Mechanisms of precursor mRNA fate control

Messenger RNA (mRNA) is critical for transferring information from DNA to protein, a process that requires a series of tightly orchestrated steps. During these steps, mRNAs are classified as either functional or faulty, and directed towards biogenesis or degradation. This ensures the efficient and faithful expression of protein-coding genes. Yet, the mechanisms that decide the fate of mRNAs remain unclear. Prior work and our preliminary data show that RNA splicing plays a critical role in making this decision, by committing functional mRNAs towards packaging into ribonucleoprotein complexes (mRNPs) and directing faulty mRNAs towards degradation. Although recent studies have revealed individual aspects of RNA splicing, packaging, and decay, it remains unclear how these processes work together to distinguish functional from faulty mRNPs and determine their fate. Here, I propose to visualize key mRNP processing intermediates from human cells to advance our understanding of mRNA fate control toward biogenesis (aim 1) or decay (aim 2). Central to our efforts is the visualization of large and dynamic precursor mRNP complexes undergoing splicing and packaging (aim 1) or splicing and decay (aim 2) using state-of-the-art cryo-electron microscopy, tomography, and protein crosslinking. This leverages our expertise and preliminary data for the integrative study of endogenous protein-nucleic acid complexes. Our research will generate new hypotheses for how mRNP biogenesis and degradation are achieved, which we will probe in targeted in vitro and in vivo structure-function experiments, including by the super-resolution imaging of mRNAs in cells. This work will consolidate three areas of RNA biology – splicing, packaging, and decay – and promises groundbreaking insights into the mechanisms that control precursor mRNA fate.