Investigating the Effects of Chromobacterium Violaceumviolacein on Human Serotonin 2C Receptor
The monoamine neurotransmitter serotonin (5-HT) plays a role in many physiological responses by binding to at least 14 receptor subtypes. The 5-HT2C receptor subtype is a 7-transmembrane, G protein-coupled receptor (GPCR) that is involved in neuronal excitability, spatial learning, mood, and appetite. The microorganism Chromobacterium violaceum produces a purple pigment, violacein, which can be extracted and purified. Violacein has antibiotic, antileishmanial, antifungal and antitumoral properties in various cancer cell lines. Violacein is derived from the amino acid tryptophan like 5-HT, and therefore they have similar chemical structures, however, no one has reported the activity of violacein at 5-HT receptors. To investigate the effect of violacein on receptor trafficking, Human Embryonic Kidney (HEK) 293 cells expressing fluorescently-tagged 5-HT2C receptor were treated with 5-HT, violacein, water or vehicle and then cells were fixed and visualized with fluorescent microscopy. Violacein treatment did not cause receptor internalization. Our recent studies suggest that the 5-HT2C receptor can activate the JAK/STAT pathway. To see if violacein can effect this pathway, HEK 293 cells expressing 5-HT2C receptor were treated with violacein or pretreated with violacein followed by incubation with 5-HT. Phosphorylation states of JAK2 and STAT3 were examined by immunoblotting. Results determined that 5-HT2C receptor activation had no effect on JAK2 phosporylation and that violacein blocked STAT3 phosphorylation. Primary radioligand binding determined that violacein has low affinity 5-HT2C receptor but has a higher affinity for adrenergic receptor. It was also determined by luciferase assay that violacein has no effect on HIV-1 viral replication. Future studies will examine G protein-coupling by measuring phosphoinositide hydrolysis and cAMP assay to investigate adrenergic pathways.
Letimicia S Fears,
"Investigating the Effects of Chromobacterium Violaceumviolacein on Human Serotonin 2C Receptor"
ETD Collection for Tennessee State University.