Our goal is to characterize further the biochemical properties of a metallothionein-like protein recently isolated from the rat brain, and to determine its possible role in preventing neurotoxicity from heavy metals. This small molecular weight protein (Mr less than 10,000), has an elution volume (Ve/Vo) of 2.06, its synthesis is stimulated by zinc and copper but not cadmium, and the zinc-stimulated protein incorporates large quantities of [35]S-cysteine. It is hypothesized that this metallothionein-like protein may be involved (a) in zinc hemeostasis, (b) in zinc transport, (c) in metal detoxification, or perhaps (d) in events related to synaptic functions. The importance of zinc in neurochemistry and neurotoxicology becomes apparent when one realizes that zinc maintains the function and/or the structure of more than 235 metalloenzymes and/or metalloproteins known to participate in the metabolism of carbohydrates, lipids, proteins, and nucleic acids. Furthermore, chronic zinc loss is associated with cerebellar dysfunction, anorexia, hypogeusia, hyposmia, impaired night vision, anencephaly, and altered learning and behavior patterns. On the other hand, zinc excess has been detected in inherited retinal dystrophy, multiple sclerosis, Pick's disease, sudanophile leucodystrophy, and Lowe's syndrome. To what extent the brain's metallothionein-like protein is altered in these disease states is not known deserving investigation.
The specific aims are to characterize further the biochemical properties of this protein by using the hepatic metallothionein as a standard and by employing techniques involving gel filtration on Sephadex G-75 columns, ion exchange chromatography on DEAE-Sephadex A-25 columns, polyacrylamide gel electrophoresis on non-denaturing gel, chromatofocusing, high performance liquid chromatography, and amino acid analysis. The possible regional distribution of metallothionein-like protein in the brain, whose zinc concentration is nonuniform, will be carried out by radioimmunoassay (RIA). In addition, the possible lipolytic activity of this protein will be assessed. Furthermore, the regulation of the synthesis of this metallothionein-like protein will be investigated by employing a culture system that uses neurons as a model and the hepatocytes as a standard: and by studying the effects of Za++, glucocorticoids and epinephrine, -ametal and hormones known to induce the synthesis of the hepatic metallothionein.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES003949-02
Application #
3251702
Study Section
Metallobiochemistry Study Section (BMT)
Project Start
1987-02-01
Project End
1990-01-31
Budget Start
1988-02-01
Budget End
1989-01-31
Support Year
2
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Nebraska Medical Center
Department
Type
Schools of Medicine
DUNS #
City
Omaha
State
NE
Country
United States
Zip Code
68198
Ebadi, M; Iversen, P L; Hao, R et al. (1995) Expression and regulation of brain metallothionein. Neurochem Int 27:1-22
Takeda, A; Norris, J S; Iversen, P L et al. (1994) Antisense oligonucleotide of c-myc discriminates between zinc- and dexamethasone-induced synthesis of metallothionein. Pharmacology 48:119-26
Ebadi, M; Iversen, P L (1994) Metallothionein in carcinogenesis and cancer chemotherapy. Gen Pharmacol 25:1297-310
Ebadi, M; Elsayed, M A; Aly, M H (1994) The importance of zinc and metallothionein in brain. Biol Signals 3:123-6
Shiraga, H; Pfeiffer, R F; Ebadi, M (1993) The effects of 6-hydroxydopamine and oxidative stress on the level of brain metallothionein. Neurochem Int 23:561-6
Hao, R; Pfeiffer, R F; Ebadi, M (1993) Purification and characterization of metallothionein and its activation of pyridoxal phosphokinase in trout (Salmo gairdneri) brain. Comp Biochem Physiol B 104:293-8
Iversen, P L; Mata, J E; Ebadi, M (1992) Synthetic antisense oligonucleotide probes the essentiality of metallothionein gene. Biol Signals 1:293-9
Iversen, P L; Ebadi, M (1992) Antisense oligonucleotide-mediated inhibition of metallothionein protein synthesis in neuroblastoma IMR 32 and Chang liver cells in culture. Biol Signals 1:57-64
Ebadi, M; Pfeiffer, R F; Huff, A (1992) Differential stimulation of hepatic and brain metallothioneins by ethanol. Neurochem Int 21:555-62
Ou, C Z; Ebadi, M (1992) Pineal and retinal protein kinase C isoenzymes: cooperative activation by calcium and zinc metallothionein. J Pineal Res 12:17-26

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