Poster abstracts

Poster number 91 submitted by Xiaoyan Li

Identifying the mechanism of PUS7 relocalization upon stress

Xiaoyan Li (University of Michigan, Department of Chemistry), Kristin S. Koutmou (University of Michigan, Department of Chemistry)

Abstract:
Pseudouridine is one of the most abundant post-transcriptional modifications found across all RNA types. This modification modulates RNA structure, dynamics and RNA-protein interactions to influence gene expression and protein synthesis. In eukaryotes, pseudouridine synthase 7 (PUS7) is an enzyme responsible for the catalysis of pseudouridine incorporation into crucial substrates for protein synthesis, tRNA, and mRNA. Dysregulation and mutations in PUS7 have been linked to various diseases, including intellectual disabilities and cancers. Our lab recently demonstrated that upon stress exposure, PUS7 translocates from the nucleus to the cytoplasm, resulting in increased mRNA pseudouridylation in both yeast and human lung cells. Cytoplasmic accumulation of PUS7 enhances stress tolerance and induces proteomic alterations. However, the precise molecular mechanisms governing PUS7 relocalization remain unclear. In this study, we aim to elucidate the protein-protein interactions that mediate PUS7's nuclear-cytoplasmic transport and to identify its nuclear export and localization sequences. These objectives will be addressed through proximity labeling, co-immunoprecipitation, liquid chromatography-mass spectrometry (LC-MS), and site-directed mutagenesis.

References:
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2. Li, J., Ma, X., Chakravarti, D., Shalapour, S. & DePinho, R. A. Genetic and biological hallmarks of colorectal cancer. Genes Dev 35, 787–820 (2021).
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4. Cui, Q. et al. Targeting PUS7 suppresses tRNA pseudouridylation and glioblastoma tumorigenesis. Nat Cancer 2, 932–949 (2021).
5. Kierzek, E. et al. The contribution of pseudouridine to stabilities and structure of RNAs. Nucleic Acids Research 42, 3492–3501 (2014).
6. de Brouwer, A. P. M. et al. Variants in PUS7 Cause Intellectual Disability with Speech Delay, Microcephaly, Short Stature, and Aggressive Behavior. Am J Hum Genet 103, 1045–1052 (2018).

Keywords: pseudouridine synthase 7, RNA modification, protein protein interaction