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Transdifferentiation is a driving force of regeneration in Halisarca dujardini (Demospongiae, Porifera).

Borisenko IE, Adamska M, Tokina DB, Ereskovsky AV - PeerJ (2015)

Bottom Line: Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl.After the blastema is formed, MET becomes the principal mechanism of regeneration.Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Embryology, Faculty of Biology, Saint-Petersburg State University , Saint-Petersburg , Russia.

ABSTRACT
The ability to regenerate is widespread in the animal kingdom, but the regenerative capacities and mechanisms vary widely. To understand the evolutionary history of the diverse regeneration mechanisms, the regeneration processes must be studied in early-evolved metazoans in addition to the traditional bilaterian and cnidarian models. For this purpose, we have combined several microscopy techniques to study mechanisms of regeneration in the demosponge Halisarca dujardini. The objectives of this work are to detect the cells and morphogenetic processes involved in Halisarca regeneration. We show that in Halisarca there are three main sources of the new exopinacoderm during regeneration: choanocytes, archaeocytes and (rarely) endopinacocytes. Here we show that epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) occur during Halisarca regeneration. EMT is the principal mechanism during the first stages of regeneration, soon after the injury. Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl. Together with archaeocytes, these cells form an undifferentiated cell mass beneath of wound, which we refer to as a blastema. After the blastema is formed, MET becomes the principal mechanism of regeneration. Altogether, we demonstrate that regeneration in demosponges involves a variety of processes utilized during regeneration in other animals (e.g., cell migration, dedifferentiation, blastema formation) and points to the particular importance of transdifferentiation in this process. Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

No MeSH data available.


Related in: MedlinePlus

Scheme of principal mode of different cells transformation into T-shaped exopinacocytes by cell flattening parallel to sponge surface, immersion of main cytoplasmic volume of cell with the nucleus inside the ectosome, and formation of a fine cytoplasmic bridge between the apical plate and the immersed part of the cell.
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fig-6: Scheme of principal mode of different cells transformation into T-shaped exopinacocytes by cell flattening parallel to sponge surface, immersion of main cytoplasmic volume of cell with the nucleus inside the ectosome, and formation of a fine cytoplasmic bridge between the apical plate and the immersed part of the cell.

Mentions: Differentiation of exopinacocytes is individual, and begins with cells migrating from the blastema towards the wound surface. Upon reaching the wound, the cells flatten, assuming positions parallel to the surface (Figs. 5C and 5D). Ultrastructural characters demonstrate that the migrating cells include archaeocytes, dedifferentiated choanocytes (Figs. 5E and 5F), endopinacocytes and exopinacocytes and newer other mesohyl cells types. Then, these cells begin to transform into T-shaped exopinacocytes, characteristic of the adult sponge: most of the cytoplasm of the cell and the nucleus are inside the ectosome. A fine cytoplasmic bridge is retained between the apical plate and the immersed part of the cell (Fig. 6). The apical parts of new exopinacocyte extend into large polygonal plates.


Transdifferentiation is a driving force of regeneration in Halisarca dujardini (Demospongiae, Porifera).

Borisenko IE, Adamska M, Tokina DB, Ereskovsky AV - PeerJ (2015)

Scheme of principal mode of different cells transformation into T-shaped exopinacocytes by cell flattening parallel to sponge surface, immersion of main cytoplasmic volume of cell with the nucleus inside the ectosome, and formation of a fine cytoplasmic bridge between the apical plate and the immersed part of the cell.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556153&req=5

fig-6: Scheme of principal mode of different cells transformation into T-shaped exopinacocytes by cell flattening parallel to sponge surface, immersion of main cytoplasmic volume of cell with the nucleus inside the ectosome, and formation of a fine cytoplasmic bridge between the apical plate and the immersed part of the cell.
Mentions: Differentiation of exopinacocytes is individual, and begins with cells migrating from the blastema towards the wound surface. Upon reaching the wound, the cells flatten, assuming positions parallel to the surface (Figs. 5C and 5D). Ultrastructural characters demonstrate that the migrating cells include archaeocytes, dedifferentiated choanocytes (Figs. 5E and 5F), endopinacocytes and exopinacocytes and newer other mesohyl cells types. Then, these cells begin to transform into T-shaped exopinacocytes, characteristic of the adult sponge: most of the cytoplasm of the cell and the nucleus are inside the ectosome. A fine cytoplasmic bridge is retained between the apical plate and the immersed part of the cell (Fig. 6). The apical parts of new exopinacocyte extend into large polygonal plates.

Bottom Line: Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl.After the blastema is formed, MET becomes the principal mechanism of regeneration.Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Embryology, Faculty of Biology, Saint-Petersburg State University , Saint-Petersburg , Russia.

ABSTRACT
The ability to regenerate is widespread in the animal kingdom, but the regenerative capacities and mechanisms vary widely. To understand the evolutionary history of the diverse regeneration mechanisms, the regeneration processes must be studied in early-evolved metazoans in addition to the traditional bilaterian and cnidarian models. For this purpose, we have combined several microscopy techniques to study mechanisms of regeneration in the demosponge Halisarca dujardini. The objectives of this work are to detect the cells and morphogenetic processes involved in Halisarca regeneration. We show that in Halisarca there are three main sources of the new exopinacoderm during regeneration: choanocytes, archaeocytes and (rarely) endopinacocytes. Here we show that epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) occur during Halisarca regeneration. EMT is the principal mechanism during the first stages of regeneration, soon after the injury. Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl. Together with archaeocytes, these cells form an undifferentiated cell mass beneath of wound, which we refer to as a blastema. After the blastema is formed, MET becomes the principal mechanism of regeneration. Altogether, we demonstrate that regeneration in demosponges involves a variety of processes utilized during regeneration in other animals (e.g., cell migration, dedifferentiation, blastema formation) and points to the particular importance of transdifferentiation in this process. Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

No MeSH data available.


Related in: MedlinePlus