A knock-in allele of Hand2 expressing Dre recombinase.

HAND2 is a basic helix-loop-helix transcription factor with diverse functions during development. To facilitate the investigation of genetic and functional diversity among Hand2-expressing cells in the mouse, we have generated Hand2, a knock-in allele expressing Dre recombinase. To avoid disrupting Hand2 function, the Dre cDNA is inserted at the 3' end of the Hand2 coding sequence following a viral 2A peptide. Hand2 homozygotes can therefore be used in complex crosses to increase the proportion of useful genotypes among offspring. Dre expression in mid-gestation Hand2 embryos is indistinguishable from wild-type Hand2 expression, and Hand efficiently recombines rox target sites in vivo. In combination with existing Cre and Flp mouse lines, Hand2 will therefore extend the ability to perform genetic intersectional labeling, fate mapping, and functional manipulation of subpopulations of cells characterized by developmental expression of Hand2.