A revision of the British Actiniæ. Part II, The Zoantheæ

Haddon, A. C.; Shackleton, Alice M.

doi:10.5962/bhl.title.46280

Cited by 16 publications

(17 citation statements)

References 2 publications

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“…Although it is not known whether these substances function in tube morphogenesis, there is evidence that at least some of these molecules, including chondroitin sulfate and hyaluronic acid, can influence related morphogenesis processes such as epithelial invagination (40)(41)(42). There is also a long history in the field of tissue engineering of using cylinders (''mandrils'') made of synthetic and͞or biological materials as templates for constructing and shaping blood vessels for clinical use (43).…”

Section: Resultsmentioning

confidence: 99%

Requirement for chitin biosynthesis in epithelial tube morphogenesis

Devine

Lubarsky

Shaw

et al. 2005

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

135

130

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Many organs are composed of branched networks of epithelial tubes that transport vital fluids or gases. The proper size and shape of tubes are crucial for their transport function, but the molecular processes that govern tube size and shape are not well understood. Here we show that three genes required for tracheal tube morphogenesis in Drosophila melanogaster encode proteins involved in the synthesis and accumulation of chitin, a polymer of N-acetyl-␤-D-glucosamine that serves as a scaffold in the rigid extracellular matrix of insect cuticle. In all three mutants, developing tracheal tubes bud and extend normally, but the epithelial walls of the tubes do not expand uniformly, and the resultant tubes are grossly misshapen, with constricted and distended regions all along their lengths. The genes are expressed in tracheal cells during the expansion process, and chitin accumulates in the lumen of tubes, forming an expanding cylinder that we propose coordinates the behavior of the surrounding tracheal cells and stabilizes the expanding epithelium. These findings show that chitin regulates epithelial tube morphogenesis, in addition to its classical role protecting mature epithelia.branching morphogenesis ͉ tracheal system ͉ Drosophila ͉ tube shape ͉ mandril M any organs, including the lungs, kidney, liver, and vascular system, are composed of branched networks of epithelial (or endothelial) tubes that transport vital fluids or gases, and the proper size and shape of the tubes are crucial for their transport function. Although there has been progress recently in elucidating the molecular basis of some of the early steps in the development of branched tubular networks, including branch budding and tube formation (1-4), very little is understood about the molecular processes that govern tube size and shape. The Drosophila tracheal (respiratory) system, with its simple cellular structure, an epithelial monolayer without surrounding support cells and accessible development and genetics, provides a valuable model system to address fundamental questions of branching morphogenesis, including how tube size and shape are controlled (5).During development of the Drosophila tracheal system, branches bud sequentially from an epithelial sac consisting of Ϸ80 cells in each hemisegment (6). Two primary branches extend toward and fuse with branches from neighboring segments, forming the dorsal trunk that spans the length of the animal, whereas others extend and ramify on internal tissues. Once the network is established, tubes expand postmitotically to reach their characteristic lengths and diameters (7). A genetic screen identified eight genes required for tube expansion (7), four of which have been cloned (8-11). All four encode claudins or other components of septate junctions, the insect equivalent of vertebrate tight junctions (12, 13). Mutations in seven other septate junction genes also affect tube expansion (9-11, 13, 14), demonstrating that these junctions not only seal the tracheal epithelium but also regulate its size a...

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Section: Resultsmentioning

confidence: 99%

Requirement for chitin biosynthesis in epithelial tube morphogenesis

Devine

Lubarsky

Shaw

et al. 2005

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

135

130

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“…Within the developing embryo, HA accumulates at sites of cell migration and proliferation and has been proposed to play important roles in craniofacial, limb, heart, and neural tube development (35)(36)(37)(38)(39)(40)(41)(42)(43)(44). Over the last 10 years, HA has received considerable attention through the identification of specific cell surface receptors and binding proteins for HA (hyaladherins).…”

Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Characterization of a Putative Mouse Hyaluronan Synthase

Spicer

Augustine

McDonald

1996

Journal of Biological Chemistry

155

104

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We report the isolation of a novel mouse gene which encodes a putative hyaluronan synthase. The cDNA was identified using degenerate reverse transcriptase-polymerase chain reaction. Degenerate primers were designed based upon an alignment of the amino acid sequences of Streptococcus pyogenes HasA, Xenopus laevis DG42, and Rhizobium meliloti NodC. A mouse embryo cDNA library was screened with the resultant polymerase chain reaction product, and multiple cDNA clones spanning 3 kilobase pairs (kb) were isolated. The open reading frame predicted a 63-kDa protein with several transmembrane sequences, multiple consensus phosphorylation sites, and four putative hyaluronan binding motifs. The amino acid sequence displayed 55% identity to mouse HAS, 56% identity to Xenopus DG42, and 21% identity to Streptococcus HasA. Northern analysis identified transcripts of 4.8 kb and 3.2 kb, which were expressed highly in the developing mouse embryo and at lower levels in adult mouse heart, brain, spleen, lung, and skeletal muscle. Transfection experiments demonstrated that mouse Has2 could direct hyaluronan coat biosynthesis in transfected COS cells, as evidenced by a classical particle exclusion assay. These results suggest that mammalian HA synthase activity is regulated by at least two related genes. Accordingly, we propose the name Has2 for this gene.Hyaluronan (HA 1 ) is a linear unbranched polymer made up of repeating disaccharide units of D-glucuronic acid(␤133)Nacetylglucosamine(␤134). More than 60 years after the isolation of hyaluronan from the vitreous humor (1), its synthetic pathway remains incompletely characterized. HA is synthesized as a free, linear polymer at the inner face of the plasma membrane of eukaryotic cells and is subsequently extruded to the outside of the cell (2-7). HA biosynthesis in mammalian cells may be regulated in part through signaling cascades (8, 9).Certain bacteria can synthesize an HA polymer that is identical to the polymer synthesized by mammalian cells (10 -12). Indeed, investigation of HA biosynthesis in the Group A Streptococcus, Streptococcus pyogenes, has recently led to the identification and cloning of several genes that encode enzymes critical for HA biosynthesis in this bacterium (11). However, until very recently, no genes have been identified that encode enzymes with similar activities in mammalian cells.Degenerate reverse transcriptase-PCR has been a useful tool in the identification and cloning of many genes and gene families (13-15). This approach relies upon conserved sequences deduced from alignments of related gene or protein sequences. The hasA gene of S. pyogenes encodes hyaluronan synthase in this bacterium (11). Sequence analysis predicts that this protein is a membrane protein with a large intracellular loop encoding the active site of the enzyme (11). Similarly, in mammalian cells, the HA synthase has been localized to the plasma membrane, with the active site on the inner face of the membrane (4, 5). Data base searches have identified the Rhizobium sp. nodulation fa...

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“…Although several papers report the critical role of proteoglycans in X. laevis development (17)(18)(19)(20)(21)(22), very limited information is available on GAG functions in amphibian embryogenesis (23)(24)(25). Therefore, we have characterized the X. laevis UGDH (xUGDH), the key enzyme in GAG biosynthesis in this model organism, as suitable for developmental studies.…”

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confidence: 99%

Molecular Cloning and Characterization of UDP-glucose Dehydrogenase from the Amphibian Xenopus laevis and Its Involvement in Hyaluronan Synthesis

Vigetti

Ori

Viola

et al. 2006

Journal of Biological Chemistry

114

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UDP-glucose dehydrogenase (UGDH) supplies the cell with UDP-glucuronic acid (UDP-GlcUA), a precursor of glycosaminoglycan and proteoglycan synthesis. Here we reported the cloning and the characterization of the UGDH from the amphibian Xenopus laevis that is one of the model organisms for developmental biology. We found that X. laevis UGDH (xUGDH) maintained a very high degree of similarity with other known UGDH sequences both at the genomic and the protein levels. Also its kinetic parameters are similar to those of UGDH from other species. During X. laevis development, UDGH is always expressed but clearly increases its mRNA levels at the tail bud stage (i.e. 30 h post-fertilization). This result fits well with our previous observation that hyaluronan, a glycosaminoglycan that is synthesized using UDP-GlcUA and UDP-N-acetylglucosamine, is abundantly detected at this developmental stage. The expression of UGDH was found to be related to hyaluronan synthesis. In human smooth muscle cells the overexpression of xUGDH or endogenous abrogation of UGDH modulated hyaluronan synthesis specifically. Our findings were confirmed by in vivo experiments where the silencing of xUGDH in X. laevis embryos decreased glycosaminoglycan synthesis causing severe embryonic malformations because of a defective gastrulation process.

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A revision of the British Actiniæ. Part II, The Zoantheæ

Cited by 16 publications

References 2 publications

Requirement for chitin biosynthesis in epithelial tube morphogenesis

Requirement for chitin biosynthesis in epithelial tube morphogenesis

Molecular Cloning and Characterization of a Putative Mouse Hyaluronan Synthase

Molecular Cloning and Characterization of UDP-glucose Dehydrogenase from the Amphibian Xenopus laevis and Its Involvement in Hyaluronan Synthesis

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