Quantitative characterization of a cardiac progenitor cell epithelium
Understanding how cellular and tissue-‐wide forces contribute to growth and form during organogenesis is a major challenge in developmental biology. The vertebrate heart tube extends as a consequence of the progressive addition of second heart field (SHF) progenitor cells within an epithelial sheet to the arterial and venous poles of the heart. Perturbation of this process results in congenital heart defects (CHD), affecting 1% of live births. T-‐box transcription factor genes implicated in CHD regulate the emergence of a boundary segregating SHF cells to alternate cardiac poles. In addition, epithelial features of the SHF, including cell longation, polarity, clonal anisotropy and epithelial tension, have been identified as regulatory targets during heart tube elongation (Cortes et al., Circ Res 2018). However, the relationship between epithelial properties and the patterning of progenitor cell subpopulations in the SHF remains unknown. Multidisciplinary quantitative approaches will be undertaken to address this question in the mouse embryo.
Epithelial polarity, Congenital Heart Diseases, Heart Morphogenesis
This project will provide new mechanistic insights into cardiac morphogenesis and the origins of CHD by integrating findings from patterning and cell biology in a progenitor cell epithelium. The candidate will 1) perform a quantitative phenomenological analysis of epithelial cellular properties (cell elongation, polarity, anisotropy and epithelial tension) and clonal growth patterns in the SHF; 2) investigate the relationship between progenitor cell patterning and epithelial features using embryo culture and mouse genetics.
Proposed approach (experimental / theoretical / computational)
The following multidisciplinary in vivo approaches will be undertaken:
1) Quantitative phenomenological analysis of epithelial cellular properties during mouse heart tube elongation including spatiotemporal mapping of cell shape and mechanical stress using state of the art fluorescent microscopy in cleared embryos. In addition, clonal growth patterns will be analysed in the progenitor cell epithelium using a novel inducible SHF Cre driver combined with a conditional confetti reporter.
2) Investigation of epithelial properties of SHF cells consequent to perturbed progenitor cell patterning. Mice carrying mutations in the arterial and venous pole regulatory genes Tbx1 and Tbx5, implicated in 22q11.2 and Holt-‐Oram syndrome, will be analysed. including investigation of the role of increased aPCKz levels in Tbx1 mutant embryos in regulating epithelial polarity. The combination of mouse genetics, imaging and quantitative analysis will contribute to modelling how the epithelial progentior cell state is regulated during early heart development.
Investigating heart morphogenesis is a complex goal that requires integration of different disciplines. This project combines quantitative visualization with molecular genetic approaches and phenomological modeling applied to an in vivo mouse model. This interdisciplinary approach will allow the identification of novel regulatory mechanisms that control heart tube elongation, a critical step in cardiac development, with significant biomedical implications. The PhD project will be carried out in a collaboration between an experimental research group studying heart development (Kelly) and a group applying mathematical modeling and quantitative approaches to investigate morphogenetic mechanisms (Villoutreix). The student will benefit from experimental and theoretical synergies as well as IBDM and CENTURI resources to enhance the successful implementation of this project and uncover new mechanisms implicated in organogenesis.
The candidate will be interested in understanding the basic mechanisms driving morphogenesis and epithelial biology. The project will be largely experimental with an important component of quantitative image analysis. Experience in molecular genetics, mouse handling and fluorescence microscopy will be an advantage but not essential.