# The Role of miR-144/Nrf2 Pathway in Muscle Oxidative Stress Induced by Oxidized Fish Oil in Megalobrama amblycephala, with an Emphasis on Protein Oxidation

## TL;DR

This study explores how miR-144 and Nrf2 help protect fish muscle from oxidative damage caused by oxidized fish oil.

## Contribution

The study identifies miR-144/Nrf2 as a novel pathway to counteract muscle deterioration caused by oxidized fish oil in fish.

## Key findings

- miR-144 agomir worsened muscle damage by suppressing Nrf2.
- miR-144 antagomir mitigated oxidative stress and improved muscle quality.
- Oxidized fish oil increased oxidative stress markers and reduced muscle protein synthesis.

## Abstract

This study investigated the role of miR-144 in mitigating oxidized fish oil (OFO)-induced muscle oxidative stress and quality deterioration in Megalobrama amblycephala. The feeding trial was conducted for 5 weeks, and four experimental diets were formulated, namely NC (fresh fish oil), OF (OFO), OF + ago (OFO and miR-144 agomir), and OF + anta (OFO and miR-144 antagomir). Histological results showed that OFO significantly reduced myofiber density (from 758.00 ± 13.69 to 636.57 ± 13.44 N/mm2) and decreased the percentage of myofibers with diameters > 50 μm (from 53.45% to 38.52%). OFO intake significantly increased the content of malondialdehyde (MDA), protein carbonyl (PC), advanced oxidation protein product (AOPP), and 3-nitrotyrosine (3-NT), and significantly decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity in muscle. OFO treatment significantly up-regulated the expression of inflammatory factors (NF-κB, TNF-α, HO-1, and IL-6), significantly down-regulated NQO1. Moreover, OFO reduced muscle differentiation and maturation by down-regulating the expression of MyoG, MYHC1, and protein synthesis genes (AKT3, TOR, and S6K1), and up-regulating the expression of protein hydrolysis genes (FoxO3a, MuRF1, HSP70, Beclin-1, P62, and ATG8). Moreover, miR-144 agomir exacerbated OFO-induced muscle damage by suppressing Nrf2, whereas miR-144 antagomir mitigated these effects. Silencing miR-144 re-activates Nrf2, alleviating oxidative damage, enhancing protein deposition, and improving muscle quality. These findings suggest that targeting the miR-144/Nrf2 axis could counteract OFO-induced muscle deterioration.