Epithelial mRNA localization in homeostasis and pathophysiology

ended

Asymmetric subcellular mRNA distributions have been observed in a variety of polar cell types and organisms. RNA polarization is instrumental at the beginning of life and determines the morphogen gradients needed for embryo patterning. In highly polar neurons, subcellular transcript localization and translation are thought to enhance cellular efficiency and timely responses to extrinsic cues. However, the functional consequence of mRNA localization has, in most cases, not been elucidated. We have shown that a large fraction of an epithelial transcriptome is localized, yet the role(s) of mRNA localization in adult tissue homeostasis and function are unknown. Moreover, we still do not know how the transcript sorting machinery works, and we lack insights into the molecular composition of the membrane-less compartments that may maintain RNA segregation in the cytoplasm. We will address these gaps by combining RNA microscopy and subcellular proximity proteomics to study the functional contribution of RNA localization in digestive epithelia. Our project will comprehensively map the subcellular space across three adult epithelial tissues – liver, jejunum, and colon. To elucidate the mechanisms that mediate sequence-specific mRNA transport and maintain localization, we will develop a system to tether a construct for proximity proteomics to localized RNAs. We will functionally test the contribution of RNA localization to tissue homeostasis and disease development by disrupting the localizing elements and machinery. Our novel toolkit will enable the spatial mapping of RNA and proteins in parallel, allowing us to annotate the subcellular space and subsequently probe the biological significance of this fundamental process in adult epithelia. This novel technology can be extended to the subcellular study of all epithelia and tissues in general; it will ultimately lead to a more comprehensive understanding of tissue function in homeostasis and disease.