Etchevers:Cardiac morphogenesis/2008/10/09

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Christelle was not able to complete the luciferase induction experiments because the tissue culture facility at Necker has been infected by molds and yeast. One of the hoods apparently had not been cleaned as it should and was contaminating everything. She has thawed out some new HeLa cells.

I wished for Candice to learn how to electroporate and perhaps process the eggs, if she has the time - and it seems she may. But we need to do some re-thinking about what to demonstrate with the dominant negative construction that Christelle has made.

Christelle sent me this article
. They did an experiment we wanted to do, to show the role "To test whether CNC cells are direct targets of the FGF signaling required for OFT remodeling, we used the well-characterized Wnt1Cre and Ap2 αIRESCre drivers to ablate Fgfr1 and Fgfr2 function in premigratory neural crest, and in premigratory neural crest and pharyngeal ectoderm, respectively (Jiang et al., 2000; Macatee et al., 2003). Surprisingly, ablation of either receptor, independently or in combination, did not disrupt OFT remodeling (see Table S1 in the supplementary material). As expected, these embryos had disrupted craniofacial development (see Fig. S3 in the supplementary material). Furthermore, when we overexpressed Spry2 in neural crest, 100% of mutants had abnormal craniofacial structures but normal OFT morphology (see Table S1 and Fig. S3 in the supplementary material). This indicates that OFT septation is independent of FGF signaling directly to CNC."

Yes, it does.

Thinking about this.

  • Heather 09:36, 9 October 2008 (EDT):

From same article (remember, they have deleted Fgf8 from the Isl1-expressing OFT mesoderm):
"BMP and TGFβ signaling are essential for CNC invasion of the OFT cushions and for pharyngeal arch artery development (High and Epstein, 2007; Liu et al., 2004; Stottmann et al., 2004); the changes that we document in these pathways in the face of compromised FGF signaling will impact these processes. Modifications to ECM components, which also affect BMP/TGFβ signaling (Macri et al., 2007), further contribute to effects on the neural crest."

"Neural crest cells modulate FGF8 signaling in the pharynx and influence not only the addition of myocardium to the OFT from the SHF (Hutson et al., 2006), but also the contractile and secretory function of the myocardium itself, including its ability to produce cardiac jelly (Stottmann et al., 2004; Waldo et al., 1999). Thus, in affected Fgf8, FGFR and Spry2 gain-of-function mutants, initial myocardial dysfunction and subsequent abnormal CNC behavior might interact in a cycle that progressively impairs OFT morphogenesis." I don't see how that can be true with respect to Fgfr2 at least, given their own results? It should interrupt the cycle effectively.

  • Heather 10:02, 9 October 2008 (EDT):