Allison Cale

Mentor: Antonellis
Genetics and Genomics

Areas of Interest

Aminoacyl-tRNA synthetases (ARSs) are a family of essential enzymes that ligate amino acids to cognate tRNAs in a two-step, ATP-dependent reaction. Humans have 37 nuclear-encoded ARS genes that are necessary for charging tRNA in the cytoplasm and mitochondria; 18 ARSs function exclusively in the cytoplasm, 17 function exclusively in the mitochondria, and 2 have isoforms of the same protein that function in both compartments. All ARSs have been implicated in recessive disease, and six ARSs have been implicated in dominant peripheral neuropathy. The mechanism of ARS-mediated dominant peripheral neuropathy is currently not well understood; haploinsufficiency has been ruled out, and gain-of-function and dominant-negative effect are two non-mutually exclusive hypotheses.  Based on the observations that the majority of pathogenic variants are loss-of-function and that all six implicated synthetases function as homodimers, I hypothesize that a dominant-negative mechanism that applies to all implicated ARSs might best explain the locus and allelic heterogeneity of this disease. If this is the case, I hypothesize that any cytoplasmic homodimeric synthetase should be capable of causing dominant peripheral neuropathy. To this end, I engineered variants in human threonyl-tRNA synthetase (TARS1), which functions as a homodimer but has NOT been implicated in dominant peripheral neuropathy. My goal is to test engineered variants for loss-of-function and dominant toxicity in yeast, and then introduce them into multicellular organisms (worm, followed by mouse) where I will assess animals for neurologic and motor behavior phenotypes. TARS1 has a duplicated paralog called TARS3, which is the only functioning ARS duplication present in humans. TARS3 is very poorly characterized at this point, and I am also interested in performing studies to understand the basic biological functions of TARS3 and how those functions overlap with, or differ from, the canonical cytoplasmic threonyl-tRNA synthetase (TARS1).