Main author: Romain Lasseur
Institution or Company: University of Iceland
Introduction: The microphthalmia-associated transcription factor (MITF) is essential for melanocyte development. However, since most of the mutations known in the mouse Mitf gene result in a complete loss of melanocytes, it has been difficult to characterize its exact role during melanocyte development. To better understand this role, we have generated a conditional mutation in the mouse Mitf gene by mutating a Lysine at the 243 position with an Arginine (MitfK243R).
Methods: We have used Tyr::Cre and Tyr::CreERT2 drivers to generate the mutation in vivo in melanoblasts and in vitro in melanocytes and the Dct::LacZ reporter to track melanoblasts during development. We performed LacZ and immunofluorescent staining on embryos to track the fate of melanoblasts. We derived melanocyte cell lines from newborn pups, characterized their phenotype and looked at their RNA transcripts through a RNA sequencing analysis.
Results: Mice homozygous for the MitfK243R mutation have spotted coats with alternating white, grey, and black areas meaning that some melanocytes are still present. The LacZ staining shows that 13.5- and 14,5-day old embryos have fewer melanoblasts in the truncal region. Melanocyte cultures from MitfK243R; TyrCreErt2 induced mice show altered proliferative abilities. RNA sequencing is still in analysis.
Conclusion: Our results suggest that the MitfK243R mutation is hypomorphic. Knowing why there are fewer melanoblasts during the development will be a major step into better understanding the role of MITF. RNA-sequencing of the melanocyte cell lines will also allow us to further determine the effects of the MitfK243R mutation on gene expression.
