Chek2 Conditional Knockout mouse models

Chek2, mouse ortholog of human CHEK2, encodes CHK2, an ATM effector kinase built from an SQ/TQ cluster, an FHA phosphopeptide binding domain and a kinase domain, activated when ATM phosphorylates threonine 68 to promote FHA-mediated dimerization and trans-autophosphorylation at the activation loop. Active CHK2 phosphorylates p53 at serine 20 to disrupt MDM2 binding, targets CDC25A and CDC25C for degradation or 14-3-3 sequestration, and phosphorylates BRCA1 and E2F1, enforcing G1 arrest and apoptosis after double strand breaks. The truncating 1100delC and missense I157T alleles confer moderate breast and prostate cancer risk, making patient-variant knockins the appropriate tool for penetrance and variant reclassification studies. Null mice are viable and radioresistant in thymocytes with defective p53 stabilization, so constitutive alleles are entirely workable, unlike Chek1. Because CHK2 acts on breaks and CHK1 on replication stress, they are not redundant. Choose nulls for apoptotic threshold and radiation response, and knockins for allele-specific cancer risk modeling.

A floxed Chek2 allele paired with Cre gives spatial control that whole body knockouts cannot offer. People use it to separate developmental roles from adult homeostasis, to model somatic mutations, and to match disease that begins in one organ.