Prkag2 Knockout mouse models

Cardiac energy sensing depends heavily on Prkag2, ortholog of human PRKAG2, which encodes the gamma2 AMPK subunit distinguished by a long amino-terminal extension upstream of its four cystathionine beta-synthase domains, the modules that bind AMP, ADP and ATP and thereby set Thr172 phosphorylation and allosteric activation of the alpha subunit. Human missense mutations in the CBS repeats, classically R302Q and N488I, impair nucleotide binding and produce PRKAG2 cardiac syndrome, a glycogen storage cardiomyopathy with ventricular pre-excitation, conduction disease and hypertrophy rather than a simple loss of kinase output. Modeling that disease requires knockin of the specific human substitution, ideally Cre-inducible for adult-onset expression, because constitutive transgenic overexpression exaggerates glycogen accumulation and confounds electrophysiologic endpoints. Conditional nulls answer a different question, namely the requirement for gamma2-containing trimers in ischemic tolerance, and should be interpreted against gamma1 expression, which persists and supports baseline AMPK activity.

Whole body loss of Prkag2 gives the clearest readout when the question is whether the gene is required at all. Follow up tissue work can still move to a conditional allele if lethality or compensation appears.