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Fourth isoform of preprotachykinin messenger RNA encoding for substance P in the rat intestine

I Khan1, S M Collins

  • 1Department of Medicine, McMaster University, Hamilton, Ontario, Canada.

Biochemical and Biophysical Research Communications
|July 29, 1994
PubMed

Insights

Researchers discovered a fourth preprotachykinin messenger RNA (PPT mRNA) isoform, primarily found in the gut and brain. Its levels significantly increased during experimental colitis in rats.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Gastroenterology

Background:

  • Three isoforms of preprotachykinin mRNA (PPT mRNA) are known to encode substance P and related neuropeptides.
  • The discovery of novel mRNA isoforms can reveal new biological functions and regulatory mechanisms.

Purpose of the Study:

  • To identify and characterize a novel fourth isoform of PPT mRNA.
  • To investigate the tissue distribution of this new isoform.
  • To determine the changes in its expression levels during experimental colitis.

Main Methods:

  • RT-PCR and Northern blot analysis were used to detect and characterize the novel PPT mRNA isoform.
  • Tissue samples from rat ileum, jejunum, colon, heart, brain, kidney, and uterus were analyzed.
  • Experimental colitis was induced in rats using trinitrobenzene sulfonic acid (TNBS).

Main Results:

  • A fourth PPT mRNA isoform, generated by alternative exclusion of exon-7 and exon-6, was identified.
  • This isoform was predominantly expressed in the ileal smooth muscle and mucosa, colon, heart, and brain.
  • Lower levels were detected in jejunal smooth muscle and mucosa, but it was absent in the kidney and uterus.
  • Expression of this PPT mRNA isoform increased by 60% in rats with TNBS-induced colitis.

Conclusions:

  • A novel fourth isoform of PPT mRNA exists, with a distinct tissue distribution.
  • The increased expression of this isoform during colitis suggests a potential role in inflammatory bowel disease.

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