Expression and regulation of kainate and AMPA receptors in the rat neural tube

Abstract

We analyzed the expression and regulation of glutamate receptor subunits in the rat neural tube (10 day embryos) and in cell cultures derived from this tissue. In the cultures, all cells were stained with antibodies against the neural progenitor marker nestin. More than 50% of the cells were also stained by the monoclonal antibodies LB1 or A2B5, which bind to neuronal and glial progenitors. Approximately 6% of the cells were stained with antibodies for the low affinity NGF receptor, a neural crest cell marker. A small percentage of cells differentiated to neurons or astrocytes, as determined by staining with anti-neurofilament and anti-GFAP antibodies, respectively. RT-PCR analysis of neural tube tissue and culture mRNAs demonstrated that the AMPA receptor subunits GluR3 and 4 and the kainate receptor subunits GluR6, 7, KA1 and KA2 were detectable at E10. The kainate receptor subunits GluR6 and KA2 were upregulated by culture conditions which stimulated cell differentiation, as determined by concomitant downregulation of nestin mRNA. Both in neural tube tissue and in cultured cells, GluR6 was 100% unedited. Finally, both GluR6 and KA2 proteins could be detected in subpopulations of neural progenitors and differentiated neurons. Our data indicate that kainate receptor genes are expressed in undifferentiated progenitor cells of the neural tube at E10, and are upregulated during neural cell differentiation.

Glutamate antagonists limit tumor growth

“…Ca 2ϩ is also essential for formation of cell processes; it regulates axon extension and pathfinding, controls formation of pseudopodia, and affects migration (26)(27)(28)(29). Glutamate receptor͞ion channel complexes, including the embryonic ones, are permeable to Ca 2ϩ (30)(31)(32).…”

Glutamate antagonists limit tumor growth

“…Ca 2ϩ is also essential for formation of cell processes; it regulates axon extension and pathfinding, controls formation of pseudopodia, and affects migration (26)(27)(28)(29). Glutamate receptor͞ion channel complexes, including the embryonic ones, are permeable to Ca 2ϩ (30)(31)(32). Little is known about functional properties of receptor͞ion channel complexes on tumor cells responding to glutamate.…”

Characterization of the Rat GRIK5 Kainate Receptor Subunit Gene Promoter and Its Intragenic Regions Involved in Neural Cell Specificity

“…KA2 transcripts can be detected in the rat as early as embryonic day 10 (E10) in the neural tube (32) and at E12 in the cortical plate (9). These findings suggest that KA2 may play a developmental role prior to synapse formation (33).…”

“…Poly(A) ϩ RNAs were purified by an Oligotex kit (QIAGEN Inc.). RNA samples (2 g/lane) were resolved by electrophoresis through a formaldehyde-containing 1% denaturing agarose gel, electrotransferred to Nytran membranes (Schleicher & Schü ll), crosslinked to the membranes by UV irradiation (Stratalinker, Stratagene), and hybridized with a random-primed [␣- 32 P]dCTP-labeled EcoRI-StuI KA2 cDNA fragment (595 bp). The specific activity of the probe was 10 8 cpm/g of DNA.…”