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

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.

Lnc-SMaRT Translational Regulation of Spire1, A New Player in Muscle Differentiation.

The destiny of a messenger RNA is determined from a combination of in cis elements, like peculiar secondary structures, and in trans modulators, such as RNA binding proteins and non-coding, regulatory RNAs. RNA guanine quadruplexes belong to the first group: these strong secondary structures have been characterized in many mRNAs, and their stabilization or unwinding provides an additional step for the fine tuning of mRNA stability and translation. On the other hand, many cytoplasmic long non-coding RNAs intervene in post-transcriptional regulation, frequently by direct base-pairing with their mRNA targets. We have previously identified the lncRNA SMaRT as a key modulator of the correct timing of murine skeletal muscle differentiation; when expressed, lnc-SMaRT interacts with a G-quadruplex-containing region of Mlx-γ mRNA, therefore inhibiting its translation by counteracting the DHX36 helicase activity. The "smart" mode of action of lnc-SMaRT led us to speculate whether this molecular mechanism could be extended to other targets and conserved in other species. Here, we show that the molecular complex composed by lnc-SMaRT and DHX36 also includes other mRNAs. We prove that lnc-SMaRT is able to repress Spire1 translation through base-pairing with its G-quadruplex-forming sequence, and that Spire1 modulation participates to the regulation of proper skeletal muscle differentiation. Moreover, we demonstrate that the interaction between DHX36 and lnc-SMaRT is indirect and mediated by the mRNAs present in the complex. Finally, we suggest an extendibility of the molecular mechanism of lnc-SMaRT from the mouse model to humans, identifying potential functional analogues.