Gene Expression Profile Of Rat Fed Deep-Fried Oil With Or Without Resistant Starch

During frying, fats and oils are heated to high temperatures while exposed to air and moisture, resulting in a complex series of reactions such as hydrolysis, oxidation and thermal alteration, bring about the loss of quality of the frying oil and thereby of the fried food. As a new source of dietary fibre, resistant starch has received much attention for both its potential health benefits and functional properties. Resistant starch positively influences the blood glucose and lipid metabolism, plays an important role in enhancing colonic health.To study the mechanism underlying the liver damage induced by deep-fried oil (DO)consumption and the beneficial effects from resistant starch (RS) supplement, differential gene expression and pathway network were analyzed based on RNA sequencing data from rats. The up/down regulated genes and corresponding signaling pathways were used to construct a novel local gene network (LGN).Gene expression profiling comparison was carried out from the data collected by RNA sequencing. Among them, 129 genes were up-regulated, whereas 300 genes were down-regulated after DO intake. To interpret the effect of DO on the gene expression levels and signaling pathways,the information of up/down regulated-genes,especially the signaling pathways involved in these processes, were collected from the Rat Genome Database. A local Gene Network (LGN) was drawn with nodes indicating biological pathways and the edges represented common genes. From a topological perspective, the average degree of the network was approximately 2.75, the average path length was 4.0964 and the aggregation coefficient was 0.3549. The topology of the network showed characteristics of small-world and scale-free network. Combining with the analysis of three centrality indices (degree centrality, betweenness centrality and closeness centrality ), we filtered out 19 key pathways (ceramide signal pathway, cell cycle pathway, etc. ) and 19 hub genes (Srebfl?Sgkl?Insig1?Ccnd1,etc.) which may play an important role during the process of liver damage induced by deep-fried oil. By analyzing the key genes and pathways, we found that deep-fried oil may cause insulin resistance, apoptosis, block the cell cycle, impair the structure and function of the cell in especial the endothelial cell which closely related to hypertension and atherosclerosis, it can also weak the immune system and result in poor growth.In order to evaluate the changes in the liver function following RS supplement, gene expression profiling comparison was also carried out from the data collected by RNA sequencing. It was found that 219 genes were up-regulated, while 143 genes were down-regulated after RS treatment. The average degree of the network was 2.42, the average path length was 3.5330 and the aggregation coefficient was 0.6401. The statistical and topological characteristics of network showed the properties of small-world and scale-free. Some changes in genes led to a larger probability occurrence of disease or infection with DO intake. More importantly, the main pathways were found to be almost the same between the two LGNs (30 pathways overlapped in total 48) with gene expression profile. There were at least 20 genes in which they were differently expressed in DO and DO-RS, and the regulations were found to be reverse compared to the other treatment.Since 11 of the 20 genes were happen to be the hub genes in the FO-DO network, this finding may indicate that RS supplement in DO-containing diet may mainly regulate the genes that related to DO damage, and RS in the diet may provide direct signals to the liver cells and modulate its effect through a network involving complex gene regulatory events.By analyzing the 9 key pathways we picked out (interleukin-12 signaling pathway, insulin signaling pathway,etc.) and the 19 hub genes (Srebfl?Sgkl?Socs2?Irs2, etc.),we came to the conclusion that RS treatment may improve insulin resistance caused by deep-fried oil,restore immune system, protect cells, promote the detoxification of liver and maintained the structure and function of endothelial cells hence effectively prevent the hypertension and atherosclerosis induced by deep-fried oil.