This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takeuchi, S. Articles by Takahashi, S. Search for Related Content PubMed PubMed Citation Articles by Takeuchi, S. Articles by Takahashi, S.

Identification of a Novel GH Isoform: A Possible Link between GH and Melanocortin Systems in the Developing Chicken Eye

Department of Biology, Faculty of Science, Okayama University, Okayama 700-8530, Japan

Address all correspondence and requests for reprints to: Sakae Takeuchi, Ph.D., Department of Biology, Faculty of Science, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan. E-mail: stakeuch{at}cc.okayama-u.ac.jp

GH is considered to play a role in the pathogenesis of diabetic retinopathy, causing neovascularization in the retina. The present study was conducted to assess the possibility that GH may play a role in ocular development by determining whether GH is expressed in the eye of the chicken during development. In the 17-d-old embryo, immunocytochemistry detected immunoreactive GH in retinal pigment epithelial (RPE) cells. Characterization of GH mRNA expressed in the eye by RT-PCR and rapid amplification of cDNA 5'-ends revealed it to be a novel GH mRNA transcribed from the middle of the intron 3 of the chicken GH (cGH) gene. The deduced protein, designated small GH isoform (s-cGH), was a cytosolic protein of 16.5 kDa with 140 amino acid (aa) residues, lacking the signal peptide and the N-terminal 71 aa residues of 22-kDa cGH, replacing them with 20 aberrant aa residues, and identical to 22-kDa cGH for the C-terminal 120-aa residue portion. Western blotting determined the molecular size of immunoreactive GH in RPE cells to be 80–84 kDa, similar to the computed molecular mass of s-cGH/GH receptor complex. Furthermore, RT-PCR demonstrated that GH receptor mRNA, but not s-cGH mRNA, was expressed in RPE cells. These results suggest that RPE cell is one of the target cells of s-cGH in the eye. During embryonic development, the immunoreactivity for s-cGH in RPE cells was initially observed on embryonic d 10, and the staining intensity increased and peaked on embryonic d 17. By hatching, s-cGH immunoreactivity in RPE cells was gradually decreased, and it was not detectable after hatching. This ontogenetic staining pattern correlates well with the pattern of the production of MSH in RPE cells. The cell type expressing s-cGH remains to be identified; however, our findings imply a possible involvement of GH in the regulation of ocular development by acting on the intraocular melanocortin system in the chicken.

This article has been cited by other articles:

				M. A Zmijewski, R. K Sharma, and A. T Slominski Expression of molecular equivalent of hypothalamic-pituitary-adrenal axis in adult retinal pigment epithelium J. Endocrinol., April 1, 2007; 193(1): 157 - 169. [Abstract] [Full Text] [PDF]

				M.-L. Baudet, B. Martin, Z. Hassanali, E. Parker, E. J. Sanders, and S. Harvey Expression, Translation, and Localization of a Novel, Small Growth Hormone Variant Endocrinology, January 1, 2007; 148(1): 103 - 115. [Abstract] [Full Text] [PDF]

				E. J. Sanders, M. A. Walter, E. Parker, C. Aramburo, and S. Harvey Opticin Binds Retinal Growth Hormone in the Embryonic Vitreous Invest. Ophthalmol. Vis. Sci., December 1, 2003; 44(12): 5404 - 5409. [Abstract] [Full Text] [PDF]

				M.-L. Baudet, E. J. Sanders, and S. Harvey Retinal Growth Hormone in the Chick Embryo Endocrinology, December 1, 2003; 144(12): 5459 - 5468. [Abstract] [Full Text] [PDF]