pMN and p3 cells (olig2andnkx2.2a) and
their corresponding adhesion molecules (cdh11
andpcdh19). We down-regulated Shh signaling
by treatment with cyclopamine, a chemical in-
hibitor of the Shh activator Smoothened, and
up-regulated Shh signaling by injection ofshha
mRNA into one-cell–stage embryos. Our data
suggest that the cell fate and adhesion gene
pairs (olig2versuscdh11andnkx2.2aversus
ventral stripe ofpcdh19) all respond to Shh per-
turbation in a dose-dependent fashion (Fig. 4, A
to D; figs. S9 and S10; and supplementary text
S6). The relative patterns between the cell fate
and adhesion genes are preserved under up-
or down-regulation of Shh, suggesting shared
regulatory logic. Finally, to further connect cell
fate regulators downstream of Shh signaling
with the adhesion code, we knocked downolig2.
We found that the twopcdh19stripes merged
into one continuous stripe with higher ampli-
tude (Fig. 4E and fig. S9, I and J), suggesting
thatolig2is responsible forpcdh19repres-
sion in the pMN domain. Together, our data
show that the combinatorial adhesion code in
the ventral spinal cord is instructed by the Shh
morphogen gradient (Fig. 4F).
The origin of patterning robustness in tis-
sues undergoing morphogenesis is an important
open question. In the zebrafish spinal cord, we
show that robust patterning requires a previ-
ously unappreciated interplay between two clas-
sic ideas for patterning—morphogen gradients
and differential adhesion. The morphogen gra-
dient, though not precise, allows cells with sim-
ilar adhesion properties to be specified near
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to correct any imperfection in the initial pattern
and to remain organized in domains through-
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ACKNOWLEDGMENTS
We thank the members of the Megason and Heisenberg labs
for critical discussions of and technical assistance during the work
and B. Appel, S. Holley, J. Jontes, and D. Gilmour for transgenic
fish. This work is supported by the Damon Runyon Cancer
Foundation, a NICHD K99 fellowship (1K99HD092623), a Travelling
Fellowship of the Company of Biologists, a Collaborative Research
grant from the Burroughs Wellcome Foundation (T.Y.-C.T.),
NIH grant R01GM107733 (T.Y.-C.T. and S.G.M.), NIH grant
R01NS102322 (T.C.-C. and H.K.), and an ERC advanced grant
(MECSPEC) (C.-P.H.).Author contributions:T.Y.-C.T., C.-P.H.,
and S.G.M. conceived and designed the projects. T.Y.-C.T.
performed the majority of the experiments. M.S. and P.X. assisted
in the initial and final stages of the mechanical measurement
of cell adhesion. T.C.-C. and H.K. generated theTgBAC(cdh2:cdh2-
mCherry2)transgenic line. T.Y.-C.T. performed the data analysis.
T.Y.-C.T., C.-P.H., and S.G.M. wrote the manuscript, with input
from all coauthors.Competing interests:The authors declare
no competing interests.Data and materials availability:The
RNA sequencing data are deposited at GEO (GSE154885).
All other data are available in the main text or the
supplementary materials.SUPPLEMENTARY MATERIALS
science.sciencemag.org/content/370/6512/113/suppl/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S13
Tables S1 and S2
References ( 33 – 47 )
MDAR Reproducibility Checklist
Movies S1 to S720 December 2019; accepted 27 July 2020
10.1126/science.aba6637116 2 OCTOBER 2020•VOL 370 ISSUE 6512 sciencemag.org SCIENCE
Fig. 4. The adhesion code is regulated by Shh signaling andolig2.(AtoD) The V-D in situ HCR profile
ofolig2andcdh11[(A) and (B)] ornkx2.2aandpcdh19[(C) and (D)] from embryos treated with vehicle
control or 100mM cyclopamine [(A) and (C)] or injected with 90 pg of H2B-BFP orshhamRNA [(B) and (D)]. Error
bars indicate SEM. (E) The V-D in situ HCR profile ofpcdh19from embryos injected with control orolig2
morpholino. Error bars indicate SEM. (F) Summary of how the Shh gradient andolig2regulatepcdh19andcdh11.
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