The Phosphorylation-Dependent Regulation of the RNA N6-Methyladenosine Methyltransferase Complex

Fundamentally, biological life depends on precise regulation of the expression of genetic information. Post-transcriptional RNA modifications are a major component of regulating gene expression, and N6-methyladenosine (m6A) is the most abundant internal mRNA and long non-coding RNA modification. Through its effects on RNA stability, structure, export, splicing, and translation, m6A influences many biological processes, including embryonic development, immune response, memory, viral infection, and cancer. m6A is selectively installed on certain mRNA transcripts by the methyltransferase-like 3 (METTL3), which acts as the catalytic subunit of the mammalian m6A methyltransferase "writer" complex and must be precisely regulated for proper biological function. Meanwhile, m6A "erasers" ALKBH5 and FTO remove said modification. This dissertation will span three main subjects, all of which are concerned with examining biological roles of mRNA m6A methylation proteins. First, the characterization and function of METTL3 phosphorylation by the ERK2 kinase reveals its role on m6A methylation in embryonic stem cells and cancer. Next, this thesis will discuss the effects of m6A methylation by METTL3 on RIG-I immune signaling and double-stranded RNA formation. Finally, we will report on the effects of the m6A demethylase ALKBH5 in cancer—in particular, how ALKBH5 promote leukemogenesis and how it forms a complex with RBM33. Together, these perspectives show how the regulation of the m6A modification has a widespread impact on development, immunity, and cancer.