Biology subjects

Mariam, Z.

Publications and source records attributed to Mariam, Z..

3 recordsLinked to original sources

bioRxiv2026

Direct Small Molecule Modulation of LILRB4 (ILT3) Restores Anti-Tumor Immunity In Vivo and in Patient-Derived Cells

Small molecule targeting of suppressive myeloid immune checkpoints remains a major challenge in cancer immunotherapy, particularly for non-enzymatic receptors lacking conventional druggable active sites. Leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3) is an immunosuppressive myeloid checkpoint implicated in tumor immune evasion, T-cell dysfunction, and resistance to immunotherapy across both solid and hematologic malignancies. Here, we report the discovery and characterization of GL-4512, a direct small molecule modulator of LILRB4 identified through a Dianthus-based temperature-related intensity change (TRIC) screening platform. Orthogonal biophysical studies, including microscale thermophoresis, surface plasmon resonance, and cellular thermal shift assays, confirmed direct target engagement with nanomolar affinity. Extensive microsecond molecular dynamics simulations combined with site-directed mutagenesis identified a previously unrecognized ligandable pocket within the flexible extracellular domain of LILRB4. Functionally, GL-4512 disrupted the immunosuppressive LILRB4-SCG2 signaling axis and suppressed downstream SHP1/SHP2 and STAT3 signaling. In patient-derived colorectal cancer and acute myeloid leukemia co-culture systems, pharmacological inhibition of LILRB4 restored anti-tumor immune activity, enhanced IFN-{gamma} and IL-2 production, increased cytotoxic T-cell activation, and reduced tumor-cell viability. GL-4512 additionally demonstrated favorable pharmacokinetic and safety properties supporting oral in vivo administration. In immunocompetent CT26 syngeneic colorectal tumors, once-daily oral treatment significantly suppressed tumor growth and enhanced intratumoral immune activation. Collectively, these findings establish LILRB4 as a tractable target for direct small molecule immunomodulation and support therapeutic targeting of suppressive myeloid immune checkpoints for cancer using non-biologic modalities.

pharmacology and toxicology↗

bioRxiv2026

PCO371 intracellular agonism at the parathyroid hormone 1 receptor produces pan-activation of signalling partners

Small-molecule agonists of class B1 G-protein-coupled receptors (GPCRs) remain rare because these receptors typically require large extracellular peptide ligands for activation. PCO371 is a notable exception: an intracellular non-peptide agonist, originally developed for osteoporosis treatment, that activates parathyroid hormone 1 receptor (PTH1R) from the cytoplasmic face of the receptor and is considered Gs-protein biased. In this study, we compared the functional, pharmacological and structural properties of PCO371 with the canonical extracellular peptide agonist PTH 1-34 at the PTH1R to define the molecular mechanisms underlying PCO371's unusual signalling profile. By manipulating receptor reserve, we demonstrate that PCO371 is a partial agonist relative to PTH 1-34, contrary to previous observations. Across Gs, Gi3, Gq, cAMP, and {beta}-arrestin-2 pathways, operational model analysis showed that PCO371 is non-biased, engaging the same transducers as PTH1-34 but with ~1000-fold lower potency. Mechanistic modelling using the Cubic Ternary Complex Activation model revealed that reduced intrinsic efficacy is sufficient to reproduce PCO371's distinct monotonic signalling kinetics, providing a quantitative explanation for its partial agonism. PCO371 binding is {beta}-arrestin-compatible but only drives measurable {beta}-arrestin-2 recruitment when PTH1R is highly expressed. Molecular modelling suggests that PC0371 stable binding needs an intact receptor-G protein complex. Overall, these insights define the mechanistic basis of intracellular agonism at a class B1 GPCR and provide a framework for designing next-generation small-molecule modulators that exploit this emerging pharmacological space.

pharmacology and toxicology↗

bioRxiv2024

In vivo functional profiling and structural characterisation of the human Glp1r A316T variant

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective therapies for type 2 diabetes (T2D) and obesity, yet patient responses are variable. Variation in the human Glp1r gene might be directly linked to therapeutic responses. A naturally occurring missense variant, A316T, protects against T2D and cardiovascular disease. Here, we have generated and characterised a human Glp1r A316T mouse model. Human Glp1rA316T/A316T mice displayed lower fasting blood glucose versus wildtype littermates, even under metabolic stress, and exhibited alterations in islet cytoarchitecture and /{beta}-cell identity under a high-fat, high-sucrose diet. This was however associated with blunted responses to GLP-1RAs in vivo. Further investigations in rodent and human {beta}-cell models demonstrated that human Glp1r A316T exhibits characteristics of constitutive activation but dampened GLP-1RA responses. Results are further supported by cryo-EM analyses and molecular dynamics simulations of GLP-1R A316T structure, collectively demonstrating that the A316T variant governs basal GLP-1R activity and pharmacological responses to GLP-1R-targeting therapies. TeaserThe Glp1r A316T missense variant displays improved glucose tolerance but impaired pharmacological incretin responses in vivo.

cell biology↗