Biology subjects

Abell, A. D.

Publications and source records attributed to Abell, A. D..

3 recordsLinked to original sources

bioRxiv2023

N-cadherin mechanosensing in ovarian follicles controls oocyte maturation and ovulation

The cell adhesion molecule N-cadherin (CDH2) is a membrane component of adherens junctions which regulates tissue morphogenesis and architecture. In the follicles of mammalian ovaries, N-cadherin adherens junctions are present between granulosa cells, cumulus cells and at the interface of cumulus cell transzonal projections and the oocyte. We demonstrate a mechanosensory role of N-cadherin integrating tissue structure and hormonal regulation of follicular morphogenic events including expansion of the cumulus oocyte complex (COC) matrix, oocyte maturation and ovulation. Two small molecule N-cadherin antagonists inhibited COC maturation in vitro. Transcriptome profiling revealed that targets of {beta}-catenin and YAP1 pathways were dysregulated by N-cadherin antagonists. In vivo, N-cadherin antagonist significantly reduced ovulation in mice compared to controls (11 vs 26 oocytes/ovary; p=5.8x10-6). Ovarian follicles exhibited structural dysgenesis with granulosa and cumulus cell layers becoming disorganised and the connection between cumulus cells and the oocyte disrupted and the transcriptome again indicated altered mechanical sensing causing dysregulation of the Hippo/YAP and {beta}-catenin pathways and ECM reorganization. Granulosa specific N-cadherin depletion in Cdh2Fl/FL;Amhr2-Cre also showed significantly altered mechanosensitive gene expression and reduced ovulation. Our findings demonstrate a critical role for N-cadherin in ovarian follicular development and ovulation, and the potential to inhibit ovulation through targeting this signalling mechanism.

cell biology↗

bioRxiv2023

Fortuitous in vitro compound degradation produces a tractable hit against Mycobacterium tuberculosis dethiobiotin synthetase: a cautionary tale of what goes in, does not always come out

We previously reported potent ligands and inhibitors of Mycobacterium tuberculosis dethiobiotin synthetase (MtDTBS), a promising target for antituberculosis drug development (Schumann et al., ACS Chem Biol. 2021, 16, 2339-2347); here the unconventional origin of the fragment compound they were derived from is described for the first time. Compound 1 (9b-hydroxy-6b,7,8,9,9a,9b-hexahydrocyclopenta[3,4]cyclobuta[1,2-c]chromen-6(6aH)-one), identified by in silico fragment screen, was subsequently shown by surface plasmon resonance to have dose-responsive binding (KD 0.6 mM). Clear electron density was revealed in the DAPA substrate binding pocket, when 1 was soaked into MtDTBS crystals, but the density was inconsistent with the structure of 1. Here we show the lactone of 1 hydrolyses to carboxylic acid 2 under basic conditions, including those of the crystallography soak, with subsequent ring-opening of the component cyclobutane ring to form cyclopentylacetic acid 3. Crystals soaked directly with authentic 3 produced electron density that matched that of crystals soaked with presumed 1, confirming the identity of the bound ligand. The synthetic utility of fortuitously formed 3 enabled subsequent compound development into nanomolar inhibitors. Our findings represent an example of chemical modification within drug discovery assays and demonstrate the value of high-resolution structural data in the fragment hit validation process. SynopsisA molecule flagged in an in silico docking screen against MtDTBS, was inadvertently hydrolysed in the crystal conditions used for hit validation. The resulting fragment-sized molecule bound to the DAPA substrate binding pocket of the target enzyme (MtDTBS) with millimolar affinity, as measured by surface plasmon resonance, but was later modified to a highly potent (nanomolar) ligand and promising lead for the development of novel tuberculosis treatments. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

biochemistry↗

bioRxiv2021

Drug targeting to sites of oxidative stress using the Baeyer-Villiger reaction

The antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) is a desirable therapeutic target for a broad range of pathologies, including chronic diseases of the lung and liver, and autoimmune, neurodegenerative, and cardiovascular disorders. However, current Nrf2 activators are limited by unwanted effects due to non-specificity, and systemic distribution and action. Here we report that a 1,2-dicarbonyl moiety masks the electrophilic reactivity of the Nrf2 activator monomethyl fumarate (MMF), otherwise responsible for its non-specific effects. The 1,2-dicarbonyl compound is highly susceptible to Baeyer-Villiger oxidation, with generation of MMF specifically on exposure to pathological levels of hydrogen peroxide or peroxynitrite. Oral treatment with the MMF generating 1,2-dicarbonyl compound reversed chronic neuropathic and osteoarthritis pain in mice, and selectively activated Nrf2 at sites of oxidative stress. This 1,2-dicarbonyl platform may be used to treat additional disorders of oxidative stress, and to selectively target other therapeutics to sites of redox imbalance.

pharmacology and toxicology↗