“
“Long-term exposure to the environmental pollutant cadmium (Cd) damages the kidneys. It causes renal tubular dysfunction as assessed by increased urinary excretion of low molecular weight proteins, such as

α1-microglobulin, β2-microglobulin (UB2M) and N-Acetyl-beta-(D)-Glucosaminidase (UNAG; Jin et al., 1999, Jin et al., 2002 and Nogawa et al., 1984). Once absorbed Cd is efficiently retained in the organism and accumulates throughout life Selleck Metformin with a biological half-time of 10–30 years in humans (Nordberg et al., 2007). Metallothioneins (MTs) are low molecular weight proteins involved in the homeostasis of zinc. Their transcription is induced by various heavy metals, such as Cd. In the cell, over 80% of Cd is bound to MT and MTs play a considerable role in the shift of accumulated Cd from the liver and intestines to the kidney (Nordberg et al., 2007). Intracellular binding of Cd to MTs offers protection against cellular damage (Jin et al., 1998). Transgenic mice constantly over-expressing MT genes are also Cd-tolerant (Palmiter et al., 1993). In contrast, knockout mice with defective MT genes are more sensitive to Cd toxicity than wild-type mice (Jin et al., 1998 and Liu et al., 2000). In MT-deficient mice, renal dysfunction can be detected even at renal concentrations of Cd below 10 μg/g tissue (Liu et al., 2000). The findings of many similar studies support the notion that

MT is the main cellular determinant Saracatinib solubility dmso of the sensitivity of mammals and cultured mammalian

cells to Cd. Cd–MT complexes accumulate in the renal cells in a low-toxicity state (Klaassen et al., 1999), and kidney dysfunction occurs when tissue levels exceed the capacity of this protective mechanism. If MT synthesis is decreased or inhibited, then serious renal dysfunction might develop in individuals with high concentrations of Cd. In previous studies, it was found that at similar urinary Cd values, workers with high levels of MT mRNA in peripheral blood lymphocytes had lower UNAG levels than those with low MT mRNA levels (Lu et al., 2001). These findings suggest that individuals with reduced expression of MT might be prone to renal dysfunction selleck compound due to exposure to Cd. The MT genes are in a cluster on chromosome band 16q13. Two of the main MTs widely expressed in the body are MT1A and MT2A ( Klaassen et al., 1999). Several single nucleotide polymorphisms (SNPs) (rs8052394 and rs11076161 in the MT1A gene, and rs10636 in MT2A gene) have been reported to be involved in aging, diabetes and atherosclerosis, probably reflecting their role in zinc homeostasis ( Giacconi et al., 2007, Kayaalti et al., 2010, Kita et al., 2006, Mazzatti et al., 2008 and Mocchegiani et al., 2008). Of these polymorphisms, rs8052394 is non-synonymous (Arg51Lys), while rs11076161 is intronic and rs10636 is located in the 3′ untranslated region (http://www.ncbi.nlm.nih.gov/snp/). Kita et al.