A novel calcitonin carboxyl-terminal peptide produced in medullary thyroid carcinoma by alternative RNA processing of the calcitonin/calcitonin gene-related peptide gene.

Abstract

The calcitonin/calcitonin gene-related peptide gene expresses two different mRNAs by tissue-specific alternative processing. The calcitonin mRNA is produced in thyroid C cells by splicing of the first three exons to the fourth polyadenylated exon. It encodes a protein precursor containing an amino-terminal peptide, calcitonin, and a carboxyl-terminal peptide (CCP I). Calcitonin gene-related peptide (CGRP) mRNA is produced in neuronal cells by splicing of the three common exons to the fifth exon and the polyadenylated sixth exon, leading to the production of a CGRP precursor. Our studies concerning the expression of the calcitonin/CGRP gene in human medullary thyroid carcinoma revealed the presence of a new RNA transcript. Amplification by polymerase chain reaction and direct sequencing showed that the novel transcript is composed of exons 1, 2, and 3, part of exon 4, exon 5, and a polyadenylated exon 6. This transcript contains an open reading frame coding for the known amino-terminal and calcitonin peptides, as well as for a novel calcitonin carboxyl-terminal peptide, CCP II. This third alternative pathway utilizes an internal donor site within the exon coding for calcitonin. The presence of CCP II was demonstrated in plasma and thyroidal tissues of medullary thyroid carcinoma patients, implying that this novel mRNA is actively translated in medullary thyroid carcinoma.

• Authors: S Minvielle, S Giscard-Dartevelle, R Cohen, J Taboulet, F Labye, A Jullienne, P Rivaille, G Milhaud, M S Moukhtar, F Lasmoles
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 266 Issue 36 Pg. 24627-31 (Dec 25 1991) ISSN: 0021-9258 [Print] United States
• PMID: 1761559 (Publication Type: Journal Article)

Chemical References

• DNA, Neoplasm
• Peptide Fragments
• RNA, Messenger
• RNA, Neoplasm
• katacalcin
• Calcitonin
• Calcitonin Gene-Related Peptide

Topics

• Amino Acid Sequence
• Base Sequence
• Blotting, Northern
• Calcitonin (biosynthesis, blood, metabolism)
• Calcitonin Gene-Related Peptide (genetics)
• Chromatography, Affinity
• DNA, Neoplasm
• Exons
• Humans
• Immunohistochemistry
• Molecular Sequence Data
• Peptide Fragments (biosynthesis, blood, metabolism)
• Polymerase Chain Reaction
• Protein Biosynthesis
• RNA Splicing
• RNA, Messenger (metabolism)
• RNA, Neoplasm (metabolism)
• Thyroid Neoplasms (genetics, metabolism)
• Transcription, Genetic