Meeting Abstract

P1.34  Tuesday, Jan. 4  The Hepatic Growth Hormone Receptors of Rainbow Trout Differentially Link to Signal Transduction Pathways REINDL, K.M.; KITTILSON, J.; JONES, E.; BERGAN, H.; SHERIDAN, M.A.*; North Dakota St. Univ., Fargo mark.sheridan@ndsu.edu

Previously, we characterized two growth hormone receptors (GHR) from rainbow trout that were differentially expressed. In this study, we examined the molecular signaling events of the rainbow trout GHRs. Salmonid GH (sGH) stimulated insulin-like growth factor-1 (IGF-1) mRNA expression in isolated hepatocytes in a time- and concentration-related manner. sGH also stimulated rapid (within 10 min) phosphorylation of Jak2, Erk1/2, and Akt; inhibitors of the JAK, ERK and Akt pathways blocked GH-stimulated IGF-1 expression. The rainbow trout GHRs, GHR1 and GHR2, were individually transfected into CHO-K1 cells. GHR1 preferentially activated JAK2/STAT5, whereas GHR2 preferentially activated Akt and ERK. These findings indicate that the JAK/STAT, ERK, and Akt pathways mediate GH-stimulated IGF-1 expression in trout hepatocytes and that the two GHRs of trout differentially link to the signal effector pathways. (This work was supported by NSF grant IOS 0920116.)