Biology subjects

Hammond, S. M.

Publications and source records attributed to Hammond, S. M..

3 recordsLinked to original sources

bioRxiv2021

Systemic antibody-oligonucleotide delivery to the central nervous system ameliorates mouse models of spinal muscular atrophy

Antisense oligonucleotides (ASOs) have emerged as one of the most innovative new genetic drug modalities, however, the high molecular weight limits their bioavailability for otherwise treatable neurological disorders. We investigated conjugation of ASOs to an antibody against the murine transferrin receptor (TfR), 8D3130, and evaluated it via systemic administration in mouse models of the neurodegenerative disease, spinal muscular atrophy (SMA). SMA like several other neurological and neuromuscular diseases, is treatable with single-stranded ASOs, inducing splice modulation of the survival motor neuron 2 (SMN2) gene. Administration of 8D3130-ASO conjugate resulted in bioavailability of 2.7% of the injected dose in brain. Additionally, 8D3130-ASO yielded therapeutically high levels of SMN2 splicing in the central nervous system of mildly affected adult SMA mice and resulted in extended survival of severe SMA mice. Systemic delivery of nucleic acid therapies with brain targeting antibodies offers powerful translational potential for future treatments of neuromuscular and neurodegenerative diseases.

molecular biology↗

bioRxiv2020

A functional screen for optimization of short hairpin RNA biogenesis and RISC loading

Gene silencing via short hairpin mediated RNAi (shRNA) is a valuable experimental tool and has promise as a therapeutic strategy. Several shRNA platforms make use of the loop and flanking sequences from the endogenous microRNA (miRNAs) miR-30a or other miRNAs to provide an RNA structure for efficient and accurate biogenesis of the RNA trigger. However, the stem regions of these shRNAs are typically designed as perfect duplex structures which is an uncommon feature for endogenous miRNA precursors. A limitation of these designs is that shRNAs with perfect duplex stems undergo extensive stem cleavage analogous to the Dicer independent miRNA miR-451, destroying the shRNA trigger sequence that is present in the 3P arm. We employed an unbiased screen of > 9000 shRNA structures to identify features that prevent stem cleavage and promote canonical biogenesis and loading into the effector complex RISC. We find that a central stem bulge or kink reduces central stem cleavage and improves accuracy of Dicer processing. Furthermore, 9 - 10 GC nucleotides in the guide strand improves shRNA efficiency. These design rules enable more effective shRNA tools and are compatible with existing sets of optimized guide/target sequences.

molecular biology↗

bioRxiv2019

Combining multi-omics and drug perturbation profiles to identify novel treatments that improve disease phenotypes in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by loss of survival motor neuron (SMN) protein. While SMN restoration therapies are beneficial, they are not a cure. We aimed to identify novel treatments to alleviate muscle pathology combining transcriptomics, proteomics and perturbational datasets. This revealed potential drug candidates for repurposing in SMA. One of the lead candidates, harmine, was further investigated in cell and animal models, improving multiple disease phenotypes, including SMN expression and lifespan. Our work highlights the potential of multiple, parallel data driven approaches for development of novel treatments for use in combination with SMN restoration therapies.

neuroscience↗