Molecular events in avian neoplasia: Regulators of cell death in development of B-cell lymphomas in the chicken bursa of Fabricius

Deregulated expression of myc oncogenes in the stem cells of the chicken bursa of Fabricius produces a pre-neoplastic lesion called a transformed follicle, first described as the initial pathological lesion in avian leukosis by Cooper et al. (1960). The effect of myc is to block differentiation at the stem cell stage and drive stem cell proliferation within bursal follicles. Additional events are required for progression to metastatic bursal lymphoma. One of these concerns modulation of the extremely active cell death pathway in the bursa, normally held in check by signals dependent on normal cell-to-cell contact within follicles. We describe here a novel member of the Bcl-2 family of cell death regulators, NR13, which seems to play an important role in regulating cell death in normal and neoplastic B-cell development in the bursa.