title: Lamin A Ser404 is a nuclear target of Akt phosphorylation in C2C12 cells.
abstract: Akt/PKB is a central activator of multiple signaling pathways coupled with a large number of stimuli. Although both localization and activity of Akt in the nuclear compartment are well-documented, most Akt substrates identified so far are located in the cytoplasm, while nuclear substrates have remained elusive. A proteomic-based search for nuclear substrates of Akt was undertaken, exploiting 2D-electrophoresis/MS in combination with an anti-Akt phosphosubstrate antibody. This analysis indicated lamin A/C as a putative substrate of Akt in C2C12 cells. In vitro phosphorylation of endogenous lamin A/C by recombinant Akt further validated this result. Moreover, by phosphopeptide analysis and point mutation, we established that lamin A/C is phosphorylated by Akt at Ser404, in an evolutionary conserved Akt motif. To delve deeper into this, we raised an antibody against the lamin A Ser404 phosphopeptide which allowed us to determine that phosphorylation of lamin A Ser404 is triggered by the well-known Akt activator insulin, and is therefore to be regarded as a physiological response. Remarkably, expression of S404A lamin A in primary cells from healthy tissue caused the nuclear abnormalities that are a hallmark of Emery-Dreifuss muscular dystrophy (EDMD) cells. Indeed, it is known that mutations at several sites in lamin A/C cause autosomal dominant EDMD. Very importantly, we show here that Akt failed to phosphorylate lamin A/C in primary cells from an EDMD-2 patient with lamin A/C mutated in the Akt consensus motif. Together, our data demonstrate that lamin A/C is a novel signaling target of Akt, and implicate Akt phosphorylation of lamin A/C in the correct function of the nuclear lamina.
authors.affiliation: Department of Anatomy and Histology and CIPro Proteomics Centre, University of Modena and Reggio Emilia, Via Del Pozzo 71, I-41100 Modena, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Cenni
authors.forename: Jessika
authors.initials: J
authors.lastname: Bertacchini
authors.forename: Francesca
authors.initials: F
authors.lastname: Beretti
authors.forename: Giovanna
authors.initials: G
authors.lastname: Lattanzi
authors.forename: Alberto
authors.initials: A
authors.lastname: Bavelloni
authors.forename: Massimo
authors.initials: M
authors.lastname: Riccio
authors.forename: Maria
authors.initials: M
authors.lastname: Ruzzene
authors.forename: Oriano
authors.initials: O
authors.lastname: Marin
authors.forename: Giorgio
authors.initials: G
authors.lastname: Arrigoni
authors.forename: Veena
authors.initials: V
authors.lastname: Parnaik
authors.forename: Manfred
authors.initials: M
authors.lastname: Wehnert
authors.forename: Nadir M
authors.initials: NM
authors.lastname: Maraldi
authors.forename: Anto
authors.initials: A
authors.lastname: de Pol
authors.forename: Lucio
authors.initials: L
authors.lastname: Cocco
authors.forename: Sandra
authors.initials: S
authors.lastname: Marmiroli
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology; D034904:Lamin Type A / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D032446:Myoblasts / Q000378:metabolism*; D010766:Phosphorylation; D040901:Proteomics / Q000379:methods; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D014162:Transfection
chemical_list: D034904:Lamin Type A; D011994:Recombinant Proteins; D012694:Serine; D051057:Proto-Oncogene Proteins c-akt