Pituitary and extrapituitary growth hormone: Pit-1 dependence?

Abstract

Growth hormone (GH) is primarily produced in pituitary somatotrophs. The synthesis of this hormone is thought to be dependent upon a pituitary-specific transcription factor (Pit-1). However, many extrapituitary tissues are now known to express GH genes. The extrapituitary production of GH may therefore indicate an extrapituitary distribution of the Pit-1 gene. The extrapituitary production of GH may, alternatively, indicate that GH expression occurs independently of Pit-1 in extrapituitary tissues. These possibilities are considered in this brief review.

Characterization of the 5' flanking region of the growth hormone gene of the marine teleost, gilthead sea bream Sparus aurata: analysis of a polymorphic microsatellite in the proximal promoter

“…These motifs were included because it is now well established that GH gene expression is not restricted to the pituitary gland and occurs in many extrapituitary tissues. 41,42 Extrapituitary expression of the GH gene was also reported in numerous fish tissues: in intestine, brain, gill, heart and peripheral blood leukocytes. [43][44][45] However, the regulation of GH expression in extrapituitary tissues is very different from that in the pituitary gland and is not dependent on Pit-1 presence as it is in the pituitary gland.…”

“…[43][44][45] However, the regulation of GH expression in extrapituitary tissues is very different from that in the pituitary gland and is not dependent on Pit-1 presence as it is in the pituitary gland. 41 Since the promoter region of the GH gene is not altered in extrapituitary tissues, we can speculate that transcription factors (TF) not specific to the pituitary gland could bind to the promoter region to induce extrapituitary GH expression. The putative TF binding sites listed above are known to be expressed in the same tissues that express GH.…”

Peptide hormones as developmental growth and differentiation factors

“…While the expression of pituitary GH is thought to be exclusively under the control of the transcription factor, Pit‐1, the extra‐pituitary expression of GH in the embryo may be Pit‐1‐independent in some regions (Harvey et al,2000b), for example in the early chick embryo spinal cord where GH expression colocalizes with Pit‐1 in some regions, but not in others (Fig. 1).…”

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“…(15,16). During the embryogenesis stages, the growth hormones were found in the brain of the chicken and rats embryo (17). The amino acid (Arg) decreases in the telencephalon and diencephalon in the chicken at the stress and fasting as well as the effect of the high degree of environmental temperature on the amino acids concentrations in the brains of young chickens.…”

“…These molecules have been found in human embryos, mice, rats, chickens and frog were marked by the mediation of the single monoclonal antibodies and it contains the sialic acid rich in carbohydrates and that the series of amino acids have similar types and are found during the period of histogensis (19). The current research objective is to identify the concentration of amino acids in the brains of the quail embryos (10,11,12,13,14,15,16,17) days of incubation as well as adult.…”