MKK3 influences mitophagy and is involved in cigarette smoke-induced inflammation.

Abstract

Cigarette smoking is the primary risk factor for COPD which is characterized by excessive inflammation and airflow obstruction of the lung. While inflammation is causally related to initiation and progression of COPD, the mitochondrial mechanisms that underlie the associated inflammatory responses are poorly understood. In this context, we have studied the role played by Mitogen activated protein (MAP) kinase kinase 3 (MKK3), a dual-specificity protein kinase, in cigarette smoke induced-inflammation and mitochondrial dysfunction. Serum pro-inflammatory cytokines were significantly elevated in WT but not in MKK3-/- mice exposed to Cigarette smoke (CS) for 2 months. To study the cellular mechanisms of inflammation, bone marrow derived macrophages (BMDMs), wild type (WT) and MKK3-/-, were exposed to cigarette smoke extract (CSE) and inflammatory cytokine production and mitochondrial function assessed. The levels of IL-1β, IL-6, and TNFα were increased along with higher reactive oxygen species (ROS) and P-NFκB after CSE treatment in WT but not in MKK3-/- BMDMs. CSE treatment adversely affected basal mitochondrial respiration, ATP production, maximum respiratory capacity, and spare respiratory capacity in WT BMDMs only. Mitophagy, clearance of dysfunctional mitochondria, was up regulated in CS exposed WT mice lung tissue and CSE exposed WT BMDMs, respectively. The proteomic analysis of BMDMs by iTRAQ (isobaric tags for relative and absolute quantitation) showed up regulation of mitochondrial dysfunction associated proteins in WT and higher OXPHOS (Oxidative phosphorylation) and IL-10 signaling proteins in MKK3-/- BMDMs after CSE exposure, confirming the critical role of mitochondrial homeostasis. Interestingly, we found increased levels of p-MKK3 by immunohistochemistry in COPD patient lung tissues that could be responsible for insufficient mitophagy and disease progression. This study identifies MKK3 as a negative regulator of mitochondrial function and inflammatory responses to CS and suggests that MKK3 could be a therapeutic target.

• Authors: Praveen Mannam, Navin Rauniyar, TuKiet T Lam, Ruiyan Luo, Patty J Lee, Anup Srivastava
• Journal: Free radical biology & medicine (Free Radic Biol Med) Vol. 101 Pg. 102-115 (12 2016) ISSN: 1873-4596 [Electronic] United States
• PMID: 27717867 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 Elsevier Inc. All rights reserved.

Chemical References

• IL1B protein, mouse
• Interleukin-1beta
• Interleukin-6
• NF-kappa B
• Plant Extracts
• Reactive Oxygen Species
• Tumor Necrosis Factor-alpha
• interleukin-6, mouse
• Adenosine Triphosphate
• MAP Kinase Kinase 3
• MAP2K3 protein, human
• Map2k3 protein, mouse

Topics

• Adenosine Triphosphate (biosynthesis)
• Animals
• Cigarette Smoking (genetics, metabolism, pathology)
• Gene Expression Profiling
• Gene Expression Regulation
• Humans
• Inflammation
• Interleukin-1beta (genetics, metabolism)
• Interleukin-6 (genetics, metabolism)
• MAP Kinase Kinase 3 (deficiency, genetics, metabolism)
• Macrophages (drug effects, metabolism)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Mitochondria (drug effects, metabolism, pathology)
• Mitophagy (drug effects)
• NF-kappa B (genetics, metabolism)
• Oxidative Phosphorylation (drug effects)
• Plant Extracts (isolation & purification, pharmacology)
• Primary Cell Culture
• Pulmonary Disease, Chronic Obstructive (genetics, metabolism, pathology)
• Reactive Oxygen Species (agonists, metabolism)
• Tobacco (chemistry)
• Tumor Necrosis Factor-alpha (genetics, metabolism)