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KMID : 0355620080340010028
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Journal of Korean Association of Oral and Maxillofacial Surgeons
2008 Volume.34 No. 1 p.28 ~ p.35
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Protein kinase C-?regulates toll-like receptor 4-mediated inducible nitric oxide synthase expression
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Lee Jin-Gu
Chin Byung-Rho
Baek Suk-Hwan
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Abstract
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Purpose: The nitric oxide (NO) release by inducible nitric oxide synthase (iNOS) is the key events in macrophage response to lipopolysaccharide (LPS) which is suggested to be a crucial mediator for inflammatory and innate immune responses. NO is an important mediator involved in many host defense action and may also lead to a harmful host response to bacterial infection. However, given the importance of iNOS in a variety of pathophysiological conditions, control of its expression and signaling events in response to LPS has been the subject of considerable investigation.
Materials and Methods: The Raw264.7 macrophage cell line was used to observe LPS-stimulated iNOS expression. The expression of iNOS is observed by Western blot analysis and real-time RT-PCR. Protein kinase C (PKC)-? overexpressing Raw264.7 cells are established to determine the involvement of PKC-? in LPS-mediated iNOS expression. NF- ?B activity is measured by I?B? degradation and NF-?B luciferase activity assay.
Results: We found that various PKC isozymes regulate LPS-induced iNOS expression at the transcriptional and translational levels. The involvement of PKC-? in LPS-mediated iNOS induction was further confirmed by increased iNOS expression in PKC-? overexpressing cells. NF-?B dependent transactivation by LPS was observed and PKC-? specific inhibitory peptide abolished this activation, indicating that NF-?B activation is dependent on PKC-?.
Conclusion: Our data suggests that PKC-? is involved in LPS-mediated iNOS expression and that its downstream target is NF-?B. Although PKC-? is a crucial mediator in the iNOS regulation, other PKC isozymes may contribute LPS-stimulated iNOS expression. This finding is needed to be elucidated in further study.
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KEYWORD
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lipopolysaccharide, inducible nitric oxide synthase, protein kinase C, NF-?B
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