Non-coding function for mRNAs in Focal Adhesion Architecture and Mechanotransduction

Messenger RNA (mRNA) compartmentalization within the cytosol is well-recognized as a key mechanism of local translation-mediated regulation of protein levels, but whether such localization could be a means of exercising non-coding mRNA function is unknown. Here, we explore non-coding functions for mRNAs associated with focal adhesions (FAs), cellular structures responsible for mediating cell adhesion and response to changes in the extracellular matrix (ECM). Using high-throughput single molecule imaging and genomic profiling approaches, we find that mRNAs with distinct sequence characteristics localize to FAs in different human cell types. Notably, [~]85% of FA-mRNAs are not translationally active at steady state or under conditions of FA dissolution or activation. Untranslated mRNA sequences are anchored to FA based on their functional states by the RNA binding protein, G3BP1, forming biomolecular granules. Removing RNA or G3BP1, but not blocking new polypeptide synthesis, dramatically changes FA protein composition and organization, resulting in loss of cell contractility and cellular ability to adapt to changing ECM. We have therefor uncovered a novel, non-coding role for mRNAs as scaffolds to maintain FA structure and function, broadening our understating of noncanonical mRNA functions.