RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation

Xiangbing Wu, Chandler Walker, Qingbo Lu, Wei Wu, Daniel B. Eddelman, Jonathan M. Parish, Xiao-Ming Xu

Research output: Contribution to journalArticle

7 Citations (Scopus)

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 cPLA2 significantly 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 cPLA2 activation 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 ROCK1 or ROCK2, two isoforms of Rho kinase, was co-localized with cPLA2 in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK1 or ROCK2 bonded directly with cPLA2 and phospho-cPLA2. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA2 activation 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 cPLA2 activation.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalMolecular Neurobiology
DOIs
StateAccepted/In press - Oct 22 2016

Fingerprint

Cytosolic Phospholipases A2
rho-Associated Kinases
Cell Death
Glutamic Acid
Wounds and Injuries
Growth Cones
Contusions
Neurites
Lipase
Spinal Cord Injuries
Immunoprecipitation
Arachidonic Acid
Fluorescent Antibody Technique
Axons
Regeneration
Protein Isoforms
Cytoplasm
Thorax
Down-Regulation

Keywords

  • Cell death
  • Cytosolic phospholipase A
  • Neuroprotection
  • Rho kinase
  • RhoA
  • Spinal cord injury

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

Cite this

RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation. / Wu, Xiangbing; Walker, Chandler; Lu, Qingbo; Wu, Wei; Eddelman, Daniel B.; Parish, Jonathan M.; Xu, Xiao-Ming.

In: Molecular Neurobiology, 22.10.2016, p. 1-11.

Research output: Contribution to journalArticle

Wu, Xiangbing ; Walker, Chandler ; Lu, Qingbo ; Wu, Wei ; Eddelman, Daniel B. ; Parish, Jonathan M. ; Xu, Xiao-Ming. / RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation. In: Molecular Neurobiology. 2016 ; pp. 1-11.
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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 cPLA2 significantly 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 cPLA2 activation 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 ROCK1 or ROCK2, two isoforms of Rho kinase, was co-localized with cPLA2 in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK1 or ROCK2 bonded directly with cPLA2 and phospho-cPLA2. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA2 activation 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 cPLA2 activation.",
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