Abstract Description

Protein tyrosine phosphatase 1B (PTP1B) plays a crucial role in insulin signaling and cellular metabolism. Its dysregulation is implicated in obesity and type 2 diabetes, conditions characterized by impaired glucose uptake and excessive adipogenesis. Understanding PTP1B’s involvement in these metabolic disorders may lead to novel therapeutic approaches. This study evaluated the inhibitory effects of Cannabis sativa-derived cannabinoids - cannabidiol (CBD), cannabigerol (CBG), cannabinol (CBN), and tetrahydrocannabinol (THC) - on two variants of human PTP1B: the full-length active enzyme and a truncated catalytic domain (1-321/PTPN1). Enzyme activity was measured using two colorimetric assays: para-nitrophenyl phosphate (pNPP) for the full-length enzyme and malachite green assay for the catalytic domain. Enzyme kinetics and inhibition mechanisms were analyzed, supported by molecular docking, molecular simulations, and Normal Mode Analysis was used to probe enzyme dynamics and inhibitor binding. THC was identified as a potent, reversible mixed-type inhibitor of full-length PTP1B, with an IC50 of 0.15 µM and a Ki of 1.8 µM. In contrast, CBD, CBG, and CBN showed statistically non-significant inhibitory activity. Molecular docking indicated THC binds at an allosteric site distinct from the catalytic domain. Simulations of PTP1B dynamics revealed flexible regions essential for allosteric modulation by THC. Additional biophysical studies employing circular dichroism and fluorescence spectroscopy are underway to characterize conformational effects of inhibitor binding. Preparations for cell culture assays in adipocytes, hepatocytes, and myocytes to assess THC-mediated enhancement of glucose uptake are being investigated. These findings suggest that THC and related cannabinoids selectively modulate PTP1B activity through allosteric inhibition, presenting a promising avenue for developing novel therapeutics targeting insulin resistance in obesity and type 2 diabetes. Further biophysical and cellular studies will elucidate their mechanisms and therapeutic potential.