Biology subjects

Mehraz, M.

Publications and source records attributed to Mehraz, M..

5 recordsLinked to original sources

bioRxiv2026

Epidemic Risks associated with high-temperature replicating infectious hematopoietic necrosis virus (IHNV) field isolates: from molecular characterization to host pathogen interactions

Infectious hematopoietic necrosis virus (IHNV) is a WOAH-notifiable pathogen responsible for severe acute disease in salmonids at temperatures ranging from 4 to 14{degrees}. At higher water temperatures, the disease is generally associated with reduced mortality and lower viral replication. In the context of climate change, rising water temperatures could favor the emergence of thermotolerant strains while representing a major physiological and metabolic stress potentially altering fish's immune responses. This study aims to characterize the impact of increasing water temperatures on IHNV replication and host-pathogen interactions. Following pre-screening, the replication kinetics of the reference strain N61 and two field isolates RtNag0a and SA-22 were characterized in EPC (Epithelioma Papulosum Cyprini) and RTG-2 (Rainbow trout gonad) cell lines at 14, 20 and 22{degrees}. Virulence and host-pathogen interactions were subsequently investigated in vivo in zebrafish (Zf) larvae using complementary microinjection and bath immersion infection models at 21.5 and 23.5{degrees}. In vitro studies revealed distinct thermal replication profiles, distinguishing thermosensitive from thermotolerant isolates, although these phenotypes were influenced by the cellular environment. The zebrafish model enabled the characterization of virulence and antiviral host responses associated with thermotolerant IHNV isolates. Notably, waterborne infection proved effective, contrasting with previous reports describing this exposure route as unsuitable for IHNV studies. These findings expand the growing list of emerging European IHNV genotypes capable of replicating at elevated temperatures (>20{degrees}) and establish zebrafish larvae as a relevant model for virulence assessment of field isolates. Together, these results provide valuable insights into the potential impact of climate warming on IHNV epidemiology and support efforts to predict and anticipate future outbreaks under changing environmental conditions.

pathology↗

bioRxiv2026

Molecular characterization of thermo-adapted Novirhabdovirus variants and virulence in vivo in rainbow trout and zebrafish at different temperatures.

Controlling viral diseases in fish is a challenge for the sustainable development of aquaculture and improving the health of fish farms. Infectious hematopoietic necrosis virus (IHNV) is a major pathogen in aquaculture. It infects cold-water fish, but loses its infectivity at temperatures above 20{degrees}C. Since fish are poikilothermic animals, their body temperature fluctuates according to that of their environment. Faced with current climate change, it is crucial to understand how these pathogens will adapt to rising temperatures. Through a strategy simulating the impact of global warming, this virus has been progressively thermo-adapted to 25{degrees}C. The selected variant, IHNV25, replicates at 25{degrees}C while maintaining efficient replication at low temperatures, like its parental strain. Genome sequencing and a reverse genetics approach revealed that only 9 amino acid substitutions, distributed across 4 of the 6 viral genes, were essential for thermo-adaptation. Although IHNV25 was highly attenuated in its natural host, the rainbow trout, at any temperatures, it proved highly virulent when injected in zebrafish larvae at 20{degrees}C and 25{degrees}C, inducing severe symptoms identical to those observed in trout (hemorrhages, oedema, and exophthalmia). At both temperatures, mortality was preceded by a massive viral replication and a delayed and inefficient interferon and inflammatory response. Unlike the parental strain, IHNV25 was also capable of infecting larvae by bath immersion at 25{degrees}C, entering via the caudal fin, thus demonstrating its ability to cross the species barrier. The identification of viral markers of thermo-adaptation will therefore be of great interest for the epidemiological surveillance of field isolates.

microbiology↗

bioRxiv2024

The ANKS3/BICC1 protein complex is a master post-transcriptional regulator of NPHP1 ciliopathy gene transcripts

Ciliopathies are a class of multi-systemic genetic diseases characterized by ciliary dysfunction. Here, we report a novel ANKS3 variant in patients with a renal ciliopathy known as nephronophthisis (NPH) associated with hepatic defects. ANKS3 is an ankyrin and sterile alpha motif domain-containing protein that interacts with many NPH proteins as well as with BICC1, an RNA-binding protein involved in renal cystic diseases. The pathogenic effect of the ANKS3 mutation was validated in the zebrafish mutant and knock-in rat model, the latter showing urine concentration defect and tubular dilatations similar to NPH patients. In addition, cilia morphology and function as well as epithelialization of kidney tubular cells was affected by loss or mutation of ANKS3. Finally, our results evidenced that these classically renal ciliopathy-associated phenotypes were linked to the negative regulation of BICC1 by ANKS3 which binds to transcripts of the major NPH gene NPHP1 and mediates their decay through the AGO2-RISC complex and recruitment into P-bodies. Altogether, our findings suggest that the ANKS3/BICC1 complex is a key post-transcriptional regulator of NPHP1 transcript stability, providing another level of regulation of cilium biogenesis and kidney homeostasis, as well as an unusual mechanism leading to NPH-related ciliopathies.

pathology↗

bioRxiv2023

The maintenance of centriole appendages and motile cilia basal body anchoring relies on TBCCD1

Centrosomes are organelles consisting of two structurally and functionally distinct centrioles, with the mother centriole having complex distal (DA) and subdistal appendages (SDA). Despite their importance, how appendages are assembled and maintained remains unclear. This study investigated human TBCCD1, a centrosomal protein essential for centrosome positioning, to uncover its localization and role at centrioles. We found that TBCCD1 localizes at both proximal and distal regions of the two centrioles, forming a complex structure spanning from SDA to DA and extending inside and outside the centriole lumen. TBCCD1 depletion caused centrosome mispositioning, which was partially rescued by taxol, and the loss of microtubules (MTs) anchored to centrosomes. TBCCD1 depletion also reduced levels of SDA proteins involved in MT anchoring such as Centriolin/CEP110, Ninein, and CEP170. Additionally, TBCCD1 was essential for the correct positioning of motile cilia basal bodies and associated structures in Paramecium. This study reveals that TBCCD1 is an evolutionarily conserved protein essential for centriole and basal body localization and appendage assembly and maintenance. A BioID screening also linked TBCCD1 to ciliopathy-associated protein networks.

cell biology↗

bioRxiv2022

Prostaglandin E1 as therapeutic molecule for Nephronophthisis and related ciliopathies

Nephronophthisis (NPH) is an autosomal recessive tubulointerstitial nephropathy belonging to the ciliopathy disorders and known as the most common cause of hereditary end-stage renal disease in children. Yet, no curative treatment is available. The major gene, NPHP1, encodes a protein playing key functions at the primary cilium and cellular junctions. Using an in cellulo medium-throughput drug-screen, we identified 51 FDA-approved compounds and selected 11 for their physicochemical properties, including prostaglandin E1 (PGE1). PGE1 was further validated to rescue ciliogenesis in immortalized patient NPHP1-/- urine-derived renal tubular cells and corroborated by the effects of its analog PGE2. The two molecules reduced pronephric cyst occurrence in vivo in nphp4 zebrafish model, and PGE1 treatment in Nphp1-/- mice led to a significant reduction of renal tubular dilatations, partially restoring cilia length within tubules. Finally, comparative transcriptomics allowed identification of key molecules downstream PGE1. Altogether, our drug-screen strategy led to the identification of PGE1 as the first potential therapeutic molecule for NPH-associated ciliopathies. Significant statementJuvenile nephronophthisis (NPH) is a renal ciliopathy due to a dysfunction of primary cilia and a common genetic cause of end-stage renal disease in children and young adults. No curative treatment is available. This paper describes the identification of Prostaglandin E1 (PGE1) as the first potential therapeutic molecule for NPH-associated ciliopathies. We demonstrated that PGE1 rescues defective ciliogenesis and ciliary composition in NPHP1-/- patient urine-derived renal tubular cells. Furthermore, PGE1 improves ciliary and kidney phenotypes in our NPH zebrafish and Nphp1-/- mouse models. Finally, in vitro experiments as well as transcriptomic analyses pointed out several pathways downstream PGE1 as cAMP, cell-cell/cell-matrix adhesion or actin cytoskeleton. Altogether, our findings provide a new alternative for treatment of NPH.

cell biology↗