Global mapping of CARM1 substrates defines enzyme specificity and substrate recognition

Nat Commun. 2017 May 24;8:15571. doi: 10.1038/ncomms15571.

Abstract

Protein arginine methyltransferases (PRMTs) introduce arginine methylation, a post-translational modification with the increasingly eminent role in normal physiology and disease. PRMT4 or coactivator-associated arginine methyltransferase 1 (CARM1) is a propitious target for cancer therapy; however, few CARM1 substrates are known, and its mechanism of substrate recognition is poorly understood. Here we employed a quantitative mass spectrometry approach to globally profile CARM1 substrates in breast cancer cell lines. We identified >130 CARM1 protein substrates and validated in vitro >90% of sites they encompass. Bioinformatics analyses reveal enrichment of proline-containing motifs, in which both methylation sites and their proximal sequences are frequently targeted by somatic mutations in cancer. Finally, we demonstrate that the N-terminus of CARM1 is involved in substrate recognition and nearly indispensable for substrate methylation. We propose that development of CARM1-specific inhibitors should focus on its N-terminus and predict that other PRMTs may employ similar mechanism for substrate recognition.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Motifs / physiology*
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Arginine / metabolism
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics
  • Chromatography, High Pressure Liquid / methods
  • Computational Biology
  • Enzyme Inhibitors
  • Female
  • Gene Knockout Techniques
  • HEK293 Cells
  • Humans
  • MCF-7 Cells
  • Methylation
  • Molecular Targeted Therapy / methods
  • Mutation
  • Proline / chemistry
  • Proline / metabolism
  • Protein Processing, Post-Translational / physiology*
  • Protein-Arginine N-Methyltransferases / antagonists & inhibitors
  • Protein-Arginine N-Methyltransferases / chemistry
  • Protein-Arginine N-Methyltransferases / genetics
  • Protein-Arginine N-Methyltransferases / metabolism*
  • Substrate Specificity / physiology
  • Tandem Mass Spectrometry / methods

Substances

  • Antineoplastic Agents
  • Enzyme Inhibitors
  • Arginine
  • Proline
  • Protein-Arginine N-Methyltransferases
  • coactivator-associated arginine methyltransferase 1