Insulin‐dependent cytoplasmic distribution of Rab4a in mouse adipocytes is inhibited by interleukin‐6, ‐8, and ‐15

Abstract

The purpose of the study was to examine the effect of interleukins, IL-6, IL-8, and IL-15, on insulin-mediated redistribution of Rab4a, an early endosome marker, in mouse 3T3-L1 adipocytes. The interleukins did not affect cell viability; however, cell number was slightly but significantly higher in cultures exposed to IL-8 and IL-15. IL-8 and IL-15 decreased lipid storage in adipocytes, whereas IL-6 had no effect. Rab4A showed cytoplasmic localization, and in control unstimulated adipocytes it was found primarily nearby nucleus, that was supported by cellular fluorescence distribution profile, and by calculated indices, that is, high percentage of near-nuclear area fluorescence and a low mean peripheral cytoplasmic fluorescence/mean near-nuclear fluorescence ratio. Insulin stimulation (100 nmol/l, 30 min) altered the cytoplasmic localization of Rab4a in control adipocytes, which was manifested by its redistribution towards plasma membrane. This effect of insulin was prevented in adipocytes exposed to IL-6, IL-8, or IL-15. We concluded that insulin-dependent Rab4a redistribution, probably reflecting stimulation of vesicle-mediated transport, is inhibited in adipocytes subjected to differentiation in the presence of IL-6, IL-8, or IL-15. Such alterations may be involved in the mechanisms contributing to development of insulin resistance associated with inflammation; however, further studies in this field are required.

The Combined Partial Knockdown of CBS and MPST Genes Induces Inflammation, Impairs Adipocyte Function-Related Gene Expression and Disrupts Protein Persulfidation in Human Adipocytes

“…Previous studies supported the relevance of these proteins in adipocyte biology. RAB4A is a small GTPase that participates in adipocyte GLUT4 trafficking, exerting an important role in glucose uptake [ 21 , 22 ]. IDH2 attenuates adipocyte inflammation through the induction of α-ketoglutarate production [ 23 ] and is required for lipogenesis in these cells [ 24 ].…”

Interleukin‐8 enhances myocilin expression, Akt‐FoxO3 signaling and myogenic differentiation in rat skeletal muscle cells

“…All images were obtained using a 60 times magnification immersion oil objective and were taken at the same focal plane; 10 independent Fields from control and experimentallytreated cells were photographed and the intensity of fluorescence was measured using the MicroImage analysis system (Olympus Optical, Warsaw, Poland). To visualize cellular profiles of FoxO3 fluorescence lines were drawn on cell images and the fluorescence distribution was estimated along with these lines, as described previously (Błaszczyk, Gajewska, Milewska, & Grzelkowska-Kowalczyk, 2017). The FoxO3 fluorescence (green) sharing the same range of linear profile with 7-AAD fluorescence (red) was considered as cytoplasmic near-nuclear fluorescence.…”