Cerberus-Nodal-Lefty-Pitx signaling cascade controls left-right asymmetry in amphioxus.
Many bilaterally symmetrical animals develop genetically programmed left-right asymmetries. In vertebrates, this process is under the control of Nodal signaling, which is restricted to the left side byNodalantagonists Cerberus and Lefty. Amphioxus, the earliest diverging chordate lineage, has profound left-right asymmetry as a larva. We show thatCerberus,Nodal,Lefty, and their target transcription factorPitxare sequentially activated in amphioxus embryos. We then address their function by transcription activator-like effector nucleases (TALEN)-based knockout and heat-shock promoter (HSP)-driven overexpression. Knockout ofCerberusleads to ectopic right-sided expression ofNodal,Lefty, andPitx, whereas overexpression ofCerberusrepresses their left-sided expression. Overexpression of Nodal in turn repressesCerberusand activatesLeftyandPitxectopically on the right side. We also show Lefty repressesNodal, whereasPitxactivatesNodalThese data combine in a model in which Cerberus determines whether the left-sided gene expression cassette is activated or repressed. These regulatory steps are essential for normal left-right asymmetry to develop, as when they are disrupted embryos may instead form two phenotypic left sides or two phenotypic right sides. Our study shows the regulatory cassette controlling left-right asymmetry was in place in the ancestor of amphioxus and vertebrates. This includes the Nodal inhibitors Cerberus and Lefty, both of which operate in feedback loops withNodaland combine to establish asymmetricPitxexpression.CerberusandLeftyare missing from most invertebrate lineages, marking this mechanism as an innovation in the lineage leading to modern chordates.
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
Guang
G
Li
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
Xian
X
Liu
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
Chaofan
C
Xing
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
Huayang
H
Zhang
Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom wangyq@xmu.edu.cn sebastian.shimeld@zoo.ox.ac.uk.
Sebastian M
0000-0003-0195-7536
SM
Shimeld
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China; wangyq@xmu.edu.cn sebastian.shimeld@zoo.ox.ac.uk.
Yiquan
Y
Wang
D000818:Animals; D019521:Body Patterning; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D018398:Homeodomain Proteins / Q000378:metabolism; D064175:Lancelets / Q000196:embryology / Q000502:physiology*; D055457:Nodal Protein / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D051761:Paired Box Transcription Factors / Q000378:metabolism; D015398:Signal Transduction
D018398:Homeodomain Proteins; D055457:Nodal Protein; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors
Nodal; TALEN; amphioxus; embryonic development; left–right asymmetry