The stem cell system in demosponges: Insights into the origin of somatic stem cells

Funayama, Noriko

doi:10.1111/j.1440-169x.2009.01162.x

Cited by 92 publications

(87 citation statements)

References 77 publications

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“…Remarkably, dissociated cells can then re-aggregate to reform an animal and choanocytes possibly revert to their original shape and function. In addition, choanocytes can trans-differentiate into archeocytes, which are amoeboid stem cells that actively migrate within the mesohyl [99]. Choanocytes are thus capable of switching between flagellated and amoeboid forms by reorganizing their actin and microtubule cytoskeletons.…”

Section: (Iii) Early Metazoamentioning

confidence: 99%

Exploring the evolutionary history of centrosomes

Azimzadeh

2014

Phil. Trans. R. Soc. B

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The centrosome is the main organizer of the microtubule cytoskeleton in animals, higher fungi and several other eukaryotic lineages. Centrosomes are usually located at the centre of cell in tight association with the nuclear envelope and duplicate at each cell cycle. Despite a great structural diversity between the different types of centrosomes, they are functionally equivalent and share at least some of their molecular components. In this paper, we explore the evolutionary origin of the different centrosomes, in an attempt to understand whether they are derived from an ancestral centrosome or evolved independently from the motile apparatus of distinct flagellated ancestors. We then discuss the evolution of centrosome structure and function within the animal lineage.

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Section: (Iii) Early Metazoamentioning

confidence: 99%

Exploring the evolutionary history of centrosomes

Azimzadeh

2014

Phil. Trans. R. Soc. B

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“…Although they are differentiated cells, they maintain piwi expression unlike other differentiated cells. This piwi expression is thought to be the molecular basis for their pluripotency: they can give rise to sperm, or dedifferentiate into archeocytes, which are migratory pluripotent cells (Funayama, 2010). In the clonal tunicate Botrylloides, a piwi homolog is activated in dormant cells that normally line the internal vasculature epithelium, and these cells can regenerate mature B A SCs, i.e.…”

Section: Mpscs and The Origin Of Egscs And Spscsmentioning

confidence: 99%

Germline stem cells and sex determination in Hydra

Nishimiya-Fujisawa¹,

Kobayashi²

2012

Int. J. Dev. Biol.

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The sex of germline stem cells (GSCs) in Hydra is determined in a cell-autonomous manner. In gonochoristic species like Hydra magnipapillata or H. oligactis, where the sexes are separate, male polyps have sperm-restricted stem cells (SpSCs), while females have egg-restricted stem cells (EgSCs). These GSCs self-renew in a polyp, and are usually transmitted to a new bud from a parental polyp during asexual reproduction. But if these GSCs are lost during subsequent budding or regeneration events, new ones are generated from multipotent stem cells (MPSCs). MPSCs are the somatic stem cells in Hydra that ordinarily differentiate into nerve cells, nematocytes (stinging cells in cnidarians), and gland cells. By means of such a backup system, sexual reproduction is guaranteed for every polyp. Interestingly, Hydra polyps occasionally undergo sex-reversal. This implies that each polyp can produce either type of GSCs, i.e. Hydra are genetically hermaphroditic. Nevertheless a polyp possesses only one type of GSCs at a time. We propose a plausible model for sex-reversal in Hydra. We also discuss so-called germline specific genes, which are expressed in both GSCs and MPSCs, and some future plans to investigate Hydra GSCs.

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“…In some cases, they remain mitotically quiescent until they are used later in development, such as in the sea urchin (Tanaka and Dan, Development 137, 4113-4126 (2010) (Newmark et al, 2008). A similar strategy is used in at least some cnidarians and sponges, which have populations of adult multipotent or totipotent stem cells that continually give rise to both germ and somatic cells (Bosch and David, 1987;Funayama, 2010;Muller et al, 2004).Regardless of the strategy used, the same set of genes appears both to specify and maintain PGCs during embryonic germline segregation and to maintain long-term multipotent progenitor cells in animals that segregate their germline after embryogenesis. Extensive functional studies in chordates and ecdysozoans have begun to identify members of this gene set, including vasa, nanos and piwi.…”

mentioning

confidence: 99%

A conserved germline multipotency program

2010

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The germline of multicellular animals is segregated from somatic tissues, which is an essential developmental process for the next generation. Although certain ecdysozoans and chordates segregate their germline during embryogenesis, animals from other taxa segregate their germline after embryogenesis from multipotent progenitor cells. An overlapping set of genes, including vasa, nanos and piwi, operate in both multipotent precursors and in the germline. As we propose here, this conservation implies the existence of an underlying germline multipotency program in these cell types that has a previously underappreciated and conserved function in maintaining multipotency.Key words: Germline, Stem cell, Vasa, Piwi, Nanos, Sea urchin Introduction Multicellular animals consist of specialized cells, most of which are differentiated and devoid of reproductive potential. However, some cells, such as stem cells, retain both the ability to self-renew and to create new differentiated cells. One such stem cell, the germline stem cell (GSC), gives rise to a continual supply of germ cells, which are specialized for the task of reproduction. Yet once egg and sperm fuse, the resulting zygote is totipotent, and thus can give rise to all cell types of the animal. Although GSCs normally give rise only to germ cells in vivo, and thus are unipotent, a significant body of evidence shows that these cells maintain the potential to acquire many cell fates. For example, mouse primordial germ cells (PGCs) acquire the morphological and cytological characteristics of embryonic stem (ES) cells when cultured in the presence of three growth factors: steel factor, leukemia inhibitory factor (LIF) and fibroblast growth factor (FGF) (Matsui et al., 1992). These cells create teratomas when injected into adult mice and chimeric pups when injected into blastocysts, thus demonstrating their pluripotency. Isolated human PGCs can also be converted to pluripotent stem cells without genetic manipulation (Shamblott et al., 1998). Furthermore, pluripotent cells spontaneously arise from isolated adult mouse spermatogonial stem cells under specific culture conditions (Guan et al., 2006). This phenomenon is not limited to vertebrates as mutations in the translational regulators mex-3 and gld-1 in Caenorhabditis elegans leads to transdifferentiation of germ cells into muscle, neurons and intestinal cells (Ciosk et al., 2006). Thus, although germ cells are highly specialized, they seemingly retain the capacity to give rise to all cell types. As such, it is possible that the developmental potential of GSCs in these organisms is not intrinsically limited but might instead be restricted by environment. What, then, is the underlying regulatory program that controls this highly potent cell type?The molecular regulation of the germline is best understood in a handful of animals, including in C. elegans, Drosophila melanogaster and the mouse. Here, we explore the diversity of germline origins more broadly by examining germline segregation mechanisms across diverse taxa f...

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The stem cell system in demosponges: Insights into the origin of somatic stem cells

Cited by 92 publications

References 77 publications

Exploring the evolutionary history of centrosomes

Exploring the evolutionary history of centrosomes

Germline stem cells and sex determination in Hydra

A conserved germline multipotency program

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