Impaired autophagy promotes bile acid-induced hepatic injury and accumulation of ubiquitinated proteins.

Chronic exposure to hydrophobic bile acids such as chenodeoxycholic acid (CDCA) and cholic acid (CA) in the liver during cholestasis causes hepatotoxicity and inflammatory response. However, the detailed mechanisms regarding the role of autophagy in cholestatic hepatotoxicity remain largely unknown. Here we determined autophagic clearance in livers of bile duct-ligated mice, in which bile acids accumulate, and in human hepatoma HepG2 cells treated with CDCA and CA. The accumulation of bile acids caused defective autophagic clearance, shown by the accumulation of insoluble p62 and ubiquitinated proteins and cell death accompanied by caspase-3 processing. Hepatocytes exposed to bile acids also showed the accumulation of autophagosomes via suppressed autophagy flux. Treatment of CDCA markedly suppressed Beclin-1 expression, which exhibits a higher cytotoxicity than CA. Moreover, pharmacological or genetic inhibition of autophagy enhanced bile acid-induced cell death. Finally, in vivo, bile duct ligation led to aberrant accumulation of p62 and ubiquitinated proteins in the liver. Our data demonstrate that inhibited autophagy is an essential component of liver injury during cholestasis.

OsMYB14, an R2R3-MYB transcription factor, regulates plant height through the control of hormone metabolism in rice.

Plant growth must be regulated throughout the plant life cycle. The myeloblastosis (MYB) transcription factor (TF) family is one of the largest TF families and is involved in metabolism, lignin biosynthesis, and developmental processes. Here, we showed that OsMYB14, a rice R2R3-MYB TF, was expressed in leaves and roots, especially in rice culm and panicles, and that it localized to the nucleus. Overexpression of OsMYB14 (OsMYB14-ox) in rice resulted in a 30% reduction in plant height compared to that of the wild type (WT), while the height of the osmyb14-knockout (osmyb14-ko) mutant generated using the CRISPR/Cas9 system was not significantly different. Microscopic observations of the first internode revealed that the cell size did not differ significantly among the lines. RNA sequencing analysis revealed that genes associated with plant development, regulation, lipid metabolism, carbohydrate metabolism, and gibberellin (GA) and auxin metabolic processes were downregulated in the OsMYB14-ox line. Hormone quantitation revealed that inactive GA19 accumulated in OsMYB14-ox but not in the WT or knockout plants, suggesting that GA20 generation was repressed. Indole-3-acetic acid (IAA) and IAA-aspartate accumulated in OsMYB14-ox and osmyb14-ko, respectively. Indeed, real-time PCR analysis revealed that the expression of OsGA20ox1, encoding GA20 oxidase 1, and OsGH3-2, encoding IAA-amido synthetase, was downregulated in OsMYB14-ox and upregulated in osmyb14-ko. A protein-binding microarray revealed the presence of a consensus DNA-binding sequence, the ACCTACC-like motif, in the promoters of the OsGA20ox1 and GA20ox2 genes. These results suggest that OsMYB14 may act as a negative regulator of biological processes affecting plant height in rice by regulating GA biosynthesis and auxin metabolism.

Intravenous sustained-release nifedipine ameliorates nonalcoholic fatty liver disease by restoring autophagic clearance.

Obesity and overweight, the most serious health problems, are associated with chronic metabolic complications such as type 2 diabetes, insulin resistance, and nonalcoholic fatty liver disease (NAFLD). However, current pharmacological therapies for obesity are challenged by potential side effects, low effectiveness, and low aqueous solubility, which limit their clinical application. Here, we develop nifedipine-loaded nanoparticles (NFD-NPs) that alleviate obesity-related metabolic dysfunction to be used as instruments for translational medicine. Nanoparticles (NPs) composed of poly (lactic-co-glycolic acid) (PLGA) not only enhance water solubility of hydrophobic nifedipine (NFD), a calcium channel blocker, without modifying the chemical structure of NFD for intravenous administration, but also allow prolonged release of NFD in vivo. NFD-NPs do not show cytotoxicity and reduce palmitate-induced protein inclusions and endoplasmic reticulum stress in human hepatoma HepG2 cells. Importantly, tail-vein injection of NFD-NPs into diet-induced obese mice results in sustained retention of NFD-NPs in the liver and suppression of metabolic derangements associated with NAFLD by enhancing autophagic clearance through Ca2+/calmodulin-dependent kinase II (CaMKII) phosphorylation, consequently decreasing diet-induced insulin resistance and improving glucose tolerance. Our findings offer new clinical tools for NP-mediated pharmaceutical strategies to treat NAFLD and its related metabolic dysfunction.