Sung Hoon Kim, M.D., Eun Song Song, M.D., Somy Yoon, Ph.D., Gwang Hyeon Eom, Ph.D., Gaeun Kang, M.D., and Young Kuk Cho, M.D.. Ann Lab Med 2021;41:318-22. https://doi.org/10.3343/alm.2021.41.3.318

Duchenne muscular dystrophy (DMD) is a prevalent, fatal degenerative muscle disease with no effective treatments. Mdx mouse model of DMD exhibits impaired muscle performance, oxidative stress, and dysfunctional autophagy. Although antioxidant treatments may improve the mdx phenotype, the precise molecular mechanisms remain unclear. This study investigates the effects of aminoguanidine hemisulfate (AGH), an inhibitor of reactive oxygen species (ROS), on mitochondrial autophagy, oxidative stress, and muscle force in mdx mice. Male wild-type (WT) and mdx mice were divided into three groups: WT, mdx, and AGH-treated mdx mice (40 mg/kg intraperitoneally for two weeks) at 6 weeks of age. Gene expression, western blotting, H&E staining, immunofluorescence, ROS assays, TUNEL apoptosis, glutathione activity, and muscle force measurements were performed. Statistical comparisons used one-way ANOVA. AGH treatment significantly reduced the protein levels of LC3, and p62 in mdx mice, indicating improved autophagy activity and the ability to clear damaged mitochondria. AGH restored the expression of mitophagy-related genes Pink1 and Parkin and increased Mfn1, rebalancing mitochondrial dynamics. It also increased Pgc1α and mtTFA levels, promoting mitochondrial biogenesis. ROS levels were reduced, with higher Prdx3 and MnSOD expression, improving mitochondrial antioxidant defenses. AGH normalized the GSSG/GSH ratio and decreased glutathione reductase and peroxidase activities, further improving redox homeostasis. Additionally, AGH reduced apoptosis, shown by fewer TUNEL-positive cells and lower caspase-3 expression. Histological analysis revealed decreased muscle damage and fewer embryonic and neonatal myosin-expressing fibers. AGH altered fiber composition, decreasing MyH7 while increasing MyH4 and MyH2. Muscle force improved significantly, with greater twitch and tetanic forces. Mechanistically, AGH modulated the AKT/FOXO1 pathway, decreasing myogenin and Foxo1 while increasing MyoD. AGH treatment restored mitochondrial autophagy, reduced oxidative stress, apoptosis, and altered muscle fiber composition via the AKT/FOXO1 pathway, collectively improving muscle force in mdx mice. We propose AGH as a potential therapeutic strategy for DMD and related muscle disorders.

Background: Tanshinone IIA (Tan IIA) is a lipophilic active constituent derived from the rhizomes and roots of Salvia miltiorrhiza Bunge (Danshen), a common Chinese medicinal herb. However, clinical applications of Tan IIA are limited due to its poor solubility in water. Methods: To overcome this limitation, we developed a calcium alginate hydrogel (CA) as a hydrophilic carrier for Tan IIA, which significantly improved its solubility. We also prepared nanoparticles with pH-responsive properties to explore their potential for controlled drug delivery. The physicochemical properties of Tan IIA/CA nanoparticles were evaluated, including their size, stability, and release profile. We also utilized RNA sequencing to further investigate the underlying anticancer mechanisms of Tan IIA/CA nanoparticles. Results: The Tan IIA/CA nanoparticles demonstrated enhanced solubility and exhibited potent anticancer activity in vitro. Additionally, the nanoparticles showed promising pH-responsive behavior, which is beneficial for controlled release applications. Further investigation into the molecular mechanisms revealed that the anticancer effects of Tan IIA/CA were mediated through apoptosis, ferroptosis, and autophagy pathways. Conclusions: This study confirms the anticancer potential and mechanisms of Tan IIA, while also presenting an innovative approach to enhance the solubility of this poorly soluble compound. The use of CA-based nanoparticles could be a valuable strategy for improving the therapeutic efficacy of Tan IIA in cancer treatment.

Intensive research has focused on minimizing the infarct area and stimulating endogenous regeneration after myocardial infarction. Our group previously elucidated that apicidin, a histone deacetylase (HDAC) inhibitor, robustly accelerates the cardiac commitment of naïve mesenchymal stem cells (MSCs) through acute loss of YAP1. Here, we propose the novel regulation of YAP1 in MSCs. We found that acute loss of YAP1 after apicidin treatment resulted in the mixed effects of transcriptional arrest and proteasomal degradation. Subcellular fractionation revealed that YAP1 was primarily localized in the cytoplasm. YAP1 was acutely relocalized into the nucleus and underwent proteasomal degradation. Interestingly, phosphor-S127 YAP1 was shuttled into the nucleus, suggesting that a mechanism other than phosphorylation governed the subcellular localization of YAP1. Apicidin successfully induced acetylation and subsequent dissociation of YAP1 from 14-3-3, an essential molecule for cytoplasmic restriction. HDAC6 regulated both acetylation and subcellular localization of YAP1. An acetylation-dead mutant of YAP1 retarded nuclear redistribution upon apicidin treatment. We failed to acquire convincing evidence for polyubiquitination-dependent degradation of YAP1, suggesting that a polyubiquitination-independent regulator determined YAP1 fate. Nuclear PSME4, a subunit of the 26 S proteasome, recognized and degraded acetyl YAP1 in the nucleus. MSCs from PSME4-null mice were injected into infarcted heart, and aberrant sudden death was observed. Injection of immortalized human MSCs after knocking down PSME4 failed to improve either cardiac function or the fibrotic scar area. Our data suggest that acetylation-dependent proteasome subunit PSME4 clears acetyl-YAP1 in response to apicidin treatment in the nucleus of MSCs.

Mira Kim, Yong Sook Kim, Youngkeun Ahn, Gwang Hyeon Eom, and Somy Yoon. Korean J Physiol Pharmacol 2023;27:407-16. https://doi.org/10.4196/kjpp.2023.27.4.407