MIRTROUT

MicroRNA and metabolic programming in rainbow trout

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 Obiettivo del progetto (Objective)

'Carnivorous fish require high-protein intake for protein synthesis and energy purposes and are currently fed high-protein diets based mainly on fishmeal. However, fish meal replacement by carbohydrates is important for sustainable aquaculture in order to decrease nitrogen waste in aquatic environment and preserve marine resources. Unfortunately, rainbow trout is considered as poor user of dietary carbohydrates. Thus, understanding how metabolism is regulated in carnivorous fish constitutes the first objective of our proposal. The second is to determine whether early metabolic programming may help us to tailor fish metabolism to new sustainable diets.

MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate protein expression mainly by targeting the 3’ UTR region of mRNAs. miRNAs have been involved in the regulation of metabolism related gene expression as well as in the control of insulin/amino acids signalling.

The main objective of this project is to analyze the nutritional regulation and metabolic programming of hepatic microRNA levels in rainbow trout. The study will be first focussed on the miRNA122 which is characteristic from the liver and involved in the regulation of cholesterol and triglycerides synthesis. Two important research projects concerning the whole sequencing of the rainbow trout genome and the analysis of the differential expression of the miRNA profile in different tissues of rainbow trout at different nutritional status are currently in progress and will give us the opportunity to enlarge the study to other interesting miRNA for hepatic metabolism and find target genes for these miRNA. Our proposal will be divided in three tasks: 1. Nutritional and hormonal regulation of hepatic miRNAs levels. 2. Time-course evolution of hepatic miRNAs during fish development and growth. 3. Influence of metabolic programming on hepatic miRNA levels and metabolism control.'

Introduzione (Teaser)

A recent research project has investigated whether trout diet can be influenced by metabolic programming during development.

Descrizione progetto (Article)

Carnivorous fish such as rainbow trout (Oncorhynchus mykiss) require a high-protein diet, but this often results in high levels of nitrogenous waste. A high-carbohydrate diet would help avoid this environmental hazard, but would require adjusting the metabolism of the fish.

The EU-funded 'MicroRNA and metabolic programming in rainbow trout' (MIRTROUT) project aimed to better understand how microRNAs control and influence metabolism in rainbow trout. MicroRNAs control gene expression related to entire metabolic pathways in mammals, but their role in fish is not well understood.

Researchers focused on miRNA-122, a microRNA expressed in the liver and known to be involved in carbohydrate metabolism. Parallel projects are identifying other potentially useful microRNAs.

MIRTROUT found that miRNA-122 controls glucose homeostasis in the liver and is regulated in trout after eating. Importantly, this regulation was dependent on the composition of the diet, as well as the metabolic hormone insulin.

Expression of miRNA-122 was analysed at different developmental stages of trout larvae, showing that regulation of miRNA-122 changes depending on the metabolic stage of the developing trout. However, developing trout fed on high-carbohydrate diets did not show any changes in miRNA-122 expression.MIRTROUT has identified miRNA-122 as an important metabolic regulator in these fish, and shown that microRNA expression can be affected by diet. This project represents a key first step towards metabolic programming of carnivorous fish.