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Molecular and cytological analyses reveal distinct transformations of intestinal epithelial cells during Xenopus metamorphosis.

Okada M, Wen L, Miller TC, Su D, Shi YB - Cell Biosci (2015)

Bottom Line: Here, we carried out different double-staining with a number of cytological and molecular markers during T3-induced and natural metamorphosis in Xenopus laevis.Our studies demonstrated conclusively that the clusters of proliferating cells in the epithelium at the climax of metamorphosis are undifferentiated epithelial cells and express the well-known adult intestinal stem cell marker gene Lgr5.Our findings suggest that morphologically identical larval epithelial cells choose two alternative paths: programmed cell death or dedifferentiation to form adult stem cells, in response to T3 during metamorphosis with apoptosis occurring prior to the formation of the proliferating adult stem cell clusters (islets).

View Article: PubMed Central - PubMed

Affiliation: Section on Molecular Morphogenesis, Program in Cellular Regulation and Metabolism (PCRM), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), 18 Library Dr., Bethesda, MD 20892 USA.

ABSTRACT

Background: The thyroid hormone (T3)-induced formation of adult intestine during amphibian metamorphosis resembles the maturation of the mammalian intestine during postembryonic development, the period around birth when plasma T3 level peaks. This process involves de novo formation of adult intestinal stem cells as well as the removal of the larval epithelial cells through apoptosis. Earlier studies have revealed a number of cytological and molecular markers for the epithelial cells undergoing different changes during metamorphosis. However, the lack of established double labeling has made it difficult to ascertain the identities of the metamorphosing epithelial cells.

Results: Here, we carried out different double-staining with a number of cytological and molecular markers during T3-induced and natural metamorphosis in Xenopus laevis. Our studies demonstrated conclusively that the clusters of proliferating cells in the epithelium at the climax of metamorphosis are undifferentiated epithelial cells and express the well-known adult intestinal stem cell marker gene Lgr5. We further show that the adult stem cells and apoptotic larval epithelial cells are distinct epithelial cells during metamorphosis.

Conclusions: Our findings suggest that morphologically identical larval epithelial cells choose two alternative paths: programmed cell death or dedifferentiation to form adult stem cells, in response to T3 during metamorphosis with apoptosis occurring prior to the formation of the proliferating adult stem cell clusters (islets).

No MeSH data available.


Related in: MedlinePlus

MGPY and EdU co-stain the clusters (islets) of proliferating adult intestinal epithelial cells at the climax of natural metamorphosis. Tadpoles at premetamorphic stage 54 (A), climax (B stage 62), and end of metamorphosis (C stage 66) were injected with EdU 1 h before being sacrificed. Cross-sections of the intestine from the resulting tadpoles were double-stained for EdU and with MGPY. Higher magnifications of boxed areas in (A–C) are shown in (a′–c′) and (a″–c″). The dotted lines depict the epithelium-mesenchyme boundary (see Fig. 1). Arrowhead indicates the clusters of proliferating cells or islets (b′)
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Fig2: MGPY and EdU co-stain the clusters (islets) of proliferating adult intestinal epithelial cells at the climax of natural metamorphosis. Tadpoles at premetamorphic stage 54 (A), climax (B stage 62), and end of metamorphosis (C stage 66) were injected with EdU 1 h before being sacrificed. Cross-sections of the intestine from the resulting tadpoles were double-stained for EdU and with MGPY. Higher magnifications of boxed areas in (A–C) are shown in (a′–c′) and (a″–c″). The dotted lines depict the epithelium-mesenchyme boundary (see Fig. 1). Arrowhead indicates the clusters of proliferating cells or islets (b′)

Mentions: To investigate this during natural metamorphosis, we carried out similar double labeling on intestinal cross-sections from tadpoles at premetamorphosis (stage 54), climax (stage 62), and end of metamorphosis (stage 66). The results showed that before or after metamorphosis, the epithelium were uniformly labeled with MGPY and some cells were also positive for EdU (Fig. 2A, C, a″, c″). Interestingly, the EdU label were preferentially at the bottom of the newly formed epithelial folds at the end of metamorphosis, suggesting that the proliferating adult cells become restricted to the bottom of the fold, which resembles the crypt in adult mammalian intestine where stem cells reside [23–25]. In contrast, at the climax of metamorphosis, clusters of epithelial cells were much more strongly stained by MGPY than the surrounding cells and these clusters were also labeled by EdU (Fig. 2B, b″), just like that during T3 induced metamorphosis. Thus, the newly formed epithelial cell clusters during metamorphosis are proliferating cells that are strongly stained by MGPY.Fig. 2


Molecular and cytological analyses reveal distinct transformations of intestinal epithelial cells during Xenopus metamorphosis.

Okada M, Wen L, Miller TC, Su D, Shi YB - Cell Biosci (2015)

MGPY and EdU co-stain the clusters (islets) of proliferating adult intestinal epithelial cells at the climax of natural metamorphosis. Tadpoles at premetamorphic stage 54 (A), climax (B stage 62), and end of metamorphosis (C stage 66) were injected with EdU 1 h before being sacrificed. Cross-sections of the intestine from the resulting tadpoles were double-stained for EdU and with MGPY. Higher magnifications of boxed areas in (A–C) are shown in (a′–c′) and (a″–c″). The dotted lines depict the epithelium-mesenchyme boundary (see Fig. 1). Arrowhead indicates the clusters of proliferating cells or islets (b′)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4696227&req=5

Fig2: MGPY and EdU co-stain the clusters (islets) of proliferating adult intestinal epithelial cells at the climax of natural metamorphosis. Tadpoles at premetamorphic stage 54 (A), climax (B stage 62), and end of metamorphosis (C stage 66) were injected with EdU 1 h before being sacrificed. Cross-sections of the intestine from the resulting tadpoles were double-stained for EdU and with MGPY. Higher magnifications of boxed areas in (A–C) are shown in (a′–c′) and (a″–c″). The dotted lines depict the epithelium-mesenchyme boundary (see Fig. 1). Arrowhead indicates the clusters of proliferating cells or islets (b′)
Mentions: To investigate this during natural metamorphosis, we carried out similar double labeling on intestinal cross-sections from tadpoles at premetamorphosis (stage 54), climax (stage 62), and end of metamorphosis (stage 66). The results showed that before or after metamorphosis, the epithelium were uniformly labeled with MGPY and some cells were also positive for EdU (Fig. 2A, C, a″, c″). Interestingly, the EdU label were preferentially at the bottom of the newly formed epithelial folds at the end of metamorphosis, suggesting that the proliferating adult cells become restricted to the bottom of the fold, which resembles the crypt in adult mammalian intestine where stem cells reside [23–25]. In contrast, at the climax of metamorphosis, clusters of epithelial cells were much more strongly stained by MGPY than the surrounding cells and these clusters were also labeled by EdU (Fig. 2B, b″), just like that during T3 induced metamorphosis. Thus, the newly formed epithelial cell clusters during metamorphosis are proliferating cells that are strongly stained by MGPY.Fig. 2

Bottom Line: Here, we carried out different double-staining with a number of cytological and molecular markers during T3-induced and natural metamorphosis in Xenopus laevis.Our studies demonstrated conclusively that the clusters of proliferating cells in the epithelium at the climax of metamorphosis are undifferentiated epithelial cells and express the well-known adult intestinal stem cell marker gene Lgr5.Our findings suggest that morphologically identical larval epithelial cells choose two alternative paths: programmed cell death or dedifferentiation to form adult stem cells, in response to T3 during metamorphosis with apoptosis occurring prior to the formation of the proliferating adult stem cell clusters (islets).

View Article: PubMed Central - PubMed

Affiliation: Section on Molecular Morphogenesis, Program in Cellular Regulation and Metabolism (PCRM), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), 18 Library Dr., Bethesda, MD 20892 USA.

ABSTRACT

Background: The thyroid hormone (T3)-induced formation of adult intestine during amphibian metamorphosis resembles the maturation of the mammalian intestine during postembryonic development, the period around birth when plasma T3 level peaks. This process involves de novo formation of adult intestinal stem cells as well as the removal of the larval epithelial cells through apoptosis. Earlier studies have revealed a number of cytological and molecular markers for the epithelial cells undergoing different changes during metamorphosis. However, the lack of established double labeling has made it difficult to ascertain the identities of the metamorphosing epithelial cells.

Results: Here, we carried out different double-staining with a number of cytological and molecular markers during T3-induced and natural metamorphosis in Xenopus laevis. Our studies demonstrated conclusively that the clusters of proliferating cells in the epithelium at the climax of metamorphosis are undifferentiated epithelial cells and express the well-known adult intestinal stem cell marker gene Lgr5. We further show that the adult stem cells and apoptotic larval epithelial cells are distinct epithelial cells during metamorphosis.

Conclusions: Our findings suggest that morphologically identical larval epithelial cells choose two alternative paths: programmed cell death or dedifferentiation to form adult stem cells, in response to T3 during metamorphosis with apoptosis occurring prior to the formation of the proliferating adult stem cell clusters (islets).

No MeSH data available.


Related in: MedlinePlus