Patterns of gene expression following contact of sympathetic neurons with their myocyte targets. Rattus norvegicus

We identified 112 known genes and 150 expressed sequence tags (ESTs) showing more than a 1.3 fold change in target-exposed neurons compared to neurons grown in the absence of target. Expression of 36 genes and 49 ESTs was upregulated, while expression of 76 genes and 101 ESTs was downregulated by the presence of target during the culture period. Overall, these changes represented approximately 1.6% of the probe set. Keywords: Patterns of gene expression by neuron-target interaction Overall design: We investigated the molecular basis of the target-regulated growth inhibition program using DNA microarrays to analyze patterns of gene expression following contact of sympathetic neurons with their myocyte targets. Total RNA was isolated from sympathetic neurons cultured alone and from neurons isolated from myocyte co-cultures. The two neuron populations showed minimal levels of atrial natriutic peptide (ANF) mRNA, a myocyte marker, compared to myocyte-containing cultures, indicating a low level of myocyte contamination for neurons purified from co-cultures. Isolated total RNA was reverse transcribed, labeled with biotin by in vitro transcription and hybridized to an Affymetrix Rat Expression Set 230A microarray with 15,900 probe sets. The hybridized microarray was washed, stained, scanned and quantified using DNA-Chip Analyzer (dChip) 1.3 (Li and Wong, 2001).