Introduction: Subcelullar distribution of glucose-transporter GLUT4 in adipocytes is pivotal to glucose homeostasis. The profile of this distribution is similar to that of EC 3.4.11.3 aminopeptidase, the unique enzyme in adipocyte known to be translocated between high (HDM) and low (LDM) density microsomal fractions toward the plasma membrane (MF) under insulin stimulus, thus originating the canonical concept of insulin-regulated aminopeptidase (IRAP). The present study investigates whether distribution of basic (APB), neutral puromycin-sensitive (PSA) and puromycin-insensitive (APM) aminopeptidases in HDM, LDM and MF from adipocytes are also influenced by insulin and obesity. Design and Methods: APB, APM and PSA activities, with or without insulin stimulus, were fluorometric monitoring in HDM, LDM and MF obtained from adipocytes isolated from healthy control (C) and monosodium glutamate obese (MSG) rats. Results: Insulin increased APM in HDM, LDM and MF from C, in LDM and MF from MSG, as well as APB in HDM and PSA in MF from MSG. Canonical traffic of these enzymes was not detected in the absence or presence of insulin in C and MSG. Conclusions: Insulin is related to the control of subcellular distribution of APM under basal status. In MSG obesity, insulin probably facilitates the performance of APM in maturation of newly synthesized proteins, the regulatory role of APM and PSA on extracellular angiotensin III, and the effect of APB in new protein synthesis. A new concept of aminopeptidase enzymes regulation by insulin and obesity dissimilar to the current concept of IRAP traffic emerged from these data.
Supported by: FAPESP, CNPq and CAPES