Disease relevance of Notochord

• Although our results implicate semaphorin signalling in mediating repulsion by the notochord, repulsion of early dorsal root ganglion axons is only partially blocked when using neuropilin/Fc reagents [1].
• Abnormalities of floor plate, notochord and somite differentiation in the loop-tail (Lp) mouse: a model of severe neural tube defects [2].
• An analysis of CC (seven cases) was performed and compared with results obtained on notochord, cartilage, classic CD (18 cases), peripheral chondromas (two cases), and peripheral chondrosarcomas (CS, eight cases) [3].
• The immunoreactivity of S-100 protein and neuron specific enolase (NSE.) was correlated with the composition of stromal glycosaminoglycans in chordomas and human notochords, in a combined histochemical and immunohistochemical study [4].
• Adriamycin induces notochord hypertrophy with conservation of sonic hedgehog expression in abnormal ectopic notochord in the adriamycin rat model [5].

High impact information on Notochord

• Signals from prechordal mesoderm control the differentiation of rostral diencephalic ventral midline cells, whereas notochord induces floor plate cells caudally [6].
• Antibodies that block Sonic Hedgehog (SHH) signaling have been used to show that SHH activity is required for the induction of floor plate differentiation by the notochord and independently for the induction of motor neurons by both the notochord and midline neural cells [7].
• A long-range signal encoded by the Sonic hedgehog (Shh) gene has been implicated as the ventral patterning influence from the notochord that induces sclerotome and represses dermomyotome in somite differentiation [8].
• The differentiation of dorsal cell types, therefore, appears to be initiated at the neural plate stage and to involve the opponent activities of a BMP-mediated dorsalizing signal from the epidermal ectoderm and a SHH-mediated ventralizing signal from the notochord [9].
• The winged-helix transcription factor HNF-3 beta is required for notochord development in the mouse embryo [10].

Chemical compound and disease context of Notochord

• An ACh-synthesizing enzyme is present in the notochord, a neural tube-dorsal root ganglion preparation, as well as in rows of myotomes separated from the latter preparation [11].

Biological context of Notochord

• Prior work has established that transient Shh signals from the notochord and floor plate confer a competence in somitic tissue for subsequent BMP signals to induce chondrogenesis [12].
• The mouse homeobox gene Not is required for caudal notochord development and affected by the truncate mutation [13].
• In addition, knockdown of Cav3 resulted in a dramatic up-regulation of eng1a expression resulting in an increase in the number of muscle pioneer-like cells adjacent to the notochord [14].
• These results suggest that Ci-trop is a direct target gene of Ci-Bra and that Brachyury plays an immediate role in the cellular morphogenesis of the notochord [15].
• Enhancers were identified in intron 1 and 2 that mediate floor plate and notochord expression [16].

Anatomical context of Notochord

• In the neurula, noggin is transcribed in the notochord and prechordal mesoderm [17].
• As with Brachyury in the mouse, Xbra is expressed in presumptive mesodermal cells around the blastopore, and then in the notochord [18].
• Floor plate and motor neuron induction by vhh-1, a vertebrate homolog of hedgehog expressed by the notochord [19].
• Here, we show that the misexpression of the Brachyury gene (Ci-Bra) of Ciona intestinalis is sufficient to transform endoderm into notochord [20].
• We identify activin-betaB and FGF2 as notochord factors that can repress endodermal SHH and thereby permit expression of pancreas genes including Pdx1 and insulin [21].

Associations of Notochord with chemical compounds

• To test for the presence of aromatic L-amino acid decarboxylase (AADC), another CA enzyme, cultures of CGs and CGs plus notochord were incubated with levodopa and processed for the detection of CA histofluorescence [22].
• A screen for N-ethyl-N-nitrosourea (ENU)-induced mutations affecting early development in the ascidian Ciona savignyi resulted in the isolation of a number of mutants including the complementing notochord mutants chongmague and chobi [23].
• The formation of notochord and neural tissue in response to XTC-MIF represents a qualitative difference between this inducing factor and the other known group of MIFs, the heparin-binding growth factors [24].
• When grafts of the epithelial layer of the DMZ of early gastrulae labelled with fluorescein dextran were transplanted to the ventral sides of unlabelled host embryos, they induced secondary axes composed of notochord, somites and posterior neural tube [25].
• Lithium treatments performed during early or medium streak stages cause excessive development of the anterior primitive streak, node and notochord, and lead to a degeneration of prospective ventral and posterior structures, as shown by the expression of the molecular markers GSC, CNOT1, BMP2 and Ch-Tbx6L [26].

Gene context of Notochord

• However, there is a progressive loss of early, Sonic hedgehog (Shh)-dependent ventral cell fates despite the normal expression of Shh in the notochord [27].
• Not expression is abolished in Foxa2 and T mutant embryos, suggesting that Not acts downstream of both genes during notochord development [13].
• These changes may be responsible for the abnormal notochord removal in Col2a1-null mice [28].
• Loss of Bapx1 affects the distribution of sclerotomal cells, markedly reducing the number that appear ventromedially around the notochord [29].
• We have analyzed the role of the notochord in somite differentiation and subsequent formation of the vertebral column using a mouse mutant, Danforth's short-tail (Sd) [30].

Analytical, diagnostic and therapeutic context of Notochord

• Consistent with this result, whole embryo in situ hybridization indicates that endogenous expression of H2A.Z is highly enriched in the notochord [31].
• Northern blot analysis, using aggrecan probes, detected same-sized messages from notochord and cartilage RNA [32].
• Transplantation of an additional notochord into the paraxial mesoderm, which prevents the formation of a myotome, reveals the absence of FGFR-1 immunoreactivity on the operated side [33].
• By immunocytochemistry, HDGF was first detected only in atrial myocytes, hind gut epithelia, and notochord of the E10 rat with a nuclear expression pattern [34].
• In vitro, chick and quail embryo ectoderm, endoderm, somites, notochord and neural tube synthesized and organized fibrous FN-matrices, as shown by immunofluorescence [35].

References