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26S multicatalytic proteinase complexes decrease during the differentiation of murine erythroleukemia cells
T Tsukahara1, H Sugita, S Ishiura
1National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.
Abstract:
Changes in multicatalytic proteinase activity during differentiation were investigated using Me2SO-induced differentiation of murine erythroleukemia cells as a model. The apparent ATP-dependent multicatalytic proteinase activity decreased in the Me2SO-treated cells with ATP-dependent incorporation of [3H]diisopropyl fluorophosphate decreasing notably after Me2SO-treatment. This decrease in activity does not seem to arise from a cessation of cell-proliferation, because no significant changes in proteinase activity were observed under different culture conditions. Hydroxyapatite column chromatography was employed to analyze the form of multicatalytic proteinase. It was clearly demonstrated that the 26S form of the proteinase decrease in the differentiated cells relative to normal cells. Multicatalytic proteinase-associated proteins that bind to the proteinase in an ATP-dependent manner were purified on an anti-multicatalytic proteinase IgG conjugated column. Only a small amount of protein was recovered from the differentiated cells. These results suggest that the decrease in multicatalytic proteinase-associated proteins that occurs upon cell-differentiation abolishes the ATP-dependent activity of the proteinase.
Insights
Dimethyl sulfoxide (Me2SO) treatment reduces multicatalytic proteinase activity in differentiating cells. This decrease is linked to reduced proteinase-associated proteins, impacting ATP-dependent activity during cell differentiation.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Cell differentiation involves complex regulatory mechanisms.
- Multicatalytic proteinases play roles in cellular processes.
- Understanding proteinase activity changes during differentiation is crucial.
Purpose of the Study:
- To investigate changes in multicatalytic proteinase activity during cell differentiation.
- To identify the molecular basis for altered proteinase activity.
- To explore the role of associated proteins in regulating activity.
Main Methods:
- Murine erythroleukemia cell differentiation induced by dimethyl sulfoxide (Me2SO).
- Assay of ATP-dependent multicatalytic proteinase activity.
- Hydroxyapatite column chromatography for proteinase form analysis.
- Purification of proteinase-associated proteins using immunoprecipitation.
Main Results:
- Me2SO-induced differentiation led to a decrease in ATP-dependent multicatalytic proteinase activity.
- The 26S form of the proteinase was reduced in differentiated cells.
- A significant decrease in multicatalytic proteinase-associated proteins was observed.
Conclusions:
- The reduction in multicatalytic proteinase-associated proteins contributes to the loss of ATP-dependent activity during cell differentiation.
- These findings elucidate a regulatory mechanism for proteinase function in differentiating cells.