Generation of an inducible destabilized-domain Cre mouse line to target disease associated microglia

Abstract

The function of microglia during progression of Alzheimers disease (AD) can be investigated using mouse models that enable genetic manipulation of microglial subpopulations in a temporal manner. We developed a mouse strain that expresses destabilized-domain Cre recombinase (DD-Cre) from the Cst7 locus (Cst7DD-Cre) and tested this in 5xFAD amyloidogenic, Ai14 tdTomato cre-reporter line mice. Dietary administration of trimethoprim to induce DD-Cre activity produces long-term labeling in disease associated microglia (DAM) without evidence of leakiness, with tdTomato-expression restricted to cells surrounding plaques. Using this model, we found that DAMs are a subset of plaque-associated microglia (PAMs) and their transition to DAM increases with age and disease stage. Spatial transcriptomic analysis revealed that tdTomato+ cells show higher expression of disease and inflammatory genes compared to other microglial populations, including non-labeled PAMs. This model should allow inducible cre-loxP targeting of DAMs, without leakiness. HighlightsO_LIWe developed a new mouse strain which specifically enables recombination of loxP sites in disease associated microglia (DAMs) and can be used to manipulate DAM-gene expression. C_LIO_LIDAMs represent a subset of plaque associated microglia (PAMs), and DAM expression increases with disease progression. C_LIO_LISpatial transcriptomic analyses reveal that DAMs have higher expression of disease and inflammatory genes compared to other PAMs. C_LI