Tamoxifen‐dependent, inducible Hoxb6CreER^T recombinase function in lateral plate and limb mesoderm, CNS isthmic organizer, posterior trunk neural crest, hindgut, and tailbud

Abstract

The ability to generate conditional mutant alleles in mice using Cre-lox technology has facilitated analysis of genes playing critical roles in multiple developmental processes at different times. We used a transgenic Hoxb6 promoter to drive tamoxifen-dependent Cre recombinase expression in several developing systems that serve as major models for elucidating inductive interactions and mechanisms of morphogenesis, including lateral plate mesoderm and descendant limb buds, neural crest progenitors of the neural tube, tailbud, and CNS isthmic organizer. The Hoxb6CreERT line gives very rapid and complete recombination over a short time window after a single tamoxifen dose, allowing precise time requirements for gene function to be assessed accurately. Embryonic cells cultured from the Hoxb6CreERT line also display rapid recombination ex vivo after tamoxifen exposure. Hence, the Hoxb6CreERT line provides a valuable tool for analyzing gene function, as well as lineage tracing studies using genetic cell marking, in several developing systems.

Transcription factor TLX1 controls retinoic acid signaling to ensure spleen development

“…We first performed lineage-tracing experiments to unequivocally demonstrate the contribution of the LPM to the SPM by crossing R26YFP reporter mice to Hoxb6-CreER mice, in which tamoxifendependent Cre expression is directed to the LPM (48). Injection of Hoxb6-CreER R26RYFP pregnant females at E8.5 with a single dose of tamoxifen followed by immunofluorescence analysis revealed a large contribution of the YFP + LPM mesodermal cells to the developing SPM (Supplemental Figure 3).…”

Dynamics of BMP signaling in limb bud mesenchyme and polydactyly

“…To determine the temporal range, we analyzed RG embryos containing HoxB6CreER , a tamoxifen-inducible Cre that has activity throughout hindlimb mesoderm (Nguyen et al, 2009). This approach allowed us to assay embryos expressing either one or two copies of RG (abbreviated as HoxB6CreER-RG or HoxB6CreER-RG/G, respectively).…”

“…While we report phenotypes for the forelimb skeletal preparations (Fig. S4; Table S3), we focused on the hindlimb because HoxB6CreER is only active in the posterior portion of the forelimb (Nguyen et al, 2009). To determine the range over which BMPs regulate digit number, we injected pregnant mice at 12-hour intervals between E9.5 and E11.5.…”

Diffusible signals and epigenetic timing cooperate in late proximo-distal limb patterning

“…S1). We then injected 4-hydroxytamoxifen (4HT) at E8.3 into crosses with the HoxB6-CreER line, in which tamoxifen-inducible Cre recombinase expression is evident in the LPM and limb bud precursors as early as E8.5 (Nguyen et al, 2009). Activation of the transgene took place in the whole hindlimb bud (HL) and the posterior half of the forelimb bud (FL) at E10.5 ( Fig.…”

“…All other strains were as previously described: R26R-eYFP (Srinivas et al, 2001), Shh GfpCre (Harfe et al, 2004), HoxB6-CreER (Nguyen et al, 2009) and RERTn (Guerra et al, 2003).…”