Disentangling molecular networks in RNA homeostasis and neuromuscular diseases - PROJECT SUMMARY Cellular compartments are critical to controlling the biochemistry that is essential for organismal survival. Most compartments are membrane-bound, sequestering enzymatic reactions from the rest of the cellular milieu. Yet, many compartments lack membranes and exchange biomolecules freely with their surroundings. Such membraneless compartments were observed over a century ago, but attracted little attention until recently. Perhaps due to methodological advancements, a marriage of physics and cell biology sparked a revolution in our appreciation for membraneless compartments. Over the past 15-years, these compartments were shown to have liquid-like properties. Recent consensus states that biological phase transitions are fundamental to their (dis)assembly. Hence, they are now commonly referred to as biomolecular condensates. Such discoveries might have eluded the public curiosity if not for compelling human genetics and disease pathology, both of which implicate condensate dysfunction in diseases of aging including neuromuscular diseases (e.g., ALS) and cancers. Yet, a direct link between physiological condensation and disease pathobiology has evaded conclusive assessment. Such causal relationships have been difficult to infer, as entirely new technologies were required to rigorously and quantitatively illuminate this new biological frontier. With this unmet need in mind, my colleagues and I have invested heavily in creating the proper tools to link condensate biology to disease. My unique perspective is informed by my previous research on pathological protein aggregation. As an independent investigator, I now bridge my experience in cellular models of protein aggregation and physiological condensation to provide much needed insights into how cell biology and disease are connected. In this proposal, we will test a groundbreaking hypothesis for condensate function. Specifically, we propose that RNA-rich condensates, including cytoplasmic stress granules and nuclear speckles, coordinate RNA homeostasis to prevent RNAs from becoming hopelessly entangled. We surmise that such RNA entanglement mechanistically drives the pathological protein aggregates of neuromuscular diseases. We will rigorously test this hypothesis by taking a cross-disciplinary approach that scales from test tube biophysics to cellular and organismal biology then forward to the clinic. We will leverage our unprecedented tools to discover ligands that disassemble pathological aggregates. If successful, we will inform an entirely new way of thinking about RNA homeostasis that is independent of classic biochemical reactions. In doing so, we will provide a foundation for understanding the function of condensates in living cells and inform tractable targets for disease intervention.
