Identification of a delta isoform of preprotachykinin mRNA in human mononuclear phagocytes and lymphocytes

We have characterized preprotachykinin (PPT-A) gene transcript splicing pro ducts and identified a fourth isoform of PPT-A mRNA transcript in human per ipheral blood-isolated monocytes and PBL. Using RT-PCR, Southern blot analy sis and nucleotide sequencing analysis, we have identified the four isoform s of PPT-A transcripts (alpha, beta, gamma and delta) in human peripheral b lood-isolated monocytes and PBL. The delta-PPT transcript present in the im mune cells lacks exons 4 and 6. The sequences of exons 3, 5 and 7 of delta- PPT transcript completely match those of beta-PPT transcript. The Phi-PPT a nd beta-PPT sequences in these cells are identical to those obtained by Tan and Too (GenBank accession number U37539) and Harmar et al. (Genbank acces sion number X54469), but differ by a single nucleotide from another entry b y Chiwakata et al. (Genbank accession number M68906). In comparison to this latter sequence, there was a C --> T change at amino acid position 87 (CCT --> CTT) which may result in a Pro to Leu change. Identification of the ne w SP mRNA transcript in both human CNS and immune cells supports the concep t of an important biological link between CNS and immune system. (C) 1998 E lsevier Science B.V. All rights reserved.