Recent studies showed that both prostaglandin E2 (PGE2) and transient receptor potential melastatin 7 (TRPM7) play important roles in migration and proliferation of human glioblastoma cells. In this study, we tested the association between PGE2 and TRPM7. We found that PGE2 increased TRPM7 currents in HEK293 and human glioblastoma A172 cells. The PGE2 EP3 receptor antagonist L‐798106 abrogated the PGE2 stimulatory effect, while EP3 agonist 17‐phenyl trinor prostaglandin E2 (17‐pt‐PGE2) mimicked the effect of PEG2 on TRPM7. The TRPM7 phosphotransferase activity‐deficient mutation, K1646R had no effect on PGE2 induced increase of TRPM7 currents. Inhibition of protein kinase A (PKA) activity by Rp‐cAMP increased TRPM7 currents. TRPM7 PKA phosphorylation site mutation S1269A abolished the PGE2 effect on TRPM7 currents. PGE2 increased both mRNA and membrane protein expression of TRPM7 in A172 cells. Knockdown of TRPM7 by shRNA abrogated the PGE2 stimulated migration and proliferation of A172 cells. Blockage of TRPM7 with 2‐aminoethoxydiphenyl borate (2‐APB) or NS8593 had a similar effect as TRPM7‐shRNA. In conclusion, our results demonstrate that PGE2 activates TRPM7 via EP3/PKA signalling pathway, and that PGE2 enhances migration and proliferation of human glioblastoma cells by up‐regulation of the TRPM7 channel.
In this study, we tested the effect of melatonin on proliferation and differentiation of neural stem/progenitor cells (NSPCs) obtained from adult mouse spinal cord. We found that melatonin increases neurosphere formation from adult spinal cord NSPCs but does not alter the differentiation of the cells. Western blot results show that adult spinal cord NSPCs express both MT1 and MT2 melatonin receptors. The melatonin receptor antagonist 4P‐PDOT abrogates the melatonin‐induced neurosphere formation. Melatonin increases the phosphorylation level of protein kinase B (AKT). Blockage of phosphatidylinositol 3‐kinase (PI3K), a kinase upstream of AKT, abolishes the stimulatory effect of melatonin on spinal cord NSPCs. We conclude that melatonin promotes the proliferation of adult spinal cord NSPCs via the PI3K/AKT signaling pathway.
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