Artificial Orchestration of Functional NMDAR Channels in HEK293 Cells

摘要

The essential importance of the present findings is that introduction of either NR3A or NR3B subunit alone was ineffective in preventing the increases in mitochondrial Ca~(2+) levels determined by Rhod-2 and intracellular free Ca~(2+) levels determined by Fluo-3, in addition to the increased cell death, in HEK293 cells with acquired NMDAR channels composed of NR1/NR2A and NR1/NR2B subunits. The findings that co-introduction of both NR3A and NR3B subunits invariably prevented the increases in those 3 biological responses mediated by NMDAR channels give strong support to the proposal that simultaneous co-expression of both NR3A and NR3B subunits is absolutely required for the efficient elicitation of dominant negative properties on Ca~(2+) influx across functional NMDAR channels in cell surface. Several independent lines of evidence indicate that incorporation of NR3 subunits into conventional NMDAR leads to smaller unitary conductance states and decreases in current amplitude, Ca~(2+) permeability and Mg~(2+) sensitivity in Xenopus oocytes (Ciabarra et al, 1995; Sucher et al, 1995; Das et al, 1998).