Yang X.-Y.,Wei fang Medical College |
Zhao E.Y.,Wayne State University |
Zhuang W.-X.,Wei fang Medical College |
Sun F.-X.,Wei fang Medical College |
And 7 more authors.
Lysophosphatidic acid (LPA) is a bioactive phospholipid that activates at least five known G-protein-coupled receptors (GPCRs): LPA1–LPA5. The nervous system is a major locus for LPA1 expression. LPA has been shown to regulate neuronal proliferation, migration, and differentiation during central nervous system development as well as neuronal survival. Furthermore, deficient LPA signaling has been implicated in several neurological disorders including neuropathic pain and schizophrenia. Parkinson’s disease (PD) is a neurodegenerative movement disorder that results from the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). The specific molecular pathways that lead to DA neuron degeneration, however, are poorly understood. The influence of LPA in the differentiation of mesenchymal stem cells (MSCs) into DA neurons in vitro and LPA1 expression in a 6-hydroxydopamine (6-OHDA) lesion model of PD in vivo were examined in the present study. LPA induced neuronal differentiation in 80.2 % of the MSC population. These MSCs developed characteristic neuronal morphology and expressed the neuronal marker, neuron-specific enolase (NSE), while expression of the glial marker, glial fibrillary acidic protein (GFAP), was absent. Moreover, 27.6 % of differentiated MSCs were positive for tyrosine hydroxylase (TH), a marker for DA neurons. In the 6-OHDA PD rat model, LPA1 expression in the substantia nigra was significantly reduced compared to control. These results suggest LPA signaling via activation of LPA1 may be necessary for DA neuron development and survival. Furthermore, reduced LPA/LPA1 signaling may be involved in DA neuron degeneration thus contributing to the pathogenesis of PD. © 2015, Springer-Verlag Italia. Source
Sun L.,Wei fang Medical College |
Liu Y.,Wei fang Medical College |
Li X.,Wei fang Medical College |
Liu F.,Wei fang Medical College |
And 3 more authors.
Chinese Journal of Clinical Oncology
Objective: This study aimed to investigate the effect and significance of a binding protein-2 (Gab2)-Akt-ARK5 signaling pathway on the invasion of glioma cells. Methods: Immunohistochemical methods were used to detect the expressions of Gab2 and ARK5 in 45 cases of glioma tissue. siRNA plasmid was used to transfect LN-229 cells, and western blot was performed to analyze the protein expressions of Gab2 and ARK5. In vitro Matrigel invasion assay was conducted to detect variations in the invasiveness of transfected cells. Western blot was also conducted to analyze the protein phosphorylation of Akt and ARK5 in the cells transfected with Gab2 plasmid. Results: Immunohistochemical assay revealed that the expressions of ARK5 and Gab2 in glioma cells were positively correlated, and both expressions were higher in high-grade glioma (WHO grade III, IV) than in low-grade glioma (WHO grade I, II). LN-229 cells transfected with ARK5 plasmid, Gab2 plasmid, ARK5 and Gab2 plasmid, and control plasmid were named si ARK5/LN-229, siGab2/LN-229, siARK5 and siGab2/LN-229, and SCR/LN-229, respectively. After transfection was performed, the protein expressions of ARK5 and Gab2 were respectively decreased in siARK5/LN-229 and siGab2/LN-229. The protein expressions of ARK5 and Gab2 in siARK5 and siGab2/LN-229 were also respectively decreased. After ARK5 or Gab2 was downregulated, the number of glioma cells, which invaded and penetrated Matrigel, was decreased (P<0.01). The number of glioma cells also decreased significantly after ARK5 and Gab2 were downregulated. The phosphorylation of Akt and ARK5 in siGab2/LN-229 cells was decreased after these cells were stimulated by insulin-like growth factor-1. Conclusion: The silencing of ARK5 or Gab2 impaired glioma cell invasiveness. The decreased protein expression of Gab2 inhibited the phosphorylation of Akt and ARK5. These results suggested that the Gab2-Akt-ARK5 signaling pathway could be relevantly involved in glioma cell invasion. Source