Expression profile of adipose tissue microRNAs and of genes in the mTOR signalling network following developmental high fat diet

High fat diet (HFD) during early development may increase the susceptibility to metabolic diseases later in life. Adipose tissue is an important regulator of energy metabolism through secretion of endocrine and paracrine/autocrine factors. In the present study we first screened the expression profiles of about 500 miRNAs in visceral white adipose tissue (VAT) from mice fed a control diet (CD) and mice fed a matched HFD during three different life stages i) in utero (UT), ii) in utero and lactation (UL), iii) in utero until termination at age 23 weeks (WL). Fourteen differentially expressed miRNAs were identified and these miRNAs were used for prediction of targeted signalling pathways. In addition, analysis of high abundance miRNAs showed a marked downregulation of the miR-200 family members in the UT group. Subsequently, the transcript levels of 89 selected genes represented in the predicted signalling pathways were determined. Six genes (Deptor, Il6, Irs1, lep, Lpin1 and prkaa1) showed a significant differential expression due to HFD feeding compared to controls, and HFD treatment had significant effects on the WL-groups. The expression pattern of Deptor, Il6, Irs1, Lep genes showed a similar direction of change across all HFD treatment groups. The differential expression of Irs1 and Deptor genes points to a persistent modification of the insulin receptor – mTOR signalling network. This finding is supported by increased serum insulin and IGF-1 levels and impaired glucose regulation in the HFD groups. This study shows that developmental HFD can lead to persistent changes in VAT miRNA expression levels that is associated with a modification of key signalling pathways regulating energy metabolism also in animals with normal BMI.dy we have screened over 500 miRNAs for differential expression in visceral white adipose tissue (vWAT) between mice fed a control diet (CD; 10% kcal from fat) and mice fed a matched high fat diet (HFD; 45% kcal from fat) during three different life stages i) in utero (UT), ii) in utero and lactation (UL), iii) in utero until termination (WL). All animals were sacrifices at an age of 23 weeks. Experimental design: In this study, male C57BL/6J wild-type mice were used. The mice were housed in air flow IVC racks (Innovive Inc., San Diego, CA, USA) in 100% PET plastic disposable cages on Nestpak Aspen 4HK bedding (Datesand Ltd., Manchester, UK) in a room with 12-h light/dark cycle, and controlled humidity (55 ± 5%) and temperature (20–24°C). Diet and municipal tap water were given ad libitum. The experiment reported in this paper was performed in conformity with the laws and regulations for animal experiments in Norway and was approved by the National Experimental Animal Board in Norway. The parental mice were fed a standard breeding diet (2018 Teklad Global 18% Protein Rodent Diet from Harlan Industries Inc., Indianapolis, IN, USA) before mating. The experimental litters were given diets of purified ingredients from Research Diets Inc. (New Brunswick, NJ, USA) in various life periods. The D12451 diet, containing 20%, 35%, and 45% of kcal from protein, carbohydrates, and fat, respectively, was used as a HFD. The D12450H diet, containing 20%, 70%, and 10% of kcal from protein, carbohydrates, and fat, respectively, was used as a matching control diet (CD). Mice were randomly assigned to the experimental groups and exposed to the CD (22 mice/17 litters) or the HFD during combinations of three periods of life; in utero, from mating via the dams (UT; 27mice/17litters); from mating to weaning (UL; 25 mice/19 litters); and from mating to termination at 23 weeks (WL; 23 mice/21 litters). For miRNA profiling following mice per group was used: CD (3 pooled samples from 12 mice); UT (3 pooled samples from 12 mice); UL (3 pooled samples from 12 mice) and WL (3 pooled samples from 12 mice). Mice were sacrificed by cervical dislocation and epididymal fat pads were isolated, rapidly frozen on dry ice and kept at -80ºC until use.