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

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.

SUBMITTER: Costa MW

PROVIDER: S-EPMC3171482 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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

Costa Mauro W MW Lee Stella S Furtado Milena B MB Xin Li L Sparrow Duncan B DB Martinez Camila G CG Dunwoodie Sally L SL Kurtenbach Eleonora E Mohun Tim T Rosenthal Nadia N Harvey Richard P RP

PloS one 20110912 9

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 SUMOyl ...[more]

PMID: 21931855

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Project description:Aims: MiRNAs are post-transcriptional regulatory molecules with recognized roles in human heart development and disease. The purpose of this study was to define human miRNA expression profile in cardiac progenitors and early-differentiated cardiomyocytes and to determine if these miRNAs that are governing cardiogenesis is dependent on NKX2-5, a highly conserved pan-cardiac transcription factor. Methods: MiRNA expression profiles of pre-NKX2-5 mesoderm, cardiac progenitors and early cardiomyocytes derived from heterozygous HES3 NKX2-5eGFP/w and null NKX2-5eGFP/eGFP hESC lines were generated by small RNA sequencing in triplicates, using Illumina HiSeq. Reads between 17-28 base pairs were selected for sequence alignment to the human genome (hg19) using Bowtie2. FeatureCounts (Subread, R package) was used to count the number of reads mapping to miRNAs and analysis of statistically differentially expressed miRNA was carried out using Limma (Bioconductor) through the statistical language R. qRT–PCR validation was performed using Taqman MicroRNA Assays. Results: We identified 11 miRNAs that were differentially expressed between pre-NKX2-5 mesoderm and cardiac progenitors, and 112 differentially expressed miRNAs between cardiac progenitors and early cardiomyocytes. Four of which were validated with qRT–PCR, including canonical myogenic miRNAs such as MIR-1-1, -133A1 and 208A that were enriched in both the cardiac progenitor and early cardiomyocyte populations. Strikingly, deletion of NKX2-5 did not result in gross changes in cardiac miRNA profile either at progenitor or cardiomyocyte stage. Instead, non-hierarchical clustering and principal component analysis demonstrated that the different stages of differentiation (day 6 vs day 10) was a larger discriminator between samples than NKX2-5 genotype. Conclusion: Our study demonstrates the application of human embryonic stem cells as an in vitro model to investigate the role of miRNAs in human cardiac development. We conclude that while specific miRNAs have been identified in our study to have a role in the early stages cardiac cell fate specification, the majority of cardiac myogenic miRNA program is regulated separately from the highly conserved NKX2-5 -dependent gene network. This study provides a framework for further investigation of other key transcription factors of cardiac muscle development that might drive cardiomyogenic expression of miRNAs.

Dataset Information

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

Publications

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

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