Neuropathic pain resulting from nerve lesions or dysfunction represents one of the most challenging neurological diseases to treat. A better understanding of the molecular mechanisms responsible for causing these maladaptive responses can help develop novel therapeutic strategies and biomarkers for neuropathic pain. We performed a miRNA expression profiling study of dorsal root ganglion (DRG) tissue from rats four weeks post spinal nerve ligation (SNL), a model of neuropathic pain. TaqMan low density arrays identified 63 miRNAs whose level of expression was significantly altered following SNL surgery. Of these, 59 were downregulated and the ipsilateral L4 DRG, not the injured L5 DRG, showed the most significant downregulation suggesting that miRNA changes in the uninjured afferents may underlie the development and maintenance of neuropathic pain. TargetScan was used to predict mRNA targets for these miRNAs and it was found that the transcripts with multiple predicted target sites belong to neurologically important pathways. By employing different bioinformatic approaches we identified neurite remodeling as a significantly regulated biological pathway, and some of these predictions were confirmed by siRNA knockdown for genes that regulate neurite growth in differentiated Neuro2A cells. In vitro validation for predicted target sites in the 3′-UTR of voltage-gated sodium channel Scn11a, alpha 2/delta1 subunit of voltage-dependent Ca-channel, and purinergic receptor P2rx ligand-gated ion channel 4 using luciferase reporter assays showed that identified miRNAs modulated gene expression significantly. Our results suggest the potential for miRNAs to play a direct role in neuropathic pain.
Objective-Vascular endothelial growth factor (VEGF) induces angiogenesis by stimulating reactive oxygen species (ROS) production primarily through the VEGF receptor-2 (VEGFR2). One of the initial responses in established vessels to stimulate angiogenesis is loss of vascular endothelial (VE)-cadherin-based cell-cell adhesions; however, little is known about the underlying mechanisms. IQGAP1 is a novel VEGFR2 binding protein, and it interacts directly with actin, cadherin, and -catenin, thereby regulating cell motility and morphogenesis. Methods and Results-Confocal microscopy analysis shows that IQGAP1 colocalizes with VE-cadherin at cell-cell contacts in unstimulated human endothelial cells (ECs). VEGF stimulation reduces staining of IQGAP1 and VE-cadherin at the adherens junction without affecting interaction of these proteins. Knockdown of IQGAP1 using siRNA inhibits localization of VE-cadherin at cell-cell contacts, VEGF-stimulated recruitment of VEGFR2 to the VE-cadherin/-catenin complex, ROS-dependent tyrosine phosphorylation of VE-cadherin, which is required for loss of cell-cell contacts and capillary tube formation. IQGAP1 expression is increased in a mouse hindlimb ischemia model of angiogenesis. Conclusions-IQGAP1 is required for establishment of cell-cell contacts in quiescent ECs. To induce angiogenesis, it may function to link VEGFR2 to the VE-cadherin containing adherens junctions, thereby promoting VEGF-stimulated, ROS-dependent tyrosine phosphorylation of VE-cadherin and loss of cell-cell contacts. (Arterioscler Thromb Vasc
Objective
Spinal cord tumors are highly malignant and often lead to paralysis and death mainly due to their infiltrative nature, high recurrence rate, and limited treatment options. In this study, we measured the antitumor efficacy of the Salmonella typhimurium A1-R tumor-targeting strain, administered systemically or intrathecally, to spinal cord cancer in orthotopic mouse models.
Materials and Methods
Tumor fragments of U87-RFP were implanted by surgical orthotopic implantation into the dorsal site of the spinal cord. Five and ten days after transplantation, 8 mice in each group were treated with A1-R (2 × 107 cfu / 200μl i.v. injection or 2 × 106 cfu / 10μl intrathecal injection).
Results
The untreated mice showed progressive paralysis beginning at 6 days after tumor transplantation and developed complete paralysis between 18 to 25 days. The mice treated i.v. with A1-R had an onset of paralysis at approximately 11 days and at day-30, 5 mice developed complete paralysis, while other 3 mice had partial paralysis. Mice treated via intrathecal injection of A1-R had an onset of paralysis at approximately 18 days and one mouse was still not paralyzed at day-30. Only one mouse developed complete paralysis at day 30 in this group. The intrathecally-treated animals had a significant increase in survival over the i.v.-treated group as well as the control group.
Conclusions
These results suggest that S. typhimurium A1-R monotherapy can effectively treat spinal cord glioma.
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