title: Metallothionein isoform gene expression in zinc-treated human peripheral blood lymphocytes.
abstract: Zinc plays an important role in the maintenance of the immune system. While the mechanisms of zinc ions interaction with immune cells are still poorly understood, a striking concurrent effect of zinc is the induction of the biosynthesis of metallothioneins (MT), a group of low molecular weight, cysteine-rich metal-binding proteins, believed to play a role in zinc homeostasis. In humans, they are encoded by a family of genes, located at 16q13 containing 10 functional and 7 non-functional MT isoforms. In this work we analyzed the spectrum of different isoforms in human peripheral blood lymphocytes. It was demonstrated by RT-PCR that the MT-2a, MT-1a, MT-1e, MT-1f, MT-1g, MT-1h and MT-1x genes are expressed in these cells and that these isoforms are further upregulated by zinc, as examined by quantitative RT-PCR. Surprisingly, RT-PCR also showed the presence, even in unstimulated cells, of MT-3 transcripts, which are considered as brain-specific isoforms. In an effort to determine whether MTmRNA abundance is translated into MT protein, MT isolated from zinc-treated lymphocytes by gel chromatography was resolved into 7 metal-binding fractions by using RP-HPLC. Automatic Edman-degradation of the different fractions revealed the presence of MT-2a, MT-1a, MT-1e, MT-1f, MT-1g, MT-1h, MT-1x and MT-1k, an isoform which until now was only identified at the level of protein in human liver and kidney tissue.
authors.affiliation: Laboratorium voor Biochemie, Katholieke Universiteit Leuven, Heverlee, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Vandeghinste
authors.forename: P
authors.initials: P
authors.lastname: Proost
authors.forename: M
authors.initials: M
authors.lastname: De Ley
mesh_terms: D000595:Amino Acid Sequence; D002104:Cadmium / Q000378:metabolism; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D004587:Electrophoresis, Agar Gel; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000737:chemistry*; D008668:Metallothionein / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D020033:Protein Isoforms; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014158:Transcription, Genetic; D015032:Zinc / Q000494:pharmacology*
chemical_list: D017931:DNA Primers; D006454:Hemoglobins; D020033:Protein Isoforms; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc