Biology subjects

Perrard, J.

Publications and source records attributed to Perrard, J..

5 recordsLinked to original sources

bioRxiv2025

Role of small intronic RNAs in the crosstalk between immune cells and beta-cells during type 1 diabetes development

Small non-coding RNAs, such as microRNAs and tRNA-derived fragments, are key regulators of cellular processes, but the functions of small intronic RNAs (sinRNAs), a recently identified RNA class, remain largely unknown. Here, we report that two sinRNAs, sinR-D and sinR-T, are upregulated in pancreatic {beta}-cells of NOD mice, a well-established model of type 1 diabetes. Using in vivo RNA-tagging, we demonstrate that these sinRNAs are packaged into extracellular vesicles released by infiltrating CD4 T lymphocytes and subsequently delivered to {beta}-cells during the early stages of autoimmune attack. Functional analyses revealed that overexpression of sinR-T has little effect on {beta}-cell viability, whereas sinR-D markedly increases {beta}-cell apoptosis. This finding suggests that the transfer of sinR-D contributes to {beta}-cell destruction and the onset of type 1 diabetes. Furthermore, pull-down experiments with biotinylated sinRNAs identified Ago2, a core component of the RNA-induced silencing complex (RISC), as a binding partner of sinR-D, indicating mechanistic parallels with microRNA-mediated regulation. Collectively, our data uncover a novel role for sinRNAs as extracellularly transferred regulators of {beta}-cell fate, expanding the repertoire of small RNAs implicated in the initiation of type 1 diabetes.

molecular biology↗

bioRxiv2025

Small non-coding RNA profiling reveals inflammatory and mitochondrial related changes in aging β-cells and islet macrophages

Aging is accompanied by functional decline and increased senescence of pancreatic {beta}-cells. These changes may be influenced by islet-resident macrophages (iMACs) that remodel tissue in response to environmental cues. To explore the molecular mechanisms underlying {beta}-cell aging and senescence, we profiled small non-coding RNAs (sncRNAs) in FACS-sorted {beta}-cells and iMACs from 3-, 12-, and 22-month-old mouse islets or from senescence-associated {beta}gal (SA-{beta}gal) positive {beta}-cells of 8-month-old mice. Overall, senescent {beta}-cells displayed distinct sncRNA signatures that only partially overlapped with those of aging. However, several miRNAs previously found to be deregulated in obese or diabetic conditions were modulated in both aging and senescent {beta}-cells, including upregulation of miRNAs linked to inflammation. In vitro exposure to pro-inflammatory cytokines partially reproduced these profiles. Aging also reshaped the {beta}-cell tRNA-derived fragment (tRF) pool, enhancing global mitochondrial tRF levels. Interestingly, some changes in miRNAs and tRFs were {beta}-cell specific, whereas others occurred also in other aged metabolic tissues. iMACs also showed age-related sncRNA remodeling, including upregulation of anti-inflammatory miRNAs and mitochondrial tRFs, suggesting adaptive immune reprogramming. Together, these data reveal a profound, coordinated reshaping of the sncRNA landscape in {beta}-cells and iMACs during aging, offering new insights into molecular mechanisms driving age-related islet dysfunction.

molecular biology↗

bioRxiv2025

The MIME-seq technique allows to monitor the interaction of small non-coding RNAs with Argonaute proteins and their transfer to other cells

The MIME-seq2.0 technique utilizes a chimeric HENMT1 methyltransferase engineered to bind to Argonaute proteins (hereafter referred to MIME enzyme) to protect the terminal sugar of small non-coding RNAs (sncRNAs) from oxidation, a reaction that inhibits unmodified RNA ligation and cloning. In this study, we confirm that the MIME-seq technique efficiently distinguishes oxidized and non-oxidized sncRNAs. Indeed, expression of the MIME enzyme in the insulin-secreting cell line MIN6B1 protected miRNAs from oxidation and permitted their detection by RNA sequencing and quantitative PCR. Comparison of the sncRNA profile between wild type and MIME-expressing cells demonstrated protection from oxidation not only of miRNAs, but also of some Y-RNA and tRNA-derived fragments. Immunoprecipitation with Ago2 antibodies confirmed that the protected Y-RNA and tRNA fragments bind to Argonaute proteins. We also used this system to track miRNA transfer between cells via extracellular vesicles (EVs). miRNAs released inside EVs of MIME-expressing Jurkat T cells or C2C12 myotubes and delivered to MIN6B1 cells were protected from oxidation, enabling sensitive and specific detection of the transferred miRNAs in the receiving cells. Overall, the MIME-seq technique provides a powerful tool for analyzing small RNA binding to Argonaute proteins in living cells and offers new possibilities for tracking RNA transfer across different cell types.

molecular biology↗

bioRxiv2025

Deltex and RING-UIM E3 ligases cooperate to create a ubiquitin-ADP-ribose hybrid mark on tankyrase, promoting its stabilization

AbstractADP-ribosylation is a key post-translational modification that impacts diverse cellular pathways. The modification can occur as mono-ADP-ribose (MAR) or be extended into poly-ADP- ribose (PAR). Tankyrase, a PAR transferase, adds PAR to itself and other proteins to influence their function and stability by tagging them for proteasomal degradation via the PAR-binding E3 ligase RNF146. This degradation can be counteracted by RING-UIM E3 ligases RNF114 and RNF166, though the process is unclear. Here we identify a new mechanism that can regulate the balance between MAR and PAR on tankyrase to control degradation. We show that Deltex E3 ligases DTX2 and DTX3 catalyze monoubiquitylation of tankyrase in cells. This ubiquitylation occurs, not on a (canonical) lysine, but rather on mono-ADP-ribose, creating a monoubiquitin- MAR hybrid mark. RNF114 and RNF166 recognize this mark using a unique hybrid reader domain comprising two binding sites - one for MAR and one for ubiquitin - and further diubiquitylate it. This ubiquitylation of MAR, which occurs near the ADP-ribose addition site, prevents PAR formation, antagonizing the action of the PAR-binding E3 ligase RNF146 and stabilizing tankyrase. These findings reveal a novel interplay between ubiquitin, ADP-ribose, and E3 ligases in cellular signaling.

biochemistry↗

bioRxiv2023

Multiple E3 ligases control tankyrase stability and function

Tankyrase 1 and 2 are ADP-ribosyltransferases that use NAD+ as a substrate to catalyze polyADP-Ribose (PAR) onto themselves and their protein binding partners. Tankyrases have diverse cellular functions, ranging from resolution of telomere cohesion to activation of the Wnt/{beta}-catenin signaling pathway. Robust and specific small molecule tankyrase inhibitors have been developed and are being investigated for cancer therapies. Tankyrase is regulated by the PAR-binding E3 ligase RNF146, which promotes K48-linked polyubiquitylation and proteasomal degradation of PARylated tankyrases and their PARylated partners. We have identified a novel interaction between tankyrase and a distinct class of E3 ligases: the RING-UIM (Ubiquitin-Interacting Motif) family. We show that RING-UIM E3 ligases (specifically RNF114 and RNF166) bind and stabilize monoubiquitylated tankyrase and promote K11-linked diubiquitylation. This action competes with RNF146-mediated K48-linked polyubiquitylation and degradation, leading to stabilization of tankyrase and to a subset of its binding partners, including Angiomotin, a protein that functions in cancer signaling pathways. Moreover, we identify multiple PAR-binding E3 ligases (in addition to RNF146) that promote ubiquitylation of tankyrase and induce stabilization or degradation. Discovery of this novel K11 ubiquitylation of tankyrase that opposes K48-mediated degradation along with identification of multiple PAR-binding E3 ligases that ubiquitylate tankyrase, provide new insights into mechanisms of tankyrase regulation and may offer new uses for tankyrase inhibitors in cancer therapy.

biochemistry↗