Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V83
Sigurdur R. Gudmundsson (1), Valerie Fock (1), Alexander Schepsky (1), Sandra Diebel (1), Indridi E. Reynisson (1), Margret H. Ogmundsdottir (1) and Eirikur Steingrimsson (1)
1. Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Vatnsmyrarvegur 16, 101 Reykjavik, Iceland
Kynnir / Presenter: Valerie Fock
Tengiliður / Corresponding author: Valerie Fock (vfock@hi.is)
Microphthalmia-associated transcription factor (MITF) is crucial for the development and differentiation of the melanocytic lineage and plays a central role in melanoma formation. Although the melanocyte-specific isoform MITF-M is primarily present within the nucleus of melanocytes and melanoma cells, the regulation of MITF’s subcellular localization and protein degradation remain poorly understood. The scope of this study was thus to characterize which domains of MITF are involved in determining the nuclear localization and stability of the protein. To address this question, EGFP-MITF fusion constructs carrying wild-type or mutant versions of MITF were generated and transfected into human embryonic kidney 293T and 501mel melanoma cells. Confocal microscopy was then applied to assess which domains of MITF mediate its nuclear localization and regulate protein stability. Our results show that a monopartite nuclear localization signal is present within the basic domain of MITF, which is required for nuclear localization of the protein. Importantly, neither DNA binding nor dimerization are necessary for nuclear retention of MITF. Finally, we demonstrate that MITF is degraded, at least in part, through the autophagosomal pathway and that a stability signal is located within the C-terminal end of MITF. Altogether, our findings strongly contribute to our understanding of MITF biology in health and disease.