Bag1 protein loss sensitizes mouse embryonic fibroblasts to glutathione depletion.

Bcl2-associated athanogene-1 protein (Bag1) acts as a co-chaperone of heat shock protein 70 and heat shock cognate 70 and regulates multiple cellular processes, including cell proliferation, apoptosis, environmental stress response, and drug resistance. Since Bag1 knockout mice exhibited fetal lethality, the in vivo function of Bag1 remains unclear. In this study, we established a mouse line expressing Bag1 gene missing exon 5, which corresponds to an encoding region for the interface of heat shock protein 70/heat shock cognate 70. Despite mice carrying homoalleles of the Bag1 mutant (Bag1Δex5) expressing undetectable levels of Bag1, Bag1Δex5 homozygous mice developed without abnormalities. Bag1Δex5 protein was found to be highly unstable in cells and in vitro. We found that the growth of mouse embryonic fibroblasts derived from Bag1Δex5-homo mice was attenuated by doxorubicin and a glutathione (GSH) synthesis inhibitor, buthionine sulfoximine. In response to buthionine sulfoximine, Bag1Δex5-mouse embryonic fibroblasts exhibited a higher dropping rate of GSH relative to the oxidized glutathione level. In addition, Bag1 might mitigate cellular hydrogen peroxide levels. Taken together, our results demonstrate that the loss of Bag1 did not affect mouse development and that Bag1 is involved in intracellular GSH homeostasis, namely redox homeostasis.

One-carbon metabolizing enzyme ALDH1L1 influences mitochondrial metabolism through 5-aminoimidazole-4-carboxamide ribonucleotide accumulation and serine depletion, contributing to tumor suppression.

Tumor cells generally require large amounts of nucleotides, and thus activate de novo purine synthesis (dnPS). In the dnPS reactions, 10-formyltetrahydorofolate (10-fTHF) supplied by one-carbon metabolism is utilized as a formyl group donor. We focused on aldehyde dehydrogenase 1 family member L1 (ALDH1L1), which metabolizes 10-fTHF to tetrahydrofolate and whose expression is often attenuated in hepatocellular carcinoma (HCC). We generated ALDH1L1-expressing HuH-7 cells to perform metabolome analysis and found that intracellular levels of serine were reduced and glycine was increased. In addition, 5-aminoimidazole-4-carboxamide ribonucleotide (ZMP), a dnPS intermediate, accumulated due to the consumption of 10-fTHF by ALDH1L1, which inhibited ZMP formylation. Importantly, ALDH1L1-expressing cells showed reduced ZMP sensitivity and higher mitochondrial activity. The suppression of mitochondrial serine catabolism by ALDH1L1 expression was speculated to be closely related to this phenotype. Gene set enrichment analysis utilizing The Cancer Genome Atlas data revealed that genes related to oxidative phosphorylation were enriched in HCC patients with high ALDH1L1 expression. Moreover, drug sensitivity data analysis demonstrated that HCC cell lines with low expression of ALDH1L1 were sensitive to ZMP and cordycepin, a structural analog of ZMP and AMP. Our study revealed that ZMP and AMP analogs might be effective in the pharmacotherapy of HCC patients with low expression of ALDH1L1.

Inhibition of SARS-CoV-2 nucleocapsid protein-RNA interaction by guanosine oligomeric RNA.

The interaction of the ß-coronavirus severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) nucleocapsid (N) protein with genomic RNA is initiated by specific RNA regions and subsequently induces the formation of a continuous polymer with characteristic structural units for viral formation. We hypothesized that oligomeric RNAs, whose sequences are absent in the 29.9-kb genome sequence of SARS-CoV-2, might affect RNA-N protein interactions. We identified two such hexameric RNAs, In-1 (CCGGCG) and G6 (GGGGGG), and investigated their effects on the small filamentous/droplet-like structures (< a few µm) of N protein-genomic RNA formed by liquid-liquid phase separation. The small N protein structures were sequence-specifically enhanced by In-1, whereas G6 caused them to coalesce into large droplets. Moreover, we found that a guanosine 12-mer (G12, GGGGGGGGGGGG) expelled preexisting genomic RNA from the small N protein structures. The presence of G12 with the genomic RNA suppressed the formation of the small N protein structures, and alternatively apparently altered phase separation to induce the formation of large droplets with unclear phase boundaries. We showed that the N-terminal RNA-binding domain is required for the stability of the small N protein structures. Our results suggest that G12 may be a strong inhibitor of the RNA-N protein interaction.

The effect of Daikenchuto on postoperative intestinal motility in patients with right-side colon cancer.

PURPOSE: Daikenchuto (DKT) has a stimulant effect on intestinal motility and reportedly has a positive effect on postoperative intestinal motility in patients with sigmoid colon cancer. In this study, we investigated the effects of DKT in patients with right-side colon cancer. METHODS: This retrospective study included 88 patients with right-side colon cancer. We orally administered 7.5 g of DKT in the DKT group and did not administer any DKT to patients in the no-DKT group. All patients ingested radiopaque markers 2 h before surgery, which were used to assess intestinal motility. The postoperative intestinal motility was radiologically assessed by counting the numbers of residual markers in the large and small intestines. RESULTS: The DKT and no-DKT groups showed no marked differences in the total number of residual markers or number of residual markers in the small intestine. However, in the elderly subgroup, the total number of residual markers in the DKT group was significantly less than in the no-DKT group. CONCLUSION: Although DKT had some small effect on the postoperative intestinal motility for most patients, it may have positive effects in elderly patients.

Discovery of radioactive silver ((110m)Ag) in spiders and other fauna in the terrestrial environment after the meltdown of Fukushima Dai-ichi nuclear power plant.

Six months after the explosion of TEPCO's Fukushima Dai-ichi nuclear power plant, radioactive silver ((110m)Ag), was detected in concentrations of 3754 Bq/kg in Nephila clavata (the orb-web spider; Joro-gumo in Japanese) collected at Nimaibashi, Iitate village in Fukushima Prefecture, whereas (110m)Ag in the soil was 43.1 Bq/kg. A survey of 35 faunal species in the terrestrial environment during the 3.5 years after the accident showed that most of Anthropoda had two orders higher (110m)Ag in their tissues than soils, although silver is not an essential element for their life. However, tracing of the activity of (110m)Ag detected in spider Atypus karschi collected regularly at a fixed location showed that it declined much faster than the physical half-life. These results suggest that (110m)Ag was at once biologically concentrated by faunal species, especially Arthropoda, through food chain. The factors affecting the subsequent rapid decline of (110m)Ag concentration in faunal species are discussed.