title: Molecular cloning of proopiomelanocortin cDNA and multi-tissue mRNA expression in channel catfish.
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, Met(1)-Ala(28)), N-terminal peptide (Gln(29)-Glu(101)), adrenocorticotropic hormone (ACTH, Ser(104)-Met(142)), alpha-melanocyte stimulating hormone (alpha-MSH, Ser(104)-Val(116)), corticotropin-like intermediate lobe peptide (CLIP, Arg(121)-Met(142)), beta-lipotropin (beta-LPH, Glu(145)-His(212)), gamma-lipotropin (gamma-LPH, Glu(145)- Ser(177)), beta-MSH (Asp(161)-Ser(177)), and beta-endorphin (beta-EP, Tyr(180)-His(212)). Catfish POMC protein does not contain a gamma-MSH region and most of the joining peptide and part of the gamma-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.
authors.affiliation: USDA-ARS Catfish Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, P.O. Box 38, Stoneville, MS 38776, USA. karsi@cvm.msstate.edu
authors.forename: Attila
authors.initials: A
authors.lastname: Karsi
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Waldbieser
authors.forename: Brian C
authors.initials: BC
authors.lastname: Small
authors.forename: Zhanjiang
authors.initials: Z
authors.lastname: Liu
authors.forename: William R
authors.initials: WR
authors.lastname: Wolters
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D053497:Corticotropin-Like Intermediate Lobe Peptide; D018076:DNA, Complementary / Q000235:genetics*; D015870:Gene Expression; D015723:Gene Library; D007059:Ictaluridae / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009928:Organ Specificity; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011333:Pro-Opiomelanocortin / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D016415:Sequence Alignment; D017421:Sequence Analysis; D000521:alpha-MSH / Q000737:chemistry / Q000235:genetics; D001615:beta-Endorphin / Q000737:chemistry / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D010446:Peptide Fragments; D012333:RNA, Messenger; D053497:Corticotropin-Like Intermediate Lobe Peptide; D000521:alpha-MSH; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone