MC29 Avian Myelocytomatosis Virus

MC29 avian myelocytomatosis virus is an acute leukemia virus and the prototype of the MC29-subgroup of the avian leukosis-sarcoma genus of type C retroviruses. It causes myelocytomatosis, endotheliomas, liver and kidney carcinomas, and sarcomas in chickens. Biochemical and genetic analyses of the RNA genome of MC29 led to the discovery of the myc oncogene. The MC29 genome contains partial complements of the essential virion genes gag and env , and v- myc as the transforming principle. The single protein product of MC29, p110 gag-myc , is a hybrid translational product of the partial gag gene and the v- myc sequences. The retroviral v- myc oncogene is a transduced mutant allele of the cellular protooncogene c- myc . The protein product of c- myc (Myc) is a bHLH-Zip protein, forms heterodimers with the bHLH-Zip protein Max, binds to specific DNA sequence elements (E-boxes), and is the central part of a transcription factor network controlling fundamental cellular processes like growth, metabolism, proliferation, differentiation, and apoptosis. Mutation and deregulation of c- myc is a frequent event in human tumorigenesis, occurring in about 30% of all human cancers. Myc and Max proteins were identified in early diploblastic organisms, suggesting that the principal functions of the Myc master regulator arose very early in metazoan evolution.