General and Comparative Endocrinology 137 (2004) 312–321 www.elsevier.com/locate/ygcen 0016-6480/$ - see front matter  2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ygcen.2004.03.012 Communications in Genomics and Proteomics Molecular cloning of proopiomelanocortin cDNA and multi-tissue mRNA expression in channel cat Wsh Attila Karsi, a,¤ GeoVrey C. Waldbieser, a Brian C. Small, a Zhanjiang Liu, b and William R. Wolters a a USDA-ARS CatWsh Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, P.O. Box 38, Stoneville, MS 38776, USA b The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Auburn University, Auburn, AL 36849, USA Received 18 November 2003; revised 17 March 2004; accepted 22 March 2004 Available online 17 April 2004 Abstract Channel catWsh (Ictalurus punctatus) proopiomelanocortin (POMC) cDNA was cloned to investigate its structure, evolution, and expression in diVerent 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. CatWsh 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 ), -melanocyte stimulating hormone (-MSH, Ser 104 –Val 116 ), corticotropin-like intermediate lobe peptide (CLIP, Arg 121 – Met 142 ), -lipotropin (-LPH, Glu 145 –His 212 ), -lipotropin (-LPH, Glu 145 – Ser 177 ), -MSH (Asp 161 –Ser 177 ), and -endorphin (-EP, Tyr 180 –His 212 ). CatWsh POMC protein does not contain a -MSH region and most of the joining peptide and part of the -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 diVerent 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 catWsh POMC is highly similar to those from other teleosts.  2004 Elsevier Inc. All rights reserved. Keywords: Fish; Pituitary; ACTH; MSH; -Endorphin; Stress 1. Introduction The vertebrate endocrine system is activated in response to external and/or internal changes sensed as stressful. These changes are detected by the central ner- vous system and immune system, and responded to by the main mediator hypothalamic–pituitary–adrenal axis (HPA) in which proopiomelanocortin (POMC) derived peptides play an important role (Slominski et al., 2000). In the pituitary of mammalian species, POMC is mainly expressed in the corticotrope cells of the pars distalis and melanotrope cells of the pars intermedia. Lobe-speciWc processing and post-translational modiWcations of the precursor protein yield biologically active peptides including adrenocorticotropic hormone (ACTH), mela- nocyte stimulating hormones (MSH), and -endorphin (-EP, Castro and Morrison, 1997; Smith and Funder, 1988). In general, mammals transcribe only one POMC gene (Drouin et al., 1989) although two non-allelic forms of POMC gene have been detected in some Wsh species. Agnathan lamprey (P. marinus) ACTH and MSHs are encoded separately by two distinct POMCs, proopiocortin (POC) and proopiomelanotropin (POM, Heinig et al., 1995; Takahashi et al., 1995). Duplicated ¤ Corresponding author. Present address: College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762-6100, USA. Fax: 1-662-325-1031. E-mail address: karsi@cvm.msstate.edu (A. Karsi).