Cloning of the prepro C-RFa gene and brain localization of the active peptide in Salmo salar

Cell Tissue Res (2006) 325: 277285

DOI 10.1007/s00441-006-0168-6REGULAR ARTICLER. A. Montefusco-Siegmund . A. Romero .G. Kausel . M. Muller . M. Fujimoto . J. FigueroaCloning of the prepro C-RFa gene and brain localization

of the active peptide in Salmo salarReceived: 25 November 2005 / Accepted: 20 January 2006 / Published online: 24 March 2006

# Springer-Verlag 2006Abstract In all vertebrates, the synthesis and release of

prolactin (Prl) from pituitary lactotroph cells is tightly

controlled by hypothalamic factors. We have cloned and

characterized a hypothalamic cDNA from Atlantic salmon

(Salmo salar) encoding C-RFa, a peptide structurally

related to mammalian Prl-releasing peptide (PrRP). The

deduced preprohormone precursor is composed of 155

amino acid residues presenting a 87.1% similarity to chum

salmon C-RFa and a 100% similarity to all fish C-RFa in

the bioactive precursor motifs. C-RFa-immunoreactive

perikarya and fibres were located in the brain of S. salar,

especially in the hypothalamus, olfactory tract, optic

tectum and cerebellum. In contrast, immunolabelled fibres

were not observed in the pituitary stalk or in the

hypophysis. However, interestingly, we detected immunolabelled cells in the rostral pars distalis of the pituitary in

the basolateral region in which Prl is synthesized. These

results were confirmed by obtaining a strong signal by

using reverse transcription/polymerase chain reaction (RTPCR) on mRNA from both hypothalamus and pituitary.

These data show, for the first time, by immunohistochemistry and RT-PCR, that C-RFa is produced in pituitary cells.

Finally, based on these results, a possible function for CRFa as a locally produced PrRP in this teleost is discussed.Keywords Hypothalamus . Pituitary . Rostral pars

distalis . C-RFa peptide . Immunohistochemistry .

Reverse transcription/polymerase chain reaction .

Salmo salar (Teleostei)This work was supported by grant no. 1040073 from FONDECYT,

Chile, by grant MECESUP AUS 0006 and by a grant from the

French Speaking Community of Belgium, University of Liege and

by AGCI, Chile.R. A. Montefusco-Siegmund . A. Romero .G. Kausel . J. Figueroa (*)

Instituto de Bioqumica, Facultad de Ciencias,

Universidad Austral de Chile,Casilla 567, Valdivia, Chilee-mail: [email protected].: [phone]Fax: [phone]M. MullerLaboratoire de Biologie Molculaire et de Gnie Gntique,

Universit de Lige,Institut de Chimie B6,B-4000, Sart-Tilman, BelgiumM. FujimotoDepartment of Biological Science,

Faculty of Life and Environmental Science,

Shimane University,Matsue, JapanIntroductionProlactin (Prl) plays a key role in freshwater adaptation

(Manzon 2002), immunomodulation...