Dual regulation of NR2B and NR2C expression by NMDA receptor activation in mouse cerebellar granule cell cultures

Abstract

In the developing cerebellum, switching of the subunit composition of NMDA receptors occurs in granule cells from NR2B-containing receptors to NR2C-containing ones. We investigated the mechanisms underlying switching of NR2B and NR2C subunit composition in primary cultures of mouse granule cells at the physiological KCl concentration (5 mM). Granule cells extensively extended their neuritic processes 48 h after having been cultured in serum-free medium containing 5 mM KCl. Consistent with this morphological change, NR2B mRNA and NR2C mRNA were down- and up-regulated, respectively, in the granule cells. This dual regulation of the two mRNAs was abrogated by blocking excitation of granule cells with TTX. This neuronal activity–dependent regulation of NR2B and NR2C mRNAs was abolished by the addition of selective antagonists of AMPA receptors and NMDA receptors. Furthermore, the dual regulation of NR2B and NR2C mRNAs in TTX-treated cells was restored by the addition of NMDA in the presence of the AMPA receptor antagonist, but not by that of AMPA in the presence of the NMDA receptor antagonist. Importantly, the NMDA receptor activation drove the NR2B/NR2C switching of NMDA receptors in the cell-surface membrane of granule cells. This investigation demonstrates that stimulation of NMDA receptors in conjunction with the AMPA receptor–mediated excitation of granule cells plays a key role in functional subunit switching of NMDA receptors in maturing granule cells at the physiological KCl concentration.

Glutamate Receptor Ion Channels: Structure, Regulation, and Function

“…Thus, convergent mechanisms of the BDNF and Ca 2ϩ signaling cascades are important for GluN2C induction in granule cells during development (Suzuki et al, 2005). NMDA receptor activation was shown to coordinate both the up-regulation of GluN2C and the down-regulation of GluN2B mRNA, including a switch of GluN2 subunit associated with cell surface NMDA receptors in cultured mouse granule cells (Iijima et al, 2008). Although much has been learned about the signal transduction pathways leading to receptor subunit changes in granule cells, the promoter control elements responsible for transcription subunit switching remain to be identified.…”

The Etv1/Er81 transcription factor orchestrates activity-dependent gene regulation in the terminal maturation program of cerebellar granule cells

“…Granule cells were cultured for 24 h in medium containing serum and then for 96 h in serum-free medium containing a physiological concentration of KCl (5 mM KCl) in the presence or absence of the indicated inhibitors (7). The addition of the inhibitors used did not affect cell viability at least up to 96 h in culture (9,32). TTX, CPP, NBQX, NNC 55-0396, and nifedipine were obtained from Tocris; ω-agatoxin TK and ω-conotoxin GVIA were obtained from Peptide Institute.…”

Differential Roles of NMDA Receptor Subtypes NR2A and NR2B in Dendritic Branch Development and Requirement of RasGRF1

“…The precise subunit combination determines the physiological and pharmacological properties of the receptor, their binding partners and downstream signaling effects (Cull-Candy and Leszkiewicz 2004;Sheng and Kim 2002;van Zundert et al 2004b). Important details about the function of the NR2C-D (Brickley et al 2003;Harney et al 2008;Iijima et al 2008) and NR3A-B subunits (Nishi et al 2001;Roberts et al 2009;Ulbrich and Isacoff 2008) are only recently emerging, whereas considerable evidence points to a central role of the NR2A and NR2B subunits in regulating plasticity. Because a close correlation was found between the timing of the critical period for structural plasticity and the switch from slow NR2B-mediated currents to fast decaying NR2A-mediated currents across a variety of brain regions (Carmignoto and Vicini 1992;Flint et al 1997;Roberts and Ramoa 1999), it has been proposed that the NR2B subunit allows dynamic synaptic changes, whereas the NR2A subunit increases temporal resolution hereby inducing refinement of the CNS (Scheetz and Constantine-Paton 1994).…”