Growth hormone receptor and binding protein characterization in Pejerrey (Odontesthes bonariensis)

BOTTA, PABLO; SCIARA, ANDRÉS A.; ARRANZ, S.E.

Carlos Paz, Córdoba

Congreso; 44th Annual Meeting SAIB; 2008

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Growth hormone (GH) is a pluripotent regulator involved in metabolism and growth in vertebrates. The biological effects of GH depend on the target tissue, the number of receptors in the target cell, and the blood free GH concentration that depends on the presence of a growth hormone-binding protein (GHBP). GHBP was described in  tetrapods and is a soluble version of the growth hormone receptor (GHR) that arise from alternative splicing of  the mRNA or from the proteolytic cleavage of the receptor. In fishes, two different genes encoding for GHR (ghr1 and) were described. We are particularly interested in the endocrinology of growth in pejerrey. The aim of the present work is to characterize ghr1 and ghr2 genes, their expression patterns, and to determine the existence of a GHBP in pejerrey. We isolated and sequenced two fragments of 1240 and 1640bp cDNAs corresponding to GHR1 and GHR2  transcripts respectively, that showed 83% and 79% identity with ghr1 y ghr2 transcripts of E. coioides (Perciformes) respectively. Both transcripts were detected in 10 tested tissues, by RT-PCR analysis. In order to determine the presence of a GHBP in pejerrey, we performed an affinity chromatography using pjGH as a ligand. We isolated a single polypeptide of 68 kDa from serum that could correspond to the GHBP. Further tandem mass spectrometry analysis should be done to elucidate the protein identity.