The three alpha2-adrenergic receptor subtypes (alpha2a, alpha2b, and alpha2c) are highly homologous G protein-coupled receptors. These receptors all couple to pertussis toxin-sensitive G proteins and have relatively similar pharmacological properties. To further explore functional differences between these receptors, we used immunocytochemical techniques to compare the ability of the three alpha2-receptor subtypes to undergo agonist-mediated internalization. The alpha2a-receptor does not internalize after agonist treatment. In contrast, we observed that the alpha2b-receptor is able to undergo agonist-induced internalization and seems to follow the same endosomal pathway used by the beta2-adrenergic receptor. Attempts to examine internalization of the alpha2c-receptor were complicated by the fact that the majority of the alpha2c receptor resides in the endoplasmic reticulum and cis/media Golgi and there is relatively little cell surface localization. Nevertheless, we were able to detect some internalization of the alpha2c-receptor after prolonged agonist treatment. However, we observed no significant movement of alpha2c-receptor from the intracellular pool to the plasma membrane during a 4-hr treatment of cells with cycloheximide, suggesting that these cells are unable to process alpha2c-receptors in the same way they process the alpha2a or alpha2b subtypes.

SPECIFIC AIMSTo study the functional role of the recently found leucine 7 to proline 7 (Leu7Pro) polymorphism in the signal peptide of preproneuropeptide Y, sympathetic responses, including neuropeptide Y (NPY) release, were compared during strenuous physical exercise between subjects with the Leu7/Pro7 genotype and their matched wild-type controls (Leu7/Leu7 genotype). To further evaluate the effect of this polymorphism on the intracellular processing of preproNPY, isolated human umbilical vein endothelial cells (HUVEC) of corresponding genotypes were compared using immunocytochemical methods to verify the presence and localization of NPY and proNPY in these cells by confocal microscopy. PRINCIPAL FINDINGS NPY-genotype influences heart rate levelSubjects with the Leu7/Pro7 genotype had a significantly higher mean heart rate over time than subjects with the Leu7/Leu7 genotype ( Fig. 1A, PϽ0.05). No statistically significant differences were detected in mean heart rate at any separate time point between the groups, however. No differences were observed in systolic or diastolic blood pressure between the genotypes during the entire study period. NPY-genotype influences exercise-induced increases in NPY and FFA concentrationsSubjects with the Leu7/Pro7 genotype had higher overall plasma NPY concentration (Fig. 1B), with statistically significant differences at 20 min maximal NPY concentrations (PϽ0.05) and near significant differ-ences at 30 min and 40 min postexercise NPY concentrations (Pϭ0.05). The mean exercise-induced increase of NPY between 0 min and 20 min was 90.4 Ϯ 12.7 pmol/l in the subjects with proline 7 (Pro7) in the preproNPY and 51.9 Ϯ 5.4 pmol/l in the subjects without this substitution (PϽ0.05, t test). There were no statistically significant differences in the concentrations of epinephrine and norepinephrine (NE) in plasma between the groups. The mean NE/NPY ratio in plasma was 84.9 Ϯ 9.7 in subjects with the Leu7/Leu7 genotype and 56 Ϯ 5.3 in subjects with the Leu7/Pro7 genotype (PϽ0.05, t test).A clear difference was observed in overall free fatty acid (FFA) concentrations between the groups (Fig. 1C): subjects with the Leu7/Pro7 genotype had significantly lower FFA concentrations than subjects with the Leu7/Leu7 genotype, with the largest difference in postexercise 40 min concentration (PϽ0.05). There were lower overall insulin concentrations in subjects with the Leu7/Pro7 genotype and no clear exerciseinduced reduction in insulin levels in this group; the statistically significant differences in concentrations were detected before the exercise at 0 min (PϽ0.05) and after exercise at 60 min (PϽ0.05). Lactate levels were identical in the two genotype groups throughout the study period. NPY-genotype determines the pattern of NPY-and proNPY-immunoreactivity (ir) in endothelial cellsClear intracellular punctate staining (Fig. 2) could be seen in HUVECs with immunocytochemical detection 1 To read the full text of this article, go to http://www. fasebj.org/cgi/doi/10.1096/fj.00 -0437fje; to cite this...

Oncolytic viruses have gained attention as a novel form of cancer treatment.