SPECIFIC ECTODERMAL ENHANCERS CONTROL THE EXPRESSION OF Hoxc GENES IN DEVELOPING MAMMALIAN INTEGUMENTS

AbstractVertebrate Hox genes are key players in the establishment of structures during the development of the main body axis. Subsequently, they play important roles either in organizing secondary axial structures such as the appendages, or during homeostasis in postnatal stages and adulthood. Here we set up to analyze their elusive function in the ectodermal compartment, using the mouse limb bud as a model. We report that the HoxC gene cluster was globally co-opted to be transcribed in the distal limb ectoderm, where it is activated following the rule of temporal colinearity. These ectodermal cells subsequently produce various keratinized organs such as nails or claws. Accordingly, deletion of the HoxC cluster led to mice lacking nails (anonychia) and also hairs (alopecia), a condition stronger than the previously reported loss of function of Hoxc13, which is the causative gene of the ectodermal dysplasia 9 (ECTD9) in human patients. We further identified two ectodermal, mammalian-specific enhancers located upstream of the HoxC gene cluster, which act synergistically to regulate Hoxc gene expression in the hair and nail ectodermal organs. Deletion of these regulatory elements alone or in combination revealed a strong quantitative component in the regulation of Hoxc genes in the ectoderm, suggesting that these two enhancers may have evolved along with mammals to provide the level of HOXC proteins necessary for the full development of hairs and nails.Significance StatementIn this study, we report a unique and necessary function for the HoxC gene cluster in the development of some ectodermal organs, as illustrated both by the hair and nail phenotype displayed by mice lacking the Hoxc13 function and by the congenital anonychia (absence of nails) in full HoxC cluster mutants. We show that Hoxc genes are activated in a colinear manner in the embryonic limb ectoderm and are subsequently transcribed in developing nails and hairs. We identify two mammalian-specific enhancers located upstream of the HoxC cluster with and exclusive ectodermal specificity. Individual or combined enhancer deletions suggest that they act in combination to raise the transcription level of several Hoxc genes during hairs and nails development.

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Mammalian-specific ectodermal enhancers control the expression ofHoxcgenes in developing nails and hair follicles

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2011078117 ◽

2020 ◽

Vol 117 (48) ◽

pp. 30509-30519

Author(s):

Marc Fernandez-Guerrero ◽

Nayuta Yakushiji-Kaminatsui ◽

Lucille Lopez-Delisle ◽

Sofía Zdral ◽

Fabrice Darbellay ◽

...

Keyword(s):

Gene Cluster ◽

Ectodermal Dysplasia ◽

Regulatory Elements ◽

Hair Follicles ◽

Limb Bud ◽

Main Body ◽

Loss Of Function ◽

Causative Gene ◽

Mouse Limb ◽

Set Up

VertebrateHoxgenes are critical for the establishment of structures during the development of the main body axis. Subsequently, they play important roles either in organizing secondary axial structures such as the appendages, or during homeostasis in postnatal stages and adulthood. Here, we set up to analyze their elusive function in the ectodermal compartment, using the mouse limb bud as a model. We report that theHoxCgene cluster was co-opted to be transcribed in the distal limb ectoderm, where it is activated following the rule of temporal colinearity. These ectodermal cells subsequently produce various keratinized organs such as nails or claws. Accordingly, deletion of theHoxCcluster led to mice lacking nails (anonychia), a condition stronger than the previously reported loss of function ofHoxc13, which is the causative gene of the ectodermal dysplasia 9 (ECTD9) in human patients. We further identified two mammalian-specific ectodermal enhancers located upstream of theHoxCgene cluster, which together regulateHoxcgene expression in the hair and nail ectodermal organs. Deletion of these regulatory elements alone or in combination revealed a strong quantitative component in the regulation ofHoxcgenes in the ectoderm, suggesting that these two enhancers may have evolved along with the mammalian taxon to provide the level of HOXC proteins necessary for the full development of hair and nail.

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RhoA/Rock activation represents a new mechanism for inactivating Wnt/β-catenin signaling in the aging-associated bone loss

Cell Regeneration ◽

10.1186/s13619-020-00071-3 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Wei Shi ◽

Chengyun Xu ◽

Ying Gong ◽

Jirong Wang ◽

Qianlei Ren ◽

...

Keyword(s):

Bone Loss ◽

Rho Kinase ◽

Small Gtpase ◽

Limb Bud ◽

Nuclear Accumulation ◽

Bone Homeostasis ◽

Loss Of Function ◽

Elderly Male ◽

Gain Of Function ◽

Embryonic Limb

AbstractThe Wnt/β-catenin signaling pathway appears to be particularly important for bone homeostasis, whereas nuclear accumulation of β-catenin requires the activation of Rac1, a member of the Rho small GTPase family. The aim of the present study was to investigate the role of RhoA/Rho kinase (Rock)-mediated Wnt/β-catenin signaling in the regulation of aging-associated bone loss. We find that Lrp5/6-dependent and Lrp5/6-independent RhoA/Rock activation by Wnt3a activates Jak1/2 to directly phosphorylate Gsk3β at Tyr216, resulting in Gsk3β activation and subsequent β-catenin destabilization. In line with these molecular events, RhoA loss- or gain-of-function in mouse embryonic limb bud ectoderms interacts genetically with Dkk1 gain-of-function to rescue the severe limb truncation phenotypes or to phenocopy the deletion of β-catenin, respectively. Likewise, RhoA loss-of-function in pre-osteoblasts robustly increases bone formation while gain-of-function decreases it. Importantly, high RhoA/Rock activity closely correlates with Jak and Gsk3β activities but inversely correlates with β-catenin signaling activity in bone marrow mesenchymal stromal cells from elderly male humans and mice, whereas systemic inhibition of Rock therefore activates the β-catenin signaling to antagonize aging-associated bone loss. Taken together, these results identify RhoA/Rock-dependent Gsk3β activation and subsequent β-catenin destabilization as a hitherto uncharacterized mechanism controlling limb outgrowth and bone homeostasis.

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Leveraging epigenetics to enhance the efficacy of immunotherapy

Clinical Epigenetics ◽

10.1186/s13148-021-01100-x ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Jonathan D. Licht ◽

Richard L. Bennett

Keyword(s):

Gene Expression ◽

Clinical Trials ◽

Antigen Presentation ◽

Tumor Cells ◽

Immune Evasion ◽

Regulatory Elements ◽

Chromatin Accessibility ◽

Epigenetic Modifications ◽

Main Body ◽

Epigenetic Mechanisms

Abstract Background Epigenetic mechanisms regulate chromatin accessibility patterns that govern interaction of transcription machinery with genes and their cis-regulatory elements. Mutations that affect epigenetic mechanisms are common in cancer. Because epigenetic modifications are reversible many anticancer strategies targeting these mechanisms are currently under development and in clinical trials. Main body Here we review evidence suggesting that epigenetic therapeutics can deactivate immunosuppressive gene expression or reprogram tumor cells to activate antigen presentation mechanisms. In addition, the dysregulation of epigenetic mechanisms commonly observed in cancer may alter the immunogenicity of tumor cells and effectiveness of immunotherapies. Conclusions Therapeutics targeting epigenetic mechanisms may be helpful to counter immune evasion and improve the effectiveness of immunotherapies.

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Effects of EMP on Mouse Embryonic Limb Bud Cells

The 2006 4th Asia-Pacific Conference on Environmental Electromagnetics ◽

10.1109/ceem.2006.257921 ◽

2006 ◽

Author(s):

Yongchun Zhou ◽

Junye Liu ◽

Guozhen Guo ◽

Kangchu Li ◽

Jie Zhang ◽

...

Keyword(s):

Limb Bud ◽

Embryonic Limb

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Misexpression of Sox9 in mouse limb bud mesenchyme induces polydactyly and rescues hypodactyly mice

Matrix Biology ◽

10.1016/j.matbio.2006.12.002 ◽

2007 ◽

Vol 26 (4) ◽

pp. 224-233 ◽

Cited By ~ 38

Author(s):

Haruhiko Akiyama ◽

H. Scott Stadler ◽

James F. Martin ◽

Takahiro M. Ishii ◽

Philip A. Beachy ◽

...

Keyword(s):

Limb Bud ◽

Mouse Limb

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High-resolution analysis of cis -acting regulatory networks at the α-globin locus

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0361 ◽

2013 ◽

Vol 368 (1620) ◽

pp. 20120361 ◽

Cited By ~ 10

Author(s):

Jim R. Hughes ◽

Karen M. Lower ◽

Ian Dunham ◽

Stephen Taylor ◽

Marco De Gobbi ◽

...

Keyword(s):

High Resolution ◽

Gene Cluster ◽

Regulatory Networks ◽

Single Gene ◽

Regulatory Elements ◽

Circular Chromosome ◽

Chromosome Conformation ◽

Cis Acting ◽

High Resolution Analysis ◽

Resolution Analysis

We have combined the circular chromosome conformation capture protocol with high-throughput, genome-wide sequence analysis to characterize the cis -acting regulatory network at a single locus. In contrast to methods which identify large interacting regions (10–1000 kb), the 4C approach provides a comprehensive, high-resolution analysis of a specific locus with the aim of defining, in detail, the cis -regulatory elements controlling a single gene or gene cluster. Using the human α-globin locus as a model, we detected all known local and long-range interactions with this gene cluster. In addition, we identified two interactions with genes located 300 kb (NME4) and 625 kb (FAM173a) from the α-globin cluster.

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Incidence and progress of rejection of embryonic limb bud transplants in the turtle,Chelydra serpentina

Journal of Morphology ◽

10.1002/jmor.1051440406 ◽

1974 ◽

Vol 144 (4) ◽

pp. 453-461 ◽

Cited By ~ 3

Author(s):

C. L. Yntema

Keyword(s):

Limb Bud ◽

Chelydra Serpentina ◽

Embryonic Limb

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Products, genetic linkage and limb patterning activity of a murine hedgehog gene

Development ◽

10.1242/dev.120.11.3339 ◽

1994 ◽

Vol 120 (11) ◽

pp. 3339-3353 ◽

Cited By ~ 31

Author(s):

D.T. Chang ◽

A. Lopez ◽

D.P. von Kessler ◽

C. Chiang ◽

B.K. Simandl ◽

...

Keyword(s):

Limb Development ◽

Genetic Linkage ◽

Pcr Primers ◽

Amino Acid Identity ◽

Protein Product ◽

Proteolytic Processing ◽

Limb Bud ◽

Gene Encoding ◽

Mouse Limb ◽

Drosophila Embryos

The hedgehog (hh) segmentation gene of Drosophila melanogaster encodes a secreted signaling protein that functions in the patterning of larval and adult structures. Using low stringency hybridization and degenerate PCR primers, we have isolated complete or partial hh-like sequences from a range of invertebrate species including other insects, leech and sea urchin. We have also isolated three mouse and two human DNA fragments encoding distinct hh-like sequences. Our studies have focused upon Hhg-1, a mouse gene encoding a protein with 46% amino acid identity to hh. The Hhg-1 gene, which corresponds to the previously described vhh-1 or sonic class, is expressed in the notochord, ventral neural tube, lung bud, hindgut and posterior margin of the limb bud in developing mouse embryos. By segregation analysis the Hhg-1 gene has been localized to a region in proximal chromosome 5, where two mutations affecting mouse limb development previously have been mapped. In Drosophila embryos, ubiquitous expression of the Hhg-1 gene yields effects upon gene expression and cuticle pattern similar to those observed for the Drosophila hh gene. We also find that cultured quail cells transfected with a Hhg-1 expression construct can induce digit duplications when grafted to anterior or mid-distal but not posterior borders within the developing chick limb; more proximal limb element duplications are induced exclusively by mid-distal grafts. Both in transgenic Drosophila embryos and in transfected quail cells, the Hhg-1 protein product is cleaved to yield two stable fragments from a single larger precursor. The significance of Hhg-1 genetic linkage, patterning activity and proteolytic processing in Drosophila and chick embryos is discussed.

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