Talk abstracts
Talk on Saturday 11:15-11:30am submitted by Xuan Guo
Dynamic regulation of alternative splicing of neurofibromatosis type 1 exon 23a in the mouse brain
Xuan Guo (Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106), Hua Lou (Department of Genetics and Genome Sciences, Center for RNA Molecular Biology, School of Medicine, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106)
Abstract:
The mechanisms by which alternative splicing is regulated in response to environmental signals are poorly understood. Our group uses neurofibromatosis type 1 (Nf1) as a model to study signaling-induced splicing regulation.
Nf1 is a tumor suppressor gene that contains an alternatively spliced exon, 23a. Our previous studies demonstrate that inclusion of this exon significantly increases Ras/ERK signaling 1,2. As ERK activity changes dynamically during learning, we hypothesize that alternative splicing of Nf1 exon 23a also undergoes dynamic regulation and plays an important role in learning and memory.
To test this hypothesis, we asked if and how inclusion of Nf1 exon 23a changes during learning in wild type mice. To examine different regions of the brain simultaneously, we carried out BaseScope RNA in situ hybridization (ISH) assay, which uses exon junction probes to analyze the splicing pattern in brain slices3. We found that during a fear conditioning learning paradigm, in several regions of the amygdala, inclusion of Nf1 23a displays a dynamic change, increasing five minutes after the mice were shocked and returning to baseline at 24 hours. No significant changes were observed in cortex, hippocampus or other amygdala regions. Interestingly, a concomitant dynamic phospho-ERK level change in amygdala was also observed.
Ketamine is used to treat major depression and has been documented to lead to increased phospho-ERK levels. We carried out similar RNA and protein assays to analyze mouse brain slices prepared from control and treated mice. A similar correlation between increased Nf1 exon 23a inclusion and phospho-ERK levels in ketamine-treated mice was observed.
These data demonstrate that dynamic changes of the alternative splicing pattern of Nf1 exon 23a occur under physiological conditions in vivo, which is correlated with the Ras-ERK activity. We are currently studying the underlying mechanisms of this regulated splicing event.
References:
1. Nguyen H T, Hinman M N, Guo X, et al. Neurofibromatosis type 1 alternative splicing is a key regulator of Ras/ERK signaling and learning behaviors in mice[J]. Hum Mol Genet. 2017, 26(19): 3797-3807.
2. Hinman M N, Sharma A, Luo G, et al. Neurofibromatosis type 1 alternative splicing is a key regulator of Ras signaling in neurons[J]. Mol Cell Biol. 2014, 34(12): 2188-2197.
3. Guo X, Zhao Y, Nguyen H, et al. Quantitative Analysis of Alternative Pre-mRNA Splicing in Mouse Brain Sections Using RNA In Situ Hybridization Assay[J]. J Vis Exp. 2018(138).
Keywords: Alternative Splicing, Nf1 exon 23a, Mouse Brain