Biology subjects

David, J. C.

Publications and source records attributed to David, J. C..

3 recordsLinked to original sources

bioRxiv2026

Optimization and Characterization of SHIP1 Ligands for Cellular Target Engagement and Activity in Alzheimer's Disease Models

Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP1), encoded by the gene INPP5D, is a lipid phosphatase that negatively regulates immune receptor signaling in hematopoietic cells and microglia. Here, we describe a pyridyl-pyrazole-piperidine scaffold and the lead compound 3-((2-chlorobenzyl)oxy)-5-(1-(piperidin-4-yl)-1H-pyrazol-4-yl)pyridine (32), which demonstrates SHIP1 target engagement, brain exposure, and evidence of a central pharmacodynamic response in vivo. Structure-activity relationship studies, guided by biochemical and cellular assays using multiple human and murine protein constructs and cells, identified SHIP1-active ligands. A thermal shift assay using full-length SHIP1 was used to assess compounds for cellular target engagement, while studies in IL-4 conditioned THP-1 cells was used to demonstrate changes in downstream AKT signaling. Targeted lipidomics revealed changes in the overall phosphoinositide pool consistent with SHIP1 target engagement and reduction of phospho-AKT levels. In a protein-lipid overlay assay, compound 32 induced changes in the relative association of SHIP1 with multiple phosphatidylinositols on a membrane surface. In high-content cellular imaging assays, compound 32 enhanced the uptake of myelin/membrane debris and fibrillar amyloid by primary murine microglia, phenocopying a genetic model with reduced SHIP1 expression. Finally, oral administration of compound 32 resulted in brain exposure sufficient to alter gene expression and reduce IL-1{beta} levels as pharmacodynamic markers of microglial activation and neuroinflammation in an amyloidosis mouse model of Alzheimers disease. Collectively, these results define a scaffold with SHIP1 target engagement, CNS exposure, and in vivo activity, providing a foundation for the optimization of brain-penetrant SHIP1 ligands suitable for further mechanistic studies and therapeutic development for the treatment of Alzheimers disease.

pharmacology and toxicology↗

bioRxiv2025

IgE occupancy and antigen valency cooperate to control FcϵRI aggregation geometry and signaling efficiency

The crosslinking of IgE-bound Fc{varepsilon}RI by multivalent allergens initiates mast cell and basophil signaling underlying Type 1 allergy. Yet, how allergen properties and IgE occupancy impact receptor aggregation and downstream signaling remain unclear. We used Phl p 1-specific IgE and recombinant fusion proteins presenting a Phl p 1-derived peptide in defined valencies and positions (MB1N, MB2N, MB4N, MB1N1C) to probe antigen-dependent signaling. Tetravalent MB4N evoked stronger degranulation and Ca2+ response than bivalent antigens, MB2N and MB1N1C. MB4N was also capable of signaling at low IgE occupancy and in Lyn-deficient cells. Monte Carlo simulations predicted that MB4N forms larger, complex receptor aggregates, while MB2N and MB1N1C produce dimers and linear chains. Consistently, addition of MB4N showed larger aggregates by electron microscopy and slower mobility by single particle tracking, compared to bivalent antigens. Thus, allergen valency and epitope spatial arrangement dictate Fc{varepsilon}RI aggregate organization and subsequent effector cell activation.

immunology↗

bioRxiv2020

De-novo purine biosynthesis is a major driver of chemoresistance in glioblastoma

This year nearly 20,000 lives will be lost to Glioblastoma (GBM), a treatment-resistant primary brain cancer. In this study, we identified a molecular circuit driven by epigenetic regulation that regulates the expression of ciliary protein ALR13B. We also demonstrated that ARL13B subsequently interacts with purine biosynthetic enzyme IMPDH2. Removal of ARL13B enhanced TMZ-induced DNA damage by reducing de-novo purine biosynthesis and forcing GBM cells to rely on the purine salvage pathway. Furthermore, targeting can be achieved by using an FDA-approved drug, Mycophenolate Moefitil. Our results suggest a clinical evaluation of MMF in combination with TMZ treatment in glioma patients.

cancer biology↗