Cell-Type Specific Expression of a Dominant Negative PKA Mutation in Mice

Abstract

We employed the Cre recombinase/loxP system to create a mouse line in which PKA activity can be inhibited in any celltype that expresses Cre recombinase. The mouse line carries a mutant Prkar1a allele encoding a glycine to aspartate substitution at position 324 in the carboxy-terminal cAMP-binding domain (site B). This mutation produces a dominant negative RIa regulatory subunit (RIaB) and leads to inhibition of PKA activity. Insertion of a loxP-flanked neomycin cassette in the intron preceding the site B mutation prevents expression of the mutant RIaB allele until Cre-mediated excision of the cassette occurs. Embryonic stem cells expressing RIaB demonstrated a reduction in PKA activity and inhibition of cAMPresponsive gene expression. Mice expressing RIaB in hepatocytes exhibited reduced PKA activity, normal fasting induced gene expression, and enhanced glucose disposal. Activation of the RIaB allele in vivo provides a novel system for the analysis of PKA function in physiology.