Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V86
J. Ballesteros (1), M. H. Ögmundsdóttir (1), B. Phung (2), L. Rönnstrand (2), E. Steingrímsson (1)
"1. Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Reykjavík, Iceland; 2. Division of Translational Cancer Research, Stem Cell Center, Department of Laboratory Medicine, Lund University, Lund, Sweden"
Kynnir / Presenter: Josue Ballesteros
Tengiliður / Corresponding author: Josue Ballesteros (jab7@hi.is)
MAPkinase pathway has been suggested to phosphorylate MITF residues Ser73 and Ser409, affecting transcription activation ability and stability of MITF. Since MITF is downstream of the BRAF pathway, activated in 50% of melanomas, it is important to characterize the pathways involved. Inhibiting BRAF does not affect MITF phosphorylation, suggesting that other pathways are involved. Interestingly, phosphorylation of Ser73 depends upon phosphorylation of Ser409, suggesting inter- or intramolecular interactions. This project aims to characterize the signaling pathways involved in mediating signals to MITF and how Ser73 phosphorylation depends on Ser409 and the functional significance of these residues. We show that the N- and C-termini of MITF interact and Ser73 and Ser409 are not required for this interaction. A novel buffer which contains phosphatase inhibitors has shown novel and unexpected molecular weights of MITF that suggest different post-translational modifications of the protein and we have shown that mTOR inhibition affects the phosphorylation pattern of MITF. This suggests that other pathways must be involved and we are now using kinase inhibitors and siRNA studies to search for the relevant pathway. Also, we will elucidate how the dependency of Ser73 phosphorylation on Ser409 is mediated and what is the functional significance of these residues since the Ser73Ala mutant may induce an impaired autophagy response upon starvation.