SSB cooperates with METTL16-mediated mA RNA methylation to promote chemoresistance in colorectal cancer cells.

mA RNA methylation is the most prevalent internal modification in mammalian mRNAs and is involved in many biological processes. METTL16 is a recently identified RNA mA methyltransferase. However, how METTL16 activity is regulated remains poorly understood. Here, we report a previously unrecognized mechanism in regulating METTL16 activity. SSB not only serves as a co-factor for METTL16 in installing mA RNA methylation by enhancing METTL16 binding to RNA but it also is a direct target of METTL16-mediated mA RNA methylation, leading to a positive auto-regulatory loop that promotes mA methylation, SSB expression, and chemoresistance in colorectal cancer cells. Our findings reveal the regulation of METTL16 activity by SSB, providing a basis for the development of future therapeutic strategies that target the METTL16/SSB axis in METTL16-dependent cancers such as colorectal cancer.