proteins c-jun; D038203:alpha-Crystallin B Chain
keywords: Myoblasts; Nrf2; Sodium arsenite; c-Jun; p38