1. Caspase-2 is upregulated after sciatic nerve transection and its inhibition protects dorsal root ganglion neurons from apoptosis after serum withdrawal.
- Author
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Vigneswara V, Berry M, Logan A, and Ahmed Z
- Subjects
- Animals, Caspase 3 genetics, Caspase 3 metabolism, Caspase Inhibitors pharmacology, Cell Nucleus enzymology, Cell Nucleus genetics, Cell Nucleus metabolism, Cell Nucleus physiology, Cytosol enzymology, Cytosol metabolism, Cytosol physiology, Female, Ganglia, Spinal cytology, Ganglia, Spinal surgery, In Situ Nick-End Labeling methods, Nerve Regeneration genetics, Nerve Regeneration physiology, Neurons cytology, Neurons metabolism, Neurons, Afferent enzymology, Neurons, Afferent metabolism, Neurons, Afferent physiology, Rats, Rats, Sprague-Dawley, Schwann Cells enzymology, Schwann Cells metabolism, Schwann Cells physiology, Sciatic Nerve cytology, Sciatic Nerve metabolism, Up-Regulation, Apoptosis physiology, Caspase 2 genetics, Caspase 2 metabolism, Ganglia, Spinal enzymology, Neurons enzymology, Sciatic Nerve enzymology
- Abstract
Sciatic nerve (SN) transection-induced apoptosis of dorsal root ganglion neurons (DRGN) is one factor determining the efficacy of peripheral axonal regeneration and the return of sensation. Here, we tested the hypothesis that caspase-2 (CASP2) orchestrates apoptosis of axotomised DRGN both in vivo and in vitro by disrupting the local neurotrophic supply to DRGN. We observed significantly elevated levels of cleaved CASP2 (C-CASP2), compared to cleaved caspase-3 (C-CASP3), within TUNEL+DRGN and DRG glia (satellite and Schwann cells) after SN transection. A serum withdrawal cell culture model, which induced 40% apoptotic death in DRGN and 60% in glia, was used to model DRGN loss after neurotrophic factor withdrawal. Elevated C-CASP2 and TUNEL were observed in both DRGN and DRG glia, with C-CASP2 localisation shifting from the cytosol to the nucleus, a required step for induction of direct CASP2-mediated apoptosis. Furthermore, siRNA-mediated downregulation of CASP2 protected 50% of DRGN from apoptosis after serum withdrawal, while downregulation of CASP3 had no effect on DRGN or DRG glia survival. We conclude that CASP2 orchestrates the death of SN-axotomised DRGN directly and also indirectly through loss of DRG glia and their local neurotrophic factor support. Accordingly, inhibiting CASP2 expression is a potential therapy for improving both the SN regeneration response and peripheral sensory recovery.
- Published
- 2013
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