Oligonucleotide therapeutics hold promise for the treatment of muscle-and heart-related diseases. However, oligonucleotide delivery across the continuous endothelium of muscle tissue is challenging. Here, we demonstrate that docosanoic acid (DCA) conjugation of small interfering RNAs (siRNAs) enables efficient (~5% of injected dose), sustainable (>1 month), and non-toxic (no cytokine induction at 100 mg/kg) gene silencing in both skeletal and cardiac muscles after systemic injection. When designed to target myostatin (muscle growth regulation gene), siRNAs induced~55% silencing in various muscle tissues and 80% silencing in heart, translating into ã 50% increase in muscle volume within 1 week. Our study identifies compounds for RNAi-based modulation of gene expression in skeletal and cardiac muscles, paving the way for both functional genomics studies and therapeutic gene modulation in muscle and heart.

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The continuous evolution of SARS-CoV-2 variants complicates efforts to combat the ongoing pandemic, underscoring the need for a dynamic platform for the rapid development of pan-viral variant therapeutics. Oligonucleotide therapeutics are enhancing the treatment of numerous diseases with unprecedented potency, duration of effect, and safety. Through the systematic screening of hundreds of oligonucleotide sequences, we identified fully chemically stabilized siRNAs and ASOs that target regions of the SARS-CoV-2 genome conserved in all variants of concern, including delta and omicron. We successively evaluated candidates in cellular reporter assays, followed by viral inhibition in cell culture, with eventual testing of leads for in vivo antiviral activity in the lung. Previous attempts to deliver therapeutic oligonucleotides to the lung have met with only modest success. Here, we report the development of a platform for identifying and generating potent, chemically modified multimeric siRNAs bioavailable in the lung after local intranasal and intratracheal delivery. The optimized divalent siRNAs showed robust antiviral activity in human cells and mouse models of SARS-CoV-2 infection and represent a new paradigm for antiviral therapeutic development for current and future pandemics.

Cell signaling relies on second messengers to transduce signals from the sensory apparatus to downstream signaling pathway components. In bacteria, one of the most important and ubiquitous second messenger is the small molecule cyclic diguanosine monophosphate (c‐di‐GMP). While the biosynthesis, degradation, and regulatory pathways controlled by c‐di‐GMP are well characterized, the mechanisms through which c‐di‐GMP controls these processes are not entirely understood. Herein we present the report of a c‐di‐GMP sensing sensor histidine kinase PdtaS (Rv3220c), which binds to c‐di‐GMP at submicromolar concentrations, subsequently perturbing signaling of the PdtaS‐PdtaR (Rv1626) two‐component system. Aided by biochemical analysis, genetics, molecular docking, FRET microscopy, and structural modelling, we have characterized the binding of c‐di‐GMP in the GAF domain of PdtaS. We show that a pdtaS knockout in Mycobacterium smegmatis is severely compromised in growth on amino acid deficient media and exhibits global transcriptional dysregulation. The perturbation of the c‐di‐GMP‐PdtaS‐PdtaR axis results in a cascade of cellular changes recorded by a multiparametric systems’ approach of transcriptomics, unbiased metabolomics, and lipid analyses.

Huntington's Disease (HD) is a severe neurodegenerative disorder caused by expansion of the CAG trinucleotide repeat tract in the huntingtin gene. Inheritance of expanded CAG repeats is needed for HD manifestation, but further somatic expansion of the repeat tract in non-dividing cells, particularly striatal neurons, hastens disease onset. Called somatic repeat expansion, this process is mediated by the mismatch repair (MMR) pathway. Among MMR components identified as modifiers of HD onset, MutS Homolog 3 (MSH3) has emerged as a potentially safe and effective target for therapeutic intervention. Here, we identify fully chemically modified short interfering RNA (siRNA) that robustly silence MSH3 in vitro and in vivo. When synthesized in a di-valent scaffold, siRNA-mediated silencing of MSH3 effectively blocked CAG repeat expansion in striatum of two HD mouse models without impacting tumor-associated microsatellite instability. Our findings establish a novel paradigm for treating patients with HD and other repeat expansion diseases.