Lamin A Ser404 Is a nuclear target of akt phosphorylation in C2C12 cells

Vittoria Cenni, Jessika Bertacchini, Francesca Beretti, Giovanna Lattanzi, Alberto Bavelloni, Massimo Riccio, Maria Ruzzene, Orlano Marin, Giorgio Arrigoni, Veena Parnaik, Manfred Wehnert, Nadir M. Maraldi, Anto De Pol, Lucio Cocco, Sandra Marmiroli

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)4727-4735
Number of pages9
JournalJournal of Proteome Research
Volume7
Issue number11
DOIs
Publication statusPublished - Nov 2008

Keywords

  • 2D-electrophoresis
  • Akt/pkb
  • Lamin A/C
  • Nucleus
  • Phosphorylation
  • Proteomics

ASJC Scopus subject areas

  • Biochemistry
  • Chemistry(all)

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