Efficient inducible Cre‐mediated recombination in Tcf21cell lineages in the heart and kidney

Abstract

Tcf21 is a class II bHLH family member with essential roles in the formation of the lungs, kidneys, gonads, spleen, and heart. Here, we report the utility of a mouse line with targeted insertion of a tamoxifen-inducible Cre recombinase, MerCreMer at the Tcf21 locus. This mouse line will permit the inducible expression of Cre recombinase in Tcf21-expressing cells. Using ROSA26 reporter mice, we show that Cre recombinase is specifically and robustly activated in multiple Tcf21-expressing tissues during embryonic and postnatal development. The expression profile in the kidney is particularly dynamic with the ability to cause recombination in mesangial cells at one time of induction and podocytes at another time. These features make the Tcf21-driven inducible Cre line (Tcf21iCre) a valuable genetic tool for spatiotemporal gene function analysis and lineage tracing of cells in the heart, kidney, cranial muscle, and gonads.

The bHLH transcription factor Tcf21 is required for lineage-specific EMT of cardiac fibroblast progenitors

“…lacZ/+ (Lu et al, 2000), Tcf21 iCre/+ (Acharya et al, 2011), Pdgfra GFP/+ (Hamilton et al, 2003) and Gata5Cre Tg/0 (Merki et al, 2005) mice have been previously described. Reporter strains used in the study include: R26R YFP (Srinivas et al, 2001), R26R…”

“…Briefly, hearts were isolated in PBS, fixed in 4% paraformaldehyde for 1 hour, frozen embedded, and sectioned. Immunohistochemistry was performed (Acharya et al, 2011) using the following antibodies: anti-GFP (Molecular Probes, Invitrogen, A11122; 1:250); anti-Pdgfr (EM Bioscience, 14-1402-81; 1:200); anti-Acta1 (Sigma, A7811; 1:400); anti-PECAM (BD Pharmingen, 553370; 1:200); biotinylated Isolectin B4 (Vector Laboratories, B1205; 1:500); and anti-SM22 (Abcam, ab14106-100; 1:500). Immunohistochemistry on paraffin sections was performed for the following antibodies: anti-periostin (Santa Cruz Biotechnology, Sc-49480; 1:50) and anti--galactosidase (Cappel, 559761; 1:500).…”

“…Immunohistochemistry on paraffin sections was performed for the following antibodies: anti-periostin (Santa Cruz Biotechnology, Sc-49480; 1:50) and anti--galactosidase (Cappel, 559761; 1:500). -Galactosidase staining was performed as described previously (Acharya et al, 2011).…”

“…S3A-C), loss of -gal + cells inside the heart was probably caused by a failure of epicardial cell migration. To test whether Tcf21 lineage cells migrate into the heart, we indelibly tagged Tcf21-expressing cells using the genetic combination of an inducible Cre driven from the Tcf21 promoter (Acharya et al, 2011) and the R26R tdT reporter allele. Cre recombinase was induced at E10.5, when Tcf21 expression is restricted to the epicardium, and hearts were isolated at specified time points.…”

“…-/-hearts form cVSMCs but lack epicardialderived cardiac fibroblasts Published reports suggest an interstitial, non-myocyte pattern of Tcf21 expression in late gestation embryonic and adult hearts, implicating expression in cardiac fibroblasts (Lu et al, 1998;Acharya et al, 2011). To determine whether Tcf21 expression was limited to a subpopulation of EPDCs after EMT, we compared Tcf21 lacZ reporter expression with that of endothelial and cVSMC markers.…”