Temperature Sensitive Interaction of α 2c ‐adrenergic receptor and Nucleophosmin in Raynaud's Phenomnenon

Abstract

Raynaud's Phenomenon (RP) is a dermatological disorder characterized by excessive vasospasms leading to ischemia. Although there is no specific treatment, research suggests that α2C-adrenergic receptor (α2C-AR) is responsible for cold induced vasospastic events and that accessory proteins may modulate receptor expression. In a proteomic experiment, Nucleophosmin (NP), a multifunctional chaperone protein, interacted with α2C-AR in a temperature sensitive manner with more interaction at 30°C than 37°C (73± 16%). Its overexpression increased membrane receptor levels at 37°C but not lower temperatures. NVP-TAE684 a highly specific inhibitor of NP phosphorylation was incubated with NP in HEK293 cells and the plasma membrane levels determined by radioligand binding. In further experiments we determined the cAMP levels in response to α2C-AR stimulation in human VSMC by incubating at 37°C and 30°C with and without inhibitors then measuring the effects of stimulation on cAMP levels. In conclusion based on the radioligand binding, NP interacts with (α2C-AR) in a temperature dependent manner such that plasma membrane levels are significantly increased at 37°C compared to cooler temperatures.