Related Experiment Videos
Induction of mitochondrial manganese superoxide dismutase by interleukin 1
A Masuda1, D L Longo, Y Kobayashi
1Division of Cancer Treatment, National Cancer Institute, Frederick Cancer Research Facility, Maryland 21701.
Abstract:
Interleukin 1 (IL 1) inhibits the growth of human melanoma A375 cells. To identify the subcellular events preceding inhibition of growth by IL 1, we have examined the effect of IL 1 on protein synthesis caused by A375 cells. IL 1 selectively and predominantly induced a 25-kDa polypeptide (p25) in A375 cells after 12 h. On subcellular fractionation, p25 was exclusively located in the 10,000 x g-pelleted (mitochondria-enriched) fraction. To identify the p25 moiety, it was purified to homogeneity by sequential chromatography on DEAE-Sephacel and reverse-phase, high-pressure liquid chromatography and its amino-terminal amino acid sequence was determined. The sequence of the 35 amino-terminal amino acids of the p25 moiety was identical to that of human manganese superoxide dismutase (Mn SOD). The enzymatic activities of SOD were induced only in the mitochondria-enriched fraction of IL 1-treated A375 cells. However, IL 1 also induced Mn SOD in normal human skin fibroblasts and peripheral blood mononuclear cells, whose growth was stimulated by IL 1. The results show that induction of Mn SOD by IL 1 is a common biochemical event in IL 1-responsive cells.
Insights
Interleukin 1 (IL 1) inhibits melanoma cell growth by inducing manganese superoxide dismutase (Mn SOD). This protein, found in mitochondria, is a key response in IL 1-treated cells.
Area of Science:
- Cell Biology
- Biochemistry
- Immunology
Background:
- Interleukin 1 (IL 1) is known to inhibit the growth of human melanoma A375 cells.
- Understanding the subcellular mechanisms behind IL 1's growth inhibition is crucial.
Purpose of the Study:
- To investigate the subcellular events triggered by IL 1 that lead to growth inhibition in A375 cells.
- To identify proteins synthesized in response to IL 1 treatment.
Main Methods:
- A375 cells were treated with IL 1, and protein synthesis was analyzed.
- Subcellular fractionation was used to localize induced proteins.
- Protein purification involved chromatography (DEAE-Sephacel, HPLC).
- Amino-terminal sequencing identified the protein.
Main Results:
- IL 1 selectively induced a 25-kDa polypeptide (p25) in A375 cells.
- p25 was localized to the mitochondria-enriched fraction.
- The amino-terminal sequence of p25 matched human manganese superoxide dismutase (Mn SOD).
- Mn SOD enzymatic activity was induced in mitochondria of IL 1-treated cells.
- Mn SOD was also induced in IL 1-stimulated fibroblasts and mononuclear cells.
Conclusions:
- IL 1 induces manganese superoxide dismutase (Mn SOD) in human melanoma cells.
- Mn SOD induction is a common biochemical event in IL 1-responsive cells, including fibroblasts and mononuclear cells.
- Mitochondrial localization and induction of Mn SOD are key subcellular events associated with IL 1's effects on cell growth.