Histone phosphorylation by TRPM6’s cleaved kinase attenuates adjacent arginine methylation to regulate gene expression

Abstract

TRPM6 and TRPM7 are members of the melastatin-related transient receptor potential (TRPM) subfamily of ion channels. Deletion of either gene in mice is embryonically lethal. TRPM6/7 are the only known examples of single polypeptides containing both an ion channel pore and a serine/threonine kinase (chanzyme). Here we show that the C-terminal kinase domain of TRPM6 is cleaved from the channel domain in a cell type-specific fashion and is active. Cleavage requires that the channel conductance is functional. The cleaved kinase translocates to the nucleus, where it is strictly localized and phosphorylates specific histone serine and threonine (S/T) residues. TRPM6-cleaved kinases (M6CKs) bind subunits of the protein arginine methyltransferase 5 (PRMT5) molecular complex that make important epigenetic modifications by methylating histone arginine residues. Histone phosphorylation by M6CK results in a dramatic decrease in methylation of arginines adjacent to M6CK-phosphorylated amino acids. Knockout of TRPM6 or inactivation of its kinase results in global changes in histone S/T phosphorylation and changes the transcription of hundreds of genes. We hypothesize that M6CK associates with the PRMT5 molecular complex in the nucleus, directing M6CK to a specific genomic location and providing site-specific histone phosphorylation. M6CK histone phosphorylation, in turn, regulates transcription by attenuating the effect of local arginine methylation.A mong the several hundred genes encoding cation channels, the melastatin-related transient receptor potential family members TRPM6 and TRPM7 are unique in also being serine/ threonine (S/T) kinases (1). The TRPM6 channel kinase was brought to greater attention when mutations in this chanzyme were found to be the cause of familial hypomagnesemia with secondary hypocalcemia (HSH; see ref. 2 for a recent review). Characterized by severe hypomagnesemia, infants with HSH suffer tetany and refractory seizures shortly after birth, resulting in permanent neurological damage or death if untreated. The mechanisms by which mutations in TRPM6 lead to HSH are unknown, although several studies stress the importance of TRPM6-mediated Mg 2+ conductance (3-5). Importantly, global TRPM6 disruption in mice is embryonic lethal (6, 7). Mice with loss of TRPM6 at intermediate developmental time points manifest a reduced life span and skeletal deformations, in addition to mild hypomagnesemia (5). These data indicate that, much like TRPM7 (8), TRPM6 may be critical for normal, developmental, tissue-specific regulation of gene activity.Recently, our laboratory uncovered a signaling pathway mediated by TRPM7, a channel sharing 52% homology with TRPM6, whereby the functional S/T kinase at the carboxyl terminus of TRPM7 is proteolytically cleaved from the channel domain, forming cleaved kinase fragments (M7CKs) that translocate to the nucleus (9). There, M7CKs bind components of chromatin-remodeling complexes to ultimately phosphorylate specific S/T residues of histones, regulate selected histone acetylatio...

Genome-Wide Association Study Reveals Candidate Genes for Litter Size Traits in Pelibuey Sheep

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Transient Receptor Potential Cation Channels in Cancer Therapy

“…It has been demonstrated that inactivation of TRP genes by aberrant methylation (hyper-and hypo-methylation) of GC-rich DNA regions, CpG islands, is suggested to be involved in tumor development and progression. In this regard, hydrogen peroxide has been found to induce demethylation of the TRPM2 promoter region and increase the expression of TRPM2 in melanocytes [113]; the TRPM6 and TRPM7 ion channels have been found to bind to the chromatin-remodeling complexes, induce histone phosphorylation, and decrease arginine methylation, resulting in changes in the transcription of hundreds of genes [114,115]; transactivation of TRPA1 promoter by Notch1 receptor intracellular domain, which promotes TRPA1 expression in erytroleukemic cells, suppresses erythroid differentiation [116]. Moreover, regarding cancer chemoresistance, miR-320a is a mediator of the chemoresistance of BC cells by targeting TRPC5 and NFATc3 and the expression of miR320a is regulated by methylation of its promoter and the transcription factor, v-ets erythroblastosis virus E26 oncogene homolog 1 [117].…”

Improved discrimination of asymmetric and symmetric arginine dimethylation by optimization of the normalized collision energy in LC-MS proteomics

“…Protein arginine methylation is a post-translational modification (PTM) that regulates the cell cycle 1 , metabolism 2,3 , signal transduction [4][5][6] , and transcriptional control [7][8][9][10][11] . Arginine methylation is catalyzed by protein arginine methyltransferases (PRMTs) and occurs in three forms, monomethylarginine (MMA), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA).…”