Höfundar:
Drífa Hrund Guðmundsdóttir, Þorkell Guðjónsson, Thejus Vankatesh, Snædís Ragnarsdóttir, Stefán Sigurðsson
Introduction:
Replication stress is a major source of genome instability and a common feature of most cancer types. Unresolved replication stress in mitosis can cause DNA double strand breaks and other chromosome aberrations, which can dramatically impact normal cell physiology. In such cases, the tumor suppressor, TP53, plays a central role in preserving genome integrity by promoting cell cycle arrest and apoptosis. Microphthalmia associated transcription factor (MITF) is crucial for melanocyte development and survival, and a major oncogene in melanoma amplified in 30-40 % of melanomas.
Methods:
RL-qPCR was used for mRNA expression analysis, protein quantification was done by western blotting and Immunofluorescence confocal microscopy, for cell cycle analyses flow cytometry was used, life cell imaging was used for apoptosis assays.
Results:
Here we demonstrate that MITF has an important role in maintaining genome stability. MITF knockdown cells show strong signs of replication stress and chromosomal abnormalities, which results in P53 mediated G1 arrest and apoptosis. Moreover, we show that MITF depletion activates P53 via Large tumor suppressor kinase 2 (LATS2) a key kinase in the Hippo signaling pathway. Interestingly, our findings indicate that the genome maintenance function of MITF is not limited to the melanocyte linage, as decreased MITF expression caused genome instability phenotypes across different cell types.
Conclusions:
Collectively, this study highlights the role of MITF as a non-melanocyte specific genome maintenance factor and uncovers a potential connection between MITF and the Hippo pathway, which is frequently deregulated in cancer.