Zinc performs diverse physiological functions, and virtually all living organisms require zinc as an essential trace element. To identify the detailed function of zinc in fungal pathogenicity, we carried out cDNA microarray analysis using the model system of Aspergillus fumigatus, a fungal pathogen. From microarray analysis, we found that the genes involved in gliotoxin biosynthesis were upregulated when zinc was depleted, and the microarray data were confirmed by northern blot analysis. In particular, zinc deficiency upregulated the expression of GliZ, which encodes a Zn2-Cys6 binuclear transcription factor that regulates the expression of the genes required for gliotoxin biosynthesis. The production of gliotoxin was decreased in a manner inversely proportional to the zinc concentration, and the same result was investigated in the absence of ZafA, which is a zinc-dependent transcription activator. Interestingly, we found two conserved ZafA-binding motifs, 5′-CAAGGT-3′, in the upstream region of GliZ on the genome and discovered that deletion of the ZafA-binding motifs resulted in loss of ZafA-binding activity; gliotoxin production was decreased dramatically, as demonstrated with a GliZ deletion mutant. Furthermore, mutation of the ZafA-binding motifs resulted in an increase in the conidial killing activity of human macrophage and neutrophil cells, and virulence was decreased in a murine model. Finally, transcriptomic analysis revealed that the expression of ZafA and GliZ was upregulated during phagocytosis by macrophages. Taken together, these results suggest that zinc plays an important role in the pathogenicity of A. fumigatus by regulating gliotoxin production during the phagocytosis pathway to overcome the host defense system.

Pleurotus eryngii produces various functional molecules that mediate physiological functions in humans. Recently, we observed that P. eryngii produces molecules that have antidepressant functions. An ethanol extract of the fruiting body of P. eryngii was obtained, and the extract was purified by XAD-16 resin using an open column system. The ethanol eluate was separated by HPLC, and the fraction with an antidepressant function was identified. Using LC-MS, the molecular structure of the HPLC fraction with antidepressant function was identified as that of tryptamine, a functional molecule that is a tryptophan derivative. The antidepressant effect was identified from the ethanol extract, XAD-16 column eluate, and HPLC fraction by a serotonin receptor binding assay and a cell-based binding assay. Furthermore, a forced swimming test (FST) showed that the mice treated with purified fractions of P. eryngii exhibited decreased immobility time compared with nontreated mice. From these results, we suggest that the extract of P. eryngii has an antidepressant function and that it may be employed as an antidepressant health supplement.

Copper is an essential metal ion that performs many physiological functions in living organisms. Deletion of Afmac1, which is a copper-responsive transcriptional activator in A. fumigatus, results in a growth defect on aspergillus minimal medium (AMM). Interestingly, we found that zinc starvation suppressed the growth defect of the Δafmac1 strain on AMM. In addition, the growth defect of the Δafmac1 strain was recovered by copper supplementation or introduction of the CtrC gene into the Δafmac1 strain. However, chelation of copper by addition of BCS to AMM failed to recover the growth defect of the Δafmac1 strain. Through Northern blot analysis, we found that zinc starvation upregulated CtrC and CtrA2, which encode membrane copper transporters. Interestingly, we found that the conserved ZafA binding motif 5′-CAA(G)GGT-3′ was present in the upstream region of CtrC and CtrA2 and that mutation of the binding motif led to failure of ZafA binding to the upstream region of CtrC and upregulation of CtrC expression under zinc starvation. Furthermore, the binding activity of ZafA to the upstream region of CtrC was inversely proportional to the zinc concentration, and copper inhibited the binding of ZafA to the upstream region of CtrC under a low zinc concentration. Taken together, these results suggest that ZafA upregulates copper metabolism by binding to the ZafA binding motif in the CtrC promoter region under low zinc concentration, thus regulating copper homeostasis. Furthermore, we found that copper and zinc interact in cells to maintain metal homeostasis.

To understand the relationship between carbon or nitrogen utilization and iron homeostasis, we performed an iron uptake assay with several deletion mutants with partial defects in carbon or nitrogen metabolism. Among them, some deletion mutants defective in carbon metabolism partially and the MEP2 deletion mutant showed lower iron uptake activity than the wild type. Mep2 is known as a high-affinity ammonia transporter in Saccharomyces cerevisiae. Interestingly, we found that nitrogen starvation resulted in lower iron uptake activity than that of wild-type cells without downregulation of the genes involved in the high-affinity iron uptake system FET3/FTR1. However, the gene expression of FRE1 and CTR1 was downregulated by nitrogen starvation. The protein level of Ctr1 was also decreased by nitrogen starvation, and addition of copper to the nitrogen starvation medium partially restored iron uptake activity. However, the expression of MAC1, which is a copper-responsive transcriptional activator, was not downregulated by nitrogen starvation at the transcriptional level but was highly downregulated at the translational level. Mac1 was downregulated dramatically under nitrogen starvation, and treatment with MG132, which is an inhibitor of proteasome-dependent protein degradation, partially attenuated the downregulation of Mac1. Taken together, these results suggest that nitrogen starvation downregulates the high-affinity iron uptake system by degrading Mac1 in a proteasome-dependent manner and eventually downregulates copper metabolism.

Background: Safe, microbiome-based interventions for autoimmune hyperthyroidism are lacking. We isolated the lactic acid bacterium NES-428 from kimchi and previously demonstrated that it shares 99% 16S-rRNA identity with Lactobacillus brevis reference strains, confirming NES-428 as a novel strain. Here we evaluated its immunomodulatory and anti-thyroid activity in cellular and murine models. Methods: Jurkat T cells (5 × 10⁶) were incubated with heat-killed NES-428 for 24 h and subsequently stimulated with phorbol 12-myristate 13-acetate/ionomycin (50 ng mL⁻¹/1 µg mL⁻¹) for 6 h; cytokine transcripts were quantified by qRT-PCR. Hyperthyroidism was induced in female BALB/c mice by three intramuscular injections of adenovirus-encoding human TSH receptor (Ad-TSHR). Mice received a daily oral dose of NES-428 (1 × 10⁹ CFU) for 15 weeks. Serum thyroxine (T₄) levels, splenocyte cytokine secretion, and thyroid histopathology were assessed. Statistical analyses employed one-way ANOVA with Tukey post hoc or log-rank tests (α = 0.05). Results: NES-428 pre-conditioning of Jurkat cells significantly down-regulated IL-2 and IFN-γ transcripts (−48% and –43%, respectively; p < 0.01) compared with stimulated controls while modestly increasing IL-4 (+26%). In Ad-TSHR mice, daily NES-428 reduced mean serum T₄ from 11.2 ± 2.1 to 5.8 ± 1.4 µg dL⁻¹ (p < 0.001), restored body weight gain, and normalized follicular architecture relative to untreated hyperthyroid animals. NES-428 supplementation also lowered splenocyte IFN-γ secretion by 58% and raised IL-4 by 41% (p < 0.05). Conclusions: The kimchi-derived strain NES-428 attenuates Th1-skewed cytokine responses and ameliorates experimental hyperthyroidism in vivo. These findings support further investigation of NES-428 as a probiotic candidate for immune modulation in Graves’ disease.

Graves’ disease is an autoimmune hyperthyroid disorder in which thyroid peroxidase (TPO) plays a central role in excessive thyroid hormone production. However, current TPO-targeting drugs, such as propylthiouracil, have limited selectivity and can cause serious adverse effects. In this study, we established an integrated discovery pipeline to identify and optimize novel small-molecule TPO inhibitors. The pipeline began with high-throughput screening of approximately 7000 compounds from the KRICT chemical library for peroxidase inhibition, followed by cytotoxicity filtering and iterative medicinal chemistry to generate NE-2 derivatives. Lead compounds (NE-2-6, NE-2-7, and NE-2-8) were evaluated using enzymatic assays, selectivity profiling against myeloperoxidase (MPO) and lactoperoxidase (LPO), molecular docking, plasma pharmacokinetic profiling, and in vivo antithyroid pharmacodynamic testing in an Ad-TSHR289-induced thyroid hyperfunction model. NE-2-6 exhibited potent TPO inhibitory activity and relative selectivity within the tested peroxidase panel. UV–visible spectral scanning and H₂O₂-dependent inhibition assays suggested that NE-2-6 perturbs the heme-associated catalytic environment of TPO; however, these data do not establish a definitive binding mode or kinetic inhibition mechanism. In the Ad-TSHR289-induced thyroid hyperfunction model, NE-2-6 reduced serum T4 levels, supporting antithyroid pharmacodynamic activity. Because autoimmune endpoints and dose-matched PK–PD relationships were not fully assessed, the findings should be interpreted as preliminary preclinical evidence supporting further evaluation of NE-2-6 as a TPO-targeting antithyroid candidate.