Lamin A Ser404 is a nuclear target of Akt phosphorylation in C2C12 cells

Cenni, Vittoria ; Bertacchini, Jessika ; Beretti, Francesca ; Lattanzi, Giovanna ; Bavelloni, Alberto ; Riccio, Massimo ; Ruzzene, Maria ; Marin, Oriano ; Arrigoni, Giorgio ; Parnaik, Veena ; Wehnert, Manfred ; Maraldi, Nadir M. ; de Pol, Anto ; Cocco, Lucio ; Marmiroli, Sandra (2008) Lamin A Ser404 is a nuclear target of Akt phosphorylation in C2C12 cells Journal of Proteome Research, 7 (11). pp. 4727-4735. ISSN 1535-3893

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Official URL: http://pubs.acs.org/doi/abs/10.1021/pr800262g

Related URL: http://dx.doi.org/10.1021/pr800262g

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.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
Keywords:Akt/PKB; Nucleus; Lamin A/C; Proteomics; 2D-electrophoresis; Phosphorylation
ID Code:75325
Deposited On:22 Dec 2011 13:06
Last Modified:22 Dec 2011 13:06

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