Characterisation of six additional human metallothionein genes

doi:10.1016/0167-4781(94)90189-9

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression

Volume 1218, Issue 3, 2 August 1994, Pages 357-365

https://doi.org/10.1016/0167-4781(94)90189-9 Get rights and content

Abstract

Human metallothionein (MT) genes are clustered in a locus on chromosome 16, and this report presents the characterisation of the remaining six uninvestigated members of the family. Nucleotide sequencing in whole or part suggested that four of these genes, MT1I, MT1J, MT1K and MT1L do not encode expressed MT proteins, based on the presence of structural faults or atypical amino acid assignments. On the other hand, the structures of MT1H and MT1X are consistent with these genes being functional and encoding unique type 1 isoforms. The promoters of both genes conferred activity to CAT expression constructs when transfected into HeLa cells, and showed differential responses to inducers of MT synthesis. Endogenous MT1H and MT1X genes were expressed at the mRNA level in HeLa cells following cadmium treatment. This work brings the number of functional class 1 and 2 MT genes in the human to eight, and confirms that each encodes structurally unique proteins.

References (51)

M. Karin
Cell
(1985)
Y. Uchida et al.
Neuron
(1991)
A.K. West et al.
Genomics
(1990)
R.I. Richards et al.
Cell
(1984)
C.J. Schmidt et al.
J. Biol. Chem.
(1985)
R. Foster et al.
J. Biol. Chem.
(1988)
N. Jahroudi et al.
J. Biol. Chem.
(1990)
G. Heidecker et al.
Gene
(1980)
B. Seed et al.
Gene
(1988)
Chomczynski et al.
Anal. Biochem.
(1987)

M. Beato

Cell

(1989)

U. Varshney et al.

Gene

(1984)

H. Kobayashi et al.

Mol. Brain Res.

(1993)

J. McNeall et al.

Gene

(1989)

P. Kille et al.

J. Biol. Chem.

(1992)

C.E. Hildebrand et al.

Exp. Cell. Res.

(1979)

C. Sadhu et al.

J. Biol. Chem.

(1988)

J.H.R. Kagi et al.

D.H. Hamer

Annu. Rev. Biochem.

(1986)

M. Karin et al.

Science

(1979)

J. Bauer et al.

J. Neuroimmunology

(1993)

R.L. Freidman et al.

Cell

(1984)

H. Nishimura et al.

Biochemistry

(1991)

H. Nishimura et al.

J. Histochem. Cytochem.

(1989)

P.F. Searle et al.

Mol. Cell. Biol.

(1984)

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Humans encode 11 MT isoforms that share a similar size and protein sequence, distinguished by their tissue expression patterns and responses to environmental stimuli. MT1 and 2 isoforms are ubiquitously expressed in human tissues [1,2] – their expression is largely inducible by exposure to heavy metals, hypoxia and oxidative stress (reviewed in Ref. [3]). In contrast, MT3 is predominantly expressed in the central nervous system [4–7] and is not regulated by metal-responsive promoter elements [8].
Metallothioneins (MTs) are crucial for metal ion homeostasis in mammalian cells. Specialized mass spectrometry methods have been developed to detect MTs in tissue extracts, though facile methods with scalable throughput are lacking. To improve analytical throughput and repeatability, we developed a standardised liquid chromatography tandem mass spectrometry (LC-MS/MS) method for robust determination of metallothionein-3 (MT3) that is amenable to microplate processing. This method uses standard protein digestion conditions with commercially available reagents and commonly practiced reversed-phase chromatography, detecting MT3 at low ng/mL levels in human brain tissue extracts. We found that trypsin digestion largely underestimated MT3 levels, whereas endopeptidase Lys-C yielded vastly higher signals with low replicate variance. The choice of target peptide was critical for accurate MT3 detection – a peptide in the α-domain yielded the most robust signals. We demonstrate the utility of this method by comparing the expression of MT3 in post-mortem brain tissues of a cohort of Alzheimer's disease (AD) individuals and age-matched controls.
MiR-545-3p/MT1M axis regulates cell proliferation, invasion and migration in hepatocellular carcinoma
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Meanwhile, DNA methylation mode is more stable than protein and RNA expression [5]. Metallothioneins (MTs) is a kind of cysteine-rich intracellular protein superfamily with low molecular weight [6]. Previous studies have proved that MTs plays important roles in cell proliferation and apoptosis, antioxidant injury, radiation resistance, chemotherapy, metal homeostasis and carcinogenesis [7–11].
Studies have shown that metallothionein 1 M (MT1M) is a tumor suppressor gene which is frequently down-regulated in human hepatocellular carcinoma (HCC). The methylation of MT1M promoter region is one of the important transcriptional regulation mechanisms that contribute to the loss of its expression. In our study, we found that there are still half of the 55 HCC tumor tissues in our cohort do not share the promoter methylation of MT1M. So, we speculated there maybe another mechanism participating in the downregulation of MT1M in HCC. Then, we provided evidences that miR-545-3p, which served as a tumor promoter, post-transcriptionally regulate MT1M in HCC through binding to its untranslated region (3′UTR). Taking together, we investigated the role of miR-545-3p in the process of HCC through regulating MT1M.
Basal and copper-induced expression of metallothionein isoform 1,2 and 3 genes in epithelial cancer cells: The role of tumor suppressor p53
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Metallothioneins (MTs) are ubiquitous low molecular weight, cysteine-rich proteins with pleiotropic functions with high affinity for metal ions such as zinc and copper. The functional human MTs consist of MT-1 (MT-IA,-IB, -IE, -1F, -IG, -IH,-IM and -IX), MT-2A, MT-3 and MT-4 [1,2]. Numerous studies have demonstrated enhanced expression of MTs in breast, colon, kidney, liver, lung, ovary, prostate and other types of cancer [3].
Metallothioneins (MTs) are a ubiquitous low-molecular weight, cysteine rich proteins with a high affinity for metal ions. The expression and induction of MTs have been associated with protection against DNA damage, oxidative stress, and apoptosis. Our past research had shown that p53 is an important factor in metal regulation of MTs. The present study was undertaken to explore further the interrelationship between p53 and MTs. We investigated whether silencing of p53 could affect expression pattern of basal and copper induced metallothioneins. The silencing of wild-type p53 (wt-p53) in epithelial breast cancer MCF7 cells affected the basal level of MT-2A RNA, whereas the levels of MT-1A and MT-1X RNA remained largely unchanged. The expression of MT-3 was undetectable in MCF7 with either functional or silenced p53. MCF7 cells with silenced wt-p53 failed to upregulate MT-2A in response to copper and showed a reduced sensitivity toward copper induced cell apoptotic death. Similarly in MCF7-E6 and MDA-MB-231 cells, the presence of inactive/mutated p53 halted MT-1A and MT-2A gene expression in response to copper. Constitutive expression of MT-3 RNA was detectable in the presence of mutated p53 (mtp53). Transient transfection of MDA-MB-231 cells with wt-p53 enabled copper induced upregulation of both MT-1A and MT-2A but not basal level of MT-2A, MT-1E, MT-1X and MT-3. Inactivation of p53 in HepG2 cells amplified the basal expression of studied MT isoforms, including MT-3, as well as copper-induced mRNA expression of MTs except MT-1H and MT-3. Presented data demonstrate a direct relation between p53 and MT-1A and MT-2A and they also indicate that wt-p53 might be a negative regulator of MT-3 in epithelial cancer cells.
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A hallmark of the MT-1 and MT-2 genes is their rapid transcriptional induction by metals such as Zn2+ and Cd2+ [44,45]. In humans, the MT-1 and MT-2 proteins are encoded by a family of genes consisting of 8 functional (MT-1A, MT-1B, MT-1E, MT-1F, MT-1G, MT-1H, MT-1X, MT-2A) and 7 nonfunctional MT isoforms (MT-1C, MT-1D, MT-1I, MT-1J, MT-1K, MT-1L, MT-2B) [46,47]. To confirm the up-regulation of MT family genes identified by microarray analysis, we performed semi-quantitative reverse transcript (RT) PCR analysis of several MT genes.
Semiconductor Quantum dots (QDs) have raised great attention because of their superior optical properties and wide utilization in biological and biomedical studies. More recently, there have been intense concerns on cytotoxicity assessment of QDs. Most QDs are made of heavy metal ions (e.g., Cd²⁺), which may result in potential in vitro toxicity that hampers their practical applications. In this article, we aim to summarize recent progress on mechanistic studies of cytotoxicity of II–IV QDs. We have studied the cytotoxicity of a series of aqueous synthesized QDs (aqQDs), i.e. CdTe, CdTe/CdS core-shell structured and CdTe/CdS/ZnS core-shell-shell structured aqQDs. Our results suggested that released cadmium ions are responsible for the observed cytotoxicity of cadmium-based QDs. The fact that CdTe/CdS/ZnS core-shell-shell structured QDs are nearly nontoxic to cells further confirmed the role of released cadmium ions on cytotoxicity, and the effective protection of the ZnS shell. However, intracellular level of Cd²⁺ ions cannot be the only reason since the comparison with CdCl₂-treated cells suggests there are other factors contributed to the cytotoxicity of aqQDs. Our studies on genome-wide gene expression profiling and subcellular localization of aqQDs with synchrotron-based scanning transmission X-ray microscopy (STXM) further suggest that the cytotoxicity of CdTe QDs not only comes from the release of Cd²⁺ ions but also intracellular distribution of QD nanoparticles in cells and the associated nanoscale effects.
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Regular paperCharacterisation of six additional human metallothionein genes

Abstract

Cell

Neuron

Genomics

Cell

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

Gene

Gene

Anal. Biochem.

Cell

Gene

Mol. Brain Res.

Gene

J. Biol. Chem.

Exp. Cell. Res.

J. Biol. Chem.

Annu. Rev. Biochem.

Science

J. Neuroimmunology

Cell

Biochemistry

J. Histochem. Cytochem.

Mol. Cell. Biol.

Regular paper
Characterisation of six additional human metallothionein genes