Molecular cloning of proopiomelanocortin cDNA and multi-tissue mRNA expression in channel catfish

Attila Karsi, Geoffrey C. Waldbieser, Brian C. Small, Zhanjiang Liu, William R. Wolters

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Channel catfish (Ictalurus punctatus) proopiomelanocortin (POMC) cDNA was cloned to investigate its structure, evolution, and expression in different tissues. POMC is an important gene in the hypothalamus-pituitary-adrenal axis, the main mediator of the stress response. POMC gene was isolated from a pituitary cDNA library and nucleotide sequence was determined. POMC cDNA is composed of 1164 nucleotides with a 639 nucleotide open reading frame encoding a protein of 212 amino acids. Catfish POMC protein contains a signal peptide (SP, Met1-Ala28), N-terminal peptide (Gln29- Glu101), adrenocorticotropic hormone (ACTH, Ser104- Met142), α-melanocyte stimulating hormone (α-MSH, Ser104-Val116), corticotropin-like intermediate lobe peptide (CLIP, Arg121-Met142), β-lipotropin (β-LPH, Glu145-His212), γ-lipotropin (γ-LPH, Glu145- Ser177), β-MSH (Asp 161-Ser177), and β-endorphin (β-EP, Tyr 180-His212). Catfish POMC protein does not contain a γ-MSH region and most of the joining peptide and part of the γ-LPH are deleted. Protein sequence alignment showed the highest similarity with the carp (Cyprinus carpio) POMC I (66.5%) and POMC II (67%), while the sea lamprey (Petromyzon marinus) POC (17.9%) and POM (18.8%) were the most divergent. The average similarity was 46.95% among the 44 POMC proteins from 36 different species analyzed. Compared to the POMC mRNA levels in the pituitary, the concentration of the POMC mRNA was 0.0594% in the anterior kidney and 0.0012-0.0045% in all the other tissues except in the skin where the lowest expression (0.0005%) was observed. Overall architecture of channel catfish POMC is highly similar to those from other teleosts.

Original languageEnglish (US)
Pages (from-to)312-321
Number of pages10
JournalGeneral and Comparative Endocrinology
Volume137
Issue number3
DOIs
StatePublished - Jul 2004
Externally publishedYes

Keywords

  • ACTH
  • Fish
  • MSH
  • Pituitary
  • Stress
  • β-Endorphin

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology

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