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Stress proteins metals

Mammalian MTs are known to accumulate after administration of various metal salts. This control is not exclusive, however, as a variety of other stimuli also trigger MT synthesis, including several hormones, tissue injury, bacterial endotoxin and interferon (see Karin, 1985 Hamer, 1986). Each of these factors relates directly or indirectly to various acute stresses. This could indicate that MT is a general stress protein. Such a definition is incomplete because MT levels also change during embryo-genesis and tissue differentiation. This has prompted the suggestion that the primary role of MT is as a modulator of cellular activity (Karin, 1985). [Pg.12]

When organisms are confronted with sudden changes such as exposure to potentially toxic substances (heavy metal ions) or the onset of starvation, these stimulations induce the production of the so-called stress responsive proteins. The most thoroughly studied stress proteins include the heat-shock proteins (HSP), the induction of which is a highly conserved response across genera. [Pg.1095]

Eckwert, H., Alberti, G. and Kohler, H.-R. (1997) The induction of stress proteins (hsp) in Oniscus asellus (Isopoda) as a molecular marker of multiple heavy metal exposure. 1. Principles and toxicological assessment. Ecotoxicology, 6, 249-262. [Pg.196]

Ryan, J.A. and L.E. Hightower. Evaluation of heavy-metal ion toxicity in fish cells using a combined stress protein and cytotoxicity assay. Environ. Toxicol. Chem. 13 1231-1240, 1994. [Pg.82]

Stress proteins No Metals and OCs Difficult to separate effects of chemicals from other stressors... [Pg.280]

An additional goal of the studies on auxin-induced gene expression will be to determine the role of the polypeptides encoded by the auxin-induced mRNAs. One of the auxin-induced soybean mRNAs has been shown to encode a heat shock protein [4]. This gene is also expressed in response to heat [3] and heavy metals [4, 7] and may represent a general stress protein. The function of the polypeptides encoded by the other auxin-regulated mRNAs is unknown. Computer comparison of the deduced amino acid sequences of the soybean auxin-induced genes with other known protein sequences has failed to reveal any homologies. [Pg.98]

The preceding brief overview has illustrated the structural and functional diversity of the classical hsps and grps. The complexity of these stress proteins and the stress response can be further appreciated by the following review on the unique and diverse effects of several metals on the expression of stress proteins. [Pg.232]

C. Metals and Their Effects on Expression of Stress Proteins... [Pg.233]

The enhanced expression of metal-induced stress proteins is controlled primarily at the transcriptional level similar to the induction of hsps by heat (Wu et al. 1986). Regulation of hsp genes in eukaryotic systems is mediated by a cw-acting heat shock control element (HSE) that is found in multiple copies upstream of the transcriptional start site (Pelham 1982). Transcriptional activation of the hsp genes is mediated by a ran -acting protein, known as the heat shock factor (HSF), which binds specifically to the HSE (Wu 1984a,b). [Pg.233]

The findings summarized in these last two induction categories imply that the regulatory mechanism(s) involved in some heat-induced proteins is independent of the mechanisms responsible for some metal-induced stress proteins. [Pg.234]

The proximal mechanism for induction of stress protein synthesis leading to the activation of HSF and gene activation is not completely understood, but evidence for several possibilities exists. Activation of HSF by prooxidants does not result in the accumulation of specific stress proteins (Bruce et al. 1993). These results suggest that induction of stress proteins by specific metals, whose toxicity is mediated via oxidative damage to membranes or DNA, may be fundamentally different from that of the heat-induced activation of the stress response (Keyse and Tyrrell 1987 Bruce et al. 1993). Thus, metals such as cadmium, mercury, nickel, arsenite, copper, lead, and iron, which induce oxygen free radicals or promote formation of lipid peroxides (Stacey and Klaassen 1981 Halliwell and Gutteridge 1984 Christie and Costa 1984 Kasprzak 1991 Donati et al. 1991), may... [Pg.234]

A comparison of stress proteins induced by various metals is presented in Table 2. This table does not represent an exhaustive list of all studies, but is intended to illustrate the degree of variability reported in the synthesis of specific proteins induced by different metals in various experimental models. Because of this variability, it is difficult to make generalizations about specific protein induction by metals. Although all these metals share the ability to induce synthesis of stress proteins in one or more experimental models, protein induction by a specific metal may have unique characteristics. The following review of the stress protein induction effects by specific metals will focus on those metals which illustrate some of the these unique characteristics. Other important or unique properties of specific metals will be discussed in Sect. G on biomarkers. [Pg.235]

The majority of literature on metal-induced stress proteins results from studies employing the arsenic oxides, sodium arsenate and sodium arsenite (Table 2). Although these compounds are very effective inducers of stress proteins, arsenite has been shown to be the more potent inducer (Bournias-Vardiabasis et al. 1990 Bauman et al. 1993). Sodium arsenite has been shown to elicit thermotolerance, self-tolerance, and cross-tolerance in response to a variety of physiologic stresses (see Sect. D). The thermotolerance induced by arsenite treatment has been correlated with the increase in newly synthesized stress proteins (Lee and Dewey 1987). Arsenite has been shown to induce the same proteins as heat in several experimental systems (De Jong et al. 1986 Bournias-Vardiabasis et al. 1990 Cohen et al. 1991 Honda et al. 1992). In contrast, there are reported differences in the stress protein responses produced by these two stressors. [Pg.235]

Table 2. Comparison of stress proteins induced by various metals... [Pg.236]

Bournias-Vardiabasis et al. (1990) exposed Drosophila embryonic cells to a number of metal ions that had previously been reported to act as teratogens in mammalian systems. Although the induced protein patterns varied between different metals, zinc induced a pattern similar to that produced by classical teratogens. Roccheri et al. (1988) reported that treatment of sea urchin embryos with zinc induced the same stress proteins as those observed in heat-treated embryos. These investigators found that zinc treatment induced a protracted synthesis of the stress proteins relative to heat. This finding might be explained by the prolonged exposure of the sea urchin embryos to zinc in the culture medium. Unlike heat shock, zinc treatment did not inhibit overall protein synthesis or induce thermotolerance in these zinc-treated sea urchin embryos. [Pg.241]

Data generated from a study of lead-induced synthesis of stress proteins illustrated that different metals have both common and individual effects on expression of stress proteins. Lead-induced stress protein synthesis was unusual in that it did not share the properties of metals, such as cadmium and arsenite, to mimic the effects of heat (Shelton et al. 1986). Rather, lead induced two minor classes of proteins. In this study, exposure of primary rat kidney epithelial cells and rat fibroblasts to lead glutamate induced synthesis of two grps and a protein of 32 kDa, which was shown to... [Pg.241]


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