Tbx5-dependent transcripts of the embryonic left ventricle

Tbx5 is expressed in the left ventricle of the developing mammalian heart. In order to test the transcriptional requirement of Tbx5 in the fetal left ventricle and bypass its early requirement in early cardiac formation, we used a combination of the ROSA26creERT2, a ubiquitously transcribed tamoxifen-dependent cre recombinase, and the Tbx5 floxed allele to remove both copies of Tbx5 at E11.5 followed by microdissection at E12.5. In addition to several well-known targets of Tbx5, we identified a novel signature of disrupted PDGF signaling. The cardiac left ventricle was microdissected from 2 mutant Gt(ROSA)26Sortm1(cre/ERT2)Tyj;Tbx5flox/flox and 5 control Gt(ROSA)26Sortm1(cre/ERT2)Tyj;Tbx5+/+ mouse embryos at embryonic day 12.5 (E12.5) following maternal intraperitoneal injection of tamoxifen at E11.5. RNA was extracted, oligo-dT selected, 50bp single-ended sequenced on the HiSeq2500 (Invitrogen) to a depth of approximately 26 million reads.