Regulated alternative splicing separates canonical and cell signaling functions of aminoacyl-tRNA synthetases

Baymiller, Maxwell J

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https://hdl.handle.net/2142/115713 Copy

Description

Title

Regulated alternative splicing separates canonical and cell signaling functions of aminoacyl-tRNA synthetases

Author(s)

Baymiller, Maxwell J

Issue Date

2022-04-19

Director of Research (if dissertation) or Advisor (if thesis)

Martinis, Susan A

Doctoral Committee Chair(s)

Martinis, Susan A

Committee Member(s)

• Chen, Jie
• Chen, Lin-Feng
• Kalsotra, Auinash

Department of Study

Biochemistry

Discipline

Biochemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• tRNA synthetases
• alternative splicing

Abstract

The aminoacyl-tRNA synthetases (aaRS) are ubiquitous and essential enzymes which set the genetic code by attaching amino acids to their cognate tRNAs. Many eukaryotic synthetases balance this key function with diverse roles in cell signaling. Alternative splicing has been proposed as a mechanism whereby aaRS may gain new functionality or be specified from their catalytic role towards alternate activities. Here, I discovered a leukocyte-specific exon-skipping event in human leucyl-tRNA synthetase (LARS) using long-read sequencing. This splice variant, LSV3, lacks all tRNA leucylation activity as skipping of LARS exon 20 causes a 71 amino acid deletion in the catalytic domain. However, LSV3 retains its role as a leucine sensor and signal transducer for the mammalian target of rapamycin (mTOR) pathway, even though the deletion includes a portion of the previously mapped Vps34-binding domain. I further found that expression of LSV3 is regulated by serine-arginine rich splicing factor 1 (SRSF1) in a cell type-specific manner, and this leads to increased exon skipping during immune cell activation and differentiation. Other alternative splicing events related to non-canonical functions of aaRS are controlled by SRSF1, including exon 2 skipping of tryptophanyl-tRNA synthetase (WARS), which induces its anti-angiogenic activity. I also identify a promising new modulator of the cell death inhibition function of glutaminyl-tRNA synthetase (QARS) via skipping of its exon 23. While when this QARS exon 23 skipping increases remains unclear, I found that LARS exon 20 skipping in LSV3 is greatly induced during cell death. Therefore, alternative splicing has provided functional specificity to the housekeeping LARS protein during cell death and immune signaling by separating its canonical and cell signaling roles.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Maxwell Baymiller

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