Member Of Metallothionein Family Research Articles

Integrative meta-analysis of publically available microarray datasets of several epithelial cell lines identifies biological processes affected by silver nanoparticles exposure

The present study aimed to identify differentially expressed genes (DEGs) under silver nanoparticle (AgNPs) treatment. We used a meta-analysis approach to integrate four publicly available microarray datasets, containing control and epithelium samples treated by either AgNPs- or Ag ions. The Fisher's method combined p-values of studies. Post hoc analyses including protein-protein interaction (PPI) and the overrepresentation test were conducted. Analytical results identified 1652 DEGs associated with AgNPs exposure. The most significant up-regulated genes, including MT1H, MT1X, and MT2A were metallothionein family members. The most significant down-regulated gene, TM4SF5, is a novel biomarker for AgNPs exposure. The PPI network analysis revealed that a member of the heat shock protein family, HSP90AA1, is the top up-regulated “hub” gene. Up-regulation of heat shock proteins and metallothionein genes is part of a cellular response to oxidative stress induced by AgNPs treatment. Interestingly, AgNPs may interact negatively with blood coagulation and amino acid metabolism systems.

Characterization analysis and heavy metal-binding properties of CsMTL3 in Escherichiacoli.

Members of the metallothionein (MT) superfamily are involved in coordinating transition metal ions. In plants, MT family members are characterized by their arrangement of Cys residues. In this study, one member of the MT superfamily, CsMTL3, was characterized from a complementary DNA (cDNA) library from young cucumber fruit; CsMTL3 is predicted to encode a 64 amino acid protein with a predicted molecular mass of 6.751 kDa. Phylogenetic analysis identified it as a type 3 family member as the arrangement of N‐terminal Cys residues was different from that of MT‐like 2. Heterologous expression of CsMTL3 in Escherichia coli improved their heavy metal tolerance, particularly to Cd2+ and Cu2+, and led to increased uptake of Cd2+ and Cu2+; increased uptake was also observed for cells expressing Arabidopsis thaliana metallothionein 3 (AtMT3) and phytochelatin‐like (PCL), with greatest uptake in PCL‐expressing cells. These findings demonstrate that CsMTL3 can improve metal tolerance, especially for Cd2+ ions, when heterologously expressed in E. coli, and suggest that the composition and arrangement of N‐terminal Cys residues are associated with binding capacity and preference for different metal ions.

Genome-Wide Characterization and Analysis of Metallothionein Family Genes That Function in Metal Stress Tolerance in Brassica napus L.

Brassica plants exhibit both high biomass productivity and high rates of heavy metal absorption. Metallothionein (MT) proteins are low molecular weight, cysteine-rich, metal-binding proteins that play crucial roles in protecting plants from heavy metal toxicity. However, to date, MT proteins have not been systematically characterized in Brassica. In this study, we identified 60 MTs from Arabidopsis thaliana and five Brassica species. All the MT family genes from Brassica are closely related to Arabidopsis MTs, encoding putative proteins that share similar functions within the same clades. Genome mapping analysis revealed high levels of synteny throughout the genome due to whole genome duplication and segmental duplication events. We analyzed the expression levels of 16 Brassica napus MTs (BnaMTs) by RNA-sequencing and real-time RT-PCR (RT-qPCR) analysis in plants under As3+ stress. These genes exhibited different expression patterns in various tissues. Our results suggest that BnaMT3C plays a key role in the response to As3+ stress in B. napus. This study provides insight into the phylogeny, origin, and evolution of MT family members in Brassica, laying the foundation for further studies of the roles of MT proteins in these important crops.

The effect and mechanism of metallothionein MT1M on hepatocellular carcinoma cell.

Liver cancer is one of the most common digestive system malignant solid tumors. Its incidence and mortality rates keep high, causing serious mental and economic burden. So far, the exact mechanism of liver cancer onset has not been fully elucidated. Metallothionein (MT) widely exists in various types of organisms with highly conserved structure. It contains the short peptide of cysteine and sulfur protein with high affinity to heavy metals, including cadmium, zinc, and copper. MT1M is an important member of MT family that has been verified to participate in regulating hepatocellular carcinoma, thyroid cancer, cervical cancer, and other tumors. However, MT1M expression and mechanism in hepatoma cells have not been fully elucidated. Hepatoma cell line HepG2 was divided into control and MT1M group. MT1M plasmid was constructed and transfected to MT1M group. Real-time PCR was used to test MT1M expression. MTT assay was applied to detect HepG2 proliferation. Flow cytometry was performed to determine HepG2 apoptosis. Caspase-3 activity was measured. Western blot was used to detect Bcl-2 and Bax protein levels. MT1M expression significantly increased after MT1M plasmid transfection compared with control (p < 0.05). MT1M group showed inhibited HepG2 proliferation, declined HepG2 apoptosis, enhanced Caspase-3 activity, reduced Bcl-2 protein level, and upregulated Bax protein compared with control (p < 0.05). MT1M can suppress HepG2 proliferation and induce HepG2 apoptosis through downregulating Bcl-2, upregulating Bax, and enhancing Caspase-3 activity.

Metal-metal interaction mediates the iron induction of Drosophila MtnB

Metallothionein (MT) protein families are a class of small and universal proteins rich in cysteine residues. They are synthesized in response to heavy metal stresses to sequester the toxic ions by metal-thiolate bridges. Five MT family members, namely MtnA, MtnB, MtnC, MtnD and MtnE, have been discovered and identified in Drosophila. These five isoforms of MTs are regulated by metal responsive transcription factor dMTF-1 and play differentiated but overlapping roles in detoxification of metal ions. Previous researches have shown that Drosophila MtnB responds to copper (Cu), cadmium (Cd) and zinc (Zn). Interestingly in this study we found that Drosophila MtnB expression also responds to elevated iron levels in the diet. Further investigations revealed that MtnB plays limited roles in iron detoxification, and the direct binding of MtnB to ferrous iron in vitro is also weak. The induction of MtnB by iron turns out to be mediated by iron interference of other metals, because EDTA at even a partial concentration of that of iron can suppress this induction. Indeed, in the presence of iron, zinc homeostasis is altered, as reflected by expression changes of zinc transporters dZIP1 and dZnT1. Thus, iron-mediated MtnB induction appears resulting from interrupted homeostasis of other metals such as zinc, which in turns induced MtnB expression. Metal-metal interaction may more widely exist than we expected.

Osteosarcoma is characterised by reduced expression of markers of osteoclastogenesis and antigen presentation compared with normal bone

Background:Osteosarcoma (OS) is the most common primary bone tumour in children and adolescents. Patients who respond poorly to chemotherapy have a higher risk of metastatic disease and 5-year survival rates of only 10–20%. Therefore, identifying molecular targets that are specific for OS, or more specifically, metastatic OS, will be critical to the development of new treatment strategies to improve patient outcomes.Methods:We performed a transcriptomic analysis of chemo-naive OS biopsies and non-malignant bone biopsies to identify differentially expressed genes specific to OS, which could provide insight into OS biology and chemoresistance.Results:Statistical analysis of the OS transcriptomes found differential expression of several metallothionein family members, as well as deregulation of genes involved in antigen presentation. Tumours also exhibited significantly increased expression of ID1 and profound down-regulation of S100A8, highlighting their potential as therapeutic targets for OS. Finally, we found a significant correlation between OS and impaired osteoclastogenesis and antigen-presenting activity. The reduced osteoclastogenesis and antigen-presenting activity were more profound in the chemoresistant OS samples.Conclusion:Our results indicate that OS displays gene signatures consistent with decreased antigen-presenting activity, enhanced chemoresistance, and impaired osteoclastogenesis. Moreover, these alterations are more pronounced in chemoresistant OS tumour samples.

Functional characterization of cadmium-responsive garlic gene AsMT2b: A new member of metallothionein family

A new gene of metallothionein (MT) family was cloned from garlic (Allium sativum) seedlings using RACE method and designated AsMT2b. The full length of AsMT2b cDNA was 520 bp encoding 80 amino acids. The deduced amino acids of AsMT2b showed that AsMT2b contained the characteristic structure of type 2 MT proteins, but the number and arrangement of the cysteine residues in the N-and C-terminal domains was different from other type 2 MT proteins. Semi-quantitative reverse transcriptase-PCR showed that transcript levels of AsMT2b were enhanced only in response to higher concentrations or longer incubation time of Cd. Such an expression pattern of AsMT2b greatly differed from that of other type 2 MT genes. Yeast cells transformed with this gene had improved resistance to Cd. AsMT2b overexpressing Arabidopsis showed stronger Cd tolerance and higher Cd accumulation compared with wild-type plants. These results suggest that AsMT2b should be useful in phytoremediation of Cd-polluted soil in the future.

An Insight of S‐Nitrosylation of Human GIF

AbstractNeural growth inhibitory factor (GIF), a member of metallothionein family (metallothionein‐3, MT3), was well known by its distinct neural growth inhibitory activity, which is not shown by other MT isoforms. However, till now, people still did not know clearly how GIF exerts its biological functions. Since it has been reported that GIF might serve as NO scavenger and was related to the release of zinc, our study was focused on the interaction of GIF and NO. By studying the reactions of human GIF and human MT1g with SNOC–a type of NO donor, it was found that GIF was more reactive than MT‐1g toward SNOC. In order to further figure out if the high reactivity of GIF in this reaction resulted from the acid‐base catalysis, several mutants were constructed: E23K, E41G/E43A, E23K/E41G/E43A. By studying their basic properties and the reactions toward SNOC, it was found that the S‐nitrosylation of GIF was not only related to the acid‐base catalysis, but also to the accessibility of metal‐thiolate clusters.