Abstract
Medulloblastoma is the most common malignant brain tumor of childhood. Therapeutic approaches to medulloblastoma have led to significant improvements but are achieved at a high cost to quality of life. The Notch pathway governs cell proliferation in many biological contexts, including medulloblastoma tumorigenesis. Using our proteomic platform, we discovered an interaction between RBPJ, a key co-factor of Notch for the mediation of Notch signals, and L3MBTL3, a methyllysine reader for which deletions are observed in medulloblastoma. We demonstrated that L3MBTL3 is part of a molecular mechanism linking the KDM1A demethylase to Notch signal modulation. We hypothesize that malfunction of this molecular mechanism may contribute to the previously suggested tumor suppressor role of L3MBTL3 in medulloblastoma. In a survival analysis using our L3mbtl3 KO mouse in combination with a genetically engineered mouse model of medulloblastoma, we validated our hypothesis that L3mbtl3 is a tumor suppressor in this disease context. Our discovery provides insights into the role of the L3MBTL3 in medulloblastoma that could be harnessed in the future for the therapeutic benefit of medulloblastoma patients.