scholarly journals Interaction between X-Delta-2 and Hox genes regulates segmentation and patterning of the anteroposterior axis

2006 ◽  
Vol 123 (4) ◽  
pp. 321-333 ◽  
Author(s):  
João N. Peres ◽  
Claire L. McNulty ◽  
Anthony J. Durston
Keyword(s):  
Hox Genes ◽  
Anteroposterior Axis

Hox gene induction in the neural tube depends on three parameters: competence, signal supply and paralogue group

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 849-859 ◽  
Author(s):  
A. Grapin-Botton ◽  
M.A. Bonnin ◽  
N.M. Douarin Le
Keyword(s):  
Gene Expression ◽  
Neural Tube ◽  
Hox Genes ◽  
Gene Induction ◽  
Paraxial Mesoderm ◽  
Environmental Cues ◽  
Hox Gene ◽  
Anteroposterior Axis ◽  
Gene Regulatory ◽  
Genomic Clusters

It has been previously shown that Hox gene expression in the rhombencephalon is controlled by environmental cues. Thus posterior transposition of anterior rhombomeres to the r7/8 level results in the activation of Hox genes of the four first paralog groups and in homeotic transformations of the neuroepithelial fate according to its position along the anteroposterior axis. We demonstrate here that although the anteroposterior levels of r2 to r6 express Hox genes they do not have inducing activity on more anterior territories. If transposed at the posterior rhombencephalon and trunk level, however, the same anterior regions are able to express Hox gene such as Hoxa-2, a-3 or b-4. We also provide evidence that these signals are transferred by two paths: one vertical, arising from the paraxial mesoderm, and one planar, travelling in the neural epithelium. The competence to express Hox genes extends up to the forebrain and midbrain but expression of Hox genes does not preclude Otx2 expression in these territories and results only in slight changes in their phenotypes. Similarly, rhombomeres transplanted to posterior truncal levels turned out to be able to express posterior genes of the first eight paralog groups to the exclusion of others located downstream in the Hox genes genomic clusters. This suggests that the neural tube is divided into large territories characterized by different Hox gene regulatory features.

scholarly journals Separate elements cause lineage restriction and specify boundaries of Hox-1.1 expression

Development ◽  
1991 ◽  
Vol 112 (1) ◽  
pp. 279-287 ◽  
Author(s):  
A.W. Puschel ◽  
R. Balling ◽  
P. Gruss
Keyword(s):  
Transgenic Mice ◽  
Hox Genes ◽  
Positional Information ◽  
Regulatory Elements ◽  
Specific Region ◽  
Regulatory Sequences ◽  
Anteroposterior Axis ◽  
Positional Identity ◽  
Developmental Programme ◽  
Responsive Element

The Hox genes are a class of putative developmental control genes that are thought to be involved in the specification of positional identity along the anteroposterior axis of the vertebrate embryo. It is apparent from their expression pattern that their regulation is dependent upon positional information. In a previous analysis of the Hox-1.1 promoter in transgenic mice, we identified sequences that were sufficient to establish transgene expression in a specific region of the embryo. The construct used, however, did not contain enough regulatory sequences to reproduce all aspects of Hox-1.1 expression. In particular, neither a posterior boundary nor a restriction of expression to prevertebrae was achieved. Here we show correct regulation by Hox-1.1 sequences in transgenic mice and identify the elements responsible for different levels of control. Concomitant with the subdivision of mesodermal cells into different lineages during gastrulation and organogenesis, Hox-1.1 expression is restricted to successively smaller sets of cells. Distinct elements are required at different stages of development to execute this developmental programme. One position-responsive element (130 bp nontranslated leader) was shown to be crucial for the restriction of expression not only along the anteroposterior axis of the embryo, setting the posterior border, but also along the dorsoventral axis of the neural tube and to the lineage giving rise to the prevertebrae. Thus, Hox-1.1 expression is established in a specific region of the embryo and in a specific lineage of the mesoderm by restricting the activity of the promoter by the combined effect of several regulatory elements.

eFGF, Xcad3 and Hox genes form a molecular pathway that establishes the anteroposterior axis in Xenopus

Development ◽  
1996 ◽  
Vol 122 (12) ◽  
pp. 3881-3892 ◽  
Author(s):  
M.E. Pownall ◽  
A.S. Tucker ◽  
J.M. Slack ◽  
H.V. Isaacs
Keyword(s):  
Hox Genes ◽  
Dominant Negative ◽  
Transformation Model ◽  
Neural Patterning ◽  
Fgf Receptor ◽  
Anteroposterior Patterning ◽  
Anteroposterior Axis ◽  
Ectopic Activation ◽  
Transforming Activity ◽  
Fgf Signalling

Classical embryological experiments suggest that a posterior signal is required for patterning the developing anteroposterior axis. In this paper, we investigate a potential role for FGF signalling in this process. During normal development, embryonic fibroblast growth factor (eFGF) is expressed in the posterior of the Xenopus embryo. We have previously shown that overexpression of eFGF from the start of gastrulation results in a posteriorised phenotype of reduced head and enlarged proctodaeum. We have now determined the molecular basis of this phenotype and we propose a role for eFGF in normal anteroposterior patterning. In this study, we show that the overexpression of eFGF causes the up-regulation of a number of posteriorly expressed genes, and prominent among these are Xcad3, a caudal homologue, and the Hox genes, in particular HoxA7. There is both an increase of expression within the normal domains and an extension of expression towards the anterior. Application of eFGF-loaded beads to specific regions of gastrulae reveals that anterior truncations arise from an effect on the developing dorsal axis. Similar anterior truncations are caused by the dorsal overexpression of Xcad3 or HoxA7. This suggests that this aspect of the eFGF overexpression phenotype is caused by the ectopic activation of posterior genes in anterior regions. Further results using the dominant negative FGF receptor show that the normal expression of posterior Hox genes is dependent on FGF signalling and that this regulation is likely mediated by the activation of Xcad3. The biological activity of eFGF, together with its expression in the posterior of the embryo, make it a good candidate to fulfil the role of the ‘transforming’ activity proposed by Nieuwkoop in his ‘activation and transformation’ model for neural patterning.

Segmental relationship between somites and vertebral column in zebrafish

Development ◽  
2002 ◽  
Vol 129 (16) ◽  
pp. 3851-3860 ◽  
Author(s):  
Elizabeth M. Morin-Kensicki ◽  
Ellie Melancon ◽  
Judith S. Eisen
Keyword(s):  
Vertebral Column ◽  
Hox Genes ◽  
De Novo ◽  
Expression Patterns ◽  
Axial Skeleton ◽  
Anteroposterior Axis ◽  
Tissue Interactions ◽  
Positional Identity ◽  
Regional Specificity

The segmental heritage of all vertebrates is evident in the character of the vertebral column. And yet, the extent to which direct translation of pattern from the somitic mesoderm and de novo cell and tissue interactions pattern the vertebral column remains a fundamental, unresolved issue. The elements of vertebral column pattern under debate include both segmental pattern and anteroposterior regional specificity. Understanding how vertebral segmentation and anteroposterior positional identity are patterned requires understanding vertebral column cellular and developmental biology. In this study, we characterized alignment of somites and vertebrae, distribution of individual sclerotome progeny along the anteroposterior axis and development of the axial skeleton in zebrafish. Our clonal analysis of zebrafish sclerotome shows that anterior and posterior somite domains are not lineage-restricted compartments with respect to distribution along the anteroposterior axis but support a ‘leaky’ resegmentation in development from somite to vertebral column. Alignment of somites with vertebrae suggests that the first two somites do not contribute to the vertebral column. Characterization of vertebral column development allowed examination of the relationship between vertebral formula and expression patterns of zebrafish Hox genes. Our results support co-localization of the anterior expression boundaries of zebrafish hoxc6 homologs with a cervical/thoracic transition and also suggest Hox-independent patterning of regionally specific posterior vertebrae.

Dysregulation of HOX as a Potential Therapeutic Target in Breast Cancer

2020 ◽  
Vol 27 ◽  
Author(s):  
Ji-Yeon Lee ◽  
Myoung Hee Kim
Keyword(s):  
Breast Cancer ◽  
Hox Genes ◽  
Therapeutic Potential ◽  
Expression Patterns ◽  
Genome Structure ◽  
Control Cell ◽  
Three Dimensional ◽  
Cellular Processes ◽  
Hox Protein

: HOX genes belong to the highly conserved homeobox superfamily, responsible for the regulation of various cellular processes that control cell homeostasis, from embryogenesis to carcinogenesis. The abnormal expression of HOX genes is observed in various cancers, including breast cancer; they act as oncogenes or as suppressors of cancer, according to context. In this review, we analyze HOX gene expression patterns in breast cancer and examine their relationship, based on the three-dimensional genome structure of the HOX locus. The presence of non-coding RNAs, embedded within the HOX cluster, and the role of these molecules in breast cancer have been reviewed. We further evaluate the characteristic activity of HOX protein in breast cancer and its therapeutic potential.

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