Biology subjects

Carles, A.

Publications and source records attributed to Carles, A..

5 recordsLinked to original sources

bioRxiv2024

Neuroprotection by chronic administration of Fluoroethylnormemantine (FENM) in mouse models of Alzheimer's disease

BackgroundFluoroethylnormemantine (FENM), a new Memantine (MEM) derivative, prevented amyloid-{beta}[25-35] peptide (A{beta}25-35)-induced neurotoxicity in mice, a pharmacological model of Alzheimers disease (AD) with high predictive value for drug discovery. Here, as drug infusion is likely to better reflect drug bioavailability due to the interspecies pharmacokinetics variation, we analyzed the efficacy of FENM after chronic subcutaneous (SC) infusion, in comparison with IP injections in two AD mouse models, A{beta}25-35 -injected mice and the transgenic APP /PSEN1{partial}E9 (APP/PS1) line. MethodsIn A{beta}25-35-treated mice, FENM was infused at 0.03-0.3 mg/kg/day during one week after A{beta}25-35 injection. For comparison, FENM and MEM were administered IP daily at 0.03-0.3 mg/kg. In 10-month-old APP/PS1 mice, FENM was administered during four weeks by daily IP injections at 0.3 mg/kg or chronic SC infusion at 0.1 mg/kg/day. Memory deficits, spatial working memory and recognition memory, were analysed. Markers of neuroinflammation, apoptosis, oxidative stress, and amyloid burden in APP/PS1 mice, were quantified. Markers of synaptic plasticity such as PSD-95 and GluN2A/B/D subunits expression in hippocampus homogenates or synaptosomes were quantified in A{beta}25-35-treated mice and synaptic long-term potentiation (LTP) in hippocampal slices was analysed in APP/PS1 mice. ResultsDeficits in spontaneous alternation and object recognition in A{beta}25-35 mice were prevented by infused FENM at all doses tested. Similar effects were observed with the daily FENM or MEM treatments. Animals infused with 0.1 mg/kg/day FENM showed prevention of A{beta}25-35-induced neuroinflammation, oxidative stress and apoptosis. FENM infusion restored A{beta}25-35-induced alterations in synaptosomal PSD-95, GluN2A and P-GluN2B levels. GluN2D levels were unchanged whatever the treatment. In APP/PS1 mice, FENM infused or administered IP alleviated spontaneous alternation deficits, neuroinflammation, increases in A{beta}1-40/A{beta}1-42 and hippocampal LTP alteration. ConclusionThese data confirmed the neuroprotective potential of FENM in the pharmacological A{beta}25-35 and transgenic APP/PS1 mouse models of AD, with a superiority to MEM, and showed that the drug can be efficiently infused chronically.

pharmacology and toxicology↗

bioRxiv2024

tp53 R217H and R242H Mutant Zebrafish Exhibit Dysfunctional p53 Hallmarks and Recapitulate Li-Fraumeni Syndrome Phenotypes

Li-Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome associated with a highly penetrant cancer spectrum characterized by germline TP53 mutations. We characterized the first LFS zebrafish hotspot mutants, tp53 R217H and R242H (human R248H and R273H), and found these mutants exhibit partial-to-no activation of p53 target genes, have a defective G1 cell-cycle checkpoint, and are resistant to apoptosis. Spontaneous tumor development histologically resembling human sarcomas developed as early as 6 months. tp53 R242H mutants had a higher lifetime tumor incidence compared to tp53 null and R217H mutants, suggesting it is a more aggressive mutation. We observed mutation-specific tumor phenotypes across tp53 mutants with associated diverse transcriptomic and DNA methylome profiles, impacting metabolism, cell signalling, and biomacromolecule synthesis and degradation. These tp53 zebrafish mutants demonstrate fidelity to their human counterparts and provide new insights into underlying tumorigenesis mechanisms and kinetics, which will guide targeted therapeutics for LFS.

cancer biology↗

bioRxiv2024

Synovial Sarcoma Chromatin Dynamics Reveal a Continuum in SS18:SSX Reprograming

Synovial sarcoma (SyS) is an aggressive soft-tissue malignancy characterized by a pathognomonic chromosomal translocation leading to the formation of the SS18::SSX fusion oncoprotein. SS18::SSX associates with mammalian BAF complexes suggesting deregulation of chromatin architecture as the oncogenic driver in this tumour type. To examine the epigenomic state of SyS we performed comprehensive multi-omics analysis on 52 primary pre-treatment human SyS tumours. Our analysis revealed a continuum of epigenomic states across the cohort at fusion target genes independent of rare somatic genetic lesions. We identify cell-of-origin signatures defined by enhancer states and reveal unexpected relationships between H2AK119Ub1 and active marks. The number of bivalent promoters, dually marked by the repressive H3K27me3 and activating H3K4me3 marks, has strong prognostic value and outperforms tumor grade in predicting patient outcome. Finally, we identify SyS defining epigenomic features including H3K4me3 expansion associated with striking promoter DNA hypomethylation in which SyS displays the lowest mean methylation level of any sarcoma subtype. We explore these distinctive features as potential vulnerabilities in SyS and identify H3K4me3 inhibition as a promising therapeutic strategy.

cancer biology↗

bioRxiv2020

The pathognomonic FOXL2 C134W mutation alters DNA binding specificity

The somatic missense point mutation c.402C>G (p.C134W) in the FOXL2 transcription factor is pathognomonic for adult-type granulosa cell tumours (AGCT) and a diagnostic marker for this tumour type. However, the molecular consequences of this mutation and its contribution to the mechanisms of AGCT pathogenesis remain unclear. To explore the mechanisms driving FOXL2C134W pathogenicity we engineered V5-FOXL2WT and V5-FOXL2C134W inducible isogenic cell lines and performed ChIP-seq and transcriptome profiling. We found that FOXL2C134W associates with the majority of the FOXL2 WT DNA elements as well as a large collection of unique elements genome-wide. We confirmed an altered DNA binding specificity for FOXL2C134W in vitro and identified unique targets of FOXL2C134W including SLC35F2 whose expression increased sensitivity to YM155 in our model. Statement of SignificanceMechanistic understanding of FOXL2C134W induced regulatory state alterations drives discovery of a rationally designed therapeutic strategy.

cancer biology↗

bioRxiv2018

MeCP2-E1 isoform is a dynamically expressed, weakly DNA-bound protein with different protein and DNA interactions compared to MeCP2-E2

MeCP2 - a chromatin-binding protein associated with Rett syndrome - has two main isoforms, MeCP2-E1 and MeCP2-E2, with 96% amino acid identity differing in a few N-terminal amino acid residues. Previous studies have shown brain region-specific expression of these isoforms which, in addition to their different cellular localization and differential expression during brain development, suggest they may also have non-overlapping molecular mechanisms. However, differential functions of MeCP2-E1 and E2 remain largely unexplored. Here, we show that the N-terminal domains (NTD) of MeCP2-E1 and E2 modulate the ability of the methyl binding domain (MBD) to interact with DNA as well as influencing the turnover rates, binding dynamics, response to nuclear depolarization, and circadian oscillations of the two isoforms. Our proteomics data indicate that both isoforms exhibit unique interacting protein partners. Moreover, genome-wide analysis using ChIP-seq provide evidence for a shared as well as a specific regulation of different sets of genes. Our findings provide insight into the functional complexity of MeCP2 by dissecting differential aspects of its two isoforms.\n\nSignificanceWhether the two E1 and E2 isoforms of MeCP2 have different structural and/or functional implications has been highly controversial and is not well known. Here we show that the relatively short N-terminal sequence variation between the two isoforms impinges them with an important DNA binding difference. Moreover, MeCP2-E1 and E2 exhibit a different cellular dynamic behavior and have some distinctive interacting partners. In addition, while sharing genome occupancy they specifically bind to several distinctive genes.

biochemistry↗