Characterization of pituitary growth hormone and its receptor in the green iguana (Iguana iguana).
Pituitary growth hormone (GH) has been studied in most vertebrate groups; however, only a few studies have been carried out in reptiles. Little is known about pituitary hormones in the order Squamata, to which the green iguana (gi) belongs. In this work, we characterized the hypophysis of Iguana iguana morphologically. The somatotrophs (round cells of 7.6-10 μm containing 250- to 300-nm secretory granules where the giGH is stored) were found, by immunohistochemistry and in situ hybridization, exclusively in the caudal lobe of the pars distalis, whereas the lactotrophs were distributed only in the rostral lobe. A pituitary giGH-like protein was obtained by immuno-affinity chromatography employing a heterologous antibody against chicken GH. giGH showed molecular heterogeneity (22, 44, and 88 kDa by SDS-PAGE/Western blot under non-reducing conditions and at least four charge variants (pIs 6.2, 6.5, 6.9, 7.4) by isoelectric focusing. The pituitary giGH cDNA (1016 bp), amplified by PCR and RACE, encodes a pre-hormone of 218 aa, of which 190 aa correspond to the mature protein and 28 aa to the signal peptide. The giGH receptor cDNA was also partially sequenced. Phylogenetic analyses of the amino acid sequences of giGH and giGHR homologs in vertebrates suggest a parallel evolution and functional relationship between the GH and its receptor.
Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Qro. 76230, Mexico.
José
J
Ávila-Mendoza
Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Qro. 76230, Mexico.
Martha
M
Carranza
Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Campus Morelos, Cuernavaca, Mor. 62210, Mexico.
Ernesto
E
Pérez-Rueda
Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Qro. 76230, Mexico.
Maricela
M
Luna
Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Qro. 76230, Mexico. Electronic address: aramburo@unam.mx.
Carlos
C
Arámburo
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism*; D007076:Iguanas / Q000235:genetics* / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D010902:Pituitary Gland / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D052683:Somatotrophs / Q000378:metabolism
D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D013006:Growth Hormone
Green iguana; Growth hormone; Growth hormone receptor; Order squamata; Pituitary; cDNA cloning