Poster abstracts

Poster number 28 submitted by Catey Dominguez

Stressing RNA splicing for therapeutic benefits in SMA

Catherine Dominguez (MCDB), Dawn Chandler (MCDB)

Abstract:
Spinal Muscular Atrophy (SMA) is a neurodegenerative disease caused by low levels of survival motor neuron (SMN) protein, due to loss of the SMN1 gene. A paralogous gene, SMN2, rescues embryonic lethality, but its inefficient splicing produces unstable proteins, resulting in SMA. No therapy exists, however a promising therapeutic option is through splicing manipulation, to correct splicing of SMN2 and reinstate SMN activity.
In previous work, we reported that hypoxic stress increases with disease state in an SMA mouse model (∆7) and that hypoxic stress exacerbates SMN2 mis-splicing. We hypothesize that culmination of cell stresses in advancing disease state exacerbate SMN2 mis-splicing; the study of which may provide new therapeutic targets.
To test this hypothesis, we use a neuronal-like cell line to analyze the effect of three stresses on SMN mRNA splicing: hypoxia, oxidative stress, and heat shock. To further characterize responses and determine how altered splicing under these stresses is achieved, we examined expression and roles of splicing trans factors.
Oxidative stress and hypoxia lead to increases in SMN mis-splicing while heat shock dramatically improves SMN2 splicing. This improvement is time and dose-dependent. Importantly, the splicing improvement correlates with increased SMN protein expression.
We also found that upregulation of one key splicing factor, Tra2β, coincides with SMN splicing changes and that this response is abolished upon Tra2β knockdown or mutation of Tra2β binding sites in SMN transcripts.
These results support Tra2β as the key factor for improving SMN splicing under heat shock. Harnessing this process for improved SMN2 splicing may therefore represent a novel therapeutic avenue for SMA. We are currently testing small molecule heat shock inducers to improve SMN splicing in the absence of thermal stress. If promising, our work will lead to preclinical trials testing heat shock inducers for ameliorating disease in animal models of SMA.

Keywords: SMN, heat shock, splicing