VAMP3 null mice display normal constitutive, insulin- and exercise-regulated vesicle trafficking

To investigate the physiological function of the VAMP3 vesicle SNARE (v-SNA RE) isoform in the regulation of GLUT4 vesicle trafficking, we generated ho mozygotic VAMP3 null mice by targeted gene disruption The VAMP3 null mice h ad typical growth rate and weight gain, with normal maintenance of fasting serum glucose and insulin levels. Analysis of glucose disposal and insulin sensitivity demonstrated normal insulin and glucose tolerance, with no evid ence for insulin resistance. Insulin stimulation of glucose uptake in isola ted primary adipocytes was essentially the same for the wild-type and VAMP3 null mice. Similarly, insulin-, hypoxia-, and exercise-stimulated glucose uptake in isolated skeletal muscle did not differ significantly. In additio n, other general membrane trafficking events including phagocytosis, pinocy tosis, and transferrin receptor recycling were also found to be unaffected in the VAMP3 null mice. Taken together, these data demonstrate that VAMP3 f unction is not necessary for either regulated GLUT4 translocation or genera l constitutive membrane recycling.