Metallothionein mRNA and protein induction by cadmium in peripheral-blood leucocytes

Abstract

To help to evaluate the role of metallothionein (MT) in peripheral-blood leucocytes, we examined MT protein and mRNA levels in these cells before and after exposure to CdCl2 in culture. Protein was assayed by 109Cd2+ binding, and RNA by dot-blot hybridization. MT was induced in both lymphocytes and adherent monocytes about 10-fold with a 12 h exposure to 10 microM-CdCl2, but absolute levels were 3-fold higher in monocytes: 57 x 10(5) (+Cd2+) versus 6 x 10(5) (-Cd2+) molecules/cell for monocytes; 18 x 10(5) (+Cd2+) versus 2 x 10(5) (-Cd2+) for lymphocytes. Polymorphonuclear cells expressed relatively little MT (0.6 x 10(5) molecules/cell), and this did not change with phorbol ester stimulation or exposure to Cd2+, arguing against a direct protective role for MT in activated neutrophils. MT mRNA levels corresponded qualitatively to expression of protein in these cells. Our data provide quantitative comparisons of leucocyte MT expression and regulation in the human population. Variation in both basal and induced MT mRNA levels reflects environmental or experimental (intra-individual) and possibly genetic (inter-individual) differences.

Induction of Metallothionein and Heme Oxygenase in Rats After Inhalation of Endotoxin

“…As yet, we have not examined metallothionein mRNA levels at time points during exposure. The continued accumulation of metallothionein protein after a time when metallothionein mRNA declined presumably reflected a longer half-life of metallothionein protein compared with metallothionein mRNA (Harley et al, 1989).…”

Cadmium reduces adipocyte size and expression levels of adiponectin and Peg1/Mest in adipose tissue

“…Exposure to Cd causes a wide variety of adverse effects such as nephrotoxicity, hepatotoxicity and immunotoxicity in human and experimental animals (Cifone et al, 1989;Harley et al, 1989;Kotsonis and Klaassen, 1977;Morselt et al, 1988). In addition, many lifestyle-related diseases such as obesity and hypertension are prevalent in modern society.…”

Metallothionein in human thrombocyte precursors, CD61+ megakaryocytes

“…The presence of mRNA or protein from any unwanted cell population other than megakaryocytes could pose a major limitation to making a precise conclusion about the MT isogene transcription by RT-PCR. As very little or no MT inducibility by Cd is reported in polymorphonuclear neutrophils by other investigator (Harley et al 1989), induction of total MT mRNA in CD61 + cells could be considered of megakaryocytic origin. However, both the tissue/celland inducer-specific MT induction (Waalkes and Klaassen 1985;Maitani et al 1987;Shadhu and Gedamu 1989;Andrews 1990;Huber and Cousins 1993;Vasconcelos et al 1996) could raise further constraints; accordingly, more investigations with pure population of megakaryocytes are required.…”