Genome-wide analysis of metallothionein gene family in maize to reveal its role in development and stress resistance to heavy metal

BACKGROUND: Maize (Zea mays L.) is a widely cultivated cereal and has been used as an optimum heavy metal phytoremediation crop. Metallothionein (MT) proteins are small, cysteine-rich, proteins that play important roles in plant growth and development, and the regulation of stress response to heavy metals. However, the MT genes for maize have not been fully analyzed so far. METHODS: The putative ZmMT genes were identified by HMMER. The heat map of ZmMT genes spatial expression analysis was generated by using R with the log2 (FPKM + 1). The expression profiles of ZmMT genes under three kinds of heavy metal stresses were quantified by using qRT-PCR. The metallothionein proteins was aligned using MAFFT and phylogenetic analysis were constructed by ClustalX 2.1. The protein theoretical molecular weight and pI, subcellular localization, TFs binding sites, were predicted using ProtParam, PSORT, PlantTFDB, respectively. RESULTS: A total of 9 ZmMT genes were identified in the whole genome of maize. The results showed that eight of the nine ZmMT proteins contained one highly conserved metallothio_2 domain, while ZmMT4 contained a Metallothio_PEC domain. All the ZmMT proteins could be classified into three major groups and located on five chromosomes. The ZmMT promoters contain a large number of hormone regulatory elements and hormone-related transcription factor binding sites. The ZmMT genes exhibited spatiotemporal specific expression patterns in 23 tissues of maize development stages and showed the different expression patterns in response to Cu, Cd, and Pb heavy metal stresses. CONCLUSIONS: We identified the 9 ZmMT genes, and explored their conserved motif, tissue expression patterns, evolutionary relationship. The expression profiles of ZmMT genes under three kinds of heavy metal stresses (Cu, Cd, Pb) were analyzed. In summary, the expression of ZmMTs have poteintial to be regulated by hormones. The specific expression of ZmMTs in different tissues of maize and the response to different heavy metal stresses are revealed that the role of MT in plant growth and development, and stress resistance to heavy metals.

Metallothionein-2a (rs1610216&rs28366003) gene polymorphisms and the risk of stomach adenocarcinoma / Polimorfismos do gene metalotioneína-2A (rs1610216& rs28366003) e o risco de adenocarcinoma de estômago

ABSTRACT BACKGROUND: Gastric cancer is the fourth most common cause of worldwide cancer. Also in contrast to the huge advances in curing, the chance of living is very low even in surgery cases. Having a genetic predisposition plays an important role in cancer development. The association between Metallothionein-2A gene polymorphisms and the risk of adenocarcinoma has been widely studied, yet there is only one study on stomach diseases. OBJECTIVE: In this study, we aimed to investigate the association between 2 (MT-2A) polymorphisms and adenocarcinoma. METHODS: This cross-sectional case control study was performed between Mach 2014 and January 2015 at the Tuba Hospital of Sari, Iran. Peripheral blood samples were collected in EDTA tube. DNA extraction was performed using the spin column procedure. The MT-2A polymorphisms MT-2A (rs1610216), (rs28366003) were determined by polymerase chain reaction-restriction fragment length polymorphism analysis in 95 a topic adenocarcinoma patients and 90 healthy individuals from Iranian population. RESULTS: The MT-2A rs1610216 polymorphism increased the risk of adeno carcinoma in our Iranian population [OR: 3.8533; 95%CI, 1.3155-11.2869; P=0.0139] and rs28366003 [OR: 4.0978; 95%CI, 1.2521-13.4108; P=0.0197]. CONCLUSION: The MT-2A gene polymorphism was associated with the risk of adenocarcinoma in the Iranian population.

RESUMO CONTEXTO: O câncer gástrico é a quarta causa mais comum de câncer em todo o mundo. Também em contraste com os enormes avanços na cura, a chance de viver é muito baixa, mesmo em casos de cirurgia. Ter uma predisposição genética desempenha um papel importante no desenvolvimento do câncer. A associação entre polimorfismos do gene metalotioneína-2A e o risco de adenocarcinoma tem sido amplamente estudada, mas há apenas um estudo sobre doenças estomacais. OBJETIVO: Neste estudo, objetivou-se investigar a associação entre 2 (MT-2A) polimorfismos e adenocarcinoma. MÉTODOS: Um estudo de controle de caso transversal foi realizado entre março de 2014 e janeiro de 2015 no hospital Tuba, Sari, Irã. Amostras de sangue periférico foram coletadas em tubo EDTA. A extração do ADN foi executada usando o procedimento da coluna da rotação. Os polimorfismos MT-2a MT-2A (rs1610216), (rs28366003) foram determinados pela análise do polimorfismo do comprimento do fragmento da reação-limitação de cadeia da polimerase em 95 pacientes com adenocarcinoma tópico e em 90 indivíduos saudáveis da população iraniana. RESULTADOS: O polimorfismo MT-2A rs1610216 aumentou o risco de adenocarcinoma de em nossa população iraniana. [OR: 3,8533; 95%CI, 1,3155-11,2869; P=0,0139] e rs28366003 [OR: 4,0978; 95%CI, 1,2521-13,4108; P=0,0197]. CONCLUSÃO: O polimorfismo do gene MT-2A foi associado ao risco de adenocarcinoma na população iraniana.

Heterologous expression of a rice metallothionein isoform (OsMTI-1b) in Saccharomyces cerevisiae enhances cadmium, hydrogen peroxide and ethanol tolerance

Abstract Metallothioneins are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. The main purpose of this study was to investigate the effect of heterologous expression of a rice metallothionein isoform (OsMTI-1b) on the tolerance of Saccharomyces cerevisiae to Cd2+, H2O2 and ethanol stress. The gene encoding OsMTI-1b was cloned into p426GPD as a yeast expression vector. The new construct was transformed to competent cells of S. cerevisiae. After verification of heterologous expression of OsMTI-1b, the new strain and control were grown under stress conditions. In comparison to control strain, the transformed S. cerevisiae cells expressing OsMTI-1b showed more tolerance to Cd2+ and accumulated more Cd2+ ions when they were grown in the medium containing CdCl2. In addition, the heterologous expression of GST-OsMTI-1b conferred H2O2 and ethanol tolerance to S. cerevisiae cells. The results indicate that heterologous expression of plant MT isoforms can enhance the tolerance of S. cerevisiae to multiple stresses.

Association of anti-obesity activity of N-acetylcysteine with metallothionein-II down-regulation

People with upper body or visceral obesity have a much higher risk of morbidity and mortality from obesity-related metabolic disorders than those with lower body obesity. In an attempt to develop therapeutic strategies targeting visceral obesity, depot- specific differences in the expression of genes in omental and subcutaneous adipose tissues were investigated by DNA array technology, and their roles in adipocyte differentiation were further examined. We found that levels of metallothionein-II (MT-II) mRNA and protein expression were higher in omental than in subcutaneous adipose tissues. The study demonstrates that MT-II may play an important role in adipocyte differentiation of 3T3L1 preadipocytes, and that N-acetylcysteine (NAC) inhibits the adipocyte differentiation of 3T3L1 cells by repressing MT-II in a time- and dose-dependent manner. Furthermore, the intraperitoneal administration of NAC to rats and mice resulted in a reduction of body weights, and a marked reduction in visceral fat tissues. These results suggest that MT-II plays important roles in adipogenesis, and that NAC may be useful as an anti-obesity drug or supplement.

Gene expression profiling in wild-type and metallothionein mutant fibroblast cell lines

The role of metallothioneins (MT) in copper homeostasis is of great interest, as it appears to be partially responsible for the regulation of intracellular copper levels during adaptation to extracellular excess of the metal. To further investigate a possible role of MTs in copper metabolism, a genomics approach was utilized to evaluate the role of MT on gene expression. Microarray analysis was used to examine the effects of copper overload in fibroblast cells from normal and MT I and II double knock-out mice (MT-/-). As a first step, we compared genes that were significantly upregulated in wild-type and MT-/- cells exposed to copper. Even though wild-type and mutant cells are undistinguishable in terms of their morphological features and rates of growth, our results show that MT-/- cells do not respond with induction of typical markers of cellular stress under copper excess conditions, as observed in the wild-type cell line, suggesting that the transcription initiation rate or the mRNA stability of stress genes is affected when there is an alteration in the copper store capacity. The functional classification of other up-regulated genes in both cell lines indicates that a large proportion (>80 percent) belong to two major categories: 1) metabolism; and 2) cellular physiological processes, suggesting that at the transcriptional level copper overload induces the expression of genes associated with diverse molecular functions. These results open the possibility to understand how copper homeostasis is being coordinated with other metabolic pathways.

Ductal breast tumours: mean nuclear area and metallothionein expression in correlation with estrogen receptor status

Estrogen is an important growth Ilictor for breast tumour playing an important role in regulating the proliferation and differentiation of normal and malignant mammary epithelial cells. Nuclear morphometry and Metallothioneins [MTs] are indicators of proliferation that have been used as predictors of prognosis in many tumours. The present study aimed to study mean nuclear area and MT; ER expression in fibroadenoma, ductal carcinoma in situ and infiltrating ductal carcinoma of the breast. Also MNA and MT expression will be correlated with histologic grade and ER status in breast carcinoma. Breast tissues from 12 patients with fibroadenoma [FA], 6 patients with ductal carcinoma in situ [DCIS] and 20 patients with infiltrating durtal carcinoma [IDC] were used in this study. Mean nuclear area [MNA] and metallothionein [MT] expression; as proliferation markers; were investigated and correlated with estrogen receptor [ER] status. All cases of fibroadenoma, 4 out of 6 cases [66.7%] of DCIS and 12 out of 20 cases [60%] of IDC were positive for ER. MNA of cancer cells was significantly larger than that of normal and benign breast tissue. A significant direct correlation was found between MNA and histologic grades. MNA of ER negative carcinomas was significantly larger than that of ER positive tumours. In normal and benign breast tissue, myoepithelial cells consistently expressed the MT protein. Two out of 6 DCIS cases [33.3%] and 13 out of 20 cases of IDC cases [65%] were positively stained for MT. MT positivity was directly correlated with histologic grade of JDC. There was a highly significant inverse correlation between MT and ER over-expression. From this study, it is concluded that in invasive ductal carcinoma of the breast, the large MNA and MT over-expression are correlated with histologic grades and ER negativity. Therefore, MNA and MT overe-expression may be possible important indicators for more aggressive and less differentiated breast carcinoma