p53- and Bax-mediated apoptosis in injured rat spinal cord

Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL 61656, USA.
Neurochemical Research (Impact Factor: 2.55). 07/2011; 36(11):2063-74. DOI: 10.1007/s11064-011-0530-2

ABSTRACT Spinal cord injury (SCI) induces a series of endogenous biochemical changes that lead to secondary degeneration, including apoptosis. p53-mediated mitochondrial apoptosis is likely to be an important mechanism of cell death in spinal cord injury. However, the signaling cascades that are activated before DNA fragmentation have not yet been determined. DNA damage-induced, p53-activated neuronal cell death has already been identified in several neurodegenerative diseases. To determine DNA damage-induced, p53-mediated apoptosis in spinal cord injury, we performed RT-PCR microarray and analyzed 84 DNA damaging and apoptotic genes. Genes involved in DNA damage and apoptosis were upregulated whereas anti-apoptotic genes were downregulated in injured spinal cords. Western blot analysis showed the upregulation of DNA damage-inducing protein such as ATM, cell cycle checkpoint kinases, 8-hydroxy-2'-deoxyguanosine (8-OHdG), BRCA2 and H2AX in injured spinal cord tissues. Detection of phospho-H2AX in the nucleus and release of 8-OHdG in cytosol were demonstrated by immunohistochemistry. Expression of p53 was observed in the neurons, oligodendrocytes and astrocytes after spinal cord injury. Upregulation of phospho-p53, Bax and downregulation of Bcl2 were detected after spinal cord injury. Sub-cellular distribution of Bax and cytochrome c indicated mitochondrial-mediated apoptosis taking place after spinal cord injury. In addition, we carried out immunohistochemical analysis to confirm Bax translocation into the mitochondria and activated p53 at Ser(3)(9)(2). Expression of APAF1, caspase 9 and caspase 3 activities confirmed the intrinsic apoptotic pathway after SCI. Activated p53 and Bax mitochondrial translocation were detected in injured spinal neurons. Taken together, the in vitro data strengthened the in vivo observations of DNA damage-induced p53-mediated mitochondrial apoptosis in the injured spinal cord.

  • [Show abstract] [Hide abstract]
    ABSTRACT: It is unknown whether transplantation of bone marrow mesenchymal stem cells (BM-MSCs) can repair spinal cord ischemia-reperfusion injury (SCII) in a rat model through an anti-apoptotic effect. Adult rats were divided into untreated or sham-operated controls, untreated models of SCII (uSCII) and BM-MSC-transplanted models of SCII (tSCII; labeled with CM-Dill transplanted at 1h and 24h after reperfusion). According to evaluation of hind-limb motor function, the motor functions of tSCII rats were significantly better than those of uSCII rats by the seventh day. H&E and TUNEL staining showed that the spinal cords of uSCII rats contained damaged neural cells with nuclear pyknosis and congestion of blood vessels, with a high percentage of apoptotic neural cells, while the spinal cords of tSCII rats were nearly normal with significantly fewer apoptotic neural cells. Immunohistochemistry and double immunofluorescence staining revealed that in tSCII rats CASP3 and neurofilament-H (NF-H) levels were 14.57% and 174% those of uSCII rats, respectively, and in tSCII rats the ratio of BAX to BCL2 was reduced by nearly 50%. The differentiation of transplanted CM-Dil-labeled BM-MSCs into neurons and astrocytes was observed in the spinal cords of the tSCII rats under laser scanning confocal microscopy. These results showed that transplantation of BM-MSCs improved functional recovery after SCII via anti-apoptosis.
    Brain research 03/2014; · 2.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study investigates the endogenous expression of Suppressor of Cytokine Signaling-3 (SOCS3) after spinal cord injury (SCI) and its effect on SCI-induced cell death in vivo. In addition, we determined whether a reduction of SOCS3 expression induced by microinjection of short hairpin RNA (shSOCS3) carried by lentivirus into spinal cord provides cellular protection after SCI. We demonstrated that complete transection of rat T8 spinal cord induced SOCS3 expression at the mRNA and protein levels as early as 2days post-injury, which was maintained up to 14days. SOCS3 immunoreactivity was detected in neurons and activated microglia after SCI. We also demonstrated that SCI induces phosphorylation of proteins that are involved in signal transduction and transcription-3 (STAT3) in neurons, which induced SOCS3 expression. Western blot analyses and double-immunofluorescent staining showed significant up-regulation of the pro-apoptotic protein Bax, increases in the ratio of Bax to the anti-apoptotic protein Bcl-2, and up-regulation of cleaved caspase-3 in neurons. Treatment with shSOCS3 inhibited SCI-induced mRNA expression of SOCS3 2days post-injury and suppressed SCI-induced Bax expression 7days after SCI, both rostral and caudal to the lesion. Moreover, treatment with shSOCS3 inhibited SCI-induced neuronal death and protected neuronal morphology both rostral and caudal to the injury site 7days post-injury. Our results suggest that the STAT3/SOCS3 signaling pathway plays an important role in regulating neuronal death after SCI.
    Experimental Neurology 06/2014; · 4.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study aimed to evaluate the effect of methylprednisolone sodium succinate, dantrolene sodium, and their combination on experimental spinal cord injury. We used 25 rats (Rattus norvegicus) that were divided into five groups. The negative control group (NC) consisted of animals without spinal cord trauma. In the groups with spinal cord trauma, the positive control group (PC) was given no treatment, the MS group was treated with methylprednisolone, the MS/DS group was treated with methylprednisolone and dantrolene, and the DS group was treated with dantrolene alone. The animals' motor function was evaluated daily, as measured with the open field test. Eight days after surgery, the animals were euthanized for spinal cord collection. Descriptive morphological evaluation, anti-NeuN immunohistochemistry, TUNEL, and anti-Bax immunofluorescence were performed. There was no significant difference between the PC, MS, MS/DS and DS groups with respect to BBB scores, neuronal and glial staining, or Bax expression (P < 0.05). Therefore, we conclude that methylprednisolone sodium succinate, dantrolene sodium, or the combination of these drugs did not reduce neuronal and glial loss, intrinsic pathway apoptosis, or promote functional recovery.
    International journal of clinical and experimental pathology. 01/2014; 7(8):4617-26.


Available from
May 15, 2014