Meeting Abstract

97.8  Wednesday, Jan. 7  Characterization of Serum and Glucocorticoid Induced Kinases (SGK) in a teleost fish, the Mozambique tilapia (Oreochromis mossambicus) JOHNSTONE III, W. M. *; BALTZEGAR, D. A.; BORSKI, R. J.; North Carolina State University, Raleigh; North Carolina State University, Raleigh; North Carolina State University, Raleigh wmjohnst@unity.ncsu.edu

Serum and glucocorticoid kinase (SGK) is a Serine/Threonine kinase belonging to the AGC [cAMP-dependant protein kinase (PKA), protein kinase G, protein kinase C (PKC)] kinase family. SGK is an immediate early response gene inducible by a plethora of stimuli including, but not limited to glucocorticoids, mineralcorticoids, cell shrinkage, cell swelling, various growth factors, DNA damage, stress, and p53. The structure and regulation of SGK has yet to be characterized in teleost fishes. We have cloned the full transcript of the SGK1 (1296 bp) isoform in the euryhaline Mozambique Tilapia. Using CLUSTALX alignment, we show that tilapia SGK1 shares 98% and 92% homology with the human and mouse isoform at the transcript and protein level, respectively. Classic structures associated with the AGC family of kinases, including a conserved ATP binding domain and active site have also been identified. We also cloned a 510 and 535 bp partial coding regions of two other isoforms identified as SGK2 and SGK3, respectively. We show that the gene for SGK1 is expressed in the teleost gill, heart, kidney, posterior intestine, brain, and pituitary. It is our hypothesis that SGK and its downstream mediators are integral in the ability of euryhaline fish to osmoregulate when faced with environmental salinity fluctuations.