Atm Conditional Knockout mouse models

Atm, the mouse ortholog of human ATM, encodes a PIKK family kinase held as an inactive dimer until the MRE11, RAD50 and NBS1 complex loads it at double strand breaks, where monomerization, autophosphorylation and acetylation by TIP60 activate phosphorylation of SQ and TQ motifs in KAP1, H2AX, CHK2 T68, p53 S15 and SMC1. This output enforces the G1/S and intra-S checkpoints, promotes heterochromatic break resection and couples oxidative stress to redox signaling. Null mice are viable but display thymic lymphoma, infertility, radiosensitivity and cerebellar signaling defects that only partially phenocopy ataxia telangiectasia, whereas kinase-dead knockin alleles are embryonic lethal because catalytically inert protein poisons break ends, a distinction that must inform allele choice. Conditional nulls are the right tool for tissue-restricted radiosensitization and synthetic lethality studies with ATR or PARP inhibitors, while patient-derived missense knockins address variant reclassification. Pair the allele with a Cre driver active in the lineage where checkpoint failure is being scored.

Conditional deletion of Atm limits the genetic change to the lineage you choose. That helps in oncology, immunology, and metabolic work where systemic loss would muddy the read. After you confirm Cre specificity, crossing to Atm floxed stock yields usable cohorts.