Thejus Venkatesh, Drífa Guðmundsdóttir, Fjóla Aðalsteinsdóttir, Linda Viðarsdóttir, Eiríkur Steingrímsson and Stefán Sigurðsson
Introduction – Genome integrity is crucial for the normal function of all cells, as failure to preserve it can lead to cancer and other diseases. Despite constant damage to the genome from extracellular and intracellular sources, cells have evolved intricate mechanisms like the DNA Damage Response (DDR) to counteract these threats. In this project, we aim to uncover the distinct roles of Melanocyte-inducing Transcription Factor (MITF) isoforms in maintaining genomic stability. While MITF’s significance in melanocytes and melanoma is well-known, its non-melanocyte-specific functions remain poorly understood.
Methods – Co-Immunoprecipitation, Mass spectrometry, iPOND, CUT and RUN, siRNA knockdown.
Results – Using the osteosarcoma cell line U2OS as our research model, we observed MITF co-localized with DNA repair proteins at sites of DNA breaks, suggesting that MITF might have a role in DNA repair, possibly independent of the protein’s transcriptional activity. The A-isoform of MITF is predominantly expressed in U2OS cells, contrasting with the M-isoform found in the melanocyte lineage. Mass spectrometry data indicates that the A-isoform has a stronger affinity to DNA replication and repair proteins compared with the M-isoform. We hypothesize that MITF-A might be involved in DNA repair by directly binding to the DNA break site or interacting with DNA repair proteins at the break site.
Conclusion – Our study reveals that MITF depletion increases genomic instability, emphasizing MITF’s crucial role in maintaining genomic stability. This is implicated by its interaction with DNA replication and repair proteins suggesting its non-melanocyte-specific genome maintenance function may be isoform-specific.
