Poster abstracts

Poster number 12 submitted by Hui-Yi Chu

Genome-wide investigations of translating mRNAs to study the cellular functions of the tRNA retrograde pathway.

Hui-Yi Chu (Molecular, Cellular, Developmental Biology program, OSU), Anita K Hopper (Department of Molecular Genetics , OSU)

Abstract:
Although it was previously thought that tRNAs are transcribed in the nucleus and unidirectly transported to cytoplasm for their function in protein synthesis. However, our lab showed that cytoplasmic tRNAs accumulate in the nucleus upon amino acid starvation in yeast and rat hepatoma cells (Shaheen and Hopper, 2005; Shaheen et al, 2007). Upon re-feeding, the accumulated cytoplasmic tRNAs are re-exported to the cytoplasm. Current data indicate that at least three members of β-importin family functionally participate in tRNA subcellular movement which includes three steps: 1) Los1, primary export of partially matured tRNA; 2) Mtr10, retrograde movement of tRNA into nucleus; 3) Msn5, re-export of fully mature tRNA to the cytoplasm. However, the biological consequences of the tRNA nuclear accumulation remain unclear. One possibility is that tRNA retrograde movement helps to down-regulate protein synthesis and change gene expression upon nutrient deprivation. To test this hypothesis, our strategy is to monitor changes in mRNAs associated with polysomes. The results of polysome profiles from msn5Δ mutants has no different relative to wild-type but mtr10Δ displays a translational elongation defect in responding nutrient stress. We have conducted microarray analyses of translating mRNAs from wild-type, msn5Δ, and mtr10Δcells under both fed and starved conditions. So far, I have learned that a subset of yeast mRNAs is affected.

Keywords: tRNA, transporter, microarray