Alex Wagner and Ashlyn Spring Will Present Their Research on February 20, 2014
Identification of novel exomic regions for targeted exome analysis using RNA-sequencing
Heritable retinal degenerative diseases are rare and exhibit great genetic heterogeneity. Consequently, identification of disease-causing variants in a patient’s exome may prove challenging, particularly when one or more of the true variants lie outside of the profiled regions in targeted exome sequencing. Presented is a method using RNA-seq in healthy tissues for identifying such regions towards the purpose of constructing augmented exome capture kits for disease variant identification. Results from this method in a patient cohort demonstrate its utility in identifying genetic variants causative of retinal dystrophies.
A novel post-synaptic signaling system involved in synaptic homeostasis at the Drosophila neuromuscular junction
Forms of homeostatic neuroplasticity stabilize synaptic outputs in spite of challenges to synaptic function. Aberrant synaptic activity may underlie a number of neurological disorders including epilepsy. As such, it is important to develop an understanding of the mechanisms that stabilize neuronal function. We utilize the Drosophila neuromuscular junction (NMJ) as a model synapse for studying homeostatic plasticity. At the NMJ, impaired postsynaptic glutamate receptor activity is offset by an increase in presynaptic glutamate release, allowing muscle depolarization to be maintained at wild-type levels. However, our understanding of the signaling systems that drive this process is minimal.
In a recent screen, we uncovered that C-terminal Src kinase (Csk) and the fibroblast growth factor Heartless (Htl) are required for synaptic homeostasis. Examination of loss-of-function Csk and Htl mutant alleles confirmed these result. Both Csk and Htl are known to regulate the activity of Src family kinases (SFKs). As such, we examined the roles of Src64B and Src42A, the SFK homologs in Drosophila, at the NMJ. This analysis has revealed a role for both Src64B and Src42A in homeostatic compensation, and led us to analyze downstream targets of SFK signaling. One potential target of SFK signaling at the NMJ is Fasciclin II (FasII), a homolog of mammalian neural cell adhesion molecule (NCAM) that forms trans-synaptic complexes. We have shown that misexpression of FasII at the NMJ blocks homeostatic compensation and that Csk, Src64B, and Htl mutant NMJs have altered FasII localization. This has led us to a model in which a signaling system consisting of Csk, SFKs, and Htl regulates synaptic homeostasis, perhaps through FasII.