LncRNAs and Regulation of Transcription
LncRNAs directly interact with regulatory proteins such as chromatin modifiers and transcription factors at genomic sites to alter the local transcriptional landscape. This influences gene expression and phenotypic outcomes. The key lncRNA-protein complexes that are differentially active in the normal versus post-stroke cortex are not yet known. What are their genomic targets and what specific actions do they perform at these sites? How do these activities influence the post-stroke pathophysiology? Our lab is currently addressing these questions. Using data from this work, we seek to map the transcriptomic networks that are modulated by specific stroke-relevant lncRNA-protein modules in response to the ischemic injury.
Enhancer RNAs and post-stroke gene expression
Enhancers undergo activity-dependent transcription to produce noncoding enhancer RNAs (eRNAs) that play central roles in organizing functional interactions between the enhancers and their downstream gene targets, and ultimately influence cellular outcomes. We recently identified several novel stroke-responsive eRNAs in the post-stroke cerebral cortex. Loss-of-function experiments resulted in pronounced molecular and phenotypic outcomes, which strongly suggest important functional roles for the eRNAs in the post-stroke brain. Our current work in this area is focused on identifying the molecular targets of the eRNAs, evaluating the cellular and physiological processes that they influence, and determining sex-dependent expression and functions of the eRNAs using in vitro and in vivo models of stroke.
Novel protein isoforms in the post-stroke brain
In gene expression, one of the most important processes is alternative splicing of RNA that results in multiple, distinct mRNAs. In mammals, alternative splicing is most prevalent in the brain. Alternative splicing enables the cell to generate a diverse complement of transcripts from a limited number of genes to facilitate diversification of function, and such molecular and functional diversity is bound to have implications for development and disease. Recently, we identified a number of novel alternatively spliced mRNA isoforms that showed significantly altered expression levels at one or more post-stroke reperfusion time-points as compared to sham controls. A thorough analysis of these novel mRNA sequences suggested that they may yield novel proteins. Altered spatiotemporal expression of these novel proteins may have implications for the pathophysiological outcomes in stroke. Our current work in this area is focused on examining the translational products (i.e. novel proteins) generated by the novel mRNAs, evaluating their cellular and subcellular expression in the mouse brain as a function of post-stroke reperfusion time, identifying their functions and functional partners, and determining their expression dynamics as a function of age and sex.