Murine central and peripheral nervous system transcriptomes: comparative gene expression.
The central and peripheral nervous systems exhibit significant embryological, morphological, and functional differences. Moreover, the pathology of most acquired and hereditary neurological diseases preferentially targets specific components of the nervous system. In order to test the hypothesis that central and peripheral neural transcriptomes show fundamental quantitative differences, Affymetrix GeneChip expression arrays were used to compare murine lumbar spinal cord (SC) and dorsal root ganglion (DRG) gene expression. As the crucial component of a novel technique to preserve RNA integrity, mice were perfusion-fixed with RNAlater before the SC and DRG were harvested. As per Affymetrix terminology, a total of 111 transcripts were present (P) on all DRG arrays, absent (A) on all SC arrays, and demonstrated at least 10-fold greater expression in DRG than in SC. Conversely, a total of 112 transcripts were present on all SC arrays, absent on all DRG arrays, and showed at least 10-fold greater expression in SC than in DRG. For a subset of transcripts, quantitative real-time RT-PCR was used to corroborate and validate microarray results. Among those genes enriched in DRG, many belonged to a few distinct functional classes: G-protein coupled receptor-protein signaling pathways, potassium transport, sodium transport, sensory perception, and cell-surface receptor-linked signal transduction. In contrast, genes associated with synaptic transmission, organic acid transport, neurotransmitter transport, and circulation were enriched in SC. Notably, the majority of genes causally associated with hereditary neuropathies were highly enriched in DRG. These differential neural gene expression profiles provide a robust framework for future molecular and genetic studies of neuropathy and SC diseases.