Mitochondrial reactive oxygen species enable proinflammatory signaling through disulfide linkage of NEMO

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Macrophages initiate proinflammatory responses during infection by secreting cytokines.
• Reactive oxygen species (ROS) are involved in macrophage immune responses.
• NADPH oxidases (Noxes) are known sources of ROS in macrophages.

Purpose of the Study:

• To identify the specific source and mechanism of ROS mediating proinflammatory signaling in macrophages infected with Listeria monocytogenes.
• To elucidate the role of mitochondrial ROS (mtROS) in activating inflammatory pathways.

Main Methods:

• Investigated ROS production in macrophages infected with Listeria monocytogenes.
• Identified mtROS as the key mediators of proinflammatory signaling.
• Characterized the interaction of mtROS with the IκB kinase (IKK) complex regulatory subunit NEMO.
• Analyzed the role of specific cysteine residues (Cys54 and Cys347) in NEMO disulfide bond formation.

Main Results:

• Mitochondria, not NADPH oxidases, produced the ROS that triggered proinflammatory signaling.
• mtROS induced disulfide linkage of NEMO via Cys54 and Cys347.
• This NEMO modification was essential for activating the IKK complex.
• Activation of IKK led to downstream signaling via ERK1/2 and NF-κB pathways, resulting in cytokine secretion.

Conclusions:

• mtROS-dependent disulfide linkage of NEMO is a critical regulatory step in the macrophage proinflammatory response to bacterial infection.
• This finding reveals a novel mechanism controlling inflammatory signaling pathways.
• Identifies a potential therapeutic target for modulating inflammatory responses.