O-GlcNAcylation promotes the cytosolic localization of the m6A reader YTHDF1 and colorectal cancer tumorigenesis
Jie Li, Muhammad Zulfiqar Ahmad, Lei Sang, Yahui Zhan, Yibo Wang, Yonghong Yan, Yue Liu, Weixiao Mi, Mei Lu, Yu Dai, Rou Zhang, Meng‐Qiu Dong, Yun‐Gui Yang, Xiaohui Wang, Jianwei Sun, Jing Li, Jing Li, Jing Li
Abstract
O-linked GlcNAc (O-GlcNAc) is an emerging post-translation modification that couples metabolism with cellular signal transduction by crosstalk with phosphorylation and ubiquitination to orchestrate various biological processes. The mechanisms underlying the involvement of O-GlcNAc modifications in N 6 -methyladenosine (m 6 A) regulation are not fully characterized. Herein, we show that O-GlcNAc modifies the m 6 A mRNA reader YTH domain family 1 (YTHDF1) and fine-tunes its nuclear translocation by the exportin protein Crm1. First, we present evidence that YTHDF1 interacts with the sole O-GlcNAc transferase (OGT). Second, we verified Ser196/Ser197/Ser198 as the YTHDF1 O-GlcNAcylation sites, as described in numerous chemoproteomic studies. Then we constructed the O-GlcNAc-deficient YTHDF1-S196A/S197F/S198A (AFA) mutant, which significantly attenuated O-GlcNAc signals. Moreover, we revealed that YTHDF1 is a nucleocytoplasmic protein, whose nuclear export is mediated by Crm1. Furthermore, O-GlcNAcylation increases the cytosolic portion of YTHDF1 by enhancing binding with Crm1, thus upregulating downstream target ( e.g. c-Myc) expression. Molecular dynamics simulations suggest that O-GlcNAcylation at S197 promotes the binding between the nuclear export signal motif and Crm1 through increasing hydrogen bonding. Mouse xenograft assays further demonstrate that YTHDF1-AFA mutants decreased the colon cancer mass and size via decreasing c-Myc expression. In sum, we found that YTHDF1 is a nucleocytoplasmic protein, whose cytosolic localization is dependent on O-GlcNAc modification. We propose that the OGT–YTHDF1–c-Myc axis underlies colorectal cancer tumorigenesis.