Transcription of human neuronal nitric oxide synthase mRNAs derived from different first exons is partly controlled by exon 1-specific promoter sequences

The human neuronal nitric oxide synthase (NOSI) gene is subject to extensive splicing. A total of 12 NOSI mRNA species have been identified. They differ in their 5' ends and are derived from 12 different first exons (termed exons Ia to II). Various cell lines whose NOSI first exon expression patterns were representative of human brain, skin, and skeletal muscle were identified. These included A673 neuroepithelioma cells, SK-N-MC neuroblastoma cells, HaCaT keratinocyte-like cells, and C2C12 myocyte-like cells. In these cell lines, correlations were found between the exon I variants preferentially expressed and the promoter activities of their cognate 5' flanking sequences. These data demonstrate that expression of the different exon I-related splice variants of NOSI mRNA is controlled directly (at least in part) by the associated 5' flanking sequences. (c) 2005 Elsevier Inc. All rights reserved.