title: Suppression of PRMT6-mediated arginine methylation of p16 protein potentiates its ability to arrest A549 cell proliferation.
abstract: The tumor suppressor p16(INK4A) (p16) blocks the cell cycle progression by inhibiting phosphorylation of the retinoblastoma protein. We describe here a novel aspect of the posttranslational control that has an important functional consequence on p16 protein. We first discovered that the p16 protein was methylated in various cell lineages. We then determined that the arginine 22, 131 and 138 of p16 were the main methylation sites. Western blotting and TUNEL analyses revealed that the p16 protein bearing these point mutations induced a higher apoptosis ratio than wild-type p16 in A549 cells. Furthermore, co-immunoprecipitation assays suggested that decrease of p16 arginine methylation level promoted the association of p16 with CDK4. Additionally, we determined that the protein arginine methyltransferase 6 (PRMT6) was responsible for the p16 arginine methylation. Results from flow cytometric analysis demonstrated that PRMT6 overexpression counteracted the cell cycle arrest at G1 phase induced by wild-type p16 in A549 cells. We also provided evidence that PRMT6 was able to interact with p16, and that the intensity of p16-CDK4 association was reduced upon PRMT6 overexpression. Together, data presented in this report establish that methylation at specific arginine residues of p16 protein by PRMT6 may be critical for the activity of p16.
authors.affiliation: The Institute of Genetics and Cytology, Northeast Normal University, 5268 Renmin Street, Changchun 130024, China.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Baiqu
authors.initials: B
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D001120:Arginine / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011484:Protein-Arginine N-Methyltransferases / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D009687:Nuclear Proteins; D010446:Peptide Fragments; D001120:Arginine; C447833:PRMT6 protein, human; D011484:Protein-Arginine N-Methyltransferases; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4