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31.
The developmental alterations in metallothionein (MT) proteins and zinc (Zn) were investigated in brains of two transgenic
strains of mice. MT protein was measured by a cadmium binding assay and Zn by atomic absorption spectrophotometry. MT proteins
were expressed at birth (day 1) both in MT-I overexpressing transgenic mouse (MT-I*) and MT-null (expressing only brain specific
isoform, MT-III) transgenic mouse. MT proteins level (mainly MT-I) in MT-I* was 16.1 Μ-g/g at birth, and thereafter increased
with age to a maximal adult level of 55.3 Μg/g (day 60). Zn level in MT-I* also increased from 8.43 Μg/g (day 1) to 20.7 Μg/g
(day 60) with age. MT protein (MT-III) in MT-null mouse was 9.71 Μg/g at birth and remained relatively unchanged during development.
Zn level in MT-null mouse at birth was 9.46 Μg/g and also remained unchanged during development. The similar alterations in
MT isoforms and Zn in brain during development suggest that MT isoforms may act as a Zn binding protein. 相似文献
32.
Ultrastructural changes in the kidneys of rats after acute cadmium exposure and the effects of exogenous metallothionein (MT)
were studied by transmission electron microscopy. Thirty-six adult Wistar rats were divided into three groups. Cadmium chloride
(CdCl2) (3.5 mg/kg/day) was injected subcutaneously in the first group. In the second group, 30 μmol/kg MT was administered in addition
to CdCl2. Control rats received 0.5 ml subcutaneous saline solution. Four rats from each group were killed on days 1, 3, 5, and 7
after administration of the compounds. Kidney tissues were taken and fixed in 2.5% glutaraldehyde solution for electron microscopic
observations. Tissue damage in kidney increased as time passed since the administration of CdCl2 in the first group. Degeneration in the proximal and distal tubules was observed. Increased apoptosis was seen in the proximal
tubules epithelium, especially on day 7. Peritubular capillaries became dilated, there was degeneration of the endothelial
cells, and the amount of intertubular collagen fibers was increased. On day 1, irregular microvilli in the proximal tubules,
deepening of the basal striations, and myelin figures; on day 3, multiple vesicular mitochondria and regions of edema around
tubules; on days 5 and 7, increased apoptotic cell in the proximal tubules and widened rough endoplasmic reticulum of the
endothelial cells of glomerular capillaries were observed. We observed that the structural alterations that increased depending
on the day of Cd administration decreased after exogenous MT administration, the dilation of the peritubular capillaries persisted,
and there were degenerated proximal tubules. It was established that cadmium chloride was toxic for kidney cortex and caused
structural damage. Exogenous MT partly prevents CdCl2-induced damage. 相似文献
33.
Shibayama Y Kawachi A Onimaru S Tokunaga J Ikeda R Nishida K Kuchiiwa S Nakagawa S Takamura N Motoya T Takeda Y Yamada K 《Life sciences》2007,81(2):103-108
An herbal health care supplement, St John's Wort (SJW, Hypericum perforatum) has become widely used in the treatment of depression, and is known to interact with therapeutic drugs. Here we report a preventive effect of SJW on cisplatin nephrotoxicity in rats. Rats were given SJW (400 mg/kg/day, p.o.) for 10 consecutive days, and were injected with cisplatin (5 mg/kg, i.v.) on the day after the final SJW treatment. Cisplatin treatment increased the serum creatinine level, which is an index of nephrotoxicity, to 1.51+/-0.22 mg/dl (mean+/-SE) from 0.28+/-0.05 mg/dl (control) on day 5 after the cisplatin injection. This increase fell significantly to 0.86+/-0.13 mg/dl by pre-treatment with SJW. Cisplatin-induced histological abnormality of the kidney was blocked by pre-treatment with SJW. When SJW was administered for 10 days, the amounts of renal metallothionein (MT) and hepatic multidrug resistance protein 2 (Mrp2) were increased to 164.8+/-13.0% and 220.8+/-39.3% (mean+/-SE) of controls, respectively. GSH levels in the kidney and liver were not changed. Total and free cisplatin concentration in serum was not influenced by SJW treatment. In conclusion, the results suggest that pre-treatment with SJW may diminish cisplatin nephrotoxicity. 相似文献
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37.
Plant metallothioneins (MTs) are extremely diverse and are thought to be involved in metal homeostasis or detoxification.
Thlaspi caerulescens is a model Zn/Cd hyperaccumulator and thus constitutes an ideal system to study the variability of these MTs. Two T. caerulescens cDNAs (accession: 665511; accession: 665515), that are highly homologous to type 1 and type 2 Arabidopsis thaliana MTs, have been isolated using a functional screen for plant cDNAs that confer Cd tolerance to yeast. However, TcMT1 has a much shorter N-terminal domain than that of A. thaliana and so lacks Cys motifs conserved through all the plant MTs classified as type 1. A systematic search in plant databases
allowed the detection of MT-related sequences. Sixty-four percent fulfil the criteria for MT classification described in Cobbett
and Goldsbrough (2002) and further extend our knowledge about other conserved residues that might play an important role in plant MT structure.
In addition, 34% of the total MT-related sequences cannot be classified strictly as they display modifications in the conserved
residues according to the current plant MTs’ classification. The significance of this variability in plant MT sequences is
discussed. Functional complementation in yeast was used to assess whether these variations may alter the MTs’ function in
T. caerulescens. Regulation of the expression of MTs in T. caerulescens was also investigated. TcMT1 and TcMT2 display higher expression in T. caerulescens than in A. thaliana. Moreover, their differential expression patterns in organs and in response to metal exposure, suggest that the two types
of MTs may have diverse roles and functions in T. caerulescens. 相似文献
38.
Metallothioneins (MTs) are thought to participate in a wide variety of physiological roles, but the mechanisms involved are still unclear. The study was designed to examine the possible factors related to these mechanisms. Methods, including transfection, MTT assay and flow cytometry, were used to investigate the effect of MTs on cell viability and their interactions with cadmium and zinc in HEK293 cells. The results showed that transient overexpression of human MT1A, MT2 and MT3 genes dynamically affected cell viability, and the effect was influenced by zinc and cadmium ions. Overexpressed MTs with added zinc showed a greater inhibitory effect on cell viability. Overexpressed MTs protected cells against low concentrations of cadmium ions (10 microM), but increased cell death in response to high concentrations (20-50 microM). Out of the three MTs, MT1A was more efficient than MT2 and MT3 in its resistance to cadmium (10 microM), and MT3 together with zinc showed more cell growth inhibition than MT1 and MT2. These results indicate that both of the divalent metal ions that could bind MTs, as well as the individual MT isoforms, affect the role of MTs on cell viability, which may explain in part why the comprehensive effect of MTs on the cells was elusive. 相似文献
39.
Feng W Cai J Pierce WM Franklin RB Maret W Benz FW Kang YJ 《Biochemical and biophysical research communications》2005,332(3):853-858
Previous studies have shown that in a cell-free system, metallothionein (MT) releases zinc when the environment becomes oxidized and the released zinc is transferred to a zinc-binding protein if such a protein is present. However, it is unknown whether and how zinc transfers from MT to other proteins in vivo. The present study was undertaken to test the hypothesis that if zinc transfer from MT to other proteins occurs in vivo, the transfer would proceed through a direct interaction between MT and a specific group of proteins. The heart extract obtained from MT-null mice was incubated with 65Zn-MT or 65ZnCl2 and the proteins receiving 65Zn were separated by blue-native PAGE (BN-PAGE) or sodium dodecyl sulfate-PAGE (SDS-PAGE), and detected by autoradiography. A unique 65Zn-binding band was observed from the 65Zn-MT-incubated, but not the 65ZnCl2-incubated preparation. The analysis using matrix assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry revealed that mitochondrial aconitase (m-aconitase) was among the proteins accepting Zn directly from Zn-MT. The m-aconitase, not the cytosolic aconitase (c-aconitase), was co-immunoprecipitated with MT. This study demonstrates that MT transfers zinc to m-aconitase through a direct interaction. 相似文献
40.
Grating-coupled surface plasmon resonance (GCSPR) is a method for the accurate assessment of analyte in a multiplexed format using small amounts of sample. In GCSPR, the analyte is flowed across specific receptors (e.g. antibodies or other proteins) that have been immobilized on a sensor chip. The chip surface is illuminated with p-polarized light that couples to the gold surface's electrons to form a surface plasmon. At a specific angle of incidence, the GCSPR angle, the maximum amount of coupling occurs, thus reducing the intensity of reflected light. Shifts in the GCSPR angle can be correlated with refractive index increases following analyte capture by chip-bound receptors. Because regions of the chip can be independently analyzed, this system can assess 400 interactions between analyte and receptor on a single chip. We have used this label-free system to assess a number of molecules of immunological interest. GCSPR can simultaneously detect an array of cytokines and other proteins using the same chip. Moreover, GCSPR is also compatible with assessments of antigen expression by intact cells, detecting cellular apoptosis and identifying T cells and B cells. This technology represents a powerful new approach to the analysis of cells and molecular constituents of biological samples. 相似文献