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Induction of stress proteins in mouse peritoneal macrophages by oxidized low-density lipoprotein
M Yamaguchi1, H Sato, S Bannai
1Department of Biochemistry, Tsukuba University Medical School, Ibaraki, Japan.
Abstract:
The synthesis of 23-kDa and 34-kDa proteins in mouse peritoneal macrophages was enhanced when they were incubated with oxidatively modified low-density lipoprotein (LDL). This response required the oxidation of the lipid of the LDL, because native LDL had little effect and acetylated LDL enhanced the synthesis of 34-kDa protein only slightly. Since macrophages can bind and sequester oxidized LDL, they are subjected to an oxidative stress. The results suggest that the 34-kDa protein, which is identical with heme oxygenase, and the 23-kDa protein serve as stress protein that might afford protection against the oxidative stress.
Insights
Oxidatively modified low-density lipoprotein (LDL) triggers mouse macrophages to produce protective stress proteins. This response highlights heme oxygenase as a key defense against oxidative stress.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Macrophages play a crucial role in immune responses and lipid metabolism.
- Oxidatively modified low-density lipoprotein (LDL) is implicated in various pathological conditions.
- Cellular stress responses are vital for maintaining homeostasis.
Purpose of the Study:
- To investigate the effect of oxidatively modified LDL on protein synthesis in mouse peritoneal macrophages.
- To identify specific proteins synthesized in response to oxidized LDL.
- To determine the role of these proteins as potential stress proteins.
Main Methods:
- Incubation of mouse peritoneal macrophages with native LDL, acetylated LDL, and oxidatively modified LDL.
- Analysis of protein synthesis using techniques to detect 23-kDa and 34-kDa proteins.
- Identification of the 34-kDa protein as heme oxygenase.
Main Results:
- Incubation with oxidatively modified LDL significantly enhanced the synthesis of 23-kDa and 34-kDa proteins.
- Native LDL showed minimal effect, while acetylated LDL had a slight effect on 34-kDa protein synthesis.
- The 34-kDa protein was identified as heme oxygenase, a known stress-response enzyme.
Conclusions:
- Oxidatively modified LDL induces a stress response in macrophages.
- The 23-kDa and 34-kDa (heme oxygenase) proteins function as stress proteins.
- These stress proteins may protect macrophages against oxidative stress induced by oxidized LDL.