Biology subjects

Regnault, C.

Publications and source records attributed to Regnault, C..

6 recordsLinked to original sources

bioRxiv2025

Alzheimer's disease risk gene Wwox protects against amyloid pathology through metabolic reprogramming

Genome wide association studies have identified multiple loci that mediate the risk of developing late-onset Alzheimers Disease (LOAD). The gene WW-domain containing oxidoreductase (WWOX) has been identified in recent LOAD risk meta-analyses, yet its function in the brain is poorly understood. Using Drosophila, we discovered that knockdown of the highly conserved Wwox gene impacts longevity and sleep, having roles in both neuronal and glial subtypes. In an amyloid beta 42 (A{beta}42) transgenic model of AD, RNAi-mediated knockdown of Wwox significantly decreased both lifespan and locomotion whilst elevating soluble A{beta}42. Transcriptomic and metabolomic analyses revealed that these effects were accompanied by elevated lactate dehydrogenase (Ldh) mRNA and lactate levels, downstream of an increase in the key unfolded protein response protein Atf4. Strikingly, we found that upregulation of Wwox in the A{beta}42 model through CRISPR activation significantly reduced amyloid load, improved longevity and locomotion. Multi-omics analysis revealed Wwox upregulation partially reversed several key A{beta}42-induced transcriptional pathways in the brain and reduced levels of L-methionine and associated enzymes. These findings support a role for reduced WWOX levels in the genetic risk of developing LOAD via pyruvate metabolism and point towards WWOX activation as a protective therapeutic strategy.

neuroscience↗

bioRxiv2024

Investigation of the threonine metabolism of Echinococcus multilocularis: the threonine dehydrogenase as a potential drug target in alveolar echinococcosis

Alveolar echinococcosis (AE) is a severe zoonotic disease caused by the metacestode stage of the fox tapeworm Echinococcus multilocularis. We recently showed that E. multilocularis metacestode vesicles scavenge large amounts of L-threonine from the culture medium that were neither stored nor overused for protein synthesis. This motivated us to study the effect of L-threonine on the parasite and how it is metabolized. We established a novel metacestode vesicle growth assay with an automated readout, which showed that L-threonine treatment led to significantly increased parasite growth. In addition, L-threonine increased the formation of novel metacestode vesicles from primary parasite cell cultures in contrast to the non-proteinogenic threonine analog 3-hydroxynorvaline. Tracing of [U-13C]-L-threonine and metabolites in metacestode vesicles and culture medium resulted in the detection of [U-13C]-labeling in aminoacetone and glycine, indicating that L-threonine was metabolized by threonine dehydrogenase (TDH). In addition, the detection of [13C2]-glutathione, suggested that E. multilocularis metacestode vesicles synthesize glutathione via L-threonine-derived glycine. EmTDH-mediated threonine metabolism in the E. multilocularis metacestode stage was further confirmed by quantitative real-time PCR, which demonstrated high expression of emtdh in in vitro cultured metacestode vesicles and also in metacestode samples obtained from infected animals. EmTDH was enzymatically active in metacestode vesicle extracts. Thus, the drugs disulfiram, myricetin, quercetin, sanguinarine and seven quinazoline carboxamides were assessed for inhibition of recombinantly expressed EmTDH, and the most potent inhibitors disulfiram, myricetin and sanguinarine were further tested for activity against E. multilocularis metacestode vesicles and primary parasite cells. Sanguinarine exhibited significant in vitro activity and IC50-values for metacestode vesicles, primary parasite cells, as well as mammalian cells were determined. Our results suggest that sanguinarine treatment should be further assessed in vivo employing suitable AE mouse models. Furthermore, the EmTDH assay could serve as high-throughput target-based discovery platform for novel anti-echinococcal compounds.

microbiology↗

bioRxiv2024

Targeting Metabolic Dependencies in Acute Myeloid Leukemia: A Dual Strategy using Arsenic Trioxide and Artesunate.

Acute myeloid leukemia (AML) remains a difficult disease to cure despite recent advances. Off-target side effects of therapy, especially prolonged cytopenia, lead to significant morbidity and mortality. There is an increased recognition that in AML, there is a potentially vulnerable dependence on OXPHOS metabolism, more so in the leukemia stem cell compartment (AML-LSC) that could be exploited. Drug re-purposing screens have suggested the possible role of artesunate (ART) in inhibiting mitochondrial respiration and arsenic trioxide (ATO) in inhibiting glycolysis. Here, we explore the potential of using a combination of ART and ATO to treat AML. Through in-vitro and in-vivo studies, we demonstrate the potential of this combination along with hypo-methylating agents and other mitocans, such as BCL-2 inhibitor venetoclax, to be used in the treatment of AML with minimal off-target effect on normal hematopoietic stem cells (HSC). These observations warrant further exploration of such novel combinations in clinical trials.

cancer biology↗

bioRxiv2022

A conserved metabolic signature associated with response to fast-acting antimalarial agents

Characterizing the mode of action of antimalarial compounds that emerge from high-throughput phenotypic screens is central to understanding how parasite resistance to these drugs can emerge. Here, we have employed untargeted metabolomics to inform on the mechanism of action of antimalarial leads with different speed of kill profiles being developed by the Novartis Institute of Tropical Diseases (NITD). Time-resolved global changes in malaria parasite metabolite profiles upon drug treatment were quantified using liquid chromatography-based mass spectrometry (LC-MS) and compared to untreated controls. Using this approach, we confirmed previously reported metabolomics profiles of the fast-killing (2.5h) drug dihydroartemisinin (DHA) and the slower killing atovaquone (ATQ). A slow acting antimalarial lead from NITD of imidazolopiperazine (IZP) class, GNF179, elicited little or no discernable metabolic change in malaria parasites in the same 2.5h window of drug exposure. In contrast, fast killing drugs, DHA and the spiroindolone (NITD246) elicited similar metabolomic profiles both in terms of kinetics and content. DHA and NITD246 induced peptide losses consistent with disruption of haemoglobin catabolism and also interfered with the pyrimidine biosynthesis pathway. Two members of the recently described novel class of antimalarial agents of the 5-aryl-2-amino-imidazothiadiazole (ITD) class also exhibited a fast-acting profile that also featured peptide losses indicative of disrupted haemoglobin catabolism. Our screen demonstrates that structurally unrelated, fast acting antimalarial compounds generate similar biochemical signatures in Plasmodium pointing to a common mechanism associated with rapid parasite death. Our study describes a potential biochemical signature that may serve to identify other fast acting drug candidates. ImportanceIn malaria drug discovery, understanding the mode of action of lead compounds is important as it helps in predicting the potential emergence of drug resistance in the field when these drugs are eventually deployed. In this study, we have employed metabolomics technologies to characterize the potential targets of antimalarial drug candidates in the developmental pipeline at NITD. We show that NITD fast acting leads belonging to spiroindolone and imidazothiadiazole class induce a common biochemical theme in drug exposed malaria parasites which is similar to another fast acting, clinically available drug, DHA. These biochemical features which are absent in a slower acting NITD lead (GNF17) point to haemoglobin digestion and inhibition of the pyrimidine pathway as potential action points for these drugs. These biochemical themes can be used to identify fast drug candidates of similar profiles in future drug discovery programs.

microbiology↗

bioRxiv2022

Cell overgrowth during G1 arrest triggers an osmotic stress response and chronic p38 activation to promote cell cycle exit

Cell size and the cell cycle are intrinsically coupled and abnormal increases in cell size are associated with senescence. The mechanism by which overgrowth primes cells to exit the cell cycle remains unclear. We investigate this using CDK4/6 inhibitors that arrest cell cycle progression in G0/G1 and are used to treat ER+/HER2-metastatic breast cancer. We demonstrate that long-term CDK4/6 inhibition promotes cellular overgrowth during the G0/G1 arrest, causing widespread proteome remodeling and p38-p53-p21-dependent cell cycle exit. Cell cycle exit is triggered by two waves of p21 induction. First, overgrowth during a G0/G1 arrest induces an osmotic stress response, producing the first wave of p21 induction. Second, when CDK4/6 inhibitors are removed, a fraction of cells escape G0/G1 arrest and enter S-phase where overgrowth-driven replication stress results in a second wave of p21 induction that causes cell cycle withdrawal from G2, or the subsequent G1. This could explain why cellular hypertrophy is associated with senescence and why CDK4/6 inhibitors have long-lasting anti-proliferative effects in patients.

cell biology↗

bioRxiv2021

Transcriptional shift and metabolic adaptations during Leishmania quiescence using stationary-phase and drug pressure as models

Microorganisms can adopt a quiescent physiological condition which acts as a survival strategy under unfavourable conditions. Quiescent cells are characterized by slow or non-proliferation and deep down-regulation of processes related to biosynthesis. Although quiescence has been described mostly in bacteria, this survival skill is widespread, including in eukaryotic microorganisms. In Leishmania, a digenetic parasitic protozoan that causes a major infectious disease, quiescence has been demonstrated, but molecular and metabolic features enabling its maintenance are unknown. Here we quantified the transcriptome and metabolome of Leishmania promastigotes and amastigotes where quiescence was induced in vitro either through drug pressure or by stationary phase. Quiescent cells have a global and coordinated reduction in overall transcription, with levels dropping to as low as 0.4% of those in proliferating cells. However, a subset of transcripts did not follow this trend and were relatively upregulated in quiescent populations, including those encoding membrane components such as amastins and GP63 or processes like autophagy. The metabolome followed a similar trend of overall downregulation albeit to a lesser magnitude than the transcriptome. Noteworthy, among the commonly upregulated metabolites were those involved in carbon sources as an alternative to glucose. This first integrated two omics layers affords novel insights into cell regulation and shows commonly modulated features across stimuli and stages.

bioinformatics↗