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Identification of a delta isoform of preprotachykinin mRNA in human mononuclear phagocytes and lymphocytes
J P Lai1, S D Douglas, E Rappaport
1Joseph Stokes Jr. Research Institute at the Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania Medical School, 19104, USA.
Abstract:
We have characterized preprotachykinin (PPT-A) gene transcript splicing products and identified a fourth isoform of PPT-A mRNA transcript in human peripheral blood-isolated monocytes and PBL. Using RT-PCR, Southern blot analysis and nucleotide sequencing analysis, we have identified the four isoforms of PPT-A transcripts (alpha, beta, gamma and delta) in human peripheral blood-isolated monocytes and PBL. The delta-PPT transcript present in the immune 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 alpha-PPT and beta-PPT sequences in these cells are identical to those obtained by Tan and Too (GenBank accession number U37539) and Harmar et al. (Genbank accession number X54469), but differ by a single nucleotide from another entry by 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 new SP mRNA transcript in both human CNS and immune cells supports the concept of an important biological link between CNS and immune system.
Insights
Researchers identified a fourth preprotachykinin (PPT-A) mRNA transcript isoform, delta-PPT, in human immune cells. This discovery highlights a potential biological connection between the central nervous system (CNS) and the immune system.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Preprotachykinin A (PPT-A) gene encodes neuropeptides involved in various physiological processes.
- Alternative splicing of mRNA transcripts leads to different PPT-A isoforms with potentially distinct functions.
- Understanding PPT-A transcript diversity is crucial for elucidating its role in both the central nervous system (CNS) and immune system.
Purpose of the Study:
- To characterize the splicing products of the preprotachykinin (PPT-A) gene.
- To identify and analyze novel PPT-A mRNA transcript isoforms in human immune cells.
- To investigate the implications of these findings for the relationship between the CNS and immune system.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) to detect and amplify PPT-A transcripts.
- Southern blot analysis for transcript characterization.
- Nucleotide sequencing to determine the precise structure of identified isoforms.
Main Results:
- Four isoforms of PPT-A transcripts (alpha, beta, gamma, and delta) were identified in human peripheral blood monocytes and peripheral blood lymphocytes (PBL).
- The novel delta-PPT transcript lacks exons 4 and 6, with conserved sequences in exons 3, 5, and 7 matching the beta-PPT transcript.
- A single nucleotide difference (C-->T) was observed in the alpha-PPT and beta-PPT sequences compared to a previously reported entry, potentially altering amino acid 87 (Pro to Leu).
Conclusions:
- The identification of the delta-PPT mRNA transcript in immune cells provides new insights into PPT-A gene expression.
- The presence of SP (Substance P) mRNA transcripts in both CNS and immune cells supports a significant biological link between these systems.
- Further research is warranted to explore the functional significance of the delta-PPT isoform and its role in neuro-immune interactions.