Biology subjects

Amaral, M. D.

Publications and source records attributed to Amaral, M. D..

8 recordsLinked to original sources

bioRxiv2026

A functional comparison of readthrough agent ELX-02 across a wide range of nonsense CFTR variants

BackgroundNonsense variants in CFTR account for ~10% of cystic fibrosis (CF) variants and cannot be treated with approved CFTR modulators. Translational readthrough agents such as ELX-02 offer a potential therapeutic strategy, but clinical trials evaluated mainly in G542X CFTR nonsense variant and underlined limited efficacy. This study aimed to evaluate ELX-02-mediated CFTR rescue across a broad range of nonsense variants using patient-derived intestinal organoids (PDIOs) to define variant-specific determinants of readthrough efficacy and assess its potential across a genetically diverse CF population. MethodThe ex vivo response to ELX-02 was assessed in 206 PDIOs carrying heterogeneous nonsense variants. CFTR function was quantified using forskolin-induced swelling (FIS) assay after 48-hour exposure to ELX-02. Responses were analysed by genotype and stop codon identity, with secondary validation performed in a selected subset of PDIOs (n = 60). ResultsELX-02-mediated CFTR rescue varied markedly, ranging from responses approaching those observed with approved CFTR modulators (LUM/IVA) to responses at or below detection limit. Overall, maximal responses were modest and at the lower end of the functional range for CFTR modulators. Rescue was dose-dependent and higher in PDIOs carrying two nonsense variants when compared with PDIOs carrying a single nonsense variant combined with a residual or minimal function variant. Nonsense variants in nucleotide-binding domain 1, including G542X, S466X, G550X and R553X, showed relatively higher responsiveness. ConclusionELX-02 induces limited and highly heterogeneous CFTR rescue across nonsense variants. PDIO-based functional screening provides a framework to guide patient selection and stratification for future readthrough therapy trials.

molecular biology↗

bioRxiv2022

Drug repurposing for Cystic Fibrosis: identification of drugs that induce CFTR-independent fluid secretion in nasal organoids

Individuals with Cystic Fibrosis (CF) suffer from severe respiratory disease due to a genetic defect in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene, which impairs airway epithelial ion and fluid secretion. New CFTR modulators that restore mutant CFTR function have been recently approved for a large group of people with CF (pwCF), but [~]19% of pwCF cannot benefit from CFTR modulators [1]. Restoration of epithelial fluid secretion through non-CFTR pathways might be an effective treatment for all pwCF. Here we developed a medium-throughput 384-wells screening assay using nasal CF airway epithelial organoids, with the aim to repurpose FDA-approved drugs as modulators of non-CFTR dependent epithelial fluid secretion. From a [~]1400 FDA-approved drug library, we identified and validated 12 FDA-approved drugs that induced CFTR-independent fluid secretion. Among the hits were several cAMP-mediating drugs, including {beta}2-adrenergic agonists. The hits displayed no effects on chloride conductance measured in Ussing chamber, and fluid secretion was not affected by TMEM16A as demonstrated by knockout (KO) experiments in primary nasal epithelial cells. Altogether, our results demonstrate the use of primary nasal airway cells for mediumscale drug screening, target validation with a highly efficient protocol for generating CRISPR-Cas9 KO cells and identification of compounds which induce fluid secretion in a CFTR- and TMEM16A-indepent manner.

cell biology↗

bioRxiv2021

CFTR modulator response measurements in subjects with cystic fibrosis using 2D differentiated nasal epithelia converted into spheroids

Cystic Fibrosis (CF) is caused by genetic defects that impair the cystic fibrosis transmembrane conductance regulator (CFTR) channel in airway epithelial cells. These defects may be overcome by specific CFTR modulating drugs, for which the efficacy can be predicted in a personalized manner using 3D nasal-brushing-derived airway organoids in a forskolin-induced swelling assay. Despite of this, previously described application of 3D airway organoids in CFTR function assays have not been fully optimal. In this report we therefore describe an alternative method of culturing nasal brushing-derived airway organoids, which are created from an equally differentiated airway epithelial monolayer of a 2D air-liquid interface culture. In addition, we have defined organoid culture conditions, with the growth factor/cytokine combination neuregulin-1{beta} and interleukine-1{beta}, which enabled consistent detection of CFTR modulator responses in nasal airway organoids cultures from subjects with CF.

cell biology↗

bioRxiv2019

Non-Coding and Loss-of-Function Coding Variants in TET2 are Associated with Multiple Neurodegenerative Diseases

We conducted genome sequencing to search for rare variation contributing to early onset Alzheimers disease (EOAD) and frontotemporal dementia (FTD). Discovery analysis was conducted on 493 cases and 671 controls of European ancestry. Burden testing for rare variation associated with disease was conducted using filters based on variant rarity (less than 1 in 10,000 or private), computational prediction of deleteriousness (CADD 10 or 15 thresholds), and molecular function (protein loss-of-function only, coding alteration only, or coding plus non-coding variants in experimentally predicted regulatory regions).\n\nReplication analysis was conducted on 16,871 independent cases and 15,941 independent controls. Rare variants in TET2 were enriched in the discovery combined EOAD and FTD cohort (p=6.5x10-8, genome-wide corrected p=0.0037). Most of these variants were canonical loss-of-function or non-coding in predicted regulatory regions. This enrichment replicated across several cohorts of AD and FTD (replication only p=0.0071). The combined analysis odds ratio was 2.2 (95% CI 1.5-3.2) for AD and FTD. The odds ratio for qualifying non-coding variants considered independently from coding variants was 2.1 (95% CI 1.2-3.9). For loss-of-function variants, the combined odds ratio (for AD, FTD, and amyotrophic lateral sclerosis, which shares clinicopathological overlap with FTD) was 3.2 (95% CI 2.0-5.3). TET2 catalyzes DNA demethylation. Given well-defined changes in DNA methylation that occur during aging, rare variation in TET2 may confer risk for neurodegeneration by altering the homeostasis of key aging-related processes. Additionally, our study emphasizes the relevance of non-coding variation in genetic studies of complex disease.

neuroscience↗

bioRxiv2019

Genome sequencing for early-onset dementia: high diagnostic yield and frequent observation of multiple contributory alleles

We assessed the utility of genome sequencing for early-onset dementia. Participants were selected from a memory disorders clinic. Genome sequencing was performed along with C9orf72 repeat expansion testing. All returned sequencing results were Sanger validated clinically. Prior clinical diagnoses included Alzheimers disease, frontotemporal dementia, and unspecified dementia. The mean age-of-onset was 54 (41-76). 50% of patients had a strong family history, 37.5% had some, and 12.5% had no known family history. Nine of 32 patients (28%) had a variant defined as pathogenic or likely pathogenic (P/LP) by American College of Medical Genetics standards, including variants in APP, C9orf72, CSF1R, and MAPT. Nine patients (including three with P/LP variants) harbored established risk alleles with moderate penetrance (odds ratios of about 2-5) in ABCA7, AKAP9, GBA, PLD3, SORL1, and TREM2. All six patients harboring these moderate penetrance variants but not P/LP variants also had one or two APOE {varepsilon}4 alleles. One patient had two APOE {varepsilon}4 alleles with no other established contributors. In total, 16 patients (50%) harbored one or more genetic variants likely to explain symptoms. We identified variants of uncertain significance (VUSs) in ABI3, ADAM10, ARSA, GRID2IP, MME, NOTCH3, PLCD1, PSEN1, TM2D3, TNK1, TTC3, and VPS13C, also often along with other variants. In summary, genome sequencing for early-onset dementia demonstrated high utility, with particular advantages where targeted testing may fail such as atypical variant-disease associations or presence of multiple moderate impact alleles. One or more established contributory alleles is often present in early-onset dementia, supporting an oligogenic model.

neuroscience↗

bioRxiv2018

Full Rescue of F508del-CFTR Processing and Function by CFTR Modulators can be Achieved by Removal of Two Unique Regulatory Regions

Background and Purpose: Cystic Fibrosis (CF) is caused by mutations in the CF Transmembrane conductance Regulator (CFTR), the only ABC transporter functioning as a channel. Unique to CFTR are two highly conformationally dynamic regions: the regulatory extension (RE) and regulatory insertion (RI). Removal of the latter rescues the trafficking defect of CFTR with F508del, the most common CF-causing mutation.\n\nWe aimed here to assess the impact of RE removal (alone or with RI or genetic revertants) on F508del-CFTR traffic and how CFTR modulator drugs corrector VX-809/lumacaftor and potentiator VX-770/ivacaftor rescue these combined variants so as to gain insight into the mechanism of action (MoA) of these drugs.\n\nExperimental Approach. We generated {triangleup}RE and {triangleup}RI CFTR variants (with and without genetic revertants) by site-directed mutagenesis and used them to stably transfect BHK cell lines. We studied CFTR expression and stability by Western blotting and pulse-chase respectively, plasma membrane levels by cell surface biotinylation and channel activity by the iodide efflux technique.\n\nKey Results. Our data demonstrate that {triangleup}RI significantly enhanced rescue of F508del-CFTR by VX-809. Thus, while the presence of the regulatory insertion seems to be precluding full rescue of F508del-CFTR processing by VX-809, this region appears essential to rescue its function by VX-770, thus suggesting some contradictory role in rescue of F508del-CFTR by these two modulators. Nevertheless, this negative impact of RI removal on VX-770-stimulated currents on F508del-CFTR can be compensated by deletion of the regulatory extension which also leads to the stabilization of this mutant. We thus propose that, despite both these regions being conformationally active, RI precludes F508del-CFTR processing while RE affects mostly its stability and channel opening.\n\nSupporting Information: Additional figures with supplementary data

biochemistry↗

bioRxiv2017

Genomic sequencing identifies secondary findings in a cohort of parent study participants

PURPOSEClinically relevant secondary variants were identified in parents enrolled with a child with developmental delay and intellectual disability.\n\nMETHODSExome/genome sequencing and analysis of 789 unaffected parents was performed.\n\nRESULTSPathogenic/likely pathogenic variants were identified in 21 genes within 25 individuals (3.2%), with 11 (1.4%) participants harboring variation in a gene defined as clinically actionable by the ACMG. Of the 25 individuals, five carried a variant consistent with a previous clinical diagnosis, thirteen were not previously diagnosed but had symptoms or family history with probable association with the detected variant, and seven reported no symptoms or family history of disease. A limited carrier screen was performed yielding 15 variants in 48 (6.1%) parents. Parents were also analyzed as mate-pairs to identify cases in which both parents were carriers for the same recessive disease; this led to one finding in ATP7B. Four participants had two findings (one carrier and one non-carrier variant). In total, 71 of the 789 enrolled parents (9.0%) received secondary findings.\n\nCONCLUSIONWe provide an overview of the rates and types of clinically relevant secondary findings, which may be useful in the design, and implementation of research and clinical sequencing efforts to identify such findings.

genomics↗

bioRxiv2016

Genomic diagnosis for children with intellectual disability and/or developmental delay

BackgroundDevelopmental disabilities have diverse genetic causes that must be identified to facilitate precise diagnoses. We describe genomic data from 371 affected individuals, 309 of which were sequenced as proband-parent trios.\n\nMethodsWhole exome sequences (WES) were generated for 365 individuals (127 affected) and whole genome sequences (WGS) were generated for 612 individuals (244 affected).\n\nResultsPathogenic or likely pathogenic variants were found in 100 individuals (27%), with variants of uncertain significance in an additional 42 (11.3%). We found that a family history of neurological disease, especially the presence of an affected 1st degree relative, reduces the pathogenic/likely pathogenic variant identification rate, reflecting both the disease relevance and ease of interpretation of de novo variants. We also found that improvements to genetic knowledge facilitated interpretation changes in many cases. Through systematic reanalyses we have thus far reclassified 15 variants, with 11.3% of families who initially were found to harbor a VUS, and 4.7% of families with a negative result, eventually found to harbor a pathogenic or likely pathogenic variant. To further such progress, the data described here are being shared through ClinVar, GeneMatcher, and dbGAP.\n\nConclusionOur data strongly support the value of large-scale sequencing, especially WGS within proband-parent trios, as both an effective first-choice diagnostic tool and means to advance clinical and research progress related to pediatric neurological disease.

genomics↗