Mef2c-F10N enhancer driven β-galactosidase (LacZ) and Cre recombinase mice facilitate analyses of gene function and lineage fate in neural crest cells

Abstract

Neural crest cells (NCC) comprise a multipotent, migratory stem cell and progenitor population that gives rise to numerous cell and tissue types within a developing embryo, including craniofacial bone and cartilage, neurons and glia of the peripheral nervous system, and melanocytes within the skin. Here we describe two novel stable transgenic mouse lines suitable for lineage tracing and analysis of gene function in NCC. Firstly, using the F10N enhancer of the Mef2c gene (Mef2c-F10N) linked to LacZ, we generated transgenic mice (Mef2c-F10N-LacZ) that express LacZ in the majority, if not all migrating NCC that delaminate from the neural tube. Mef2c-F10N-LacZ then continues to be expressed primarily in neurogenic, gliogenic and melanocytic NCC and their derivatives, but not in ectomesenchymal derivatives. Secondly, we used the same Mef2c-F10N enhancer together with Cre recombinase to generate transgenic mice (Mef2c-F10N-Cre) that can be used to indelibly label, or alter gene function in, migrating NCC and their derivatives. At early stages of development, Mef2c-F10N-LacZ and Mef2c-F10N-Cre label NCC in a pattern similar to Wnt1-Cre mice, with the exception that Mef2c-F10N-LacZ and Mef2c-F10N-Cre specifically label NCC that have delaminated from the neural plate, while premigratory NCC are not labeled. Thus, our Mef2c-F10N-LacZ and Mef2c-F10N-Cre transgenic mice provide new resources for tracing migratory NCC and analyzing gene function in migrating and differentiating NCC independently of NCC formation.

Endothelin signaling activates Mef2c expression in the neural crest through a MEF2C-dependent positive-feedback transcriptional pathway

“…The cleft palate phenotype and apparent craniofacial obstruction and neonatal lethality observed in Mef2c F1Δ/Δ mice is similar to, but less severe than, the phenotype observed in Mef2c neural crest-specific conditional knockout mice (Mef2c NCKO ), which also die at birth due to cleft palate and craniofacial obstruction (Verzi et al, 2007). The less severe phenotype observed in Mef2c F1Δ/Δ mice compared with Mef2c NCKO mice is consistent with the fact that Mef2c has at least two neural crest enhancers, Mef2c-F1 and Mef2c-F10N (Aoto et al, 2015;De Val et al, 2008), and, as a result, deletion of Mef2c-F1 does not result in a complete loss of Mef2c expression in the neural crest.…”

“…S1). Interestingly, another neural crest-specific enhancer in the Mef2c locus, Mef2c-F10N (Aoto et al, 2015;De Val et al, 2008), did not respond in this ET-1 induction assay, suggesting that it is not similarly a target for Endothelin signaling (data not shown). The Mef2c-F1 neural crest enhancer contains a 300-bp minimal region that is sufficient to direct expression in vivo (Agarwal et al, 2011).…”

“…Indeed, Mef2c-F1 contains SOX binding sites that are bound by Sox10 and are essential for the initial activation of the enhancer in vivo (Agarwal et al, 2011). Additionally, Mef2c expression could be activated initially through other neural crest enhancers, including F10N (Aoto et al, 2015;De Val et al, 2008) or other unidentified enhancers.…”

Specific and spatial labeling of P0‐Cre versus Wnt1‐Cre in cranial neural crest in early mouse embryos

“…Multiple Cre transgenic mouse lines have been generated using a NC marker gene promoter, e.g., Wnt1-Cre (Echelard et al , 1994; Jiang et al , 2002; McMahon et al , 1992), P0-Cre (Wang et al , 2011; Yamauchi et al , 1999; Zhang et al , 1995), Dhh-Cre (Gershon et al , 2009; Wang et al , 2007), Pax3-Cre (Jarad and Miner, 2009), HtPA-Cre (Lee et al , 2013), Sox10-Cre (Simon et al , 2012), Mef2c-F10N-Cre (Aoto et al , 2015). Use of these models has yielded new data pertaining to NC cell specifications in mice, e.g., distinct genesis of skin-derived precursors in craniofacial and dorsal skin from NC and mesoderm, respectively (Jinno et al , 2010), NC and placodal derivation of the otic vesicle (Freyer et al , 2011), and a dual origin of sensory organs that include olfactory epithelium (Katoh et al , 2011), tooth bud epithelium (Wang et al , 2011), and taste bud cells (Boggs et al , 2016; Liu et al , 2012).…”

Sox10ERT2CreERT2 mice enable tracing of distinct neural crest cell populations

“…NCCs comprise transient and multipotent cells formed at different stages and of distinct origins. Several genetic tools, such as Wnt1Cre (Danielian et al, ), Wnt1Cre2 (Lewis et al, ), Sox10Cre (Matsuoka et al, ), S4F:Cre (Stine et al, ), Sox10‐CreER T2 (McKenzie et al, ), Sox10‐iCreER T2 (Simon et al, ), Mef2cCre (Aoto et al, ), and Ht‐PA‐Cre (Pietri et al, ) have been generated to drive Cre expression in premigratory and postmigratory neural crest cells, facilitating examination of gene function in multiple processes. Of the transgenic lines generated with Sox10 locus, Sox10Cre (Matsuoka et al, ) and Sox10‐CreER T2 (McKenzie et al, ) used the same PAC clone spanning 170kb around Sox10 locus, and Sox10‐iCreER T2 (Simon et al, ) used a ∼140 kb BAC clone.…”