Complex SUMO-1 regulation of cardiac transcription factor Nkx2-5

Mauro Da Costa, Stella Lee, Milena Furtado, Li Xin, Duncan Sparrow, Camilla Martinez, Sally Dunwoodie, Eleonora Kurtenbach, Tim Mohun, Nadia Rosenthal, Richard Harvey

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31 Citations (Scopus)

Abstract

Reversible post-translational protein modifications such as SUMOylation add complexity to cardiac transcriptional regulation. The homeodomain transcription factor Nkx2-5/Csx is essential for heart specification and morphogenesis. It has been previously suggested that SUMOylation of lysine 51 (K51) of Nkx2-5 is essential for its DNA binding and transcriptional activation. Here, we confirm that SUMOylation strongly enhances Nkx2-5 transcriptional activity and that residue K51 of Nkx2-5 is a SUMOylation target. However, in a range of cultured cell lines we find that a point mutation of K51 to arginine (K51R) does not affect Nkx2-5 activity or DNA binding, suggesting the existence of additional Nkx2-5 SUMOylated residues. Using biochemical assays, we demonstrate that Nkx2-5 is SUMOylated on at least one additional site, and this is the predominant site in cardiac cells. The second site is either non-canonical or a shifting site, as mutation of predicted consensus sites and indeed every individual lysine in the context of the K51R mutation failed to impair Nkx2-5 transcriptional synergism with SUMO, or its nuclear localization and DNA binding. We also observe SUMOylation of Nkx2-5 cofactors, which may be critical to Nkx2-5 regulation. Our data reveal highly complex regulatory mechanisms driven by SUMOylation to modulate Nkx2-5 activity.
Original languageEnglish
Article numbere24812
Number of pages13
JournalPLoS ONE
Volume6
Issue number9
DOIs
Publication statusPublished - 2011

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