The U6 SnRNA MA Methyltransferase METTL16 Regulates SAM Synthetase Intron Retention

Overview

Journal Cell

Publisher Cell Press

Specialty Cell Biology

Date 2017 May 20

PMID 28525753

Citations 577

Authors

Kathryn E Pendleton

Beibei Chen

Kuanqing Liu

Olga V Hunter

Yang Xie

Benjamin P Tu

Nicholas K Conrad

Affiliations

Soon will be listed here.

Abstract

Maintenance of proper levels of the methyl donor S-adenosylmethionine (SAM) is critical for a wide variety of biological processes. We demonstrate that the N-adenosine methyltransferase METTL16 regulates expression of human MAT2A, which encodes the SAM synthetase expressed in most cells. Upon SAM depletion by methionine starvation, cells induce MAT2A expression by enhanced splicing of a retained intron. Induction requires METTL16 and its methylation substrate, a vertebrate conserved hairpin (hp1) in the MAT2A 3' UTR. Increasing METTL16 occupancy on the MAT2A 3' UTR is sufficient to induce efficient splicing. We propose that, under SAM-limiting conditions, METTL16 occupancy on hp1 increases due to inefficient enzymatic turnover, which promotes MAT2A splicing. We further show that METTL16 is the long-unknown methyltransferase for the U6 spliceosomal small nuclear RNA (snRNA). These observations suggest that the conserved U6 snRNA methyltransferase evolved an additional function in vertebrates to regulate SAM homeostasis.

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