Home of the Future Hines Lab

CMT-associated mutations in tRNA synthetase (aaRS) genes lead to tRNA sequestration, ribosome stalling, and activation of the integrated stress response (ISR) in mouse motor neurons.

ISR activation causes 2 major cellular consequences - decreased cap-dependent translation, and selective expression of the transcription factor, ATF4, and stress response genes (SRGs).

Recent results (paper in prep) show that expression of ATF4 and stress response genes mediates the neuropathy phenotype seen in mouse models of aaRS-CMT.

hiPSCs can be differentiated into a relatively pure population of motor neurons (MNs), which are sparse in the spinal cord.

Can also make skeletal muscle from hiPSCs and co-culture in compartmentalized dishes with MNs to form NMJs in vitro.

It is not feasible to obtain quality tissue samples from a subset of rare disease patients to confirm mechanistic hypotheses. But rare mutations can be engineered into hiPSCs to confirm animal study results in a in vitro human neuromuscular system.

This system can also be used for high throughput therapeutic testing.

A mouse with ataxia and muscle wasting was isolated from a mutagenesis screen for neuromuscular phenotypes. 

Genetic mapping and whole genome sequencing revealed segregating mutations in Stk36 and Tuba4a.

Both variants were CRISPR-engineered into C57BL/6J mice. The Tuba4a mice recreate the original phenotype, while Stk36 mice are overtly normal.

By 30d, mice with this mutation (Tuba4aQ176P) have Purkinje neuron degeneration, abnormal skeletal muscle pathology, and decreased bone density.