Posts Tagged: epithelium

Epithelial Properties of the Second Heart Field

Epithelial Properties of the Second Heart Field

Claudio Cortes, Alexandre Francou, Christopher De Bono, Robert G. Kelly

Epithelial-based models for second heart field (SHF) deployment. A, Regional Wnt5a expression promotes cell intercalation in the posterior SHF conferring a pushing force, whereas increased epithelial cohesiveness in the anterior SHF confers a pulling force. Together, these 2 forces promote SHF cell deployment toward the arterial pole of the heart. B, Segmented apical view of the dorsal pericardial wall epithelium at mouse embryonic day 9.5 (E9.5), with color-coded apical surface area, showing cell elongation in the posterior region (arrows) consistent with regional epithelial stress. C, Active actomyosin complexes visualized using a diphosphorylated nonmuscle myosin (ppMLC2) antibody are isotropically distributed before rupture of the dorsal mesocardium (left). ppMLC2 subsequently accumulates on the long membrane of elongated cells in the SHF (arrows, center); in contrast, active ppMLC2 distribution remains isotropic in Nkx2-5 mutant embryos (right). D, The axis of cell division is oriented toward the arterial pole on both the left and the right sides of the dorsal pericardial wall in wild-type but not in Tbx1 mutant embryos. E, Model linking epithelial tension in the SHF to heart tube elongation through biomechanical feedback. Scale bar: 10 µm. OFT indicates outflow tract. Panel A reproduced from Li et al67 with permission (Copyright ©2016, Elsevier Inc); panels B–D adapted from Francou et al118 with permission (Copyright ©The Author(s), 2017). [Powerpoint File]

Epithelial Properties of the Second Heart Field

Epithelial Properties of the Second Heart Field

Claudio Cortes, Alexandre Francou, Christopher De Bono, Robert G. Kelly

Features of polarized epithelial cells and Wnt signaling pathways. A, Basic features of epithelial cells showing stereotypical apicobasal cell domains and underlying mesenchymal cells. Planar cell polarity, orthogonal to the apicobasal axis, is indicated by the large arrow. B, Detailed schema of the boxed region in A showing tight junctions separating apical and basolateral membrane domains and adherens junctions, focusing on elements discussed in the text. C, Cartoon showing intersections between β-catenin Wnt signaling, noncanonical Wnt signaling, and planar cell polarity pathway components referred to in this review. DVL indicates dishevelled; GSK3, glycogen synthase kinase 3; JNK, Jun N-terminal kinase; LEF, lymphoid enhancer binding factor; LRP, lipoprotein receptor-related protein; and TCF, T-cell factor. [Powerpoint File]