Bbc3 Conditional Knockout mouse models

Bbc3, ortholog of human BBC3, encodes PUMA, a BH3-only protein that is among the most direct transcriptional outputs of p53 and therefore the principal transducer of DNA damage, oncogene stress, and glucocorticoid or cytokine withdrawal into mitochondrial apoptosis. PUMA is unusual among BH3-only members in binding all antiapoptotic relatives, BCL2, BCL2L1, BCL2L2, MCL1, and BCL2A1, with high affinity, so it both liberates and directly activates BAX and BAK; p53-independent induction via FOXO3A and CHOP extends its reach to trophic factor loss and ER stress. Nulls are viable and fertile but show marked resistance of thymocytes and hematopoietic progenitors to irradiation, and phenotypes are frequently blunted because Pmaip1 (NOXA), Bid, and Bcl2l11 cover overlapping stress inputs, making compound alleles necessary. Choose a conditional null when asking whether a tissue requires PUMA for damage-induced deletion, and pair it with p53 pathway alleles when tumor latency or therapy response is the endpoint.

Bbc3 conditional knockout mice carry a floxed allele so you delete function only where Cre is active. The germline allele stays intact until you cross to a tissue specific Cre. Labs reach for this design when a global knockout is lethal, when they need adult onset loss, or when regional redundancy hides a whole body phenotype.