Proteotoxic stress drives numerous degenerative diseases. Cells initially adapt to misfolded proteins by activating the unfolded protein response (UPR), including endoplasmic-reticulum-associated protein degradation (ERAD). However, persistent stress triggers apoptosis. Enhancing ERAD is a promising therapeutic approach for protein misfolding diseases. The ER-localized Zn2+ transporter ZIP7 is conserved from plants to humans and required for intestinal self-renewal, Notch signaling, cell motility, and survival. However, a unifying mechanism underlying these diverse phenotypes was unknown. In studying Drosophila border cell migration, we discovered that ZIP7-mediated Zn2+ transport enhances the obligatory deubiquitination of proteins by the Rpn11 Zn2+ metalloproteinase in the proteasome lid. In human cells, ZIP7 and Zn2+ are limiting for deubiquitination. In a Drosophila model of neurodegeneration caused by misfolded rhodopsin (Rh1), ZIP7 overexpression degrades misfolded Rh1 and rescues photoreceptor viability and fly vision. Thus, ZIP7-mediated Zn2+ transport is a previously unknown, rate-limiting step for ERAD in vivo with therapeutic potential in protein misfolding diseases.

A novel peptide Ser-Asp-Asp-Val-Leu (SDDVL) of excellent zinc-chelating capacity (13.77 mg/g) was identified in millet bran protein hydrolysates. In silico prediction demonstrated that SDDVL had no potential toxicity. The results of structural characterization demonstrated that both amino group and carboxyl group of SDDVL were the primary zinc-chelating sites. Moreover, SDDVL-zinc chelate showed higher stability (p < 0.05) than ZnSO4 and zinc gluconate under different processing conditions including most pasteurization conditions, heating at 100°C for 10-50 min, various pH values (8.0-10.0), treatment of glucose (4-8 g/100 g) or NaCl (1-4 g/100 g), and simulated gastrointestinal digestion. In addition, SDDVL-zinc chelate showed higher zinc transport capacity than ZnSO4 and zinc gluconate in Caco-2 cells (p < 0.05). These results suggested that millet bran peptide had a positive effect on the gastrointestinal stability and bioavailability of Zn, and SDDVL-zinc chelate could be used as ingredient of zinc supplements. PRACTICAL APPLICATION: The current study provided a practical method to identify peptides of excellent zinc-chelating capacity from millet bran protein hydrolysates. This study demonstrated that in silico prediction assisted with suitable database was a fast, practical, and economic way to evaluate the security and to analysis the physicochemical properties of novel peptides. Moreover, it provided an efficient method to assess the stability of peptide-zinc chelate under different food processing conditions, which was the theoretical basis for utilization of peptide as ingredient of zinc fortifications.

Zinc is an essential micronutrient for plant growth and development, and functions as a cofactor for hundreds of transcription factors and enzymes in numerous biological processes. Zinc deficiency is common abiotic stress resulting in yield loss and quality deterioration of crops, but zinc excess causes toxicity for biological systems. In plants, zinc homeostasis is tightly modulated by zinc transporters and binding compounds that uptake/release, transport, localize, and store zinc, as well as their upstream regulators. Lazarus 1 (LAZ1), a member of DUF300 protein family, functions as transmembrane organic solute transporter in vertebrates. However, the function of LAZ1 in plants is still obscure. In the present study, the ZmLAZ1-4 protein was confirmed to bind to zinc ions by bioinformatic prediction and thermal shift assay. Heterologous expression of ZmLAZ1-4 in the zinc-sensitive yeast mutant, Arabidopsis, and maize significantly facilitated the accumulation of Zn2+ in transgenic lines, respectively. The result of subcellular localization exhibited that ZmLAZ1-4 was localized on the plasma and vacuolar membrane, as well as chloroplast. Moreover, the ZmLAZ1-4 gene was negatively co-expressed with ZmBES1/BZR1-11 gene through co-expression and real-time quantitative PCR analysis. The results of yeast one-hybrid and dual-luciferase assay suggested that ZmBES1/BZR1-11 could bind to ZmLAZ1-4 promoter to inhibit its transcription. All results indicated that ZmLAZ1-4 was a novel zinc transporter on plasma and vacuolar membrane, and transported zinc under negative regulation of the ZmBES1/BZR1-11 transcription factor. The study provides insights into further underlying the mechanism of ZmLAZ1-4 regulating zinc homeostasis.

BACKGROUND: Overwhelming evidences suggest oxidative stress is a major cause of sperm dysfunction and male infertility. Zinc is an important non-enzymatic antioxidant with a wide range of biological functions and plays a significant role in preserving male fertility. Notably, zinc trafficking through the cellular and intracellular membrane is mediated by specific families of zinc transporters, i.e., SLC39s/ZIPs and SLC30s/ZnTs. However, their expression and function were rarely evaluated in the male germ cells. The aim of this study is to determine and characterize the crucial zinc transporter responsible for the maintenance of spermatogenesis.
METHODS: The expression patterns of all 14 ZIP members were characterized in the mouse testis. qRT-PCR, immunoblot and immunohistochemistry analyses evaluated the ZIP12 gene and protein expression levels. The role of ZIP12 expression was evaluated in suppressing the sperm quality induced by exposure to an oxidative stress in a spermatogonia C18-4 cell line. Zip12 RNAi transfection was performed to determine if its downregulation altered cell viability and apoptosis in this cell line. An obese mouse model fed a high-fat-diet was employed to determine if there is a correlation between changes in the ZIP12 expression level and sperm quality.
RESULTS: The ZIP12 mRNA and protein expression levels were higher than those of other ZIP family members in both the mouse testis and other tissues. Importantly, the ZIP12 expression levels were very significantly higher in both mice and human spermatogonia and spermatozoa. Moreover, the testicular ZIP12 expression levels significantly decreased in obese mice, which was associated with reduced sperm zinc content, excessive sperm ROS generation, poor sperm quality and male subfertility. Similarly, exposure to an oxidative stress induced significant declines in the ZIP12 expression level in C18-4 cells. Knockdown of ZIP12 expression mediated by transfection of a ZIP12 siRNA reduced both the zinc content and viability whereas apoptotic activity increased in the C18-4 cell line.
CONCLUSIONS: The testicular zinc transporter ZIP12 expression levels especially in spermatogonia and spermatozoa are higher than in other tissues. ZIP12 may play a key role in maintaining intracellular zinc content at levels that reduce the inhibitory effects of rises in oxidative stress on spermatogonia and spermatozoa viability during spermatogenesis which help counteract declines in male fertility.

Determination of the effects of BirA on transcription and virulence in enterohemorrhagic Escherichia coli (EHEC) O157:H7.
The effect of BirA on EHEC O157:H7 gene expression and phenotypes was assessed by RNA-seq combined with adherence, quantitative biofilm and survival assays.
Many genes associated with virulence, amino acid synthesis and transport, and zinc transport were upregulated, whereas genes encoding stress proteins were downregulated in ΔbirA::km+Ac_birA. Accordingly, ΔbirA::km+Ac_birA adhesion to Caco-2 cells, biofilm formation and survival during oxidative stress were higher, whereas its survival during heat shock was lower than that of the wild-type.
This study demonstrates the wide-ranging regulatory functions of BirA, especially its role in controlling virulence and stress responses in EHEC O157:H7. [Formula: see text].

The present study explored the mechanisms of dietary Zn influencing Zn and lipid deposition in the fore- and mid- intestine in yellow catfish Pelteobagrus fulvidraco, and investigated whether the mechanism was intestinal-region dependent. For this purpose, yellow catfish were fed three diets containing Zn levels of 8·83, 19·20 and 146·65 mg Zn/kg, respectively. Growth performance, intestinal TAG and Zn contents as well as activities and mRNA expression of enzymes and genes involved in Zn transport and lipid metabolism in the fore- and mid-intestine were analysed. Dietary Zn increased Zn accumulation as well as activities of Cu-, Zn-superoxide dismutase and ATPase in the fore- and mid-intestine. In the fore-intestine, dietary Zn up-regulated mRNA levels of ZnT1, ZnT5, ZnT7, metallothionein (MT) and metal response element-binding transcription factor-1 (MTF-1), but down-regulated mRNA levels of ZIP4 and ZIP5. In the mid-intestine, dietary Zn up-regulated mRNA levels of ZnT1, ZnT5, ZnT7, MT and MTF-1, but down-regulated mRNA levels of ZIP4 and ZIP5. Dietary Zn reduced TAG content, down-regulated activities of 6-phosphogluconate dehydrogenase (6PGD), glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME) and fatty acid synthase (FAS) activities, and reduced mRNA levels of 6PGD, G6PD, FAS, PPARγ and sterol-regulator element-binding protein (SREBP-1), but up-regulated mRNA levels of carnitine palmitoyltransferase IA, hormone-sensitive lipase (HSLa), adipose TAG lipase (ATGL) and PPARα in the fore-intestine. In the mid-intestine, dietary Zn reduced TAG content, activities of G6PD, ME, isocitrate dehydrogenase and FAS, down-regulated mRNA levels of 6PGD, G6PD, FAS, acetyl-CoA carboxylase a, PPARγ and SREBP-1, but up-regulated mRNA expression of HSLa, ATGL and PPARγ. The reduction in TAG content following Zn addition was attributable to reduced lipogenesis and increased lipolysis, and similar regulatory mechanisms were observed between the fore- and mid-intestine.