Characterization of growth hormone (GH) in Chinese soft shelled turtle: Molecular identification, capability in activating GH receptor and tissue distribution
Abstract Growth hormone (GH) participates in many physiological processes through the activation of its membrane anchored receptor (GHR) in vertebrates. Because of its pivotal role in regulating growth and development, a large number of studies examining GH GHR have been conducted in mammals, birds and fish. However, whether a functional GH GHR pair exists in the Chinese soft shelled turtle (st has not been previously studied. Here, the full length cDNA encoding GH was cloned from Chinese soft shelled turtle (Trionyx sinensis) pituitary. The results revealed that it consisted of 784 bp and encoded a precursor of 217 amino acids. Furthermore, recombinant stGH was prepared and purified from Escherichia coli (E. coli) strain BL21. Using the 5xSTAT5 Luciferase reporter system, we found that stGHR expressed in human hepatocellular carcinoma cells could be activated in a dose dependent manner by recombinant stGH, thereby triggering the intracellular JAK2 STAT5 signaling pathway, suggesting stGH is a functional ligand for stGHR. Quantitative real time PCR revealed that GH mRNA was predominantly and abundantly expressed in pituitary, while GHR exhibited ubiquitous expression in all tissues examined, including pituitary and liver. Collectively, our data indicate a conserved GH GHR pair might function in reptiles including Chinese soft shelled turtle, as that in mammals, birds and fishes.