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Published on: February 9, 2024
Molecular mechanisms of fMLP-induced superoxide generation and degranulation in mouse neutrophils
Yasunori Kanaho1, Takanobu Sato, Tsunaki Hongu
1Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennodai, Ibaraki 305-8575, Japan. ykanaho@md.tsukuba.ac.jp
Abstract:
In this manuscript, involvement of PLD in fMLP-induced superoxide generation and degranulation were re-investigated using PLD(-/-) neutrophils, and the molecular mechanisms of these neutrophil functions were examined. Neither PLD1 nor PLD2 is involved in these fMLP-induced neutrophil functions. The results obtained in this study provide evidence that cPKC plays an important role in fMLP-induced superoxide generation. On the other hand, Ca(2+)-dependent signaling pathway and cPKC seem to be involved in degranulation.
Insights
Phospholipase D (PLD) is not involved in neutrophil responses to fMLP. Instead, conventional protein kinase C (cPKC) mediates superoxide generation, while calcium and cPKC regulate degranulation.
Area of Science:
- Immunology and Molecular Biology
- Cellular Signaling Pathways
Background:
- Neutrophil functions, including superoxide generation and degranulation, are critical for innate immunity.
- Phospholipase D (PLD) has been implicated in regulating these neutrophil responses, but its precise role remains debated.
Purpose of the Study:
- To re-investigate the involvement of PLD isoforms (PLD1 and PLD2) in formyl-methionyl-leucyl-phenylalanine (fMLP)-induced neutrophil functions.
- To elucidate the molecular mechanisms underlying fMLP-induced superoxide generation and degranulation in neutrophils.
Main Methods:
- Utilized PLD-deficient (PLD-/-) neutrophils to assess their functional responses.
- Examined superoxide generation and degranulation pathways triggered by fMLP stimulation.
Main Results:
- Neither PLD1 nor PLD2 plays a significant role in fMLP-induced superoxide generation or degranulation in neutrophils.
- Conventional protein kinase C (cPKC) was identified as a key mediator of fMLP-induced superoxide generation.
- Both Ca(2+)-dependent signaling and cPKC appear to be involved in the regulation of neutrophil degranulation.
Conclusions:
- The findings challenge the previously assumed role of PLD in fMLP-stimulated neutrophil functions.
- cPKC is a critical signaling molecule for superoxide production, while calcium and cPKC pathways are essential for degranulation.
- This study clarifies the signaling pathways governing key neutrophil responses, distinct from PLD involvement.
