Linking tRNA localization with activation  of nutritional stress responses.
Cells respond to nutrient deprivation a variety of ways. In addition to global downregulation of cap-dependent protein synthesis mediated by the GCN2 and mTORC1 signaling pathways, a catabolic process autophagy is upregulated to provide internal building blocks and energy needed to sustain viability. It has recently been shown that during nutrient deprivation tRNAs accumulate in the nucleus, but the functional role of this accumulation remains unknown. This study investigates whether subcellular localization of tRNAs plays a role in signaling nutritional stress and autophagy. We report that human fibroblasts that accumulate tRNA in the nucleus due to downregulation of their transportin, Xpo-t, show reduced mTORC1 activity and upregulated autophagy. This suggests that subcellular localization of tRNAs may regulate an intracellular response to starvation independently of the cellular nutritional status.
Huynh
Le-Nguyen
LN
Department of Molecular and Cellular Biochemistry, College of Medicine, Comprehensive Cancer Center, Columbus, Ohio, USA.
Thangavel
Muthusamy
M
Chen
Timothy
T
Cottrell
Ryan
R
Mitchell
Joy Maria
JM
Praetorius-Ibba
Mette
M
D000596:Amino Acids / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D055785:Gene Knockdown Techniques; D006801:Humans; D028884:Karyopherins / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D034443:RNA Transport / Q000187:drug effects*; D034741:RNA, Small Interfering / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects*
D000596:Amino Acids; D015415:Biomarkers; D028884:Karyopherins; D034741:RNA, Small Interfering; D012343:RNA, Transfer