Automethylation of CARM1 allows coupling of transcription and mRNA splicing

McArdle Laboratory for Cancer Research and Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53706, USA.
Nucleic Acids Research (Impact Factor: 9.11). 12/2010; 39(7):2717-26. DOI: 10.1093/nar/gkq1246
Source: PubMed

ABSTRACT Coactivator-associated arginine methyltransferase 1 (CARM1), the histone arginine methyltransferase and coactivator for many transcription factors, is subject to multiple post-translational modifications (PTMs). To unbiasedly investigate novel CARM1 PTMs we employed high-resolution top-down mass spectrometry. Surprisingly, mouse CARM1 expressed in insect and mammalian expression systems was completely dimethylated at a single site in the C-terminal domain (CTD). We demonstrate that dimethylation of CARM1 occurs both in vivo and in vitro and proceeds via an automethylation mechanism. To probe function of automethylation, we mutated arginine 551 to lysine to create an automethylation-deficient CARM1. Although mutation of CARM1's automethylation site did not affect its enzymatic activity, it did impair both CARM1-activated transcription and pre-mRNA splicing. These results strongly imply that automethylation of CARM1 provides a direct link to couple transcription and pre-mRNA splicing in a manner differing from the other steroid receptor coactivators. Furthermore, our study identifies a self-regulatory signaling mechanism from CARM1's catalytic domain to its CTD.

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    • "Proteins involved in pre-mRNA splicing are also modified by methylation. The coactivator-associated arginine methyltransferase 1 (CARM1), which methylates H3 at R17 and is a transcriptional coactivator, methylates RNA binding proteins ELAV1/HuR, SNRPB/SmB, SNRPC/U1C and SF3B4/SAP49 (Kuhn et al., 2011). CARM1 has a role in alternative splicing. "
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    ABSTRACT: Epigenetics refer to a variety of processes that have long-term effects on gene expression programs without changes in DNA sequence. Key players in epigenetic control are histone modifications and DNA methylation which, in concert with chromatin remodeling complexes, nuclear architecture and microRNAs, define the chromatin structure of a gene and its transcriptional activity. There is a growing awareness that histone modifications and chromatin organization influence pre-mRNA splicing. Further there is emerging evidence that pre-mRNA splicing itself influences chromatin organization. In the mammalian genome around 95% of multi-exon genes generate alternatively spliced transcripts, the products of which create proteins with different functions. It is now established that several human diseases are a direct consequence of aberrant splicing events. In this review we present the interplay between epigenetic mechanisms and splicing regulation, as well as discuss recent studies on the role of histone deacetylases in splicing activities.
    09/2012; 52(3):377-88. DOI:10.1016/j.jbior.2012.04.003
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    • "Moreover, AtPRMT10 R13K could fully rescue the late-flowering defect of the atprmt10-1 mutant. Nevertheless, it is worth noting that the auto-methylation of mouse CARM1 has been shown to link transcription and pre-mRNA splicing (Kuhn et al., 2011). The biological significance of AtPRMT10 auto-methylation remains to be investigated in Arabidopsis. "
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    ABSTRACT: Arabidopsis AtPRMT10 is a plant-specific type I protein arginine methyltransferase that can asymmetrically dimethylate arginine 3 of histone H4 with auto-methylation activity. Mutations of AtPRMT10 derepress FLOWERING LOCUS C (FLC) expression resulting in a late-flowering phenotype. Here, to further investigate the biochemical characteristics of AtPRMT10, we analyzed a series of mutated forms of the AtPRMT10 protein. We demonstrate that the conserved "VLD" residues and "double-E loop" are essential for enzymatic activity of AtPRMT10. In addition, we show that Arg54 and Cys259 of AtPRMT10, two residues unreported in animals, are also important for its enzymatic activity. We find that Arg13 of AtPRMT10 is the auto-methylation site. However, substitution of Arg13 to Lys13 does not affect its enzymatic activity. In vivo complementation assays reveal that plants expressing AtPRMT10 with VLD-AAA, E143Q or E152Q mutations retain high levels of FLC expression and fail to rescue the late-flowering phenotype of atprmt10 plants. Taken together, we conclude that the methyltransferase activity of AtPRMT10 is essential for repressing FLC expression and promoting flowering in Arabidopsis.
    Protein & Cell 06/2012; 3(6):450-9. DOI:10.1007/s13238-012-2935-3 · 2.85 Impact Factor
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    • "Similarly, post-translational phosphorylation at tyrosine-87 increased interaction with rpS2 and enzymatic activity of PRMT3 (Handrkova et al., 2011), whereas the same modification at serine-229 blocks dimerization and significantly decreases MTase activity of CARM1 (Feng et al., 2009). In addition, automethylation of CARM1 was also found to be essential for its in vivo functions (Kuhn et al., 2011). Lastly, truncation analysis demonstrated that N-termini of PRMT8 and AtPRMT10 negatively regulate their enzymatic activity (Sayegh et al., 2007; Cheng et al., 2011). "
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    ABSTRACT: Post-translational methylation at arginine residues is one of the most important covalent modifications of proteins, involved in a myriad of essential cellular processes in eukaryotes, such as transcriptional regulation, RNA processing, signal transduction, and DNA repair. Methylation at arginine residues is catalyzed by a family of enzymes called protein arginine methyltransferases (PRMTs). PRMTs have been extensively studied in various taxa and there is a growing tendency to unveil their functional importance in plants. Recent studies in plants revealed that this evolutionarily conserved family of enzymes regulates essential traits including vegetative growth, flowering time, circadian cycle, and response to high medium salinity and ABA. In this review, we highlight recent advances in the field of post-translational arginine methylation with special emphasis on the roles and future prospects of this modification in plants.
    Journal of Genetics and Genomics 05/2012; 39(5):195-208. DOI:10.1016/j.jgg.2012.04.001 · 2.92 Impact Factor
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