Biology subjects

Morini, E.

Publications and source records attributed to Morini, E..

12 recordsLinked to original sources

bioRxiv2026

ELP1 Gene Augmentation Restores Visual Function in a Mouse Model of Familial Dysautonomia

Familial dysautonomia (FD) is an autosomal recessive sensory and autonomic neurodevelopmental and degenerative disorder characterized by complex neurological phenotypes. One of its most debilitating features is progressive optic neuropathy, which leads to severe visual impairment in FD patients by the third decade of life. Although several preclinical approaches have shown partial rescue of retinal ganglion cell (RGC) degeneration through increasing Elongator acetyltransferase complex subunit 1 (ELP1) expression in the retina, currently no treatments exist to prevent vision loss in FD. In this study, we performed a comprehensive analysis of visual function in a retina-specific FD mouse model (Pax6-Cre;Elp1loxp/loxp) and evaluated a gene supplementation strategy to restore human ELP1 protein levels in the retina. Longitudinal retinal assessments indicated that FD mice exhibit significant retinal nerve fiber layer (RNFL) thinning, as observed in FD patients. FD mice also showed reduced flash visual evoked potentials (VEPs), pattern electroretinography (pERGs), and photopic negative responses (phNRs) amplitudes, along with impaired visual acuity and contrast sensitivity, as assessed using optomotor response assay (OMR). Full-field electroretinography (ffERG) revealed reduced amplitude of dark-adapted a-waves, dark and light-adapted b-waves, indicating combined RGC and bipolar cell dysfunction. Intravitreal delivery of an adeno associated vector (AAV) vector (AAV2.U1a.hELP1) effectively restored physiological ELP1 protein expression, which resulted in a significant rescue of retinal structure and function. Gene supplementation with AAV2.U1a.hELP1 resulted in broad functional and structural improvement compared with untreated FD mice. In summary, our findings provide the first demonstration that ELP1 gene supplementation can effectively rescue RGC function in an FD mouse model and support AAV2.hELP1 at an optimized dose (5.4x108 vg) as a promising therapeutic approach for FD-associated optic neuropathy.

genetics↗

bioRxiv2025

AAV2-mediated intravitreal delivery of exon-specific U1 snRNA rescues optic neuropathy in a mouse model of familial dysautonomia.

Familial dysautonomia (FD) is a rare autosomal recessive neurodegenerative disorder caused by a splicing mutation in the ELP1 gene. It predominantly affects the sensory and autonomic nervous systems, with progressive vision loss due to optic neuropathy being a universal and debilitating symptom. Retinal pathology in FD involves progressive thinning of the retinal nerve fiber layer (RNFL), resulting from the degeneration of retinal ganglion cells (RGCs). Notably, FD-associated vision loss has a postnatal onset, offering a critical window for therapeutic intervention before severe visual impairment develops in adolescence. Currently, no approved treatments exist to prevent or reverse vision loss in FD. In this study, we present a novel RNA-based therapeutic approach targeting ELP1 pre-mRNA splicing in the retina. We engineered exon-specific U1 small nuclear RNAs (ExSpeU1s) to enhance inclusion of exon 20 in the mutant ELP1 transcripts in the retina, thereby restoring full-length ELP1 expression. Delivery of ExSpeU1 via adeno-associated virus serotype 2 (AAV2) to the retina improved ELP1 splicing, rescued RGC loss, and visual function in an FD mouse model. These findings highlight ExSpeU1-mediated splicing correction as a promising therapeutic approach for treating optic neuropathy in FD, offering potential to preserve vision and improve quality of life for patients.

molecular biology↗

bioRxiv2025

Poison exon splicing in the human brain: a new frontier for understanding and targeting neurological disorders

BackgroundPoison exons (PE) are highly conserved exons whose inclusion creates premature termination codons (PTCs) and triggers nonsense-mediated decay (NMD) of the mature transcript. Despite their important role in post-transcriptional regulation, PEs remain poorly annotated due to the lack of systematic transcriptome-wide approaches. ResultsA comparative analysis of 957 eukaryotic transcriptomes revealed that Homo Sapiens exhibits the highest enrichment of NMD-targeted isoforms. By systematically predicting and annotating splicing events that generate PTCs, we found 9,814 PEs in the human genome. Using RNA-seq dataset from GTEx and BrainSpan, we analyzed PE splicing across tissues and developmental stages and identified 83 PEs uniquely found in the human brain, 973 PEs with brain-specific differential splicing, and 1,284 PEs differentially spliced during brain development. By integrating ClinVar variant annotations with SpliceAI predictions, we identified 1,625 pathogenic variants associated with neurological disorders that are predicted to affect the splicing of 743 PEs, and we functionally validated the impact of a subset of them using CRISPR prime-editing in human cells. Functional characterization of the deep intronic NDUFAF6 c.420+784C>T variant associated with Leigh syndrome demonstrated increased PE inclusion and a significant reduction in NDUFAF6 protein levels in iPSC-derived induced neurons. Mutant cells also exhibited impaired mitochondrial membrane potential compared to controls. Together, these findings provide functional evidence that the c.420+784C>T variant promotes aberrant PE inclusion, leading to reduced NDUFAF6 expression and mitochondrial dysfunction. ConclusionsOur findings highlight PEs as pivotal regulators of gene expression in the human brain and support the therapeutic targeting of PE splicing in neurological diseases.

genetics↗

bioRxiv2025

MAPT Splicing Modulators as a Therapeutic Strategy for Tauopathies

Tauopathies are neurodegenerative diseases characterized by the abnormal accumulation of microtubule-associated protein tau (MAPT) in the brain. These disorders, like frontotemporal dementia (FTD-Tau), currently lack effective therapies and can occur sporadically or be inherited when associated with MAPT gene mutations. The MAPT gene region encompassing exon 10 and adjacent introns is a hotspot for pathogenic variants, including splicing mutations that enhance exon 10 inclusion and increase 4R tau expression, and gain-of-function mutations that generate aggregation-prone mutant 4R tau protein. For these 4R-specific tauopathies, a targeted mRNA splicing approach that promotes exon 10 exclusion may offer therapeutic benefit. In this study, we discovered novel splicing modulator compounds (SMCs) that promote MAPT exon 10 exclusion, and demonstrated their efficacy in FTD patient-derived neuronal models carrying the tau-P301L gain-of-function mutation or the tau-S305N splicing mutation. Treatment with SMC reduced 4R tau expression and decreased the accumulation of hyperphosphorylated tau (pTau), oligomeric and insoluble tau, thereby rescuing tau-associated neuronal toxicity. Importantly, our lead SMC corrected the 3R/4R splice ratio in vivo and significantly reduced pTau in the brain of a gene- replacement (GR) mouse model expressing the human tau-N279K splicing mutation. These findings support the therapeutic potential of this class of small molecules and establish MAPT pre- mRNA splicing modulation as a promising strategy for the treatment of 4R tauopathies. One Sentence SummaryDiscovery of SMCs that correct MAPT splicing, reduce 4R tau, and rescue pathology in patient- derived neuronal and in vivo models of 4R tauopathies.

neuroscience↗

bioRxiv2024

Engineered CRISPR-Base Editors as a Permanent Treatment for Familial Dysautonomia

Familial dysautonomia (FD) is a fatal autosomal recessive sensory and autonomic neuropathy. FD is caused by a T-to-C point mutation in intron 20 of the Elongator acetyltransferase complex subunit 1 (ELP1) gene, which results in tissue-specific skipping of exon 20 to cause a premature termination codon and thus redues ELP1 protein levels. Here, we developed a CRISPR-Cas-based cytosine base editing strategy to permanently correct the disease-causing mutation and restore canonical mRNA splicing. Through systematic engineering of base editors and guide RNAs, we identified an optimal editor configuration capable of achieving up to 70% on-target correction in human cells and that restored ELP1 exon 20 inclusion. To enable in vivo delivery, a dual adeno-associated virus (AAV) intein-split base editor was delivered via intravenous injections in a humanized FD mouse mode, resulting in genetic correction and significantly increased ELP1 exon 20 inclusion in the brain and other tissues. In FD patient-derived iPSC-sympathetic neurons, we observed [~]10% correction efficiency but rescued disease-associated neuronal hyperactivity, demonstrating that partial correction can restore functional phenotypes. Genome-wide analyses revealed minimal off-target editing across multiple human cell types, supporting the specificity of this approach. Together, these findings establish a precise and permanent genome editing strategy for FD and supports the development of a one-time disease-modifying therapy for FD and highlights the therapeutic potential of base editing for splicing disorders.

bioengineering↗

bioRxiv2023

PMS1 as a target for splice modulation to prevent somatic CAG repeat expansion in Huntington's disease

Huntingtons disease (HD) is a dominantly inherited neurodegenerative disorder whose motor, cognitive, and behavioral manifestations are caused by an expanded, somatically unstable CAG repeat in the first exon of HTT that lengthens a polyglutamine tract in huntingtin. Genome-wide association studies (GWAS) have revealed DNA repair genes that influence the age-at-onset of HD and implicate somatic CAG repeat expansion as the primary driver of disease timing. To prevent the consequent neuronal damage, small molecule splice modulators (e.g., branaplam) that target HTT to reduce the levels of huntingtin are being investigated as potential HD therapeutics. We found that the effectiveness of the splice modulators can be influenced by genetic variants, both at HTT and other genes where they promote pseudoexon inclusion. Surprisingly, in a novel hTERT-immortalized retinal pigment epithelial cell (RPE1) model for assessing CAG repeat instability, these drugs also reduced the rate of HTT CAG expansion. We determined that the splice modulators also affect the expression of the mismatch repair gene PMS1, a known modifier of HD age-at-onset. Genome editing at specific HTT and PMS1 sequences using CRISPR-Cas9 nuclease confirmed that branaplam suppresses CAG expansion by promoting the inclusion of a pseudoexon in PMS1, making splice modulation of PMS1 a potential strategy for delaying HD onset. Comparison with another splice modulator, risdiplam, suggests that other genes affected by these splice modulators also influence CAG instability and might provide additional therapeutic targets.

genetics↗

bioRxiv2023

Reduction of retinal ganglion cell death in mouse models of familial dysautonomia using AAV-mediated gene therapy and splicing modulators

Familial dysautonomia (FD) is a rare neurodevelopmental and neurodegenerative disease caused by a splicing mutation in the Elongator Acetyltransferase Complex Subunit 1 (ELP1) gene. The reduction in ELP1 mRNA and protein leads to the death of retinal ganglion cells (RGCs) and visual impairment in all FD patients. Currently, patient symptoms are managed, but there is no treatment for the disease. We sought to test the hypothesis that restoring levels of Elp1 would thwart the death of RGCs in FD. To this end, we tested the effectiveness of two therapeutic strategies for rescuing RGCs. Here we provide proof-of-concept data that gene replacement therapy and small molecule splicing modifiers effectively reduce the death of RGCs in mouse models for FD and provide pre-clinical data foundation for translation to FD patients.

neuroscience↗

bioRxiv2022

Development of a novel oral treatment that rescues gait ataxia and retinal degeneration in a phenotypic mouse model of familial dysautonomia.

Familial Dysautonomia (FD) is a rare neurodegenerative disease caused by a splicing mutation in the Elongator complex protein 1 gene (ELP1). This mutation leads to the skipping of exon 20 and a tissue-specific reduction of ELP1 protein, mainly in the central and peripheral nervous systems. FD is a complex neurological disorder accompanied by severe gait ataxia and retinal degeneration. There is currently no effective treatment to restore ELP1 protein expression in individuals with FD, and the disease is ultimately fatal. After identifying kinetin as a small molecule able to correct the ELP1 splicing defect, we worked on its optimization to generate novel splicing modulator compounds (SMCs) that can be used in patients. Here, we optimize the potency, efficacy, and bio-distribution of second-generation kinetin derivatives to develop an oral treatment for FD that can efficiently pass the blood-brain barrier and correct the ELP1 splicing defect in the nervous system. We demonstrate that the novel compound, PTC258, efficiently restores correct ELP1 splicing in mouse tissues, including brain, and most importantly, prevents the progressive neuronal degeneration that is characteristic of FD. Postnatal oral administration of PTC258 to the phenotypic mouse model TgFD9;Elp1{Delta}20/flox increases full-length ELP1 transcript in a dose-dependent manner and leads to a two-fold increase in functional ELP1 protein in the brain. Remarkably, PTC258 treatment improves survival, gait ataxia, and retinal degeneration in the phenotypic FD mice. Our findings highlight the great therapeutic potential of this novel class of small molecules as an oral treatment for FD.

genetics↗

bioRxiv2022

Tissue and cell-type specific molecular and functional signatures of 16p11.2 reciprocal genomic disorder across mouse brain and human neuronal models

Recurrent deletion and duplication of [~]743 kilobases of unique genomic sequence and segmental duplications at chromosome 16p11.2 underlie a reciprocal genomic disorder (RGD; OMIM 611913 and 614671) associated with neurodevelopmental and psychiatric phenotypes, including intellectual disability, autism spectrum disorder (ASD), and schizophrenia (SCZ). To define molecular alterations associated with the 16p11.2 RGD, we performed transcriptome analyses of mice with reciprocal copy number variants (CNVs) of the syntenic chromosome 7qF3 region and human neuronal models derived from isogenic human induced pluripotent stem cells (hiPSCs) carrying CRISPR-engineered CNVs at 16p11.2. Analysis of differentially expressed genes (DEGs) in mouse cortex, striatum, cerebellum and three non-brain tissues, as well as in human neural stem cells and induced glutamatergic neurons revealed that the strongest and most consistent effects occurred within the CNV sequence, with notable instances of differential expression of genes in the immediate vicinity that could reflect position effect. While differential expression of genes outside of chromosome 16p11.2 was largely region, tissue, and cell type-specific, a small but significant minority of such DEGs was shared between brain regions or human cell types. Gene Ontology (GO) enrichment analyses to identify cellular processes dysregulated due to these CNVs found support in select circumstances for terms related to energy metabolism, RNA metabolism, and translation but did not reveal a single universally affected process. Weighted gene co-expression network analysis identified modules that showed significant correlation with reciprocal or individual CNV genotype and better captured shared effects, indicating that energy metabolism, RNA metabolism, translation and protein targeting were disrupted across all three brain regions. The first two of these processes also emerged in the human neural stem cell (NSC) data. A subset of co-expression modules that correlated with CNV genotype revealed significant enrichments for known neurodevelopmental disorder genes, loss-of-function constrained genes, FMRP targets, and chromatin modifiers. Intriguingly, neuronal differentiation of the hiPSCs revealed that both the deletion and duplication CNV resulted in similar deficits in neurite extension and branching and alterations in electrical activity. Finally, generation of cerebral organoid derivatives indicated that the CNVs reciprocally altered the ratio of excitatory and inhibitory GABAergic neurons generated during in vitro neurodevelopment, consistent with a major mechanistic hypothesis for ASD. Collectively, our data suggest that the 16p11.2 RGD involves disruption of multiple biological processes, with a relative impact that is context-specific. Perturbation of individual and multiple genes within the CNV region will be required to dissect single-gene effects, uncover regulatory interactions, and define how each contributes to abnormal neurodevelopment.

genomics↗

bioRxiv2021

Selective retinal ganglion cell loss and optic neuropathy in a humanized mouse model of familial dysautonomia

Familial dysautonomia (FD) is an autosomal recessive neurodegenerative disease caused by a splicing mutation in the gene encoding Elongator complex protein 1 (ELP1, also known as IKBKAP). This mutation results in tissue-specific skipping of exon 20 with a corresponding reduction of ELP1 protein, predominantly in the central and peripheral nervous system. Although FD patients have a complex neurological phenotype caused by continuous depletion of sensory and autonomic neurons, progressive visual decline leading to blindness is one of the most problematic aspect of the disease, as it severely affects their quality of life. To better understand the disease mechanism as well as to test the in vivo efficacy of targeted therapies for FD, we have recently generated a novel phenotypic mouse model, TgFD9; Elp1{triangleup}20/flox. This mouse exhibits most of the clinical features of the disease and accurately recapitulates the tissue-specific splicing defect observed in FD patients. Driven by the dire need to develop therapies targeting retinal degeneration in FD, herein, we comprehensively characterized the progression of the retinal phenotype in this mouse, and we demonstrated that it is possible to correct ELP1 splicing defect in the retina using the splicing modulator compound (SMC) BPN-15477.

neuroscience↗

bioRxiv2021

Developmental regulation of neuronal gene expression by Elongator complex protein 1 dosage.

Elongator is a highly conserved protein complex required for transcriptional elongation, intracellular transport and translation. Elongator complex protein 1 (ELP1) is the scaffolding protein of Elongator and is essential for its assembly and stability. Familial dysautonomia (FD), a hereditary sensory and autonomic neuropathy, is caused by a mutation in ELP1 that lead to a tissue-specific reduction of ELP1 protein. Our work to generate a phenotypic mouse model for FD led to the discovery that homozygous deletion of the mouse Elp1 gene leads to embryonic lethality prior to mid-gestation. Given that FD is caused by a reduction, not loss, of ELP1, we generated two new mouse models by introducing different copy numbers of the human FD ELP1 transgene into the Elp1 knockout mouse (Elp1-/-) and observed that human ELP1 expression rescues embryonic development in a dose dependent manner. We then conducted a comprehensive transcriptome analysis in mouse embryos to identify genes and pathways whose expression correlates with the amount of ELP1. We found that ELP1 is essential for the expression of genes responsible for the formation and development of the nervous system. Further, gene length analysis of the differentially expressed genes showed that the loss of Elp1 mainly impacts the expression of long genes and that by gradually restoring Elongator their expression is progressively rescued. Finally, through evaluation of co-expression modules, we identified gene sets with unique expression patterns that depended on ELP1 expression. Overall, this study highlights the crucial role of ELP1 during early embryonic neuronal development and reveals gene networks and biological pathways that are regulated by Elongator.

developmental biology↗

bioRxiv2020

A deep learning approach to identify new gene targets of a novel therapeutic for human splicing disorders

Pre-mRNA splicing is a key control point in human gene expression. Disturbances in splicing due to mutation or aberrant splicing regulatory networks lead to dysregulated protein expression and contribute to a substantial fraction of human disease. Several classes of active and selective splicing modulator compounds have been recently identified, thus proving that pre-mRNA splicing is a viable target for therapy. We describe herein the identification of BPN-15477, a novel splicing modulator compound, that restores correct splicing of exon 20 in the Elongator complex protein 1 (ELP1) gene carrying the major IVS20+6T>C mutation responsible for familial dysautonomia. We then developed a machine learning approach to evaluate the therapeutic potential of BPN-15477 to correct splicing in other human genetic diseases. Using transcriptome sequencing from compound-treated fibroblast cells, we identified treatment responsive sequence signatures, the majority of which center at the 5 splice site of exons whose inclusion or exclusion is modulated by SMC treatment. We then leveraged this model to identify 155 human disease genes that harbor ClinVar mutations predicted to alter pre-mRNA splicing as potential targets for BPN-15477 treatment. Using in vitro splicing assays, we validated representative predictions by demonstrating successful correction of splicing defects caused by mutations in genes responsible for cystic fibrosis (CFTR), cholesterol ester storage disease (LIPA), Lynch syndrome (MLH1) and familial frontotemporal dementia (MAPT). Our study shows that deep learning techniques can identify a complex set of sequence signatures and predict response to pharmacological modulation, strongly supporting the use of in silico approaches to expand the therapeutic potential of drugs that modulate splicing.

bioinformatics↗