title: Proteome analysis associated with cadmium adaptation in U937 cells: identification of calbindin-D28k as a secondary cadmium-responsive protein that confers resistance to cadmium-induced apoptosis.
abstract: Cadmium is a well known environmental toxicant and carcinogen. To identify proteins involved in cellular adaptive responses to cadmium, we established cadmium-adapted U937 cells that exhibit resistance to cadmium-induced apoptosis, and we performed comparative proteome analysis of these cells with parental cells that were either untreated or treated with cadmium. Newly identified proteins that were changed in expression level in both adapted cells and cadmium-treated parental cells included proteins implicated in cell proliferation and malignant transformation. Most interesting, a calcium-binding protein calbindin-D(28k) was increased only in the adapted cells but not in cadmium-exposed parental cells. The level of calbindin-D(28k) increased by the degree of cadmium adaptation and was stably maintained without selective pressure of cadmium. Cadmium-adapted U937 cells were resistant to the toxic effects of cytosolic calcium rise by cadmium treatment and by depletion of intracellular calcium stores, suggesting that enhanced calcium buffering by up-regulated calbindin-D(28k) may be responsible for acquiring resistance to cadmium-induced apoptosis. We demonstrated that overexpression of calbindin-D(28k) in MN9D neuronal cells resulted in reduced cadmium-induced apoptosis. Our study documents for the first time that cells respond to long term cadmium exposure by increasing calbindin-D(28k) expression, thereby attenuating cadmium-induced apoptosis.
authors.affiliation: Department of Biology and Protein Network Research Center, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Jeon
authors.forename: Hyung-Seung
authors.initials: HS
authors.lastname: Jin
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Choi
authors.forename: Chang-Kiu
authors.initials: CK
authors.lastname: Moon
authors.forename: Young J
authors.initials: YJ
authors.lastname: Oh
authors.forename: Tae H
authors.initials: TH
authors.lastname: Lee
mesh_terms: D000222:Adaptation, Physiological; D017209:Apoptosis / Q000187:drug effects*; D002021:Buffers; D002104:Cadmium / Q000633:toxicity*; D064092:Calbindin 1; D064026:Calbindins; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D020543:Proteome / Q000302:isolation & purification / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D020298:U937 Cells
chemical_list: D002021:Buffers; C576498:CALB1 protein, human; D064092:Calbindin 1; D064026:Calbindins; D020543:Proteome; D064030:S100 Calcium Binding Protein G; D002104:Cadmium; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; D002118:Calcium