title: NOD2 activation induces oxidative stress contributing to mitochondrial dysfunction and insulin resistance in skeletal muscle cells.
abstract: Nucleotide-binding oligomerization domain protein-2 (NOD2) activation in skeletal muscle cells has been associated with insulin resistance, but the underlying mechanisms are not yet clear. Here we demonstrate the implication of oxidative stress in the development of mitochondrial dysfunction and insulin resistance in response to NOD2 activation in skeletal muscle cells. Treatment with the selective NOD2 ligand muramyl dipeptide (MDP) increased mitochondrial reactive oxygen species (ROS) generation in L6 myotubes. MDP-induced ROS production was associated with increased levels of protein carbonyls and reduction in citrate synthase activity, cellular ATP level, and mitochondrial membrane potential, as well as altered expression of genes involved in mitochondrial function and metabolism. Antioxidant treatment attenuated MDP-induced ROS production and restored mitochondrial functions. In addition, the presence of antioxidant prevented NOD2-mediated activation of MAPK kinases and the inflammatory response. This was associated with reduced serine phosphorylation of insulin receptor substrate-1 (IRS-1) and improved insulin-stimulated tyrosine phosphorylation of IRS-1 and downstream activation of Akt phosphorylation. These data indicate that oxidative stress plays a role in NOD2 activation-induced inflammatory response and that MDP-induced oxidative stress correlates with impairment of mitochondrial functions and induction of insulin resistance in skeletal muscle cells.
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
authors.forename: Chandan K
authors.initials: CK
authors.lastname: Maurya
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
authors.forename: Deepti
authors.initials: D
authors.lastname: Arha
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
authors.forename: Amit K
authors.initials: AK
authors.lastname: Rai
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
authors.forename: Shashi Kant
authors.initials: SK
authors.lastname: Kumar
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India.
authors.forename: Jyotsana
authors.initials: J
authors.lastname: Pandey
authors.affiliation: Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
authors.forename: Deepa R
authors.initials: DR
authors.lastname: Avisetti
authors.affiliation: Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
authors.forename: Shasi V
authors.initials: SV
authors.lastname: Kalivendi
authors.affiliation: Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: Amira
authors.initials: A
authors.lastname: Klip
authors.affiliation: Division of Biochemistry, CSIR-Central Drug Research Institute, Lucknow 226031, India. Electronic address: akhilesh_tamrakar@cdri.res.in.
authors.forename: Akhilesh K
authors.initials: AK
authors.lastname: Tamrakar
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002478:Cells, Cultured; D007124:Immunoenzyme Techniques; D007333:Insulin Resistance; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: C512493:NOD2 protein, rat; D053473:Nod2 Signaling Adaptor Protein; D012333:RNA, Messenger; D017382:Reactive Oxygen Species
keywords: Free radicals; Inflammation; Innate immunity; Insulin resistance; Mitochondrial function; NOD