title: Catalytic activity of nuclear PLC-beta(1) is required for its signalling function during C2C12 differentiation.
abstract: Here we report that PLC-beta(1) catalytic activity plays a role in the increase of cyclin D3 levels and induces the differentiation of C2C12 skeletal muscle cells. PLC-beta(1) mutational analysis revealed the importance of His(331) and His(378) for the catalysis. The expression of PLC-beta(1) and cyclin D3 proteins is highly induced during the process of skeletal myoblast differentiation. We have previously shown that PLC-beta(1) activates cyclin D3 promoter during the differentiation of myoblasts to myotubes, indicating that PLC-beta(1) is a crucial regulator of the mouse cyclin D3 gene. We show that after insulin treatment cyclin D3 mRNA levels are lower in cells overexpressing the PLC-beta(1) catalytically inactive form in comparison to wild type cells. We describe a novel signalling pathway elicited by PLC-beta(1) that modulates AP-1 activity. Gel mobility shift assay and supershift performed with specific antibodies indicate that the c-jun binding site is located in a cyclin D3 promoter region specifically regulated by PLC-beta(1) and that c-Jun binding activity is significantly increased by insulin and PLC-beta(1) overexpression. Mutation of AP-1 site decreased the basal cyclin D3 promoter activity and eliminated its induction by insulin and PLC-beta(1). These results hint at the fact that PLC-beta(1) catalytic activity signals a c-jun/AP-1 target gene, i.e. cyclin D3, during myogenic differentiation.
authors.affiliation: Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, 40126 Bologna, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Ramazzotti
authors.forename: Irene
authors.initials: I
authors.lastname: Faenza
authors.forename: Gian Carlo
authors.initials: GC
authors.lastname: Gaboardi
authors.forename: Manuela
authors.initials: M
authors.lastname: Piazzi
authors.forename: Alberto
authors.initials: A
authors.lastname: Bavelloni
authors.forename: Roberta
authors.initials: R
authors.lastname: Fiume
authors.forename: Lucia
authors.initials: L
authors.lastname: Manzoli
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Martelli
authors.forename: Lucio
authors.initials: L
authors.lastname: Cocco
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D055162:Biocatalysis / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology*; D056743:Cyclin D3; D016213:Cyclins / Q000235:genetics; D020869:Gene Expression Profiling; D007328:Insulin / Q000494:pharmacology; D008049:Lipase / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D024510:Muscle Development / Q000187:drug effects; D016296:Mutagenesis / Q000187:drug effects; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D016328:NF-kappa B / Q000378:metabolism; D054799:Phospholipase C beta / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D021381:Protein Transport / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C534696:CCND3 protein, human; C534697:Ccnd3 protein, mouse; C534698:Ccnd3 protein, rat; D056743:Cyclin D3; D016213:Cyclins; D007328:Insulin; D050505:Mutant Proteins; D016328:NF-kappa B; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D008049:Lipase; D054799:Phospholipase C beta