The Regina Vasilatos-Younken laboratory is interested in the biological actions of growth hormone (GH), with emphasis on components of the signal transduction pathway that are essential for GH action.

We have found that chronic GH induces expression of JAK2 protein and tyrosine phosphorylation in liver and skeletal muscles, and that this expression is tissue-specific with respect to JAK2 isoforms. An important focus of our lab is on the metabolic effects of GH, specifically, regulation of hepatic type III iodothyronine deiodinase (5DIII) gene expression, and have found that GH decreases 5DIII message, ultimately resulting in a secondary hyperthyroid state in vivo, with loss of skeletal muscle mass.

Although GH has long been recognized to have direct metabolic effects, and is currently administered to non-GH deficient children and adults for therapeutic purposes, the unrecognized consequences for growth or even preservation of muscle mass may be significant. A recent new emphasis in our laboratory, in collaboration with Dr. Ramachandran's laboratory, is the role and regulation of adiponectin in avian models.