EGCG down-regulates MuRF1 expression through 67-kDa laminin receptor and the receptor signaling is amplified by eriodict
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ORIGINAL PAPER
EGCG down‑regulates MuRF1 expression through 67‑kDa laminin receptor and the receptor signaling is amplified by eriodictyol Motoki Murata1,2 · Yuki Shimizu1 · Yuki Marugame1 · Ayaka Nezu1 · Konatsu Fujino1 · Shuhei Yamada1 · Motofumi Kumazoe1 · Yoshinori Fujimura1 · Hirofumi Tachibana1 Received: 25 February 2020 / Accepted: 17 May 2020 © The Japanese Society of Pharmacognosy 2020
Abstract (–)-epigallocatechin-3-O-gallate (EGCG) is a bioactive polyphenol in green tea. Previous studies have demonstrated the beneficial effects of EGCG on muscle mass and muscle atrophy. In the current study, we investigated the mechanisms underlying effect of EGCG on muscle atrophy. It was demonstrated that EGCG suppressed muscle-specific ubiquitin ligase, muscle RING Finger 1 (MuRF1) expression through 67-kDa laminin receptor (67LR). Previous studies have shown that eriodictyol potentiates the anti-tumor activities of EGCG by amplifying 67LR signaling. Therefore, we investigated the effects of EGCG and eriodictyol on the MuRF1 expression in C2C12 myotubes. The combined treatment of EGCG and eriodictyol significantly suppressed MuRF1 expression in dexamethasone-treated C2C12 myotubes. Tail suspension was maintained for 10 consecutive days using C57BL6/J mice, and during this time EGCG and eriodictyol were orally administered. In the gastrocnemius muscle, the muscle mass loss was inhibited by the combination of EGCG and eriodictyol. Therefore, EGCG may prevent muscle atrophy by inducing 67LR signaling and eriodictyol amplifies this pathway. Keywords EGCG · Eriodictyol · Muscle atrophy · 67LR · MuRF1
Introduction Skeletal muscle is the largest organ that enables individuals to move and regulates glucose homeostasis. Skeletal muscle is readily influenced by active state and can alter its size accordingly. Skeletal muscle atrophy is the loss or decrease in muscle mass in response to aging, inactivity, starvation, nerve injury, or a variety of diseases including excessive glucocorticoids and cancers [1, 2]. Loss of skeletal muscle mass can lead to low functional status and decreased quality of life [3]. However, the current medication for muscle atrophy remains unresolved. Therefore, there is an urgent need for the development of novel treatments to prevent skeletal muscle atrophy. * Hirofumi Tachibana [email protected]‑u.ac.jp 1
Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 744 Motooka, Nishi‑ku, Fukuoka 819‑0305, Japan
Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
2
Loss of skeletal muscle mass is a result of lean protein degradation, which is initiated by the activation of the ubiquitin–proteasome system [4]. Three enzymes are required for ubiquitination that marks proteins for degradation. The ubiquitin-activating and ubiquitin-conjugating enzymes prepare ubiquitin for conjugation, but the key role in this sequential cascade is played by ubiquitin ligase, which performs the final step in the p
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