Expression of granulocyte colony-stimulating factor 3 receptor in the spinal dorsal horn following spinal nerve ligation-induced neuropathic pain.

In previous studies that have profiled gene expression in patients with complex regional pain syndrome (CRPS), the expression of granulocyte colony-stimulating factor 3 receptor (G­CSFR) was elevated, as were a number of pain­associated genes. The present study determined the expression of G­CSFR and the mechanisms by which it may affect hypersensitivity, focusing on the signal transducer and activator of transcription 3 (STAT3)/transient receptor potential cation channel subfamily V 1 (TRPV1) signaling pathway in particular, which is an important mediator of pain. Following L5 spinal nerve ligation (SNL) surgery, the protein and mRNA levels of G­CSFR increased in the ipsilateral spinal dorsal horn when compared with the sham and/or contralateral control. Double immunofluorescence further demonstrated that G­CSFR colocalized with TRPV1 and phosphorylated STAT in the neurons of the spinal dorsal horn. G­CSF treatment led to an increase in G­CSFR and TRPV1 expression and phosphorylation of STAT3. These results indicate that G­CSF­induced G­CSFR expression may activate TRPV1 by promoting phosphorylation of STAT3. Collectively, the results suggest, for the first time, that the expression of G­CSFR in neurons following peripheral nerve injury may be involved in the induction and maintenance of neuropathic pain through the STAT3 and TRPV1 signaling pathway.

Expression of PGC1α in glioblastoma multiforme patients.

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) is a key modulator of mitochondrial biogenesis. It is a coactivator of multiple transcription factors and regulates metabolic processes. However, little is known about the expression and function of PGC1α in glioblastoma multiforme (GBM), the most prevalent and invasive type of brain tumor. The purpose of the present study was to investigate the biological function, localization and expression of PGC1α in GBM. It was observed that PGC1α expression is increased in the tumor cells, and a higher level of expression was observed in the mitochondria. Bioinformatics analyses identified that metabolic and mitochondrial genes were highly expressed in GBM cells, with a high PGC1α mRNA expression. Notably, mitochondrial function-associated genes were highly expressed in cells alongside high PGC1α expression. Collectively, the results of the present study indicate that PGC1α is associated with mitochondrial dysfunction in GBM and may have a role in tumor pathogenesis and progression.

RhoGDI2 expression in astrocytes after an excitotoxic lesion in the mouse hippocampus.

The Rho GDP-dissociation inhibitor (RhoGDI) originally downregulates Rho family GTPases by preventing nucleotide exchange and membrane association. Although RhoGDI2 functions as a metastasis regulator, little is known in glial cells under neuropathological conditions. We monitored RhoGDI2 expression in the mouse brain after administering a kainic acid(KA)-induced excitotoxic lesion. In control, RhoGDI2 immunoreactivity (IR) was evident in the neuronal layer of the hippocampus. However, RhoGDI2 IR was increased in astrocytes markedly throughout the hippocampus at day 3 post-treatment with KA. To further investigate the molecular mechanism of RhoGDI2-induced cellular migration, primary astrocytes were transfected with the flag-tagged RhoGDI2 cDNA. Cell migration assay revealed that RhoGDI2 cDNA transfection inhibits astrocyte migration. Overexpression of RhoGDI2 leads to inhibit protein kinase B (PKB) activation and cdc42 and cAMP-responsive element-binding protein (CREB) phosphorylation. In conclusion, our results suggested for the first time that RhoGDI2 is required for PKB and CREB activation and cdc42 expression in astrocyte migration after KA-mediated excitotoxic lesion in mouse brain.

IQGAP1 expression in spared CA1 neurons after an excitotoxic lesion in the mouse hippocampus.

Repeated seizures induce permanent alterations in the hippocampal circuits in experimental models with intractable temporal lobe epilepsy. Sprouting and synaptic reorganization induced by seizures has been well-studied in the mossy fiber pathway. However, studies investigating sprouting and synaptic reorganization beyond the mossy fiber pathway are limited. The present study examined the biochemical changes of CA1 pyramidal neurons undergoing morphological changes after excitotoxicity-induced hippocampal CA3 neuronal death. IQ-domain GTPase-activating proteins (IQGAP1), is an effector of Rac1 and Cdc42 and an actin-binding protein, was upregulated in CA1 pyramidal neurons after kainic acid-induced hippocampal CA3 neuronal degeneration. IQGAP1 + cells were colocalized with Nestin, but not in astrocytes or mature neurons. Furthermore, IQGAP1 did not originate from newly divided local precursors or NG2 + cells. IQGAP1 and adenomatous polyposis coli localized in CA1 pyramidal neurons, and Cdc42 activation was followed by IQGAP1 recruitment. These findings suggest that IQGAP1 is upregulated in pre-existed sparing neurons of the CA1 layer undergoing morphological changes after excitoxicity-induced hippocampal CA3 neuronal death. It demonstrates the utility of IQGAP1 as a possible marker for spared pyramidal neurons, which may contribute to structural and functional alternations responsible for the development of epilepsy.