Regulation of Cu,Zn superoxide dismutase with copper. Caeruloplasmin maintains levels of functional enzyme activity during differentiation of K562 cells

Percival, Susan S.; Harris, Edward D.

doi:10.1042/bj2740153

Cited by 34 publications

(18 citation statements)

References 34 publications

(33 reference statements)

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“…The overall picture presented here is reminiscent of the results obtained by Percival and Harris [28]. These authors reported the presence of a Cu,Zn-SOD with reduced activity in K562 cells induced to differentiate by a 96-h-long exposure to haemin.…”

Section: Effects Of Copper On the Growth Of K562 Cellssupporting

confidence: 84%

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Copper-dependent metabolism of Cu,Zn-superoxide dismutase in human K562 cells. Lack of specific transcriptional activation and accumulation of a partially inactivated enzyme

Steinkühler

Carrı̀

Micheli

et al. 1994

Biochemical Journal

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The regulation of Cu,Zn-superoxide dismutase by copper was investigated in human K562 cells. Copper ions caused a dose- and time-dependent increase, up to 3-fold, of the steady-state level of Cu,Zu-superoxide dismutase mRNA. A comparable increase was also observed for actin and ribosomal protein L32 mRNAs, but not for metallothionein mRNA which was augmented more than 50-fold and showed a different induction pattern. The copper-induced mRNAs were actively translated as judged from their enhanced loading on polysomes, the concomitantly increased cellular protein levels and an augmented incorporation of [3H]lysine into acid-precipitable material. Cu,Zn-superoxide dismutase protein followed this general trend, as demonstrated by dose- and time-dependent increases in immunoreactive and enzymically active protein. However, a specific accumulation of Cu,Zn-superoxide dismutase was noticed in cells grown in the presence of copper, that was not detectable for other proteins. Purification of the enzyme demonstrated that Cu,Zn-superoxide dismutase was present as a reconstitutable, copper-deficient protein with high specific activity (kcat./Cu = 0.89 x 10(9) M-1.s-1) in untreated K562 cells and as a fully metallated protein with low specific activity (kcat./Cu = 0.54 x 10(9) M-1.s-1) in copper-treated cells. Pulse-chase experiments using [3H]lysine indicated that turnover rates of Cu,Zn-superoxide dismutase in K562 cells were not affected by growth in copper-enriched medium, whereas turnover of total protein was significantly enhanced as a function of metal supplementation. From these results we conclude that: (i) unlike in yeast [Carrì, Galiazzo, Ciriolo and Rotilio (1991) FEBS Lett. 278, 263-266] Cu,Zn-superoxide dismutase is not specifically regulated by copper at the transcriptional level in human K562 cells, suggesting that this type of regulation has not been conserved during the evolution of higher eukaryotes; (ii) copper ions cause an inactivation of the enzyme in intact K562 cells; and (iii) the metabolic stability of Cu,Zn-superoxide dismutase results in its relative accumulation under conditions that lead to increased protein turnover.

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Section: Effects Of Copper On the Growth Of K562 Cellssupporting

confidence: 84%

“…Copper concentration determinations [28]. The cells were washed with 50 ml of RPMI medium supplemented with 10% (v/v) fetal-calf serum and 5 mM unlabelled lysine and resuspended at 0.5 x 106 cells/ml in 100 ml of this medium.…”

Section: Introductionmentioning

confidence: 99%

Copper-dependent metabolism of Cu,Zn-superoxide dismutase in human K562 cells. Lack of specific transcriptional activation and accumulation of a partially inactivated enzyme

Steinkühler

Carrı̀

Micheli

et al. 1994

Biochemical Journal

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“…ApoSOD pools were also inferred for differentiating K562 cells (10,11,15) and differentiating HL-60 cells (12). However, the apoSOD pool in lymphoblasts that was detected here is unlikely to be due to copper deficiency, and no cell-differentiating factors were used in the lymphoblast studies.…”

Section: Discussionmentioning

confidence: 97%

Identification of an Apo-Superoxide Dismutase (Cu,Zn) Pool in Human Lymphoblasts

Petrović

Comi

Ettinger

1996

Journal of Biological Chemistry

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Copper incorporation (64 Cu(II)) into Cu,Zn-superoxide dismutase (SOD) was studied in human lymphoblasts. Rapid incorporation of copper with a proportionate increase in SOD activity was detected. No copper incorporation or SOD activation was detected when 64 Cu(II) was added to cell cytosols rather than to intact cells. Thus, incorporation of 64 Cu was not due to isotopic exchange. Cycloheximide had no significant effect on copper incorporation and activation of SOD when the data were corrected for total cell copper. Thus, the data were consistent with copper incorporation into a preexisting apoSOD pool rather than newly synthesized SOD, and no new SOD synthesis was detected over a 15-h incubation period. The size of the apoSOD pool was estimated to be Ϸ35% of the total SOD in lymphoblasts. When cells were preincubated for 15 h with excess copper (15 M Cu(II)), the size of the apo pool markedly decreased but was not eliminated, suggesting that the apoSOD was not due to copper deficiency. These experiments also indicated that newly arrived copper was preferentially incorporated into the apoSOD pool, while the function(s) of an apoSOD pool remains unknown. Copper binding to apoSOD may provide a rapid protective response against copper toxicity.Cu,Zn-superoxide dismutase (SOD) 1 is found in the cytosolic fraction of all cells (1, 2) and has also been detected in nuclei and perioxisomes (2-5). However, the cellular site(s) and stage of protein synthesis of copper incorporation into SOD remain unknown. Moreover, an apo form of SOD was detected in a variety of copper-deficient cells or in cells in which the amount of the apoSOD pool appeared to vary with the state of differentiation (6 -15). The total amount of SOD mRNA and protein may also vary with the state of differentiation of some cells types (16). The cellular location of the apo form of SOD is unknown. While some copper incorporation into apoSOD was reported when high (2 mM) concentrations of copper were added to whole cell homogenates (10), no copper incorporation has been reported for copper addition to the cytosolic fractions from cells containing an apoSOD pool. Since copper is incorporated into apoSOD in neutral buffer, this suggests that either there are factors in cell cytosols which inhibit copper incorporation or that the apoSOD pool is not cytosolic.The time and copper concentration dependencies of copper binding to cytosolic copper binding proteins and copper incorporation into SOD were determined during incubations of lymphoblasts with 64 Cu(II). Since SOD copper does not readily exchange isotopic copper, 64 Cu incorporation exclusively into newly synthesized SOD was anticipated. However, little or no de novo synthesis of SOD protein was detected in lymphoblasts over the time course of these experiments. Instead, an apoSOD pool was detected in lymphoblasts, which were neither copperdeficient nor -differentiating. The results in this and a companion study on copper incorporation into SOD in Menkes (17) lymphoblasts (18) suggest a possible role of...

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“…In yeast, the expression of SOD1 is regulated by copper ions at the level of transcription (Carri et al 1991). Lutropin, Cu 2+ , and reactive oxygen seem to induce SOD1 in rat (Laloraya et al 1988;Nicotera et al 1989;Percival and Harris 1991).…”

Section: Introductionmentioning

confidence: 98%

Heavy metal-mediated activation of the rat Cu/Zn superoxide dismutase gene via a metal-responsive element

Yoo¹,

Chang²,

Rho³

1999

Mol Gen Genet

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The Cu/Zn superoxide dismutase (SODI) catalyzes the dismutation of superoxide radicals produced in the course of biological oxidations. When placed under the control of the rat SOD1 gene promoter and transfected into human HepG2 hepatoma cells, the activity of a chloramphenicol acetyltransferase reporter gene was found to increase three- to four-fold in the presence of heavy metals (cadmium, zinc and copper). Functional analysis of mutant derivatives of the SOD1 gene promoter and the use of a heterologous promoter system confirmed that the induction of the SOD1 gene by metal ions requires a metal-responsive element (MRE) located between positions -273 and -267 (GCGCGCA). It was also shown by gel mobility shift assays that an MRE binding protein is induced by the exposure of the human liver cell line HepG2 to heavy metals. These results suggest that the MRE participates in the induction of the SOD1 gene by heavy metals.

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Regulation of Cu,Zn superoxide dismutase with copper. Caeruloplasmin maintains levels of functional enzyme activity during differentiation of K562 cells

Cited by 34 publications

References 34 publications

Copper-dependent metabolism of Cu,Zn-superoxide dismutase in human K562 cells. Lack of specific transcriptional activation and accumulation of a partially inactivated enzyme

Copper-dependent metabolism of Cu,Zn-superoxide dismutase in human K562 cells. Lack of specific transcriptional activation and accumulation of a partially inactivated enzyme

Identification of an Apo-Superoxide Dismutase (Cu,Zn) Pool in Human Lymphoblasts

Heavy metal-mediated activation of the rat Cu/Zn superoxide dismutase gene via a metal-responsive element

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