Biology subjects

Parent, A. V.

Publications and source records attributed to Parent, A. V..

5 recordsLinked to original sources

bioRxiv2026

MAFA drives pancreatic islet maturation through coordination of cell growth, metabolic maturation, and resilience to stress.

Stem cell-derived islets (SC-islets) are a promising source for replacing the loss of insulin-secreting {beta} cells in insulin-dependent diabetes patients, but compared to their primary human counter parts, SC-islets are considered functionally immature and do not immediately regulate blood glucose after transplantation. To better understand the molecular underpinnings of {beta} cell maturation, we genetically engineered human pluripotent stem cells (hPSCs) to control the induction of the {beta} cell-maturing transcription factor MAFA or a MAFA S64F mutant variant associated with premature {beta} cell aging and senescence in SC-islets. We employ a combination of in vitro assays, multi-omics analyses, and murine in vivo transplantation studies to demonstrate that MAFA remodeling of the SC-islet transcriptional landscape promotes SC-islet biogenesis and metabolic maturation giving rise to greater SC-islet resilience and insulin secretory capacity. Parallel MAFA S64F studies highlight the importance for compensatory mechanisms for sustaining accelerated oxidative metabolism and enhanced insulin secretion without inducing intracellular stress responses and islet dysfunction. Overall, these results reveal MAFA-governed transcriptional changes that drive SC-islet functional maturation, which provides the foundation for maturing SC-islets in vitro, preserving {beta} cell integrity, and improving SC-islet cell replacement therapies.

cell biology↗

bioRxiv2026

A universal platform for simultaneous TCRα/β removal enables safer and more potent TCR therapies and autoimmune modeling

Adoptive T-cell therapies using tumour-specific T-cell receptors (TCRs) are limited by competition with endogenous receptors, which impairs efficacy and poses risks of off-target autoreactivity. Here we present a CRISPR-based platform that completely and selectively eliminates both endogenous TCR- and -{beta} chains without affecting introduced transgenic TCRs, irrespective of codon optimization. This approach achieves >90% deletion efficiency in Jurkat and primary human T cells, markedly enhancing the expression, pairing fidelity, and functional potency of transgenic receptors. Using a clinically relevant HLA-A*02:01-restricted DMF5 TCR, we show that dual TCR ablation boosts antigen-specific activation and cytotoxicity in vitro and significantly enhances tumor clearance in vivo in human immune system (HIS) mice, while preventing graft-versus-host disease (GVHD). Targeted locus amplification revealed that CRISPR-induced double-strand breaks did not alter lentiviral integration profiles, confirming genomic safety. Extending this approach to four insulin-reactive TCRs demonstrated that removal of endogenous receptors increased transduction efficiency and functional activity, with one (1E6) showing selective activation and infiltration of stem cell-derived islet grafts (SC-islets) in vivo. This study establishes a universal, safe, and scalable genome-editing platform for generating functionally precise human T cells. By integrating cancer immunotherapy and autoimmune disease modelling within a single framework, it provides a strong preclinical rationale for dual endogenous TCR removal as a route to improved specificity, safety, and therapeutic efficacy in TCR-based cell therapies.

immunology↗

bioRxiv2023

Redox Regulation of m6A Methyltransferase METTL3 in Human β-cells Controls the Innate Immune Response in Type 1 Diabetes

Type 1 Diabetes (T1D) is characterized by autoimmune-mediated destruction of insulin-producing {beta}-cells. Several observations have renewed interest in the innate immune system as an initiator of the disease process against {beta}-cells. Here, we show that N6-Methyladenosine (m6A) is an adaptive {beta}-cell safeguard mechanism that accelerates mRNA decay of the 2-5-oligoadenylate synthetase (OAS) genes to control the antiviral innate immune response at T1D onset. m6A writer methyltransferase 3 (METTL3) levels increase drastically in human and mouse {beta}-cells at T1D onset but rapidly decline with disease progression. Treatment of human islets and EndoC-{beta}H1 cells with pro-inflammatory cytokines interleukin-1 {beta} and interferon mimicked the METTL3 upregulation seen at T1D onset. Furthermore, m6A-sequencing revealed the m6A hypermethylation of several key innate immune mediators including OAS1, OAS2, and OAS3 in human islets and EndoC-{beta}H1 cells challenged with cytokines. METTL3 silencing in human pseudoislets or EndoC-{beta}H1 cells enhanced OAS levels by increasing its mRNA stability upon cytokine challenge. Consistently, in vivo gene therapy, to prolong Mettl3 overexpression specifically in {beta}-cells, delayed diabetes progression in the non-obese diabetic (NOD) mouse model of T1D by limiting the upregulation of Oas pointing to potential therapeutic relevance. Mechanistically, the accumulation of reactive oxygen species blocked METTL3 upregulation in response to cytokines, while physiological levels of nitric oxide promoted its expression in human islets. Furthermore, for the first time to our knowledge, we show that the cysteines in position C276 and C326 in the zinc finger domain of the METTL3 protein are sensitive to S-nitrosylation (SNO) and are significant for the METTL3 mediated regulation of OAS mRNA stability in human {beta}-cells in response to cytokines. Collectively, we report that m6A regulates human and mouse {beta}-cells to control the innate immune response during the onset of T1D and propose targeting METTL3 to prevent {beta}-cell death in T1D.

molecular biology↗

bioRxiv2018

Exploration of Anti-Yo and Anti-Hu paraneoplastic neurological disorders by PhIP-Seq reveals a highly restricted pattern of antibody epitopes

Paraneoplastic neurological disorders (PNDs) are immune-mediated diseases of the nervous system understood to manifest as part of a misdirected anti-tumor immune response. Identifying PND-associated autoantibodies and their cognate antigens can assist with proper diagnosis and treatment while also enhancing our understanding of tumor-associated immune processes, triggers for autoimmune disease, and the functional significance of onconeuronal proteins. Here, we employed an enhanced version of phage display immunoprecipitation and sequencing (PhIP-Seq) leveraging a library of over 731,000 unique phage clones tiling across the entire human proteome to detect autoantibodies and create high-resolution epitope profiles in serum and CSF samples from patients suffering from two common PNDs, the anti-Yo (n = 36 patients) and anti-Hu syndromes (n = 44 patients). All patient samples positive for anti-Yo antibody by a validated clinical assay yielded polyspecific enrichment of phage presenting peptides from the canonical anti-Yo (CDR2 and CDR2L) antigens, while 38% of anti-Hu patients (17/44) had a serum and/or CSF sample that significantly enriched peptides deriving from the ELAVL family of proteins, the anti-Hu autoantigenic target. The anti-Hu antibodies showed a remarkably convergent antigenic signature across 15/17 patients corresponding to residues surrounding and including the degenerate motif, RLDxLL, shared by ELAVL2, 3 and 4. Lastly, PhIP-Seq identified several known and novel autoantigens in these same patient samples, representing potential biomarkers that could aid in the diagnosis and prognosis of PND and cancer.

immunology↗

bioRxiv2018

Landscape of stimulation-responsive chromatin across diverse human immune cells

The immune system is controlled by a balanced interplay among specialized cell types transitioning between resting and stimulated states. Despite its importance, the regulatory landscape of this system has not yet been fully characterized. To address this gap, we collected ATAC-seq and RNA-seq data under resting and stimulated conditions for 25 immune cell types from peripheral blood of four healthy individuals, and seven cell types from three fetal thymus samples. We found that stimulation caused widespread chromatin remodeling, including a large class of response elements shared between stimulated B and T cells. Furthermore, several autoimmune traits showed significant heritability in stimulation-responsive elements from distinct cell types, highlighting the critical importance of these cell states in autoimmunity. Use of allele-specific read-mapping identified thousands of variants that alter chromatin accessibility in particular conditions. Notably, variants associated with changes in stimulation-specific chromatin accessibility were not enriched for associations with gene expression regulation in whole blood - a tissue commonly used in eQTL studies. Thus, large-scale maps of variants associated with gene regulation lack a condition important for understanding autoimmunity. As a proof-of-principle we identified variant rs6927172, which links stimulated T cell-specific chromatin dysregulation in the TNFAIP3 locus to ulcerative colitis and rheumatoid arthritis. Overall, our results provide a broad resource of chromatin landscape dynamics and highlight the need for large-scale characterization of effects of genetic variation in stimulated cells.

genomics↗