Biology subjects

Heremans, Y.

Publications and source records attributed to Heremans, Y..

4 recordsLinked to original sources

bioRxiv2026

Liver-directed AAV gene therapy metabolically corrects AKU in Hgd deficient mice

BackgroundAlkaptonuria (AKU) is a rare autosomal recessive metabolic disorder caused by deficiency of homogentisate 1,2-dioxygenase (HGD), resulting in systemic accumulation of homogentisic acid (HGA), ochronosis, and progressive multisystem disease. Although nitisinone (NTBC) lowers HGA levels, it does not correct the underlying genetic defect and induces hypertyrosinemia, highlighting the need for curative treatment approaches. We evaluated liver-directed adeno-associated virus (AAV)-mediated HGD gene therapy as a potential treatment for AKU. MethodsHgd-deficient (Hgd-/-) mice received liver-directed AAV2/8 vectors expressing codon-optimized human HGD under a liver-specific promoter. Reporter vectors were first used to assess hepatic biodistribution and transduction efficiency. Therapeutic efficacy was subsequently evaluated following AAV2/8-HGD administration (1 x 1012 vg/mouse). HGD expression was assessed by DNAscope, Western blotting, and RT-qPCR. Metabolic correction was determined using targeted LC-MS/MS and untargeted LC-HRMS metabolomics and compared with NTBC-treated Hgd-/- mice. ResultsReporter studies demonstrated liver-predominant transduction, with dose-dependent hepatocyte transduction reaching 89-93% at the highest dose. AAV2/8-HGD treatment produced robust hepatic HGD expression, with codon-optimized human HGD transcript levels approximately 33-fold higher than endogenous murine Hgd expression. Twelve weeks after treatment, plasma and urinary HGA levels were significantly reduced, with plasma HGA restored to near wild-type concentrations. Untargeted metabolomics further demonstrated marked reductions in HGA-derived phase I and II metabolites and revealed significant modulation of tricarboxylic acid cycle metabolism, consistent with partial restoration of metabolic homeostasis. Compared with NTBC-treated mice, AAV2/8-HGD achieved comparable plasma HGA reduction without elevation of upstream tyrosine pathway metabolites. ConclusionsLiver-directed AAV2/8-HGD gene therapy achieved substantial biochemical correction in Hgd-/- mice and restored metabolic flux without inducing hypertyrosinemia. These findings provide proof-of-concept supporting AAV-mediated HGD replacement as a promising long-term therapeutic strategy for AKU.

genetics↗

bioRxiv2025

The gut insulin receptor acts as gatekeeper of intestinal barrier integrity

An impaired gut barrier has emerged as a potential driver of the low-grade inflammation that accompanies obesity and its complications. Among these, hyperglycemia per se has been proposed to sustain such increased intestinal permeability and subsequent translocation of bacterial endotoxins in the systemic circulation. Because reduced insulin signaling in the gut epithelium has also been reported upon obese conditions, we hypothesized that, beyond hyperglycemia, defective intestinal insulin signaling could directly compromise epithelial integrity. To mimic this diabesity feature, we induced deletion of the insulin receptor (IR) in the adult gut epithelium of IR{Delta}GUT mice. Remarkably, gut IR loss persistently maintained normal body weight and glucose homeostasis, thereby allowing the specific role of insulin action to be investigated. While IR{Delta}GUT mice exhibited increased intestinal paracellular permeability, mechanistic characterization of this gut leakiness revealed that IR{Delta}GUT mice displayed a rapid and drastic decline in Paneth cells anti-microbial defenses. This paralleled the onset of a cecal dysbiosis, as characterized by increased abundance of Pseudomonadota, and enhanced microbiota encroachment. Of note, IR{Delta}GUT mice exhibited intestinal stem cell (ISC) defects, as evidenced by reduced expression of ISC markers and ISC-mediated growth of intestinal organoids. Although expression of niche factors such as Wnt3a was diminished in Paneth cells isolated from IR{Delta}GUT mice, pharmacological activation of the canonical Wnt pathway failed to rescue the growth defects of IR-deleted gut organoids. The direct contribution of IR-downstream signaling to ISCs homeostasis was confirmed by the transcriptional reprogramming of FACS-sorted ISCs from IR{Delta}ISC mice. Finally, while gut IR loss did not worsen endotoxemia or impaired glycemic control upon HFD-feeding, IR{Delta}GUT displayed a higher susceptibility to chemically induced colitis and enteric infections (S. typhimurium, C. rodentium), underscoring intestinal insulin signaling as a key determinant of barrier integrity and epithelial homeostasis.

physiology↗

bioRxiv2024

ER stress relief drives beta cell proliferation

Regenerating endogenous pancreatic {beta}-cells is a potentially curative yet currently elusive strategy for diabetes therapy. Mimicking the microenvironment of the developing pancreas and leveraging vascular signals that support pancreatic endocrinogenesis may promote {beta}-cell regeneration. We aimed to investigate whether recovery from experimental hypovascularization of the endocrine pancreas, achieved by modulating the transgenic production of a VEGF-A blocker in {beta}-cells, could trigger mouse {beta}-cell proliferation. Serendipitously, we found that transgene overexpression in {beta}-cells induces endoplasmic reticulum (ER) stress and that subsequent relief from this stress stimulates {beta}-cell proliferation independent of vessel recovery. Transient GFP overexpression in vivo and chemical induction of ER stress in vitro replicated this {beta}-cell cycling response. Our findings highlight the potential side effects of ER stress due to transgene overexpression in {beta}-cells and assert that ER stress relief serves as a potent regenerative stimulus.

molecular biology↗

bioRxiv2020

MECOM permits pancreatic acinar cell dedifferentiation avoiding cell death under stress conditions

Maintenance of the pancreatic acinar cell phenotype suppresses tumor formation. Hence, repetitive acute or chronic pancreatitis, stress conditions in which the acinar cells dedifferentiate, predispose for cancer formation in the pancreas. Dedifferentiated acinar cells acquire a large panel of duct cell-specific markers. However, it remains unclear to what extent dedifferentiated acini differ from native duct cells and which genes are uniquely regulating acinar cell dedifferentiation. Moreover, most studies have been performed in mice since the availability of human cells is scarce. Here, we applied a non-genetic lineage tracing method of human pancreatic exocrine acinar and duct cells that allowed cell-type-specific gene expression profiling by RNA sequencing. Subsequent to this discovery analysis, one transcription factor that was unique for dedifferentiated acinar cells was functionally characterized. RNA sequencing analysis showed that human dedifferentiated acinar cells expressed genes in Pathways of cancer with prominence of MECOM (EVI-1), a transcription factor that was not expressed by duct cells. During mouse embryonic development, pre-acinar cells also transiently expressed MECOM and in the adult mouse pancreas, MECOM was re-expressed when mice were subjected to acute and chronic pancreatitis, conditions in which acinar cells dedifferentiate. In human cells and in mice, MECOM expression correlated with and was directly regulated by SOX9. Mouse acinar cells that, by genetic manipulation, lose the ability to upregulate MECOM showed impaired cell adhesion, more prominent acinar cell death and suppressed acinar cell dedifferentiation by limited ERK signaling. In conclusion, we transcriptionally profiled the two major human pancreatic exocrine cell types, acinar and duct cells, during experimental stress conditions. We provide insights that in dedifferentiated acinar cells, cancer pathways are upregulated in which MECOM is a critical regulator that suppresses acinar cell death by permitting cellular dedifferentiation.

cancer biology↗