Regulation Of ASIC1 By Ca²⁺/Calmodulin-dependent Protein Kinase ? In Human Glioblastoma Multiforme

Glioblastoma multiforme?GBM?is the most malignant of the gliomas.GBM expresses several members of the epithelial sodium channel/Degenerin?ENaC/Deg?family,which includes members of acid sensing ion channel?ASICs?subfamily.GBM is characteristically associated with a basally active amiloride-sensitive cation current,which is not seen in normal human astrocytes or low grade gliomas.Recent studies have implicated that ASIC1,a proton-gated cation channel,plays an important role in glioma cell migration.Among the ASIC subunits,only ASIC1 a has been found to permeate calcium.However,whether Ca²⁺/calmodulin-dependent protein kinase II?CaMK??regulates ASIC1 in glioblastoma multiforme?GBM?has not been determined.Here we report that ASIC1 and CaMK? assemble to form a functional complex at the plasma membrane of GBM.We found that the ability of cell migration is significantly attenuated in the GBM cells that were pre-treated with autocamtide-2related inhibitory peptide?AIP?,a CaMK?-specific inhibitor,or a selective ASIC1 blocker psalmotoxin 1?PcTX-1?.These two inhibitors exert an additive inhibitory effect on GBM cell migration.Furthermore,the inhibitory effect of AIP or PcTX-1 on migration was diminished in the GBM cells that were knocked down of ASIC1;while these two inhibitors applied together to these cells,the GBM cell migration was slightly,but significantly decreased.Using whole-cell patch-clamp recordings we detected an amiloride-sensitive current in GBM cells and this current was significantly inhibited by both PcTX-1 and AIP.Moreover,the magnitude of this current was dramatically decreased in the ASIC1 knockdown GBM cells,albeit addition of AIP failed to further decrease the amplitude of this current.These data together suggest that ASIC1 and CaMK? form a functional complex in GBM cells,and that CaMK? regulates the activity of ASIC1,and the activity of ASIC1 is associated with the migration ability of GBM cells.