Project Summary/Abstract
When faced with environmental stress, cells and organisms must conserve resources by decreasing global
translation and simultaneously upregulating stress-responsive genes. How cells do this has eluded
researchers yet promises insight into basic cell biology and novel therapeutics. This proposal takes an
innovative approach to the problem by developing a naturally stress-tolerant fish as a model for the cellular
stress response and using it to examine the contribution of membraneless organelles (in particular stress
granules (SGs)) and small non-coding RNAs (ncRNAs) to gene expression regulation and stress tolerance.
SGs are highly conserved stress-induced assemblies of RNA and protein which may regulate gene expression
by selective sequestration of RNAs and proteins, however their function remains unknown. Small ncRNAs,
such as microRNAs, can regulate the gene expression of particular mRNAs by preventing their translation into
protein, yet identifying adaptive ncRNAs that function in the stress response remains challenging. The annual
killifish Austrofundulus limnaeus inhabits temporary ponds in Venezuela that expose developing fish embryos
to harsh environmental conditions, including anoxia. A. limnaeus embryos can survive over 100 days without
oxygen and cells derived from A. limnaeus embryos can survive two weeks without oxygen. A. limnaeus
display unique SG and ncRNA biology. Our preliminary data show that A. limnaeus cells treated with sodium
arsenite do not form SGs, but still shut down translation. This surprising finding suggests that SG avoidance
may be adaptive and support anoxia tolerance in killifish cells. Small ncRNA studies in anoxia-tolerant
vertebrates identified mitochondria-derived small ncRNAs (mitosRNAs) as putative regulators of gene
expression driving anoxia-induced metabolic depression in A. limnaeus embryos. These mitosRNAs may
therefore underpin organismal anoxia tolerance and represent a novel stress response mechanism. This
proposal will address the following questions: 1. How do killifish cells decouple translation inhibition from stress
granule formation?; 2. How do mitosRNAs regulate protein synthesis under stress?; and 3. How do SG
avoidance and mitosRNA expression support anoxia tolerance? Understanding the mechanism and
consequences of these cellular phenomena will offer unique insight into fundamental cell biology that may
inform treatments for heart attack and stroke, as well as mitochondrial and neurodegenerative diseases. This
proposal will facilitate the career development and transition to independence of a female scientist committed
to promoting and supporting diversity in STEM. The mentored phase will be conducted in the rich training
environment of Brigham and Women’s Hospital/Harvard Medical School to facilitate her career development.
Transitioning to independence will poise her to advance inclusive excellence in higher education and STEM,
including fostering the success of diverse trainees her in lab.