Left-right asymmetry: nodal points.
The striking left-right asymmetry of visceral organs is known to depend on left- and right-side-specific cascades of gene expression during early embryogenesis. Now, developmental biologists are characterizing the earliest steps in asymmetry determination that dictate the sidedness of asymmetric gene expression. The proteins and structures involved control fascinating physiological processes, such as extracellular fluid flow and membrane voltage potential and yet little is known about how their activities are coordinated to control laterality. By analogy with intercellular signalling in certain epithelial and endothelial cells, however, it is reasonable to speculate that at least three of these players, monocilia, gap junction communication and the Ca2+ channel polycystin-2, participate in a signalling pathway that propagates left-right cues through multicellular fields.
Mercola
Mark
M
Stem Cell and Regeneration Program, The Burnham Institute, 10901 N Torrey Pines Road, La Jolla, CA 92037, USA. mmercola@burnham.org
D000818:Animals; D019521:Body Patterning / Q000235:genetics* / Q000502:physiology; D002642:Chick Embryo; D004398:Dyneins / Q000378:metabolism / Q000502:physiology; D045604:Extracellular Fluid / Q000502:physiology; D017629:Gap Junctions / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D011509:Proteoglycans / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D053669:Syndecan-2; D050396:TRPP Cation Channels; D014981:Xenopus / Q000196:embryology; D029867:Xenopus Proteins; D015027:Zebrafish / Q000196:embryology; D029961:Zebrafish Proteins
D004398:Dyneins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011509:Proteoglycans; D053669:Syndecan-2; D050396:TRPP Cation Channels; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C508246:Sdc2 protein, mouse; C508248:sdc2 protein, Xenopus; C508249:sdc2 protein, zebrafish