Receptor for Advanced Glycation End Products Regulates Adipocyte Hypertrophy and Insulin Sensitivity in Mice

Abstract

Receptor for advanced glycation end products (RAGE) has been shown to be involved in adiposity as well as atherosclerosis even in nondiabetic conditions. In this study, we examined mechanisms underlying how RAGE regulates adiposity and insulin sensitivity. RAGE overexpression in 3T3-L1 preadipocytes using adenoviral gene transfer accelerated adipocyte hypertrophy, whereas inhibitions of RAGE by small interfering RNA significantly decrease adipocyte hypertrophy. Furthermore, double knockdown of high mobility group box-1 and S100b, both of which are RAGE ligands endogenously expressed in 3T3-L1 cells, also canceled RAGE-medicated adipocyte hypertrophy, implicating a fundamental role of ligands–RAGE ligation. Adipocyte hypertrophy induced by RAGE overexpression is associated with suppression of glucose transporter type 4 and adiponectin mRNA expression, attenuated insulin-stimulated glucose uptake, and insulin-stimulated signaling. Toll-like receptor (Tlr)2 mRNA, but not Tlr4 mRNA, is rapidly upregulated by RAGE overexpression, and inhibition of Tlr2 almost completely abrogates RAGE-mediated adipocyte hypertrophy. Finally, RAGE−/− mice exhibited significantly less body weight, epididymal fat weight, epididymal adipocyte size, higher serum adiponectin levels, and higher insulin sensitivity than wild-type mice. RAGE deficiency is associated with early suppression of Tlr2 mRNA expression in adipose tissues. Thus, RAGE appears to be involved in mouse adipocyte hypertrophy and insulin sensitivity, whereas Tlr2 regulation may partly play a role.

N ε -(Carboxymethyl)lysine-Receptor for Advanced Glycation End Product Axis Is a Key Modulator of Obesity-Induced Dysregulation of Adipokine Expression and Insulin Resistance

“…In ApoE/RAGE double knockout mice, it was demonstrated that RAGE regulated adiposity. Monden et al 28 demonstrated that an increase in body weight induced by high-fat diet is suppressed in RAGE knockout mice. In contrast to these studies, we did not observe an effect of RAGE on adiposity in the Leptr Db-/-background.…”

“…Previous research has also demonstrated that RAGE deficiency significantly decreased the expression of proinflammatory mediators and lower levels of oxidative stress, whereas adiponectin levels and antioxidative defense mechanisms were higher in RAGE-deficient mice. [24][25][26][27][28] In addition, the favorable effect of RAGE deficiency on insulin sensitivity and glucose metabolism was also demonstrated in RAGE knockout mice fed a high-fat diet. 27,28 RAGE deficiency was also associated with higher glucose transporter-4 expression in adipose tissue in these mice.…”

“…[24][25][26][27][28] In addition, the favorable effect of RAGE deficiency on insulin sensitivity and glucose metabolism was also demonstrated in RAGE knockout mice fed a high-fat diet. 27,28 RAGE deficiency was also associated with higher glucose transporter-4 expression in adipose tissue in these mice. 28 In cultured adipocytes, nondefined AGEs impair insulin signaling by increasing generation of intracellular reactive oxygen species and activation of inflammatory pathways.…”

“…28 In cultured adipocytes, nondefined AGEs impair insulin signaling by increasing generation of intracellular reactive oxygen species and activation of inflammatory pathways. 29,30 Ueno et al 25 recently demonstrated attenuated insulin-stimulated glucose uptake in RAGE-overexpressing 3T3-L1 adipocytes.…”

“…[24][25][26][27][28] In addition, the favorable effect of RAGE deficiency on insulin sensitivity and glucose metabolism was also demonstrated in RAGE knockout mice fed a high-fat diet.…”