Mutations in HNRNPH2 cause an X-linked disorder characterized by developmental delay, intellectual disability, motor and gait disturbances, and seizures. Murine models that reproduce key clinical features of HNRNPH2-related neurodevelopmental disorder suggest that it may result from a toxic gain of function of the mutant protein or a complex loss of normal HNRNPH2 function with impaired compensation by its paralog, HNRNPH1. In this study, we tested gapmer antisense oligonucleotides (ASOs) that target murine Hnrnph2 in a non-allele-specific manner. The lead ASO reduced Hnrnph2 messenger RNA (mRNA) and protein expression while inducing compensatory up-regulation of Hnrnph1 expression in both wild-type and Hnrnph2 mutant mouse brains. A single intracerebroventricular injection of the Hnrnph2 ASO into neonatal mutant Hnrnph2 mice rescued molecular and audiogenic seizure phenotypes and improved certain motor and cognitive phenotypes. ASO treatment at the juvenile stage also rescued audiogenic seizures. In contrast, Hnrnph2 ASO administration did not alter survival, body weight, or the incidence of hydrocephalus. In human induced pluripotent stem cell-derived neurons, a human-specific HNRNPH2 research ASO reduced HNRNPH2 mRNA and up-regulated HNRNPH1 mRNA. Mechanistically, we found that HNRNPH1 expression is regulated by alternative splicing and that HNRNPH2 modulates this process. These findings provide a preclinical proof of concept for HNRNPH2 ASO therapy and offer insights into its underlying molecular mechanism.

Abstract Endolysosomal membrane damage is a detrimental process in mammalian cells that results in leakage of the luminal contents into the cytosol. However, the nature and extent of the leakage during membrane damage is unknown. Here, we show that endomembrane damage induces the rapid formation of intraluminal condensates in endolysosomes. A subset of resident luminal proteins undergo spatially coordinated condensation upon endomembrane damage. Electron microscopy reveals distinct luminal morphology, and cryo-electron tomography confirms the condensed ultrastructure in their native state. Condensate formation occurs across mechanistically distinct modes of membrane injury and is reversibly dissociated upon lysosomal recovery. Remarkably, these condensates impose a previously unrecognised barrier to endolysosomal escape of therapeutic oligonucleotides. Despite endomembrane damage, luminal oligonucleotide therapeutics are sequestered in damaged endolysosomes through condensate-mediated biophysical immobilisation. Targeting condensate sequestration could represent a novel strategy to improve oligonucleotide-based therapeutics.

Cellular senescence contributes to neurodegeneration in Alzheimer's disease (AD), yet brain-penetrant senotherapeutic strategies remain limited. Here, we identify long interspersed nuclear element 1 (LINE-1) retrotransposons as key regulators of neuronal senescence and the senescence-associated-secretory-phenotype (SASP) in AD. Using transdifferentiated induced neurons (iNs) that preserve donor-specific aging-associated molecular signatures, we show that pharmacological inhibition of LINE-1 with nucleoside reverse transcriptase inhibitors (nRTIs) or antisense oligonucleotides reduces p16 expression, suppresses SASP and interferon-stimulated gene programs, and attenuates paracrine induction of reactive astrogliosis. Spatial transcriptomic analysis of human AD brain tissue further supports that senescent neurons with high LINE-1 expression are localized to inflammatory niches in the brain. Although bulk analysis finds no significant differences in LINE-1 expression between AD and control neurons, long-read single-cell RNA sequencing of iNs identifies a subset of neurons with elevated LINE-1 activity which display transcriptional signatures of neurodegeneration, immune activation, and senescence are enriched in AD relative to controls. RNA velocity analysis indicates that LINE-1 activation precedes the induction of canonical senescence markers, supporting a causal rather than consequential role. Mechanistically, LINE-1-derived cytoplasmic DNA activates the cGAS-STING innate immune pathway in post-mitotic neurons, and inhibition of cGAS phenocopies the effects of LINE-1 suppression. Together, these findings establish a LINE-1/cGAS-STING axis as a driver of neuronal senescence in AD and highlight LINE-1 inhibition as a tractable senomorphic strategy for neurodegenerative disease.

SCN2A variants are among the most common genetic causes of developmental and epileptic encephalopathies (DEEs), which can present with uncontrolled seizures at birth and account for 1-2% of all epileptic encephalopathies. A substantial fraction of causal variants are gain-of-function or mixed-function variants associated with increased channel open probability or greater sodium current flux. Here two parallel n = 1 clinical studies were conducted in two patients (9-year-old and 14-year-old boys) with SCN2A-related DEE. Individualized allele-selective antisense oligonucleotides (ASOs) were designed to target heterozygous intronic single-nucleotide polymorphisms (SNPs) for decreased expression of mutant SCN2A transcript while preserving the wild-type copy. Primary endpoints included quantitative change from baseline in seizure frequency and neurodevelopment, including motor scores. Efficacy measures were also individualized to each patient's phenotype, including refractory seizures, developmental delay, autism spectrum disorder, choreoathetosis and gastrointestinal dysfunction. Patients experienced a reduction in seizure frequency (26% and 90% in the two patients, respectively), decreased use of concomitant medications and improvement in neurodevelopmental skills. Both ASOs were well tolerated, with no ASO-related serious adverse events. Continued long-term follow-up of these preliminary positive safety and efficacy findings is needed to confirm the disease-modifying potential of these ASOs. Haplotype phasing in a separate cohort of infants with SCN2A-related disorder (SCN2A-RD), diagnosed by rapid whole-genome sequencing, identified 16% of patients with compatible SNPs. These data provide a pathway from n = 1 to n of more patients with SCN2A-RD and other monogenic disorders. ClinicalTrials.gov registration: NCT06314490 .

Abstract Mapping subcellular drug distribution is essential for understanding trafficking and off-target effects. NanoSIMS enables chemical imaging of labeled therapeutics, but signal interpretation requires ultrastructural correlation with electron microscopy, a manual and laborious process. We present an automated AI-driven pipeline for correlating chemical and ultrastructural images, enabling multiscale, organelle-precise imaging of molecules in cells and tissues. The method integrates bidirectional optical flow, confidence-guided affine transformation, and automated template matching for cross-scale EM alignment. Morphology-rich ion channels (e.g., 32 S) estimate transformations that propagate to sparse therapeutic signals (e.g., 79 Br, 15 N), overcoming low signal-to-noise challenges. We validate this framework across diverse cell and tissue types, tracking oligonucleotide and antibody therapeutics in vitro and in vivo to reveal cell-type- and organelle-specific distribution patterns. This work establishes a generalizable platform for automated multimodal registration and organelle-resolved subcellular pharmacology.

Aberrant RNA splicing contributes to many human diseases, and splice-switching antisense oligonucleotides are ideally suited as a therapeutic strategy to modulate splicing and restore normal gene expression. Nusinersen (Spinraza™) has revolutionized the treatment of spinal muscular atrophy. It is a splice-switching oligonucleotide (SSO) modified with 2'-O-methoxyethyl (MOE). Here, we evaluate a next-generation ribose modification, 2'-O-[2-(methylamino)-2-oxoethyl] (NMA), which enhances the pharmacological properties of SSOs. We identified a long-lasting NMA-modified human candidate SSO, salanersen, that is three to four-fold more potent than nusinersen in human SMN2 transgenic mice. To evaluate the generality of the NMA chemistry, we applied it to modulation of SCN1A exon 20N splicing, a therapeutic strategy for Dravet syndrome. An NMA-modified SSO is 3.5 -fold more potent than STK-001, a MOE-modified SSO currently in clinical trials. Our data establish the NMA chemistry as a broadly applicable ribose modification that markedly improves the pharmacological profile of SSOs, supporting its development as a next-generation platform for splicing modulation therapies.

Antisense oligonucleotides (ASOs) enter cells efficiently, but the compartment from which productive escape occurs remains uncertain. We used live-cell microscopy, ratiometric pH measurements and 3D focused ion beam scanning electron microscopy (FIB-SEM) in U2OS cells to track a Malat1-targeting ASO from uptake to delivery. The ASO entered by endocytosis and accumulated in late endosomes, endolysosomes and lysosomes, where it induced luminal neutralization without galectin-3 recruitment or limiting-membrane rupture. Under conditions that reduced Malat1-RNA by >90%, quantitative imaging showed that less than 4% of internalized ASOs reached the nucleus. L-leucyl-L-leucine methyl ester (LLOMe)-induced membrane damage released co-internalized dextran but not ASOs, showing that ASOs remain sequestered even in damaged late endocytic compartments. In apilimod-expanded organelles, ASOs concentrated at limiting membranes and intraluminal foci with constrained motion, consistent with association with membrane and luminal structures. Although G3BP1/2 has been proposed to plug damaged endocytic membranes, we detected no recruitment of G3BP1 to endosomes or lysosomes; loss of G3BP1 and G3BP2 increased functional delivery modestly. We therefore propose that productive escape occurs earlier in endocytosis, most likely in early or recycling endosomes, where ASOs would still be unbound within the lumen and where membrane fusion and fission could generate perforations permitting release.

Advances in human genetics and neurosciences have elucidated the fundamental mechanisms underlying many inherited neurological diseases and are providing detailed molecular insights into the causes of sporadic neurological diseases, yet disease-modifying therapies are currently unavailable for most of these conditions. There is a need for alternative therapeutic modalities for the treatment of neurological diseases to capitalize on these exciting genetic and genomic findings. One such platform technology is antisense oligonucleotides (ASOs). ASOs are synthetic nucleic acids or nucleic acid analogs, generally 13–25 nucleotides in length, which bind to RNA by Watson–Crick base paring. Upon binding the ASO modulates the function of the RNA, either promoting its degradation or altering its function to disrupt the flow of genetic information from DNA to proteins. In addition to protein-coding RNAs, noncoding RNAs can be targets of ASO-based drugs, significantly broadening therapeutic targets for drug discovery compared to small molecules and protein-based therapeutics. Antisense technology provides a direct route from human genomic information to creating drugs that address the fundamental cause of a broad range of neurological and neuromuscular disorders. As of the date of this writing, there are four approved antisense drugs for neurological disorders, approximately a dozen drugs in various stages of clinical trials and a rich pipeline of antisense drugs in preclinical and discovery research. Approved ASO drugs are currently available for the treatment of spinal muscular atrophy, polyneuropathy due to hereditary transthyretin amyloidosis and Duchenne muscular dystrophy (DMD). Clinical programs are ongoing for ASOs in adults with Huntington’s disease, SOD1- and C9ORF72-mutation carriers with amyotrophic lateral sclerosis, familial and idiopathic Parkinson’s disease, Alzheimer’s disease, DMD, and polyneuropathy. ASO technology is poised to change the therapeutic landscape in the near future for many central nervous system, peripheral, neurological, and neuromuscular diseases.

Splicing factor proline- and glutamine-rich (SFPQ) is an RNA binding protein that broadly regulates RNA metabolism. Although its nuclear roles are well studied, evidence of SFPQ's cytoplasmic functionality is emerging. Altered expression and nuclear-to-cytoplasmic redistribution of SFPQ have been recognized in amyotrophic lateral sclerosis (ALS) pathology, yet the mechanistic bases for these phenomena remain undetermined. We identified altered SFPQ splicing in ALS, increasing the expression of an alternative mRNA isoform lacking a nuclear localization sequence, which we termed "altSFPQ." We find that altSFPQ mRNA contributes to SFPQ autoregulation and is highly unstable yet exhibits context-specific translation with cytoplasm-predominant localization. Notably, reduced canonical SFPQ coincides with increased altSFPQ transcript expression in familial and sporadic ALS models, providing a mechanistic basis for SFPQ nuclear-to-cytoplasmic redistribution in patients with ALS. Last, we observe that the altSFPQ protein has reduced phase separation potential and differential protein binding compared to its canonical counterpart, providing insight into its mechanistic relevance to physiology and ALS pathogenesis.

Huntington's disease arises from a CAG expansion in the huntingtin gene beyond a critical threshold. Current therapeutics primarily aim to reduce toxicity by lowering levels of mutant HTT mRNA and protein. Genetic data support a role for somatic instability in HTT's CAG repeat as a driver of age of motor dysfunction onset, but currently, the relationship between instability and HTT lowering remains unexplored. Here, we investigate various HTT-lowering modalities to establish the relationship between HTT lowering and instability in Huntington's disease knock-in mice. We find that repressing transcription of mutant Htt reduces instability, using genetic and pharmacological approaches. Remarkably, zinc finger proteins that target CAG repeats, but lack a repressive domain, protect from somatic instability despite not reducing HTT mRNA or protein levels. These results suggest that DNA-targeted HTT-lowering treatments may have advantages compared to other HTT-lowering approaches, and that steric blockage of CAG repeats may reduce instability while sparing HTT expression.

Neurological disorders with onset before or at birth are a leading cause of morbidity and mortality in infants and children. Prenatal treatment has the potential to reduce or prevent irreversible neuronal loss and facilitate normal neurodevelopment. We hypothesized that antisense oligonucleotides (ASOs) delivered to the amniotic fluid by intra-amniotic (IA) injection could safely distribute to the fetal central nervous system (CNS) and provide therapeutic benefit in the motor neuron disease spinal muscular atrophy (SMA), caused by mutations of the survival of motor neuron 1 gene ( SMN1 ), leading to deficiency of SMN protein. Although the splice-switching ASO nusinersen ameliorates SMA when delivered postnatally, substantial deficits can remain in severely affected infants. Here, IA injection of ASOs into two mouse models of severe SMA increased SMN expression in the CNS. In SMAΔ7 mice, which manifest pathology in utero, prenatal treatment improved motor neuron numbers, motor axon development, motor behavioral tests, and survival when compared with those in mice treated postnatally (between P1 and P3). To assess the feasibility of prenatal treatment in a large-animal model, ASOs were delivered midgestation to fetal sheep by IA or intracranial injection. ASOs delivered by IA injection distributed to the spinal cord at therapeutic concentrations and to multiple peripheral tissues without evidence of substantial toxicity to the fetus or mother. These data demonstrated that IA delivery of ASOs holds potential as a minimally invasive approach for prenatal treatment of SMA and possibly other severe, early-onset neurological disorders.

The mRNA transcript of the human STMN2 gene, encoding for stathmin-2 protein (also called SCG10), is profoundly impacted by TAR DNA-binding protein 43 (TDP-43) loss of function. The latter is a hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Using a combination of approaches, including transient antisense oligonucleotide-mediated suppression, sustained shRNA-induced depletion in aging mice, and germline deletion, we show that stathmin-2 has an important role in the establishment and maintenance of neurofilament-dependent axoplasmic organization that is critical for preserving the caliber and conduction velocity of myelinated large-diameter axons. Persistent stathmin-2 loss in adult mice results in pathologies found in ALS, including reduced interneurofilament spacing, axonal caliber collapse that drives tearing within outer myelin layers, diminished conduction velocity, progressive motor and sensory deficits, and muscle denervation. These findings reinforce restoration of stathmin-2 as an attractive therapeutic approach for ALS and other TDP-43-dependent neurodegenerative diseases.

An unprecedented number of potentially disruptive therapeutic technologies are under development. Forward-looking policies, incentives and infrastructure are needed to harness these advances to provide effective and globally equitable healthcare.

Nanoscale secondary ion mass spectrometry (NanoSIMS) makes it possible to visualize elements and isotopes in a wide range of samples at a high resolution. However, the fidelity and quality of NanoSIMS images often suffer from distortions because of a requirement to acquire and integrate multiple image frames. We developed an optical flow-based algorithm tool, NanoSIMS Stabilizer, for all-channel postacquisition registration of images. The NanoSIMS Stabilizer effectively deals with the distortions and artifacts, resulting in a high-resolution visualization of isotope and element distribution. It is open source with an easy-to-use ImageJ plugin and is accompanied by a Python version with GPU acceleration.

Recent studies proposing induced glia-to-neuron conversion raised the potential for generating new neurons to replace those lost due to injury, aging or neurodegenerative diseases. Here, single-cell spatial transcriptomics [Multiplexed Error Robust Fluorescence In Situ Hybridization (MERFISH)] is used to construct a spatial cell atlas of the subventricular and dentate gyrus neurogenic niches of young and aged adult murine brain. RNAs that encode the RNA binding protein Polypyrimidine Tract-Binding Protein (PTBP1) in the aged murine brain are determined to be highest in glia that line previously active neurogenic niches. A glial cell population with ependymal character within an initially quiescent subventricular neurogenic niche in the aged murine brain is identified that upon transient suppression of PTBP1 reenters the cell cycle, replicates DNA, and converts into neurons through a canonical adult neurogenesis pathway. Glia-derived neurons migrate from this niche, with some neurons transiting to the striatum and acquiring a transcriptome characteristic of GABAergic inhibitory neurons. Similar PTBP1 expressing quiescent glia are identified in the corresponding neurogenic niche of aged human brain. Thus, transient reduction of PTBP1 holds potential for inducing the generation of new neurons in quiescent neurogenic niches of the aged nervous system, thereby offering promising therapeutic applications.Bullet point summary ### Competing Interest StatementD.W.C. is a consultant for and C.F.B, P. J-N. and C.H. are employees of Ionis Pharmaceuticals.

Spinal and bulbar muscular atrophy (SBMA) is an adult-onset neurodegenerative disorder caused by the expansion of a polyglutamine tract in the androgen receptor (AR). Here, we show that polyglutamine-expanded AR accumulates in the nucleus of motor neurons and induces aberrant up-regulation of glutamatergic synaptic genes, mediated by a master transcriptional repressor, Rest, during early postnatal development in a mouse model of SBMA. Further analysis indicates that the up-regulation of Rest-target synaptic genes is caused by an increased expression of Rest4, a neuron-specific isoform of Rest that derepresses the promoter activity of Rest-binding lesions. In addition, calcium imaging shows that induced pluripotent stem cell-derived motor neurons expressing polyglutamine-expanded AR are hyperexcitable compared to those expressing wild-type AR. Reducing neonatal AR or switching Rest4 to Rest using antisense oligonucleotides attenuates the up-regulation of the synaptic genes and ameliorates the disease phenotype and histopathology in SBMA mice. The late-onset neurodegeneration in SBMA is attributable to the synaptic defects and resulting hyperexcitability of motor neurons at early postnatal stages, which would be therapeutically targeted.

The design, syntheses and antibacterial evaluation of sulfone analogues of previously disclosed metallo-(3-lactamase inhibitors (MBLis) are described. The novel derivatives were overall more effective in gram-negative bacterial cell-based assays when combined with imipenem and relebactam. The major contributors to the improved anti-bacterial activity are enhanced enzyme-inhibitor interactions and reduced bacterial cell efflux monitored via an efflux assay involving isogenic Pseudomonas aeruginosa efflux + and efflux - tool strains.