Establishment of Left–Right Asymmetry in Chick and Mouse Embryos

Abstract

All vertebrates have consistent left–right structural asymmetry, and deviations from the typical asymmetry in humans are clinically important. Studies elucidating the mechanisms that establish left–right asymmetry have lead to some of the most elegant advances in the field of embryology. In the past several decades, while we have gained an extensive understanding of the development of left–right asymmetry during embryogenesis, many questions remain to be addressed to fully appreciate the molecular mechanisms underlying its establishment. In this review article, the authors summarise the gene regulatory network that controls left–right patterning. They also focus on our current understanding of how left–right symmetry is broken.

Key Concepts:

  • Primary cilia rotating in a clockwise direction generate a unidirectional leftward fluid flow at a structure called the node, resulting in left–right symmetry breakage in mouse embryos. Similar leftward flow is observed in many vertebrate embryos.

  • Planar cell polarity (PCP) signalling, initially identified in the fruitfly, controls the uniform orientation of hairs and bristles on the body.

  • A primary cilium is a microtubule‐based antenna‐like structure lacking the central pairs of microtubules. This ‘9+0’ microtubular structure and lack of dynein arms render them immotile, whereas motile cilia have a ‘9+2’ microtubular structure with dynein arms.

  • BMP signalling negatively regulates cell cycle at the ventral surface of the node.

  • The posterior tilt of nodal cilia regulated by planar cell polarity is critical to generate a unilateral leftward flow from the rotation of the nodal cilia.

  • The ventral surface of the node is quiescent that allows formation of cilia.

Keywords: chick; cilia; gene expression; left–right patterning; mouse; node

Figure 1.

The known left–right cascade of gene activity in chick embryo. (a–d) show four successive stages (see text) as seen in plan view from above, with anterior at top. (a) Primitive streak stage; (b) a short ‘head process’ stage, with mesoderm emerging laterally and ahead of the regressing Hensen's node; (c) a late headfold or neurula stage (about four somites segmenting in mesoderm). Dotted line in (c) showing the level of transverse section in (f); (d) stage with the newly looped heart tube, and onset of embryo torsion (twisting); (e) transverse section through posterior Hensen's node at stage of (b). Note consistent anatomically asymmetrical appearance, as well as gene expressions, in node whose deep structure is in continuity with (upper) epiblast layer. Separate bilateral lower layer is mesoderm; (f) transverse section, ahead of regressed node but posterior to segmented somites, at stage of (c). Colour code for gene expressions: green, Act‐RIIa; blue, Shh; yellow, nodal and red, cSnR. Note that in (f), the lefty genes known from other vertebrates (see text) would occupy a left lateral position similar to nodal but also a narrow domain at the left lateral side of the Shh expression domain at the neural midline (floorplate) above the notochord. Abbreviations: Hn, Hensen's node; nc, notochord; s, somite and h, formed heart tube.

Figure 2.

Autonomy and interference in left–right patterning between twinned axial plans. (a) Shows a plan view from above of a case in which anteriorly opposed streaks have formed by earlier events at near‐opposite sites at a blastular (103–104 cell) stage. The gene expression colours around each node, and corresponding asymmetrical appearance, represent how in such a case each streak autonomously sets up the same, correct left–right asymmetry cascade in relation to its anteroposterior (and dorsoventral) aspects, ruling out prior use of any blastoderm‐wide left–right information (symbolised by double arrowheads from right). (b) Shows a similar view of a case where events initiating streaks were not fully opposed, so that convergence movements of streak development have led them to a more parallel, though separated, conformation. Frequent disturbance or reversal of laterality in just the right‐hand axis of such cases suggests that a preferential gene expression on the right normally first ‘converts’ a molecular chirality aligned in the vicinity of each streak into differential right‐ and left‐specific gene expressions. Right‐hand twin members are thus at risk of abnormal symmetrisation. Colour code for gene expressions: green, Act‐RIIa; blue, Shh; yellow, nodal and red, cSnR.

Figure 3.

Scanning electron microscopic analysis of the node at mouse embryonic day (E) E7.75. (a) Wild‐type mouse embryo shows a cup shaped structure with evenly distributed ciliated cells when viewed from the ventral side. (b) High‐magnification images from (a). At E7.75, around 1–2 µm length of primary cilia (red arrows) is formed in node cells (pit cells).

Figure 4.

Cell cycle quiescence regulates the nodal cilia formation in mouse embryos. Immunohistochemical analysis at E8.0 shows the expression of Ki‐67 (a) and p27Kip1 (b). Tissue section was counterstained by DAPI (c, e). Note that Ki‐67 is not detectable in cells of the ventral surface of node where nodal cilia are developed whereas p27Kip1 is produced exclusively in the ventral surface of node (d). Reproduced from Komatsu et al. (). © The Company of Biologists Ltd.

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References

Afzelius BA (1976) A human syndrome caused by immotile cilia. Science 193: 317–319.

Beckers A, Alten L, Viebahn C, Andre P and Gossler A (2007) The mouse homeobox gene Noto regulates node morphogenesis, notochordal ciliogenesis, and left right patterning. Proceedings of the National Academy of Sciences of the USA 104: 15765–15770.

Bellomo D, Lander A, Harragan I and Brown NA (1996) Cell proliferation in mammalian gastrulation: the ventral node and notochord are relatively quiescent. Developmental Dynamics 205: 471–485.

Bonnafe E, Touka M, AitLounis A et al. (2004) The transcription factor RFX3 directs nodal cilium development and left‐right asymmetry specification. Molecular and Cellular Biology 24: 4417–4427.

Brokaw CJ (2005) Computer simulation of flagellar movement IX. Oscillation and symmetry breaking in a model for short flagella and nodal cilia. Cell Motility and the Cytoskeleton 60: 35–47.

Brown NA and Wolpert L (1990) The development of handedness in left/right asymmetry. Development 109: 1–9.

Cartwright JH, Piro O and Tuval I (2004) Fluid‐dynamical basis of the embryonic development of left–right asymmetry in vertebrates. Proceedings of the National Academy of Sciences of the USA 101: 7234–7239.

Caspary T, Larkins CE and Anderson KV (2007) The graded response to Sonic Hedgehog depends on cilia architecture. Developmental Cell 12: 767–778.

Chen J, Knowles HJ, Hebert JL and Hackett BP (1998) Mutation of the mouse hepatocyte nuclear factor/forkhead homologue 4 gene results in an absence of cilia and random left–right asymmetry. Journal of Clinical Investigation 102: 1077–1082.

Hamada H, Meno C, Watanabe D and Saijoh Y (2002) Establishment of vertebrate left–right asymmetry. Nature Reviews Genetics 3: 103–113.

Harris PC and Torres VE (2009) Polycystic kidney disease. Annual Review of Medicine 60: 321–337.

Hashimoto M, Shinohara K, Wang J et al. (2010) Planar polarization of node cells determines the rotational axis of node cilia. Nature Cell Biology 12: 170–176.

Hirokawa N, Tanaka Y, Okada Y and Takeda S (2006) Nodal flow and the generation of left‐right asymmetry. Cell 125: 33–45.

Iomini C, Tejada K, Mo W, Vaananen H and Piperno G (2004) Primary cilia of human endothelial cells disassemble under laminar shear stress. Journal of Cell Biology 164: 811–817.

Isaac A, Sargent MG and Cooke J (1997) Control of vertebrate left–right asymmetry by a snail‐related zinc finger gene. Science 275: 1301–1304.

Komatsu Y, Kaartinen V and Mishina Y (2011) Cell cycle arrest in node cells governs ciliogenesis at the node to break left–right symmetry. Development 138: 3915–3920.

Lancaster MA and Gleeson JG (2009) The primary cilium as a cellular signaling center: lessons from disease. Current Opinion in Genetics and Development 19: 220–229.

Lee JD and Anderson KV (2008) Morphogenesis of the node and notochord: the cellular basis for the establishment and maintenance of left–right asymmetry in the mouse. Developmental Dynamics 237: 3464–3476.

Levin M, Johnson RL, Stern CD, Kuehn M and Tabin C (1995) A molecular pathway determining left–right asymmetry in chick embryogenesis. Cell 82: 803–814.

Levin M, Pagan S, Roberts DJ et al. (1997) Left/right patterning signals and the independent regulation of different aspects of situs in the chick embryo. Developmental Biology 189: 57–67.

Lowe LA, Supp DM, Sampath K et al. (1996) Conserved left–right asymmetry of nodal expression and alterations in murine situs inversus. Nature 381: 158–161.

Maisonneuve C, Guilleret I, Vick P et al. (2009) Bicaudal C, a novel regulator of Dvl signaling abutting RNA‐processing bodies, controls cilia orientation and leftward flow. Development 136: 3019–3030.

Marcon L and Sharpe J (2012) Turing patterns in development: what about the horse part? Current Opinion in Genetics and Development 22: 578–584.

Marszalek JR, Ruiz‐Lozano P, Roberts E, Chien KR and Goldstein LS (1999) Situs inversus and embryonic ciliary morphogenesis defects in mouse mutants lacking the KIF3A subunit of kinesin‐II. Proceedings of the National Academy of Sciences of the USA 96: 5043–5048.

McGrath J, Somlo S, Makova S, Tian X and Brueckner M (2003) Two populations of node monocilia initiate left–right asymmetry in the mouse. Cell 114: 61–73.

Neugebauer JM, Amack JD, Peterson AG, Bisgrove BW and Yost HJ (2009) FGF signalling during embryo development regulates cilia length in diverse epithelia. Nature 458: 651–654.

Nonaka S, Tanaka Y, Okada Y et al. (1998) Randomization of left–right asymmetry due to loss of nodal cilia generating leftward flow of extraembryonic fluid in mice lacking KIF3B motor protein. Cell 95: 829–837.

Nonaka S, Yoshiba S, Watanabe D et al. (2005) De novo formation of left–right asymmetry by posterior tilt of nodal cilia. PLoS Biology 3: e268.

Okada Y, Nonaka S, Tanaka Y et al. (1999) Abnormal nodal flow precedes situs inversus in iv and inv mice. Molecular Cell 4: 459–468.

Okada Y, Takeda S, Tanaka Y, Belmonte JC and Hirokawa N (2005) Mechanism of nodal flow: a conserved symmetry breaking event in left–right axis determination. Cell 121: 633–644.

Shinohara K, Kawasumi A, Takamatsu A et al. (2012) Two rotating cilia in the node cavity are sufficient to break left–right symmetry in the mouse embryo. Nature Communications 3: 622.

Song H, Hu J, Chen W et al. (2010) Planar cell polarity breaks bilateral symmetry by controlling ciliary positioning. Nature 466: 378–382.

Sulik K, Dehart DB, Iangaki T et al. (1994) Morphogenesis of the murine node and notochordal plate. Developmental Dynamics 201: 260–278.

Supp DM, Witte DP, Potter SS and Brueckner M (1997) Mutation of an axonemal dynein affects left–right asymmetry in inversus viscerum mice. Nature 389: 963–966.

Tanaka Y, Okada Y and Hirokawa N (2005) FGF‐induced vesicular release of Sonic hedgehog and retinoic acid in leftward nodal flow is critical for left–right determination. Nature 435: 172–177

Yokoyama T, Copeland NG, Jenkins NA et al. (1993) Reversal of left–right asymmetry: a situs inversus mutation. Science 260: 679–682.

Yoshiba S, Shiratori H, Kuo IY et al. (2012) Cilia at the node of mouse embryos sense fluid flow for left–right determination via Pkd2. Science 338: 226–231.

Zallen JA (2007) Planar polarity and tissue morphogenesis. Cell 129: 1051–1063.

Zhang M, Bolfing MF, Knowles HJ, Karnes H and Hackett BP (2004) Foxj1 regulates asymmetric gene expression during left–right axis patterning in mice. Biochemical and Biophysical Research Communications 324: 1413–1420.

Further Reading

Ibanes M and Izpisua Belmonte JC (2009) Left–right axis determination. Wiley Interdisciplinary Reviews Systems Biology and Medicine 1: 210–219.

Matsui T and Bessho Y (2012) Left–right asymmetry in zebrafish. Cellular and Molecular Life Sciences 69: 3069–3077.

Schweickert A, Walentek P, Thumberger T and Danilchik M (2012) Linking early determinants and cilia‐driven leftward flow in left–right axis specification of Xenopus laevis: a theoretical approach. Differentiation; Research in Biological Diversity 83: S67–S77.

Vandenberg LN and Levin M (2013) A unified model for left–right asymmetry? Comparison and synthesis of molecular models of embryonic laterality. Developmental Biology 379: 1–15.

Wallingford JB (2012) Planar cell polarity and the developmental control of cell behavior in vertebrate embryos. Annual Review of Cell and Developmental Biology 28: 627–653.

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Komatsu, Yoshihiro, and Mishina, Yuji(Jul 2014) Establishment of Left–Right Asymmetry in Chick and Mouse Embryos. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0000727.pub2]