SOCS1 and SOCS3 are the main negative modulators of the somatotrophic axis in liver of homozygous GH-transgenic zebrafish ( Danio rerio )

• Published in: General and comparative endocrinology Vol. 161; no. 1; pp. 67 - 72
• Main Authors: Studzinski, Ana Lupe Motta, Almeida, Daniela Volcan, Lanes, Carlos Frederico Ceccon, Figueiredo, Márcio de Azevedo, Marins, Luis Fernando
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2009
• Subjects: Animals; Animals, Genetically Modified; Danio rerio; Endocrinology & Metabolism; Freshwater; GH-transgenic zebrafish; Growth; Growth Hormone - physiology; Homozygote; Homozygous; Insulin-Like Growth Factor I - metabolism; Janus Kinase 2 - metabolism; Liver - drug effects; Liver - metabolism; Somatotrophic axis regulation; STAT5 Transcription Factor - metabolism; Suppressor of cytokine signaling; Suppressor of Cytokine Signaling 1 Protein; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins - physiology; Zebrafish - genetics; Zebrafish Proteins - metabolism; Zebrafish Proteins - physiology; Somatotrophic axis regulation; Suppressor of cytokine signaling; GH-transgenic zebrafish; Growth; Homozygous
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2008.10.008

Abstract Homozygote individuals (HO) of the GH-transgenic zebrafish lineage (F0104), despite expressing double the amount of growth hormone (GH) in relation to the hemizygote (HE) individuals, presented smaller growth in relation to the last, and similar to the non-transgenic (NT) group. Through the analysis of the expression of genes of the somatotrophic axis in the livers of HO and NT individuals, it was verified that GHR, JAK2 and STAT5.1 did not present significant differences among the analyzed genotypes (NT and HO). However, in the IGF-I gene expression, an accentuated decrease was observed in group HO ( p < 0.01), suggesting a resistance effect to excess GH. This resistance could be related to the insufficient amount of energy for supporting the accelerated metabolic demand caused by excess circulating GH. Analysis of the genes involved in the regulation of GH signalization by dephosphorylation (PTP-H1 and PTP-1B) did not show any significant alteration when comparing groups HO and NT. However, the analysis of the SOCS1 and SOCS3 genes showed an induction in homozygotes of 2.5 times ( p < 0.01) and 4.3 times ( p < 0.05), respectively, in relation to non-transgenics. The results of the present work demonstrate that, in homozygotes, GH signaling is reduced by the action of the SOCS1 and SOCS3 proteins.