Biology subjects

van Wijk, E.

Publications and source records attributed to van Wijk, E..

9 recordsLinked to original sources

bioRxiv2026

ARTIFICIAL SELECTION DIVERSIFIES BIRDSONG THROUGH POLYGENIC CHANGES ACROSS SENSORY AND MOTOR SYSTEMS

Vocal learning, or the ability to acquire and produce contextualized sounds through social interaction, underlies human speech yet has evolved in a few animal lineages, including songbirds. In songbirds, learned song is produced by a dedicated neural circuit and depends on auditory feedback for its acquisition and maintenance. Roughly four centuries of artificial selection on the domestic canary (Serinus canaria) have produced song breeds whose vocalizations diverge as much as those of distinct species, offering a rare intraspecific system in which to identify the genetic and neural changes underlying vocal divergence. Here we show that selection for song reshaped the canary song control system. Compared with breeds selected for plumage or body form, song breeds show increased neural progenitor proliferation and breed-specific changes in neuronal recruitment, sensorimotor brain region volume, and auditory sensitivity. Genome-wide analyses reveal a polygenic architecture underlying song divergence, enriched for transcriptional regulation and synaptic transmission genes. Among these, we find a coding variant in ADGRV1, the gene mutated in human Usher syndrome type 2C, associated with low-frequency singing and elevated auditory thresholds in canary. Disrupting ADGRV1 in zebrafish alters hair cell dynamics, linking adgrv1 mutation to a peripheral sensory mechanism. These findings demonstrate that learned vocal behavior can diversify rapidly through changes spanning sensory, neurogenic, and motor systems, with hearing itself as a substrate for selection.

evolutionary biology↗

bioRxiv2026

Genome sequencing reveals novel pathogenic deep-intronic PCDH15 variants, amenable to antisense oligonucleotide-based splice correction

Despite substantial advances in diagnostic testing, 10-15% of Usher syndrome patients remain without a genetic diagnosis, having significant implications for genetic counseling and potential future therapeutic interventions. In this study, genome sequencing data from probands clinically presenting with Usher syndrome were analyzed. Two novel deep-intronic variants were identified in PCDH15, c.3983+3635A>G and c.3123-1728A>G, in two independent patients. Both deep-intronic variants were classified as likely pathogenic and predicted to alter PCDH15 pre-mRNA splicing. Using a minigene splice assay and iPSC-derived photoreceptor precursor cells from patients, we confirmed that both variants lead to the inclusion of a pseudoexon in the PCDH15 transcript introducing a stop codon and subsequent premature termination of protein translation. We designed and evaluated antisense oligonucleotides (ASOs) with the purpose of redirecting aberrant pre-mRNA splicing caused by both deep-intronic variants. For both variants, designed ASOs were successful in restoring normal splicing patterns, highlighting their potential as a future therapeutic intervention strategy to halt the progression of retinitis pigmentosa caused by these novel variants. Overall, these findings contribute to the understanding of Usher syndrome caused by deep-intronic pathogenic variants in PCDH15 and describe for the first time the use of an ASO-mediated splice correction strategy for individuals diagnosed with these variants.

genetics↗

bioRxiv2026

Patient-Derived Inner Ear Organoids as a Disease Modeling and Therapy Validation Platform For Hereditary Inner Ear Disorders

BackgroundHereditary inner ear disorders comprise a highly heterogenous group of disorders and are a major cause of hearing and vestibular dysfunction. Despite advances in genetic diagnosis, the development of precision therapies has been limited by the lack of relevant and scalable human model systems that can accommodate the wide spectrum of disease-causing variants and support the evaluation of therapeutic interventions. We established patient-derived inner ear organoids (IEOs) as a platform to assess antisense oligonucleotide (ASO)-based therapeutic strategies for hereditary hearing loss. MethodsTwo representative genetic models were selected: recessive syndromic Usher syndrome type IIa (USH2A) and dominant non-syndromic DFNA9 (COCH). Human induced pluripotent stem cells (iPSCs) were generated from a patient carrying a homozygous pathogenic USH2A variant and a patient carrying a frequently occurring pathogenic COCH variant. In parallel, isogenic iPSC lines were created by introducing the same disease-causing variants into a healthy donor background. Following differentiation into IEOs, disease-associated transcript expression was evaluated. Splice-switching and RNase H1-mediated gapmer ASOs were assessed for target engagement. ASO biodistribution and cellular uptake was also examined in both IEOs and adult human vestibular tissue. ResultsPatient-derived and isogenic iPSCs were successfully differentiated into IEOs that recapitulated disease-associated transcript expression. ASOs showed efficient uptake into disease-relevant cell populations in both IEOs and adult human vestibular tissue. In USH2A-variant IEOs, splice-switching ASO treatment corrected aberrant splicing. In COCH-variant IEOs, gapmer ASO treatment reduced total COCH transcript levels, achieving up to 75% knockdown in patient-derived IEOs. ConclusionsPatient-derived and isogenic variant IEOs provide a versatile and scalable human platform for evaluating ASO therapies for hereditary hearing loss. Their adaptability to diverse genetic variants, inheritance patterns, and ASO modalities makes them well suited to address the genetic heterogeneity of hereditary inner ear diseases and establishes IEOs as a broadly applicable preclinical model for rare hereditary inner ear diseases.

neuroscience↗

bioRxiv2026

Expanding the options for therapeutic exon skipping as a future treatment for USH2A-associated disease by 3D structural modeling of newly formed hybrid domains

Usher syndrome, the leading cause of hereditary deaf-blindness affecting approximately 1 in 15,000 individuals worldwide, is currently still untreatable. Antisense oligonucleotide-based exon skipping has shown significant therapeutic promise for USH2A-associated retinal dysfunction. Selection of (combinations of) exons suitable for therapeutic exon skipping within the fibronectin type 3 (FN3) domain-encoding region of USH2A currently requires that skipped exons exactly align with complete protein domains. However, only few exon combinations meet this criterion, which significantly restricts the therapeutic potential of this strategy. Our study addresses this limitation by incorporating AlphaFold2 structural modelling into the exon skipping target selection pipeline. Following this adjusted framework, we can predict exon skipping combinations that allow remaining domain fragments to form structurally viable hybrid domains. As a proof-of-concept, we examined and confirmed the functionality of usherin{Delta}exon54-58 that contains a hybrid FN3 domain, using zebrafish as a model. This highligts the potential of the newly developed paradigm for identifying exon skipping targets with potential therapeutic relevance. Our results emphasize the value of structural modeling in identifying new therapeutic exon skipping targets, aiming to improve precision, efficiency, applicability, and cost-effectiveness in the development of genetic therapies for hereditary diseases such as Usher syndrome.

bioinformatics↗

bioRxiv2026

Usherin in the pineal gland: altered sleep in zebrafish models of Usher syndrome type 2a

Usher syndrome type 2A (USH2a), the most common form of hereditary deaf-blindness, is frequently accompanied by fatigue and poor sleep quality. As these sleep problems occur independently of visual decline, it is hypothesized that the USH2A-encoded protein usherin regulates sleep and circadian rhythmicity via an extra-retinal mechanism. Ush2a knockout zebrafish models were utilized to investigate this hypothesis. Immunohistochemical analysis demonstrated usherin localisation in pineal gland photoreceptor cells in wild-type larvae, alongside the USH2 complex proteins Adgrv1 and Whrna. Cross-species transcriptomic and proteomic analyses confirmed USH2A expression in all mammalian pineal gland tissues studied. Circadian clock gene expression was measured over 24 h and showed preserved oscillatory patterns in wild-type and mutant zebrafish. Ex vivo superfusion of pineal glands revealed sustained circadian melatonin release with comparable phase and period to controls, although potential differences in absolute melatonin levels could not be excluded. Despite intact clock gene expression and melatonin release in ush2a mutants, behavioural classification over 24-h recordings revealed altered sleep-wake behaviour: ush2a mutants displayed elevated daytime sleep and significantly prolonged and more variable sleep latency. The dissociation between intact molecular rhythms and abnormal sleep behaviour likely implicates that usherin plays a role in sleep-wake regulation independent of the circadian pacemaker and melatonin synthesis. These findings suggest a novel role of usherin in the pineal gland and establish a mechanistic link between usherin dysfunction and sleep disturbances, providing a biological basis for the fatigue and sleep problems reported in USH2a patients.

animal behavior and cognition↗

bioRxiv2024

Pushing the limits of single molecule transcript sequencing to uncover the largest disease-associated transcript isoforms in the human neural retina

Sequencing technologies have long limited the comprehensive investigation of large transcripts associated with inherited retinal diseases (IRDs) like Usher syndrome, which involves 11 associated genes with transcripts up to 19.6 kb. To address this, we used PacBio long-read mRNA isoform sequencing (Iso-Seq) following standard library preparation and an optimized workflow to enrich for long transcripts in the human neural retina. While our workflow achieved sequencing of transcripts up to 15 kb, this was insufficient for Usher syndrome-associated genes USH2A and ADGRV1, with transcripts of 18.9 kb and 19.6 kb, respectively. To overcome this, we employed the Samplix Xdrop System for indirect target enrichment of cDNA, a technique typically used for genomic DNA capture. This method facilitated the successful capture and sequencing of ADGRV1 transcripts as well as the full-length 18.9 kb USH2A transcripts. By combining algorithmic analysis with detailed manual curation of sequenced reads, we identified novel isoforms and alternative splicing events across the 11 Usher syndrome-associated genes, with implications for diagnostics and therapy development. Our findings demonstrate the Xdrop systems adaptability for cDNA capture and the advantages of integrating computational and manual transcript analyses. The full neural retina sequencing dataset is available via EGA under identifier EGAD50000000720.

genetics↗

bioRxiv2020

Antisense oligonucleotide-based treatment of retinitis pigmentosa caused by USH2A exon 13 mutations

Mutations in USH2A, encoding usherin, are the most common cause of syndromic and non-syndromic retinitis pigmentosa (RP). The two founder mutations in exon 13 (c.2299delG and c.2276G>T) collectively account for ~34% of USH2A-associated RP cases. Skipping of exon 13 from the USH2A transcript during pre-mRNA splicing presents a potential treatment modality in which the resulting transcript is predicted to encode a slightly shortened usherin protein. Morpholino-induced skipping of ush2a exon 13 in larvae of the previously published ush2a exon 13 zebrafish mutant resulted in the production of usherin{Delta}exon13 and completely restored retinal function. RNA antisense oligonucleotides were investigated for their potential to specifically induce human USH2A exon 13 skipping. Lead candidate QR-421a induced dose-dependent exon 13 skipping in iPSC-derived photoreceptor precursors from a patient homozygous for the USH2A c.2299delG mutation. Intravitreal delivery of QR-421a in non-human primates showed that QR-421a penetrates the retinal outer nuclear layer and induces detectable levels of exon 13 skipping until at least 3 months post injection. In conclusion, QR-421a-induced exon skipping proves to be a highly promising treatment for RP caused by mutations in exon 13 of the USH2A gene.

genetics↗

bioRxiv2020

Allele-specific antisense oligonucleotide therapy for dominantly inherited hearing impairment DFNA9.

The c.151C>T founder mutation in COCH is a frequent cause of late onset, dominantly inherited hearing impairment and vestibular dysfunction (DFNA9) in the Dutch/Belgian population. The initial clinical symptoms only manifest between the 3rd and 5th decade of life, which leaves ample time for therapeutic intervention. The dominant inheritance pattern and established non-haploinsufficiency disease mechanism indicate that suppressing translation of mutant COCH transcripts has high therapeutic potential. Single-Molecule Real-Time (SMRT) sequencing resulted in the identification of 11 variants with a low population-frequency (< 10%), that are specific to the c.151C>T mutant COCH allele. Proof of concept was obtained that gapmer antisense oligonucleotides (AONs), directed against the c.151C>T mutation or mutant allele-specific intronic variants, are able to specifically induce mutant COCH transcript degradation when delivered to transgenic cells expressing COCH minigenes. Sequence optimization of the AONs against the c.151C>T mutation resulted in a lead molecule that reduced the levels of mutant COCH transcripts by ~60% in a transgenic cell model, without affecting wildtype COCH transcript levels. With the proven safety of AONs in humans, and rapid advancements in inner ear drug delivery, our in-vitro studies indicate that AONs offer a promising treatment modality for DFNA9.

genetics↗

bioRxiv2017

CiliaCarta: An Integrated And Validated Compendium Of Ciliary Genes

The cilium is an essential organelle at the surface of most mammalian cells whose dysfunction causes a wide range of genetic diseases collectively called ciliopathies. The current rate at which new ciliopathy genes are identified suggests that many ciliary components remain undiscovered. We generated and rigorously analyzed genomic, proteomic, transcriptomic and evolutionary data and systematically integrated these using Bayesian statistics into a predictive score for ciliary function. This resulted in 285 candidate ciliary genes. We found experimental evidence of ciliary associations for 24 out of 36 analyzed candidate proteins. In addition, we show that OSCP1, which has previously been implicated in two distinct non-ciliary functions, causes a cilium dysfunction phenotype when depleted in zebrafish. The candidate list forms the basis of CiliaCarta, a comprehensive ciliary compendium covering 836 genes. The resource can be used to objectively prioritize candidate genes in whole exome or genome sequencing of ciliopathy patients and can be accessed at http://bioinformatics.bio.uu.nl/john/syscilia/ciliacarta/.

bioinformatics↗