MuLV insertional mutagenesis is a model system for identifying genes that drive development of lymphoma and leukaemia.
Infection of newborn mice with murine leukaemia virus (MuLV) leads to a viremia throughout the hematopoietic compartment. Mice develop immunological tolerance such that replication and superinfection continues throughout the lifetime of the animal. Integration of the proviral genomes leads to deregulation and disruption of nearby genes by a variety of mechanisms. After a period of months the accumulation of these insertion mutations leads to hematopoietic malignancies driven by a spectrum of genes including known human cancer drivers.
By infecting mice that are predisposed to malignancies of a particular lineage or subtype, the spectrum of mutations identified can be skewed toward events that cooperate with the predisposing lesions.
Retroviral integration sites are identified using ligation mediated PCR, sequencing the resulting PCR products and mapping these to the mouse genome. Loci that are recurrently mutated include many known drivers of human hematopoietic malignancies. Other genes correspond to the upstream regulators and downstream targets of known cancer drivers.
Defining the genes that mediate selection of non coding alterations of cancer cells is challenging. Studies of recurrent aneuploidy, large scale copy number aberrations and loci associated with cancer by GWAS may implicate multiple genes simultaneously. Furthermore identifying the genes that are recurrently deregulated by non coding mutations or by alterations in DNA methylation can be statistically intractable. The data of insertional mutagenesis screens can help prioritise genes for validation as drivers and/or targets.
Several cohorts of mice infected with MuLV were analysed by a novel ligation mediated PCR protocol and sequenced on the Illumina platform. Samples typically have 1-20 clonal mutations and thousands of subclonal mutations. In total the database contains >700,000 retroviral insertions isolated the hematopoietic tissues of infected mice.
Each lymphoma sample is matched to flow cytometry data indicating malignancy subtype such that subsets of B & T lymphoma can be queried separately.
A series of mice infected with MuLV and sacrificed at time points post infection were included in order to define the extent of selection taking place throughout lymphoma development.
Other insertional mutagenesis datasets