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A zebrafish model of Roberts syndrome reveals that Esco2 depletion interferes with development by disrupting the cell cycle.

Mönnich M, Kuriger Z, Print CG, Horsfield JA - PLoS ONE (2011)

Bottom Line: A microarray analysis of Esco2-depleted embryos revealed that different subsets of genes are regulated downstream of Esco2 when compared with cohesin subunit Rad21.Genes downstream of Rad21 showed significant enrichment for transcriptional regulators, while Esco2-regulated genes were more likely to be involved the cell cycle or apoptosis.We propose that cell proliferation defects and apoptosis could be the primary cause of the features of RBS.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Dunedin School of Medicine, The University of Otago, Dunedin, New Zealand.

ABSTRACT
The human developmental diseases Cornelia de Lange Syndrome (CdLS) and Roberts Syndrome (RBS) are both caused by mutations in proteins responsible for sister chromatid cohesion. Cohesion is mediated by a multi-subunit complex called cohesin, which is loaded onto chromosomes by NIPBL. Once on chromosomes, cohesin binding is stabilized in S phase upon acetylation by ESCO2. CdLS is caused by heterozygous mutations in NIPBL or cohesin subunits SMC1A and SMC3, and RBS is caused by homozygous mutations in ESCO2. The genetic cause of both CdLS and RBS reside within the chromosome cohesion apparatus, and therefore they are collectively known as "cohesinopathies". However, the two syndromes have distinct phenotypes, with differences not explained by their shared ontology. In this study, we have used the zebrafish model to distinguish between developmental pathways downstream of cohesin itself, or its acetylase ESCO2. Esco2 depleted zebrafish embryos exhibit features that resemble RBS, including mitotic defects, craniofacial abnormalities and limb truncations. A microarray analysis of Esco2-depleted embryos revealed that different subsets of genes are regulated downstream of Esco2 when compared with cohesin subunit Rad21. Genes downstream of Rad21 showed significant enrichment for transcriptional regulators, while Esco2-regulated genes were more likely to be involved the cell cycle or apoptosis. RNA in situ hybridization showed that runx1, which is spatiotemporally regulated by cohesin, is expressed normally in Esco2-depleted embryos. Furthermore, myca, which is downregulated in rad21 mutants, is upregulated in Esco2-depleted embryos. High levels of cell death contributed to the morphology of Esco2-depleted embryos without affecting specific developmental pathways. We propose that cell proliferation defects and apoptosis could be the primary cause of the features of RBS. Our results show that mutations in different elements of the cohesion apparatus have distinct developmental outcomes, and provide insight into why CdLS and RBS are distinct diseases.

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Late embryonic and larval expression of esco2 in zebrafish.Whole-mount in situ hybridization of zebrafish at the indicated stage with an esco2 antisense riboprobe. A, B, and D are dorsal views, C, E, and F lateral views. Anterior is to the left for all. ov, otic vesicle; epz, eye proliferative zone; pf, pectoral fin; t, tectum; mhb, mid-hindbrain boundary; hpz, hindbrain proliferative zone; ba, branchial arches; p, pharynx; h, heart; g, gut.
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pone-0020051-g001: Late embryonic and larval expression of esco2 in zebrafish.Whole-mount in situ hybridization of zebrafish at the indicated stage with an esco2 antisense riboprobe. A, B, and D are dorsal views, C, E, and F lateral views. Anterior is to the left for all. ov, otic vesicle; epz, eye proliferative zone; pf, pectoral fin; t, tectum; mhb, mid-hindbrain boundary; hpz, hindbrain proliferative zone; ba, branchial arches; p, pharynx; h, heart; g, gut.

Mentions: Considering their related functions, we first asked if zebrafish esco2 is expressed in the same cells as cohesin during embryo development. To determine spatiotemporal expression of the esco2 gene, a riboprobe of the esco2 gene was hybridized with zebrafish embryos collected at intervals up to 4 days post-fertilization (dpf). esco2 expression was ubiquitous in early development (data not shown), however from about 24 hours post-fertilization (hpf), specific patterns of esco2 transcript distribution were observed. From 24–48 hpf, esco2 was expressed in the brain ventricles and otic vesicles (Fig. 1A–E). From 36–48 hpf, esco2 is expressed faintly in the developing pectoral fin (Fig. 1B, C) and in a layer of retinal cells (Fig. 1B–E). At 36 hpf, expression of esco2 was detected in the mid-hindbrain boundary and hindbrain proliferative zone, and in the branchial arches (Fig. 1B, C). At 4 dpf, robust esco2 expression was detected in the developing pharynx, the gut and the heart (Fig. 1F). In summary, the expression pattern of esco2 during zebrafish embryo development closely resembles that of cohesin subunits [49], and is predominantly found in proliferative cells. This is consistent with the finding that Esco2 is important for the establishment of sister chromatid cohesion in conjunction with cohesin.


A zebrafish model of Roberts syndrome reveals that Esco2 depletion interferes with development by disrupting the cell cycle.

Mönnich M, Kuriger Z, Print CG, Horsfield JA - PLoS ONE (2011)

Late embryonic and larval expression of esco2 in zebrafish.Whole-mount in situ hybridization of zebrafish at the indicated stage with an esco2 antisense riboprobe. A, B, and D are dorsal views, C, E, and F lateral views. Anterior is to the left for all. ov, otic vesicle; epz, eye proliferative zone; pf, pectoral fin; t, tectum; mhb, mid-hindbrain boundary; hpz, hindbrain proliferative zone; ba, branchial arches; p, pharynx; h, heart; g, gut.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102698&req=5

pone-0020051-g001: Late embryonic and larval expression of esco2 in zebrafish.Whole-mount in situ hybridization of zebrafish at the indicated stage with an esco2 antisense riboprobe. A, B, and D are dorsal views, C, E, and F lateral views. Anterior is to the left for all. ov, otic vesicle; epz, eye proliferative zone; pf, pectoral fin; t, tectum; mhb, mid-hindbrain boundary; hpz, hindbrain proliferative zone; ba, branchial arches; p, pharynx; h, heart; g, gut.
Mentions: Considering their related functions, we first asked if zebrafish esco2 is expressed in the same cells as cohesin during embryo development. To determine spatiotemporal expression of the esco2 gene, a riboprobe of the esco2 gene was hybridized with zebrafish embryos collected at intervals up to 4 days post-fertilization (dpf). esco2 expression was ubiquitous in early development (data not shown), however from about 24 hours post-fertilization (hpf), specific patterns of esco2 transcript distribution were observed. From 24–48 hpf, esco2 was expressed in the brain ventricles and otic vesicles (Fig. 1A–E). From 36–48 hpf, esco2 is expressed faintly in the developing pectoral fin (Fig. 1B, C) and in a layer of retinal cells (Fig. 1B–E). At 36 hpf, expression of esco2 was detected in the mid-hindbrain boundary and hindbrain proliferative zone, and in the branchial arches (Fig. 1B, C). At 4 dpf, robust esco2 expression was detected in the developing pharynx, the gut and the heart (Fig. 1F). In summary, the expression pattern of esco2 during zebrafish embryo development closely resembles that of cohesin subunits [49], and is predominantly found in proliferative cells. This is consistent with the finding that Esco2 is important for the establishment of sister chromatid cohesion in conjunction with cohesin.

Bottom Line: A microarray analysis of Esco2-depleted embryos revealed that different subsets of genes are regulated downstream of Esco2 when compared with cohesin subunit Rad21.Genes downstream of Rad21 showed significant enrichment for transcriptional regulators, while Esco2-regulated genes were more likely to be involved the cell cycle or apoptosis.We propose that cell proliferation defects and apoptosis could be the primary cause of the features of RBS.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Dunedin School of Medicine, The University of Otago, Dunedin, New Zealand.

ABSTRACT
The human developmental diseases Cornelia de Lange Syndrome (CdLS) and Roberts Syndrome (RBS) are both caused by mutations in proteins responsible for sister chromatid cohesion. Cohesion is mediated by a multi-subunit complex called cohesin, which is loaded onto chromosomes by NIPBL. Once on chromosomes, cohesin binding is stabilized in S phase upon acetylation by ESCO2. CdLS is caused by heterozygous mutations in NIPBL or cohesin subunits SMC1A and SMC3, and RBS is caused by homozygous mutations in ESCO2. The genetic cause of both CdLS and RBS reside within the chromosome cohesion apparatus, and therefore they are collectively known as "cohesinopathies". However, the two syndromes have distinct phenotypes, with differences not explained by their shared ontology. In this study, we have used the zebrafish model to distinguish between developmental pathways downstream of cohesin itself, or its acetylase ESCO2. Esco2 depleted zebrafish embryos exhibit features that resemble RBS, including mitotic defects, craniofacial abnormalities and limb truncations. A microarray analysis of Esco2-depleted embryos revealed that different subsets of genes are regulated downstream of Esco2 when compared with cohesin subunit Rad21. Genes downstream of Rad21 showed significant enrichment for transcriptional regulators, while Esco2-regulated genes were more likely to be involved the cell cycle or apoptosis. RNA in situ hybridization showed that runx1, which is spatiotemporally regulated by cohesin, is expressed normally in Esco2-depleted embryos. Furthermore, myca, which is downregulated in rad21 mutants, is upregulated in Esco2-depleted embryos. High levels of cell death contributed to the morphology of Esco2-depleted embryos without affecting specific developmental pathways. We propose that cell proliferation defects and apoptosis could be the primary cause of the features of RBS. Our results show that mutations in different elements of the cohesion apparatus have distinct developmental outcomes, and provide insight into why CdLS and RBS are distinct diseases.

Show MeSH
Related in: MedlinePlus