ASO targeting RBM3 temperature‐controlled poison exon splicing prevents neurodegeneration in vivo

Abstract

Neurodegenerative diseases are increasingly prevalent in the aging population, yet no disease‐modifying treatments are currently available. Increasing the expression of the cold‐shock protein RBM3 through therapeutic hypothermia is remarkably neuroprotective. However, systemic cooling poses a health risk, strongly limiting its clinical application. Selective upregulation of RBM3 at normothermia thus holds immense therapeutic potential. Here we identify a poison exon within the RBM3 gene that is solely responsible for its cold‐induced expression. Genetic removal or antisense oligonucleotide (ASO)‐mediated manipulation of this exon yields high RBM3 levels independent of cooling. Notably, a single administration of ASO to exclude the poison exon, using FDA‐approved chemistry, results in long‐lasting increased RBM3 expression in mouse brains. In prion‐diseased mice, this treatment leads to remarkable neuroprotection, with prevention of neuronal loss and spongiosis despite high levels of disease‐associated prion protein. Our promising results in mice support the possibility that RBM3‐inducing ASOs might also deliver neuroprotection in humans in conditions ranging from acute brain injury to Alzheimer's disease. image Alternative splicing coupled to nonsense‐mediated decay is revealed to control cold‐induced expression of the neuroprotective protein RBM3. Inducing RBM3 by modulating its alternative splicing through ASOs at normothermia is neuroprotective in vivo and has great therapeutic potential. Cold‐induced expression of the neuroprotective protein RBM3 is controlled through alternative splicing coupled to nonsense‐mediated decay. Mapping cis‐regulatory elements in the RBM3 poison exon reveals an evolutionarily conserved exonic splicing enhancer (ESE). Targeting the ESE using ASOs with FDA‐approved chemistry leads to a long‐lasting increase of RBM3 at normothermia. An RBM3‐inducing ASO is strongly neuroprotective in a mouse model for prion disease and holds great promise as a therapeutic strategy in other neurodegenerative conditions.