Emily Petruccelli and Tryphena Cuffy will be presenting in Student Seminar on June 23rd at noon
In Dr. Toshi Kitamoto’s lab we are interested in understanding how the external environment affects neural plasticity leading to changes in behavior. I am specifically interested in how unconventional steroid hormone action- occurring independent of new mRNA synthesis- affects neuromodulation in complex behaviors. Importantly, drug abuse, as well as many neuropsychiatric diseases, are associated with steroid hormone dysfunction. Unfortunately, the function and mechanism of “nongenomic” steroid actions are not well understand or are highly controversial. To address this gap in our knowledge, I am using the plethora of genetic tools and established behavioral paradigms of the tractable model organism Drosophila.
Recently, the G-protein coupled receptor DopEcR was identified as a novel nonclassical ecdysone receptor in flies. Ecdysone is the major insect molting hormone of insects and is well known for its role in regulating developmental transitions and oogenesis in adult females. However, work in our lab and others have shown that ecdysone also regulates complex adult behaviors such as long-term memory formation, sleep and longevity. To understand how nongenomic signaling of ecdysone impacts neural plasticity and behavior, we identified and examined hypomorphic DopEcR mutants. Interestingly, DopEcR-mediated signaling appears to be important for both associative and non-associative learning as well as for regulating ethanol-induced behavior. I am currently generating a null DopEcR mutant using homologous recombination techniques and further characterizing the incoordinating, sedation and tolerance of mutants exposed to ethanol vapor.
Since both steroid hormone signaling and ethanol-induced behaviors are highly conserved between flies and mammals, this work will advance vertebrate research efforts to understand nongenomic steroid action and better our understanding of neuroendocrinology.
Exfoliation syndrome (XFS) is a common age-related disorder characterized by the pathological accumulations of fibrillar exfoliative material in the anterior chamber of the eye. Patients with XFS can go on to develop exfoliative glaucoma; potentially as a result of an accumulation of exfoliative material at the drainage structures of the eye. Human eyes with XFS exhibit a striking pattern of Marcel-like iris transillumination defects. The same pattern is recapitulated in mice containing the Lystbg-J mutation. We have found that the molecular basis of the bg-J mutation is a three base pair deletion in the WD40 encoding region of the Lyst gene. In yeast two-hybrid assays others have identified a small number of proteins capable of interacting with the LYST WD40 motif – one of these being CSNK2B. Testing CSNK2B, as a candidate interacting protein, previous GST-pulldown experiments confirmed that wild-type LYST can bind to CSNK2B whereas LYSTbg-J can not. This result suggests that LYST may play a role in regulating activity or localization of CSNK2B. In testing this hypothesis, experiments with primary fibroblasts expressing a GFP-tagged CSNK2B fusion protein suggest that LYST regulates the subcellular localization of CSNK2B. Furthermore, two CSNK2B substrates (PER2 and CDH1) exhibit functional deficits in the presence of the Lystbg-J mutation. Combined, these results implicate CSNK2B and its substrates in the pathogenesis of XFS. In addition, another striking phenotype associated with the bg-J mutation is a dysfunction in the circadian regulation of pressure in the eye – intraocular pressure. Many patients, who exhibit elevated intraocular pressure along with glaucoma, are treated with drugs that lower that intraocular pressure. My goal is to also investigate elevated intraocular pressure in glaucoma patients using the B6-Lystbg-J mouse as a model.