Chemical Inducers of Obesity-Associated Metabolic Stress Activate Inflammation and Reduce Insulin Sensitivity in 3T3-L1 Adipocytes

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I. S. Stafeev^1,2,a*, S. S. Michurina^1,3, N. V. Podkuychenko^1,3, M. Y. Menshikov¹, Ye. V. Parfyonova^1,2#, and A. V. Vorotnikov^1,4,b#*

¹Institute of Experimental Cardiology, National Medical Research Center of Cardiology, 121552 Moscow, Russia

²Lomonosov Moscow State University, Faculty of Fundamental Medicine, 117192 Moscow, Russia

³Lomonosov Moscow State University, Faculty of Biology, 119991 Moscow, Russia

⁴Lomonosov Moscow State University, Medical Center, 119991 Moscow, Russia

^# These authors contributed equally to this work.

^* To whom correspondence should be addressed.

Received October 8, 2018; Revised January 23, 2019; Accepted January 23, 2019

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Obesity is accompanied by dyslipidemia, hypoxia, endoplasmic reticulum (ER) stress, and inflammation, representing the major risk factor for the development of insulin resistance (IR) and type 2 diabetes. We modeled these conditions in cultured 3T3-L1 adipocytes and studied their effect on insulin signaling, glucose uptake, and inflammatory response via activation of stress-dependent JNK1/2 kinases. Decreased insulin-induced phosphorylation of the insulin cascade components IRS, Akt, and AS160 was observed under all tested conditions (lipid overloading of cells by palmitate, acute inflammation induced by bacterial lipopolysaccharide, hypoxia induced by Co²⁺, and ER stress induced by brefeldin A). In all the cases, except the acute inflammation, glucose uptake by adipocytes was reduced, and the kinetics of JNK1/2 activation was bi-phasic exhibiting sustained activation for 24 h. By contrast, in acute inflammation, JNK1/2 phosphorylation increased transiently and returned to the basal level within 2-3 h of stimulation. These results suggest a critical role of sustained (latent) vs. transient (acute) inflammation in the induction of IR and impairment of glucose utilization by adipose tissue. The components of the inflammatory signaling can be promising targets in the development of new therapeutic approaches for preventing IR and type 2 diabetes.

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KEY WORDS: insulin resistance, type 2 diabetes, inflammation, glucose transport

DOI: 10.1134/S0006297919050092

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