Modulation of α 2C ‐adrenergic receptor export trafficking by multiple Rab GTPases

At 37°C, α 2C ‐adrenergic receptor (AR) is poorly transported to the plasma membrane. Cold exposure enhances α 2C ‐AR translocation to the cell surface and this effect is exaggerated in some individuals leading to Raynaud Phenomenon. To identify the factors limiting α 2C ‐AR transport, the receptor was co‐transfected with well defined Rab GTPase dominant negative mutants in HEK293T cells. Subsequently, the α 2C ‐AR plasma membrane levels were determined at 37°C and 30°C by [ 3 H]RX‐821002 binding. Inhibition of the endoplasmic reticulum (ER) to Golgi traffic with Rab1N124I equally attenuated α 2C ‐AR cell surface targeting at both temperatures. Blockade of the retrograde traffic from the Golgi to the ER using Rab2N119I had no effect on α 2C ‐AR cell surface expression. In contrast, inhibition of the retrograde traffic by Rab6N126I augmented α 2C ‐AR plasma membrane levels at 30°C, but not at 37°C. Reduction of Golgi to plasma membrane traffic by Rab11N124I did not influenced receptor translocation to the cell surface. However, Rab8T22N decreased α 2C ‐AR plasma membrane levels with similar extent at 37°C and 30°C. Our data indicate that Rab6‐dependent retrograde traffic is required to prevent exaggerated transport of α 2C ‐AR to the plasma membrane at low temperature. (R01GM076167, 5P20RR018766)