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A mutant HSDM1C1 fibrosarcoma line selected for defective eicosanoid precursor uptake lacks arachidonate-specific
Abstract:
Mutagenesis followed by suicide with highly radioactive tritiated arachidonic acid has been used to select for mouse fibrosarcoma (HSDM1C1) cells defective in eicosanoid precursor uptake. Survivors of the selection were screened by replica plating and autoradiographic assay of [3H]arachidonate esterification; a mutant cell line, EPU-1, was established. EPU-1 cells contain one-third as much arachidonate as normal HSDM1C1 cells. The mutant lacks arachidonate-specific acyl-CoA synthetase, which accounts for decreased arachidonate uptake. EPU-1 exhibits enhanced turnover of arachidonoyl- but not linoleoyl-phosphatidylcholine. Bradykinin-induced arachidonate release and prostaglandin E2 synthesis are decreased in EPU-1. Thus, arachidonoyl-CoA synthetase is required for arachidonate homeostasis in HSDM1C1 cells.
Insights
Researchers identified a mutant cell line, EPU-1, with reduced arachidonic acid uptake due to a lack of arachidonate-specific acyl-CoA synthetase. This enzyme is crucial for maintaining arachidonic acid balance in fibrosarcoma cells.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Genetics
Background:
- Eicosanoids, derived from arachidonic acid, play critical roles in cellular signaling and inflammation.
- Understanding the regulation of arachidonic acid uptake and metabolism is essential for comprehending cellular homeostasis.
Purpose of the Study:
- To isolate and characterize mouse fibrosarcoma cells with defects in eicosanoid precursor uptake.
- To identify the molecular basis for altered arachidonic acid metabolism in the selected mutant cell line.
Main Methods:
- Mutagenesis of HSDM1C1 mouse fibrosarcoma cells using radioactive arachidonic acid.
- Selection of resistant survivors and screening via replica plating and [3H]arachidonate esterification assays.
- Biochemical analysis of arachidonic acid uptake, acyl-CoA synthetase activity, and phospholipid turnover.
Main Results:
- Isolation of a mutant cell line, EPU-1, exhibiting significantly reduced arachidonic acid uptake.
- EPU-1 cells lack functional arachidonate-specific acyl-CoA synthetase, explaining the uptake defect.
- The mutant showed altered turnover of arachidonoyl-phosphatidylcholine and decreased bradykinin-induced release and prostaglandin E2 synthesis.
Conclusions:
- Arachidonoyl-CoA synthetase is indispensable for maintaining arachidonic acid homeostasis in HSDM1C1 fibrosarcoma cells.
- Defects in this enzyme impact cellular arachidonic acid levels, phospholipid metabolism, and eicosanoid production.
- This study provides insights into the specific role of arachidonate-specific acyl-CoA synthetase in cellular lipid metabolism.