Biology subjects

Antignac, C.

Publications and source records attributed to Antignac, C..

4 recordsLinked to original sources

bioRxiv2026

Structure of the human KEOPS/tRNA complex and characterization of pathogenic variants responsible for the Galloway Mowat syndrome.

N6-threonyl-carbamoylation of adenosine 37 of ANN-type tRNAs (t6A) is a universal modification essential for translational accuracy and efficiency. The t6A pathway uses two sequentially acting enzymes, YRDC and OSGEP, the latter being a subunit of the multiprotein KEOPS complex. Structures of the subunits and subcomplexes of human KEOPS are known, but knowledge on the detailed interactions with tRNA is lacking. We present here the first structure of complete hKEOPS and of its complex with a substrate tRNA by cryo-electron microscopy. The CAA tail of tRNA is bound to the TPRKB subunit and the anti-codon loop is positioned at the entrance of the catalytic site of OSGEP subunit. The flexibility of the OSGEP-TP53RK interface allows hKEOPS to fit the surface of the tRNA elbow. We recently identified mutations in all genes encoding for proteins of the t6A pathway in children with Galloway-Mowat syndrome (GAMOS), a clinically heterogeneous recessive disease characterized by early-onset steroid-resistant nephrotic syndrome and microcephaly. We here expressed and characterized the majority of the Galloway Mowat mutants. All mutants could be purified at high yields and seem to be stable in vitro. The t6A activity for most of the mutants is above 40% of the WT. Using CRISPR-Cas9 technology we replaced the genes encoding the t6A pathway proteins in yeast by their human homologues. This yeast construct was perfectly viable and produced WT levels of t6A modified tRNA. Using this tool, we observed that most of the GAMOS mutants were viable in yeast and yielded comparable t6A modified tRNA levels. Our data indicate that healthy human cellular development depends on an optimized level of t6A tRNA modification and is not compatible with a total loss of function of the t6A machinery.

biochemistry↗

bioRxiv2025

Therapeutic splice modulation of COL4A5 reinstates collagen IV assembly in an organoid model of X-linked Alport syndrome

Kidney organoids are an emerging tool for disease modeling, especially genetic diseases. Among them, X-linked Alport syndrome (XLAS) is a hematuric nephropathy affecting the glomerular basement membrane (GBM) secondary to pathogenic variations in the COL4A5 gene encoding the 5 subunit of type IV collagen [5(IV)]. In patients carrying pathogenic variations affecting splicing, the use of antisense oligonucleotides (ASOs) offers immense therapeutic hope. In this study, we develop a framework combining the use of patient-derived cells and kidney organoids to provide evidence of the therapeutic efficacy of ASOs in XLAS patients. Using multiomics analysis, we describe the development of GBM in wild-type and mutated human kidney organoids. We show that GBM maturation is a dynamic process, which requires long organoid culture. Then, using semi-automated quantification of 5(IV) at basement membranes in organoids carrying the splicing variants identified in patients, we demonstrate the efficacy of ASO treatment for 5(IV) restoration. These data contribute to our understanding of the development of GBM and pave the way for a therapeutic screening platform for patients.

genetics↗

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↗

bioRxiv2018

Cystinosin regulates kidney inflammation through its interaction with galectin-3

Inflammation is implicated in the pathogenesis of many disorders. Here, we show that cystinosin, protein defective in the lysosomal storage disorder cystinosis, is a critical regulator of galectin-3 during inflammation. Cystinosis is a lysosomal storage disorder and despite ubiquitous expression of cystinosin, kidney is the primary organ to be impacted by the disease. Here, we show that cystinosin interacts with galectin-3 and enhances its lysosomal localization and degradation. Galectin-3 is also found overexpressed in the kidney of the mouse model of cystinosis, Ctns-/-mice. Absence of galectin-3 in Ctns-/- mice led to a better renal function and structure, and decreased macrophage/monocyte infiltration in the kidney. Finally, galectin-3 interacts with a protein implicated in the recruitment of monocytes and macrophages during inflammation, Monocyte Chemoattractant Protein-1 (MCP1), that was found increased in the serum of Ctns-/- mice. These findings highlight a new role of cystinosin and galectin-3 interaction in inflammation, providing a mechanistic explanation for kidney disease pathogenesis in cystinosis, which may lead to the identification of new drug targets to delay its progression.

molecular biology↗