Identifying the Role of Tyrosine Hydroxylase (TH) in GEMIN5-mediated Neurodevelopmental Syndrome



Poster Number: M212


Rhheaa Mehta, University of Pittsburgh

The multiprotein survival motor neuron (SMN) complex plays an important role in the assembly of small nuclear ribonucleoproteins (snRNPs), a key component of spliceosomes. GEMIN5 is a large RNA- binding protein within the complex. In recent years, several rare autosomal recessive GEMIN5 variants leading to loss-of-function (LOF) mechanisms have been identified via multiple model systems, such as iPSCs and flies. GEMIN5 patients present with ataxia, cerebellar atrophy, developmental delays, and motor dysfunction.
In flies, the LOF mutations have been effectively mimicked via use of RNAi-based knockdown (KD) of the orthologous gene rigor mortis (rig). Flies with this KD exhibit several developmental defects, reduced lifespan, and motor dysfunction. While doing RNA sequencing in iPSCs, our lab showed altered levels of tyrosine hydroxylase (TH) in patient neurons. However, the molecular mechanisms are still unclear, leading our focus towards a dopaminergic-targeted KD of rig linked to Th, building off of the tubulin-linked universal RNAi-based rig KD.
The GAL4-UAS system was linked to TH, allowing for spatial control over expression. We examined the effect of the RNAi-rig KD with regard to motor function and development through crawling (3rd instar larvae) and climbing (adult) assays. We perceived a significant motor dysfunction (p=0.0382) between control and rig KD larva in the motor function assay suggesting that reducing rig levels in TH neurons Is detrimental.
Further directions of this study are numerous. Firstly, we would focus on replication of the TH-linked RNAi-rig KD through technical and biological replicates and increasing our sample size. Additionally, we would look at upregulation of TH and observe the effects on motor function and development. And finally, we would replicate the TH-linked rig KD in other models, such as iPSCs.