Biology subjects

Jaspard-Vinassa, B.

Publications and source records attributed to Jaspard-Vinassa, B..

4 recordsLinked to original sources

bioRxiv2024

Cerebral Small Vessel Disease genetic determinant TRIM47 controls brain homeostasis via the NRF2 antioxidant system

Cerebral small vessel disease (cSVD) is a leading cause of stroke, cognitive decline and dementia, for which no specific mechanism-based treatments are available to date. Genome-wide and whole-exome association studies previously identified robust associations of common variants at chr17q25 with cSVD features on magnetic resonance imaging, with converging bioinformatic and experimental data for a causal involvement of TRIM47. Preliminary functional evaluation of TRIM47, an ubiquitin ligase enriched in brain endothelial cells (ECs), suggested its potential role in blood brain barrier (BBB) integrity. Here, we show that TRIM47 regulates brain EC resilience and adaptive responses to oxidative stress by binding to KEAP1, stabilizing NRF2 protein levels and promoting the NRF2 antioxidant signaling pathway. In vivo, Trim47-deficient mice exhibit downregulation of NRF2 target genes, BBB dysfunction, astrogliosis and cognitive impairments. Endothelial-specific deletion of Trim47 recapitulates these phenotypes. Treatment with the NRF2 activator tert- butylhydroquinone normalized BBB integrity and cognitive function in Trim47-deficient mice, highlighting the role of endothelial TRIM47 in driving brain homeostasis through NRF2 pathway activation. This work indicates that loss of the protective TRIM47/NRF2 axis may increase the susceptibility to developing human cSVD and that targeting the TRIM47/NRF2 axis could be a promising therapeutic approach for vascular cognitive impairment and dementia.

neuroscience↗

bioRxiv2022

Novel uAUG creating variants in the 5UTR of ENG causing Hereditary Hemorrhagic Telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare vascular disorder causing abnormal vessel formation and characterized by autosomal dominant transmission. The associated considerable variability in symptoms and clinical severity complicate the management of the disease. In clinical routine, 3 main genes, ACVRL1 (also known as ALK1), ENG and SMAD4 are screened for pathogenic variants at the origin of HHT. About 80% of HHT cases are caused by pathogenic coding variants in ACVRL1 and ENG. However, at least 15% remain with no molecular explanations in the 3 main genes. We here report the identification of 2 never reported variants, c.-79C>T and c.-68G>A, in the 5UTR of ENG in 2 unrelated HHT patients. These 2 variants are predicted to create upstream AUGs (uAUGs) in the 5UTR, which are in frame with a stop codon located within the CoDing Sequence (CDS), thus generating Overlapping upstream Open reading frames (uoORFs). In other cases, uAUGs can lead to fully upstream ORFs (uORFs) when associated with stop codons located within the 5UTR or to elongated CDS (eCDS) when in frame with the CDS and associated with the main stop codon. In order to assess the pathogenicity of these ENG variants, we performed in vitro functional assays based on the expression of wild-type and mutant constructs in human cells. We found that these 5UTR ENG variants were associated with a decrease of protein levels in HeLa and HUVEC cells. They were also associated with a decreased ability to activate BMP9-stimulated ALK1 receptor in a BMP-response element (BRE) assay. This assay is a mandatory element before providing a definitive molecular diagnosis and has been so far applied only on coding ENG variants. We applied the same experimental workflow on 3 additional uoORF-creating variants (c.-142A>T, c.-127C>T and c.-10C>T) and one eCDS-creating variant (c.-9G>A) in the 5UTR of ENG previously reported in HHT patients. We found that all the analysed uoORF-creating variants alter endoglin levels and function. A comparison of our experimental results with patients clinical characteristics suggests that uoORF-creating variants leading to ENG protein levels [≤] 40% in vitro would be associated with HHT. Additional experiments relying on an artificial deletion in our mutated constructs show that created uAUGs predicted to create uoORFs are able to initiate the translation indicating that the associated effect is likely caused by an alteration of the translation mechanism. Overall, we here identified two never reported 5UTR ENG variations in HHT patients and shed new lights on the role of upstream ORFs on ENG regulation. Our findings contribute to the amelioration of molecular diagnosis in HHT.

molecular biology↗

bioRxiv2020

MORFEE: a new tool for detecting and annotating single nucleotide variants creating premature ATG codons from VCF files

SummaryVariants in 5UTR regions that create upstream translation initiation AUG codons are a class of neglected non coding variations. When they associate with a premature stop codon and create upstream open reading frames (uORFs) whose translation competes with that of natural proteins, they can have strong impact on human diseases. We here describe MORFEE, a new bioinformatics tool that detects, annotates and predicts, from a standard VCF file, the creation of uORF by any 5UTR variants on uORF creation. MORFEE was applied to two genomic resources and identified candidate functional variants that could explain statistical association signals observed in the context of Genome Wide Association Studies or could be responsible for rare forms of diseases. In conclusion MORFEE is an easy-to-use tool complementary to existing ones that can help resolving genetic investigations that remained so far unfruitful. Availability and implementationMORFEE is written in R with code and package available at https://github.com/daissi/MORFEE. Contactdavid-alexandre.tregouet@inserm.fr; david-alexandre.tregouet@u-bordeaux.fr

bioinformatics↗

bioRxiv2020

A novel rare c. -39C>T mutation in the PROS1 5'UTR causing PS deficiency by creating a new upstream translation initiation codon and inhibiting the production of the natural protein.

Inherited Protein S deficiency (PSD) (MIM176880) is a rare automosal dominant disorder caused by rare mutations, mainly located in the coding sequence of the structural PROS1 gene, and associated with an increased risk of venous thromboembolism. To identify the molecular defect underlying PSD observed in an extended French pedigree with 7 PSD affected members in who no candidate deleterious PROS1 mutation was detected by Sanger sequencing of PROS1 exons and their flanking intronic regions or via a MLPA approach, a whole genome sequencing strategy was adopted. This led to the identification of a never reported C to T substitution at c.-39 from the natural ATG codon of the PROS1 gene that completely segregates with PSD in the whole family. This substitution ACG->ATG creates a new start codon upstream of the main ATG. We experimentally demonstrated that the variant generates a novel overlapping ORF and inhibits the translation of the wild type protein from the main ORF in HeLa cells. This work describes the first example of 5UTR PROS1 mutation causing PSD through the creation of an upstream ORF, a mutation that is not predicted to be deleterious by standard annotation softwares.

genetics↗