Deficiency in AIM2 induces inflammation and adipogenesis in white adipose tissue leading to obesity and insulin resistan
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ARTICLE
Deficiency in AIM2 induces inflammation and adipogenesis in white adipose tissue leading to obesity and insulin resistance Zhenwei Gong 1 & Xinyi Zhang 2,3,4,5 & Kai Su 1 & Ruihua Jiang 1 & Zhe Sun 6 & Wei Chen 7 & Erick Forno 7 & Eric S. Goetzman 8 & Jieru Wang 7 & H. Henry Dong 1 & Partha Dutta 2,3,4 & Radhika Muzumdar 1 Received: 1 March 2019 / Accepted: 11 July 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract Aims/hypothesis Absent in melanoma 2 (AIM2) is a cytosolic sensor for double-stranded DNA and a tumour suppressor. Binding of double-stranded DNA to AIM2 forms the AIM2 inflammasome, leading to activation of caspase-1 and production of IL-1β and IL-18. Although inflammasome-independent effects of AIM2 have been reported, its role in energy metabolism is unknown. We aimed to evaluate the effect of AIM2 in energy metabolism and glucose homeostasis. Methods Male and female whole body Aim2 knockout (Aim2−/−) mice were used in the current study. Body weight, food intake, body composition, energy expenditure, fasting blood glucose levels, GTT and body temperature were measured at indicated time points. RNA sequencing was carried out on gonadal white adipose tissue (gWAT) in 14-month-old female mice. mRNA and protein levels in tissues were analysed by quantitative real-time PCR and immunoblot. Immune cell infiltration in gWAT was examined by flow cytometry. Stromal vascular fractions isolated from gWAT were used to investigate adipocyte differentiation. Results Male and female Aim2−/− mice were obese compared with wild-type controls from 7 weeks of age until 51 weeks of age, with increased adiposity in both subcutaneous and visceral fat depots. While there were no differences in food intake, Aim2−/− mice demonstrated decreased energy expenditure and impaired brown adipose tissue function compared with wild-type controls. Fasting glucose and insulin levels were elevated, and Aim2−/− mice were glucose intolerant on intraperitoneal GTT. RNA sequencing revealed marked upregulation of the IFN-inducible gene Ifi202b, which encodes protein 202 (p202) and elevated inflammatory signalling in gWAT of Aim2−/− mice. Increased infiltration of total and Ly6Clow monocytes was noted at 8 weeks of age in gWAT, before the onset of obesity and insulin resistance. Ifi202b knockdown blocked adipogenesis in stromal vascular fractions and reduced inflammation in bone marrow-derived macrophages, demonstrating a key role of p202 in mediating the increased adipogenesis and inflammation in Aim2−/− mice. Conclusions/interpretation These results demonstrate a fundamental role for AIM2 in energy metabolism, inflammation and insulin resistance. Our studies establish a novel link between the innate immunity proteins, AIM2 and p202, and metabolism.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00125-019-04983-x) contains peer-reviewed but unedited supplementary material, which is available to authorised users. * Zhenwei Gong [email protected]
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