METTL3-STAT5B interaction facilitates the co-transcriptional m6A modification of mRNA to promote breast tumorigenesis
Poshan Yugal Bhattarai, Garam Kım, Sung‐Chul Lim, Hong Seok Choi
Abstract
Enhanced expression of methyltransferase-like 3 (METTL3) promotes the m 6 A modification of specific mRNAs, contributing to breast tumorigenesis. While the mRNA substrates targeted by METTL3 are well characterized, the factors dictating the selection of these specific mRNA remain elusive. This study aimed to examine the regulatory role of the transcription factor STAT5B in METTL3-induced m 6 A modification. METTL3 specifically interacts with STAT5B in response to mitogenic stimulation by epidermal growth factor (EGF). Chromatin immunoprecipitation and CRISPR/Cas9 mutagenesis showed that STAT5B recruits METTL3 to gene promoters like CCND1 , where METTL3 interacts with RPB1, dependent on CDK9-mediated RPB1 (Ser2) phosphorylation during transcription elongation . Inhibition and depletion of either STAT5B or CDK9 prevented the EGF-induced m 6 A modification of CCND1 . The translation efficiency of CCND1 was increased following m 6 A modification, thereby increasing cell proliferation . STAT5B facilitated METTL3-induced tumor formation by increasing CCND1 expression in an orthotopic mouse model. In clinical context, a positive correlation was observed between p-STAT5B and METTL3 expression in high-grade breast tumors. This study elucidates a novel mechanism that underlies the specificity of m 6 A modification in breast cancer cells, thereby underscoring its potential therapeutic value.