title: RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2Activation.
abstract: Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A2(cPLA2), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA2. Inhibition of RhoA, Rho kinase and cPLA2significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA2activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA2. The immunofluorescence staining showed that ROCK1or ROCK2, two isoforms of Rho kinase, was co-localized with cPLA2in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK1or ROCK2bonded directly with cPLA2and phospho-cPLA2. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA2activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA2activation.
authors: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W. 15th Street, NB 500E, Indianapolis, IN, 46202, USA.|Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Xiangbing
authors: X
authors: Wu
authors: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W. 15th Street, NB 500E, Indianapolis, IN, 46202, USA.|Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Chandler L
authors: CL
authors: Walker
authors: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W. 15th Street, NB 500E, Indianapolis, IN, 46202, USA.|Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Qingbo
authors: Q
authors: Lu
authors: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W. 15th Street, NB 500E, Indianapolis, IN, 46202, USA.|Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.|Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Wei
authors: W
authors: Wu
authors: Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Daniel B
authors: DB
authors: Eddelman
authors: Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors: Jonathan M
authors: JM
authors: Parish
authors: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W. 15th Street, NB 500E, Indianapolis, IN, 46202, USA. xu26@iupui.edu.|Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. xu26@iupui.edu.|Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. xu26@iupui.edu.|Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. xu26@iupui.edu.
authors: Xiao-Ming
authors: XM
authors: Xu
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology; D005260:Female; D054513:Group IV Phospholipases A2 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D054460:rho-Associated Kinases / Q000502:physiology*
chemical_list: C515854:Rock1 protein, mouse; C515855:Rock2 protein, mouse; D054460:rho-Associated Kinases; D054513:Group IV Phospholipases A2; C516391:Pla2g4a protein, rat
keywords: Cell death; Cytosolic phospholipase A2; Neuroprotection; Rho kinase; RhoA; Spinal cord injury