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Concomitant transcriptional activation of nitric oxide synthase and heme oxygenase genes during nitric oxide-mediated
S Kurata1, M Matsumoto, U Yamashita
1Department of Biochemical Genetics, Tokyo Medical and Dental University.
Abstract:
During in vitro activation of mouse peritoneal macrophages with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS), their synthesis of peroxynitrite and their cytostatic activity against mouse lymphocytic leukemia (L1210) cells were examined. The activation of the genes for nitric oxide synthase (iNOS) and heme oxygenase (HO-1) was also determined during the activation of the macrophages. Results showed that activation of peroxynitrite synthesis in macrophages was accompanied by the transcriptional activation of iNOS and HO-1 genes. Both genes seem to be activated simultaneously upon activation of the macrophages. Simultaneous activation of iNOS and HO-1 genes may be important because degradation of heme by HO-1 is one of the most important reaction that produces CO in higher organisms, and nitric oxide (NO) and carbon monoxide (CO) can react with heme-containing guanylate cyclase.
Insights
Mouse macrophages activated with interferon-gamma and lipopolysaccharide synthesize peroxynitrite and exhibit cytostatic activity. Both inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) genes are simultaneously activated during this process.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages play a crucial role in immune responses.
- Interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) are potent activators of macrophages.
- Peroxynitrite is a reactive nitrogen species with diverse biological functions.
Purpose of the Study:
- To investigate peroxynitrite synthesis and cytostatic activity in activated macrophages.
- To examine the transcriptional activation of inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) genes.
- To understand the relationship between iNOS and HO-1 gene activation.
Main Methods:
- In vitro activation of mouse peritoneal macrophages using IFN-gamma and LPS.
- Measurement of peroxynitrite synthesis.
- Assessment of cytostatic activity against L1210 leukemia cells.
- Determination of iNOS and HO-1 gene expression levels.
Main Results:
- Macrophage activation led to increased peroxynitrite synthesis.
- Activated macrophages demonstrated cytostatic effects on L1210 cells.
- Transcriptional activation of both iNOS and HO-1 genes was observed.
- iNOS and HO-1 genes were activated simultaneously.
Conclusions:
- Simultaneous activation of iNOS and HO-1 is a key feature of macrophage activation.
- The coordinated expression of iNOS and HO-1 may be critical for regulating cellular responses.
- The production of nitric oxide (NO) and carbon monoxide (CO) from these pathways could influence cellular signaling via guanylate cyclase.