Dongwook Yeo

Muscle Immobilization Activates Mitophagy and Disrupts Mitochondrial Dynamics in Mice.

Skeletal muscle atrophy following prolonged immobilization (IM) is a catabolic state characterized by increased proteolysis and functional deterioration. Previous research indicates that discord of mitochondrial homoeostasis plays a critical role in muscle atrophy. We hypothesized that muscle IM would activate the ubiquitin‐proteolysis, autophagy–lysosome (mitophagy) pathway, mitochondrial dynamics remodelling and apoptosis partially controlled by the FoxO signalling pathway.

Anti-inflammatory effect of avenanthramides via NF-κB pathways in C2C12 skeletal muscle cells

ABSTRACT Avenanthramides (Avns), the polyphenol compounds found only in oats, have been shown to exhibit anti‐inflammatory effects mainly by inhibiting nuclear factor (NF)‐&kgr;B activation in select cell lines. However, the molecular mechanism by which Avns regulate the NF‐&kgr;B pathway is still unclear. The purpose of this study was to investigate (1) the molecular mechanism by which three main fractions of Avns (AvnA, AvnB and AvnC) interact with I&kgr;B Kinase &bgr; (IKK&bgr;); and (2) whether this interaction results in reduced inflammatory responses in skeletal muscle cells. The protein‐ligand docking and molecular dynamics simulation studies suggest that Avns acted as an allosteric inhibitor for modulating IKK&bgr;’s affinity for the NF‐&kgr;B complex. Thus, Avns reduced IKK&bgr; kinase activity in response to tert‐butyl hydroperoxide (tBHP) stimulation and attenuated tBHP‐induced TNF&agr; and IL‐1&bgr; mRNA expression. Furthermore, the three‐fold increases in cyclooxygenase‐2 (COX‐2) protein and luciferase activity with tBHP treatment were reduced by 50% with Avns (P < .01), along with decreased prostaglandin E2 levels (P < .01). These data indicate that Avns are potent inhibitors of NF&kgr;B‐mediated inflammatory response due to the downregulation of IKK&bgr; activity in C2C12 cells. Graphical abstract A schematic overview of the role of AVA in inhibiting I&kgr;B kinase activity in relation to down‐regulation of pro‐inflammatory cytokines and the COX‐2 / PGE2 pathway. Avenanthramides, Avn; I&kgr;B kinase, IKK; Nuclear factor‐&kgr;B (NF‐&kgr;B)1, p50; RelA, p65; Cyclooxygenase‐2, COX‐2; Prostaglandin E2, PGE2. Protein phosphorylation, P. Figure. No Caption available. HighlightsProtein‐ligand docking and molecular dynamics simulation studies support that avenanthramides (Avn) allosterically inhibits IKK&bgr; thus inhibiting the NF‐&kgr;B pathway.AvnA, AvnB and AvnC, the major forms found in oats, can inhibit the NF‐&kgr;B pathway through IKK&bgr; due to allosteric binding.Down‐regulation of COX‐2 / PGE2 pathwayand TNF&agr; and IL‐1&bgr; expression demonstrate the anti‐inflammatory effects of Avns in muscle cells.

Absorption and Elimination of Oat Avenanthramides in Humans after Acute Consumption of Oat Cookies

Background Avenanthramides (AVA) are a group of diphenolic acids found only in oats that have anti-inflammatory and antioxidant effects. Absorption of AVAs in humans after oral consumption of natural oat flour is unknown. Objective To examine the appearance of AVAs in plasma after oral ingestion of oat cookies and estimate key pharmacokinetic parameters. Methods Male and female nonobese participants (n = 16) consumed three cookies made with oat flour containing high (229.6 mg/kg, H-AVA) or low (32.7 mg/kg, L-AVA) amounts of AVAs, including AVA-A, AVA-B, and AVA-C. Blood samples were collected at 0, 0.5, 1, 2, 3, 5, and 10 h after ingestion. Plasma total (conjugated and free) AVA concentrations were quantified using UPLC-MS, and pharmacokinetic parameters for each AVA were estimated. Results AVAs reached peak concentrations in plasma between 2 and 3 h for the H-AVA group and between 1 and 2 h for the L-AVA group. Maximal plasma concentrations for AVAs were higher in the H-AVA than in the L-AVA group. AVA-B demonstrated a longer half-life and slower elimination rate than AVA-A and AVA-C. Conclusions AVAs found naturally in oats are absorbed in the plasma after oral administration in humans. AVA-B has the slowest elimination rate and the longest half-life compared to AVA-A and AVA-C, while AVA-C demonstrated the lowest plasma concentrations. This study is registered with ClinicalTrials.gov identifier NCT02415374.

Avenanthramides attenuate inflammation and atrophy in muscle cells

Background Chronic inflammation is an important etiologic mechanism for muscle atrophy. Oat-derived phytochemical avenanthramides (AVAs) have been shown to suppress inflammatory responses in human clinical studies and in several cell lines in vitro, but their role in skeletal muscle is unclear. The aim of this study was to investigate whether AVA treatment can prevent tumor necrosis factor (TNF)-α-induced muscle fiber atrophy in C2C12 cells. Methods We treated 70% confluent cells for 24 h with AVA. Then, TNF-α was added to cell-cultured medium. Subsequently, cells were harvested at different time points. The cells were examined using various biochemical techniques for measuring protein, messenger RNA levels, nuclear binding activity, and viability. Fluorescence microscope was used for analysis of the myotube morphology. Results Cells treated with TNF-α significantly increased nuclear factor κB activation, indicated by a marked decrease of IκB (p < 0.05) and a 6.6-fold increase in p65-DNA binding (p < 0.01); however, 30 μmol of AVA-A, -B, and -C treatment reduced the binding by 33%, 18%, and 19% (p < 0.01), respectively, compared with cells treated with TNF-α without AVA. The interleukin-6 level increased by 2.5 fold (p < 0.01) with TNF-α, but decreased by 24%, 32%, and 28% (p < 0.01), respectively, with AVA-A, -B, and -C. The interleukin-1β level also showed a 47% increase with TNF-α (p < 0.01), whereas this increment was abolished in all AVA-treated cells. Reactive oxygen species production was 1.3-fold higher in the TNF-α-treated group (p < 0.01) but not in the TNF-α + AVAs groups. Messenger RNA levels of muscle-specific E3 ubiquitin ligase atrogin-1 increased 23% in TNF-α vs. control (p < 0.05) but was decreased by 46%, 34%, and 53% (p < 0.01), respectively, with treatment of AVA-A, -B, and -C. Moreover, TNF-α treatment increased the muscle RING finger 1 messenger RNA level by 76% (p < 0.01); this change was abolished by AVAs. Cells treated with TNF-α demonstrated a reduced proliferation compared with control cells (p < 0.01), but this effect was not seen in TNF-α + AVAs cells. The diameter of the C2C12 myotube decreased by 28% (p < 0.01) with TNF-α, whereas it showed no change when AVAs were included in the cell media. Conclusion These results indicated that AVAs can reduce proinflammatory cytokine and reactive oxygen species production and ameliorate TNF-α-induced myotube atrophy in muscle cells.

Data on the mode of binding between avenanthramides and IKKβ domains in a docking model

The data presented in this article are related to the research paper entitled “Anti-inflammatory effect of avenanthramides via NF-κB pathways in C2C12 skeletal muscle cells.” (Kang et al., in press) [1] This article includes experimental procedures used to analyze the mode of binding between and IkB kinase (IKKβ) and avenanthramides which are a group of phenolic alkaloids found in oats. The protein-ligand docking and the computer simulation method of molecular dynamics (MD) for studying the physical interactions of molecules were performed.