Gli3 utilizes Hand2 to synergistically regulate tissue-specific transcriptional networks
- Cincinnati Children's Hospital Medical Center, United States
- The Jackson Laboratory, United States
- University of Basel, Switzerland
- Harvard University, United States
Abstract
Despite a common understanding that Gli TFs are utilized to reiterate a Hh morphogen gradient, genetic analyses suggest craniofacial development does not completely fit this paradigm. Using the mouse model (Mus musculus), we demonstrated that rather than being driven by a Hh threshold, robust Gli3 transcriptional activity during skeletal and glossal development required interaction with the basic helix-loop-helix TF Hand2. Not only did genetic and expression data support a co-factorial relationship, but genomic analysis revealed that Gli3 and Hand2 were enriched at regulatory elements for genes essential for mandibular patterning and development. Interestingly, motif analysis at sites co-occupied by Gli3 and Hand2 uncovered mandibular-specific, low-affinity, 'divergent' Gli binding motifs (<strong>d</strong>GBMs). Functional validation revealed these <strong>d</strong>GBMs conveyed synergistic activation of Gli targets essential for mandibular patterning and development. In summary, this work elucidates a novel, sequence-dependent mechanism for Gli transcriptional activity within the craniofacial complex that is independent of a graded Hh signal.
Data availability
Sequencing data have been deposited in GEO under accession codes GSE141431, GSE141173.ChIP data have been deposited in GEO under accession code GSE146961All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1,5,8,9, Figure 1-figure supplement 1, Figure 8-figure supplement 2, and Figure 9-figure supplement 1
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Single cell sequencing of dissected mouse mandibular prominence at embryonic day e11.5 and e13.5NCBI Gene Expression Omnibus, GSE141173.
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Gli3 and Hand2 ChIP-sequencing of developing face and mandibular prominenceNCBI Gene Expression Omnibus, GSE146961.
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Genome-wide candidate HAND2 target regions in mouse embryonic tissuesNCBI Gene Expression Omnibus, GSE55707.
Article and author information
Author details
Samantha A Brugmann
Funding
National Institutes of Health (R35DE027557)
- Samantha A Brugmann
National Institutes of Health (R01GM124251)
- Kevin A Peterson
National Institutes of Health (F31DE027872)
- Kelsey H Elliott
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Kathryn Song Eng Cheah, The University of Hong Kong, Hong Kong
Ethics
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols (IACUC2017-0063) of Cincinnati Children's Hospital Medical Center.
Version history
- Received: February 27, 2020
- Accepted: October 1, 2020
- Accepted Manuscript published: October 2, 2020 (version 1)
- Version of Record published: October 14, 2020 (version 2)
Copyright
© 2020, Elliott et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Gli3 utilizes Hand2 to synergistically regulate tissue-specific transcriptional networks
eLife 9:e56450.
https://doi.org/10.7554/eLife.56450
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We previously showed that SerpinE2 and the serine protease HtrA1 modulate fibroblast growth factor (FGF) signaling in germ layer specification and head-to-tail development of Xenopus embryos. Here, we present an extracellular proteolytic mechanism involving this serpin-protease system in the developing neural crest (NC). Knockdown of SerpinE2 by injected antisense morpholino oligonucleotides did not affect the specification of NC progenitors but instead inhibited the migration of NC cells, causing defects in dorsal fin, melanocyte, and craniofacial cartilage formation. Similarly, overexpression of the HtrA1 protease impaired NC cell migration and the formation of NC-derived structures. The phenotype of SerpinE2 knockdown was overcome by concomitant downregulation of HtrA1, indicating that SerpinE2 stimulates NC migration by inhibiting endogenous HtrA1 activity. SerpinE2 binds to HtrA1, and the HtrA1 protease triggers degradation of the cell surface proteoglycan Syndecan-4 (Sdc4). Microinjection of Sdc4 mRNA partially rescued NC migration defects induced by both HtrA1 upregulation and SerpinE2 downregulation. These epistatic experiments suggest a proteolytic pathway by a double inhibition mechanism:
SerpinE2 ┤HtrA1 protease ┤Syndecan-4 → NC cell migration.
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Human fetal development has been associated with brain health at later stages. It is unknown whether growth in utero, as indexed by birth weight (BW), relates consistently to lifespan brain characteristics and changes, and to what extent these influences are of a genetic or environmental nature. Here we show remarkably stable and lifelong positive associations between BW and cortical surface area and volume across and within developmental, aging and lifespan longitudinal samples (N = 5794, 4–82 y of age, w/386 monozygotic twins, followed for up to 8.3 y w/12,088 brain MRIs). In contrast, no consistent effect of BW on brain changes was observed. Partly environmental effects were indicated by analysis of twin BW discordance. In conclusion, the influence of prenatal growth on cortical topography is stable and reliable through the lifespan. This early-life factor appears to influence the brain by association of brain reserve, rather than brain maintenance. Thus, fetal influences appear omnipresent in the spacetime of the human brain throughout the human lifespan. Optimizing fetal growth may increase brain reserve for life, also in aging.
