In vivo knockdown of Brachyury results in skeletal defects and urorectal malformations resembling caudal regression syndrome

Pennimpede, Tracie; Proske, Judith; König, Andrea; Vidigal, Joana A.; Morkel, Markus; Bramsen, Jesper B.; Herrmann, Bernhard G.; Wittler, Lars

doi:10.1016/j.ydbio.2012.09.003

Cited by 50 publications

(42 citation statements)

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“…This fits the observation that murine T +/2 heterozygous embryos showed a 50% reduction of T-gene expression in the tail bud and notochord compared with wild-type mice (Pennimpede et al 2012). Pennimpede et al (2012) previously suggested that the T protein is directly involved in the maintenance of the mammalian seven cervical vertebrae blueprint because of the homeotic C7 . T1 transformation of cervical vertebrae in 30% of mice from in vivo T-gene knockdown experiments.…”

Section: T-gene Effects On Mammalian Blueprintsupporting

confidence: 88%

“…The murine brachyury (T) gene with its mutant alleles was the first gene that was identified and positionally cloned based on a genetic defect only, the long-known brachyury resulting in vertebral and spinal defects (Dobrovolskaia-Zavadskaia 1927;Herrmann et al 1990). Numerous subsequent studies confirmed that the coordinated expression of the T gene during gastrulation is essential for appropriate notochord, neural tube, and mesoderm development (Chesley 1935;Pennimpede et al 2012;Satoh et al 2012). Recently, the T gene has gained interest because of its association with the human chordoma, a sporadic and hereditary tumor originating from relicts of the notochord (Yang et al 2009;Pillay et al 2012;Nibu et al 2013).…”

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confidence: 99%

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The Mammalian Cervical Vertebrae Blueprint Depends on theT(brachyury) Gene

Kromik

Ulrich²,

Kusenda

et al. 2015

Genetics

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A key common feature of all but three known mammalian genera is the strict seven cervical vertebrae blueprint, suggesting the involvement of strong conserving selection forces during mammalian radiation. This is further supported by reports indicating that children with cervical ribs die before they reach reproductive age. Hypotheses were put up, associating cervical ribs (homeotic transformations) to embryonal cancer (e.g., neuroblastoma) or ascribing the constraint in cervical vertebral count to the development of the mammalian diaphragm. Here, we describe a spontaneous mutation c.196A . G in the Bos taurus T gene (also known as brachyury) associated with a cervical vertebral homeotic transformation that violates the fundamental mammalian cervical blueprint, but does not preclude reproduction of the affected individual. Genome-wide mapping, haplotype tracking within a large pedigree, resequencing of target genome regions, and bioinformatic analyses unambiguously confirmed the mutant c.196G allele as causal for this previously unknown defect termed vertebral and spinal dysplasia (VSD) by providing evidence for the mutation event. The nonsynonymous VSD mutation is located within the highly conserved T box of the T gene, which plays a fundamental role in eumetazoan body organization and vertebral development. To our knowledge, VSD is the first unequivocally approved spontaneous mutation decreasing cervical vertebrae number in a large mammal. The spontaneous VSD mutation in the bovine T gene is the first in vivo evidence for the hypothesis that the T protein is directly involved in the maintenance of the mammalian seven-cervical vertebra blueprint. It therefore furthers our knowledge of the T-protein function and early mammalian notochord development.KEYWORDS homeotic transformation; genetic defect; brachyury H IGH evolutionary diversification of the vertebral column exists in vertebrates, but the number of cervical vertebrae within mammals has been fixed at seven for .200 million years of evolution since the beginning of the long and wide mammalian radiation (Hautier et al. 2010). The reason why all mammals share this fundamental blueprint of cervical vertebrae, compared with a more relaxed rule for the number of posterior vertebrae analogous to other nonmammalian vertebrates, remains unknown. Nevertheless, evolutionary and clinical data indicate that the cervical vertebral development of mammals is under high selection pressure. For example, in human pediatrics, 83% of children with a deviating number of cervical vertebrae die in their first year, while the surviving individuals do not reach reproductive age (Galis et al. 2006). A detailed knowledge of the key factors involved in the spatial regulation of vertebral development will help to understand these forces.Mutation models, either spontaneous or artificially induced, can reveal the complex processes that occur during vertebral development. Vertebral and accompanied spinal defects are described for many species, including cattle [e.g., complex vert...

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Section: T-gene Effects On Mammalian Blueprintsupporting

confidence: 88%

mentioning

confidence: 99%

The Mammalian Cervical Vertebrae Blueprint Depends on theT(brachyury) Gene

Kromik

Ulrich²,

Kusenda

et al. 2015

Genetics

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“…Our results indicate that notochord progenitors can also be diverted to neural fate in the absence of T function. Interestingly, ectopic neural structures were also observed in a previous report using a doxycycline-regulated T knockdown (14), but lack of lineage tracing and tissue restriction of the knockdown precluded establishing a definite causal relationship.…”

Section: T-knockdown Notochord Progenitors Survive But Adopt Neural Andmentioning

confidence: 74%

Putative oncogene Brachyury ( T ) is essential to specify cell fate but dispensable for notochord progenitor proliferation and EMT

Zhu

Kwan

Mackem

2016

Proc. Natl. Acad. Sci. U.S.A.

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The transcription factor Brachyury (T) gene is expressed throughout primary mesoderm (primitive streak and notochord) during early embryonic development and has been strongly implicated in the genesis of chordoma, a sarcoma of notochord cell origin. Additionally, T expression has been found in and proposed to play a role in promoting epithelial-mesenchymal transition (EMT) in various other types of human tumors. However, the role of T in normal mammalian notochord development and function is still not well-understood. We have generated an inducible knockdown model to efficiently and selectively deplete T from notochord in mouse embryos. In combination with genetic lineage tracing, we show that T function is essential for maintaining notochord cell fate and function. Progenitors adopt predominantly a neural fate in the absence of T, consistent with an origin from a common chordoneural progenitor. However, T function is dispensable for progenitor cell survival, proliferation, and EMT, which has implications for the therapeutic targeting of T in chordoma and other cancers.notochord | Brachyury | cell fate | EMT T he notochord, the defining characteristic of chordates, serves as a signaling center for dorsoventral patterning of both the adjacent neural tube and the somites. Sonic hedgehog (Shh) expressed from the notochord specifies ventral neural fates in spinal cord and ventral somitic fate to form sclerotome that gives rise to the vertebrae of the axial skeleton (1, 2). Genetic lineage tracing in the mouse has revealed that later, during the process of intervertebral disk formation, the notochord fragments into discrete segments and differentiates to form the nucleus pulposus of the intervertebral disks (3, 4). It has been proposed that this process generates the notochord "remnants" that can persist within vertebral bodies in adults (5), which are thought to give rise to chordomas, a rare sarcoma of notochord cell origin. A major advance in understanding the pathogenesis of chordoma has been the discovery that Brachyury (T) gene, which is highly expressed in these tumors, is duplicated in certain familial chordomas (6). T expression, which is pathognomonic for diagnosis of these sarcomas (7), has consequently become a major focus for therapeutic targeting in treatment of these cancers (7,8).T is the founding member of the T-box gene family of transcription factors (9, 10). During embryonic development, T is expressed in the notochord and primitive streak, and is essential for trunk/tail primary mesoderm formation and migration from the primitive streak, which drives axis elongation (11,12). Loss of T function in mouse embryos results in body axis truncation caudal to the forelimb, showing that T is dispensable for anterior-most mesoderm formation (rostral to somite 7). The embryonic role in epithelial-mesenchymal transition (EMT) of cells migrating from primitive streak during mesoderm formation has piqued interest that T, which is variably expressed in a number of common cancers in addition to chordoma (8), may...

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“…20 Antisense probes were generated by PCR from a total cDNA library from E10.5 where PCR products contained a 3 0 T7 RNA polymerase-binding site for in vitro transcription. Probes were purified using G-50 Sephadex columns (GE Healthcare, Munich, Germany).…”

Section: In Situ Hybridization Of Mouse Embryo Sectionsmentioning

confidence: 99%