Barbadin

Barbadin is a selective inhibitor of the β-arrestin/β2-adaptin interaction, with IC₅₀ values of 19.1μM and 15.6μM for β-arrestin1 and β-arrestin2, respectively. Barbadin exerts its inhibitory effect by blocking the internalization of β2-adrenergic receptors, V2 vasopressin (V2R), and angiotensin II type 1 (AT1R) receptors^[1,2]. Barbadin is commonly used in studies investigating neutrophil function modulation, G protein-coupled receptor (GPCR) internalization, and related signaling pathways^[3,4].

In vitro, pretreatment of HEK293T cells with Barbadin (50μM) for 30min completely blocked V2R agonist arginine vasopressin (AVP)-induced ERK1/2 phosphorylation, but did not affect epidermal growth factor (EGF)-induced ERK activation^[1]. Pretreatment of MDA-MB-231 cells with Barbadin (100μM) for 30min, followed by AVP stimulation for 45min, significantly increased the level of the autophagy marker LC3II^[5]. Pretreatment of HEK293 cells expressing wild-type μ-opioid receptor (MOR1) with Barbadin (100μM) for 15 or 30min significantly inhibited DAMGO (10μM)-induced receptor internalization and MAPK signaling pathway activation^[6]. Treatment of goldfish pituitary cells via a cell column perifusion system with Barbadin (25μM) for 65min significantly increased basal growth hormone secretion levels, but had no sustained effect on basal luteinizing hormone secretion^[7].

In vivo, bilateral injection of Barbadin (300ng/side) via pre-implanted cannulas into the dorsal striatum of a tardive dyskinesia (TD) mouse model induced by long-term oral haloperidol (2mg/kg/day; 21 days) blocked the ameliorative effect of the A2A receptor agonist CGS 21680A (1ng/side) on vacuous chewing movements (VCMs)^[8].

References:
[1] BEAUTRAIT A, PARADIS J S, ZIMMERMAN B, et al. A new inhibitor of the β-arrestin/AP2 endocytic complex reveals interplay between GPCR internalization and signalling[J]. Nature communications, 2017, 8(1): 15054.
[2] HESSIEN M, DONIA T, TABLL A A, et al. Mechanistic-based classification of endocytosis-related inhibitors: does it aid in assigning drugs against SARS-CoV-2?[J]. Viruses, 2023, 15(5): 1040.
[3] SUNDQVIST M, HOLDFELDT A, WRIGHT S C, et al. Barbadin selectively modulates FPR2-mediated neutrophil functions independent of receptor endocytosis[J]. Biochimica et Biophysica Acta (BBA)-Molecular Cell Research, 2020, 1867(12): 118849.
[4] HE Y, LIU H, YIN N, et al. Barbadin potentiates long-term effects of lorcaserin on POMC neurons and weight loss[J]. Journal of Neuroscience, 2021, 41(26): 5734-5746.
[5] DONIA T, ABOUDA M, KELANY M, et al. β-Arrestin inhibition induces autophagy, apoptosis, G0/G1 cell cycle arrest in agonist-activated V2R receptor in breast cancer cells[J]. Medical Oncology, 2021, 38(4): 38.
[6] SHIRAKI A, SHIMIZU S. The molecular associations in clathrin-coated pit regulate β-arrestin-mediated MAPK signaling downstream of μ-opioid receptor[J]. Biochemical and Biophysical Research Communications, 2023, 640: 64-72.
[7] KHALID E, CHANG J P. β-Arrestin-dependent signaling in GnRH control of hormone secretion from goldfish gonadotrophs and somatotrophs[J]. General and Comparative Endocrinology, 2020, 287: 113340.
[8] NAGAOKA K, ASAOKA N, NAGAYASU K, et al. Enhancement of adenosine A2A signaling improves dopamine D2 receptor antagonist-induced dyskinesia via β-arrestin signaling[J]. Frontiers in Neuroscience, 2023, 16: 1082375.