<i>smedinx-11</i>is a planarian stem cell gap junction gene required for regeneration and homeostasis

Oviedo, Néstor J.; Levin, Michael

doi:10.1242/dev.006635

Cited by 104 publications

(112 citation statements)

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“…Other previously described genes show a similar pattern of expression in area A (as well as elsewhere). For instance, smedinx-1 is expressed in this area (Oviedo and Levin, 2007) and its expression is not affected by irradiation. The marker TCEN49, expressed in most cell types except epidermal cells Vispo et al, 1996) and a Zinc-dependent metalloprotease are also expressed in the posterior midline just posterior to the pharynx.…”

Section: Discussionmentioning

confidence: 95%

Diverse miRNA spatial expression patterns suggest important roles in homeostasis and regeneration in planarians

González‐Estévez¹,

Arseni²,

Thambyrajah³

et al. 2009

Int. J. Dev. Biol.

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miRNAs are an important class of non-protein coding small RNAs whose specific functions in animals are rapidly being elucidated. It is clear that miRNAs can play crucial roles in stem cell maintenance, cell fate determination and differentiation. We use planarians, which possess a large population of pluripotent somatic stem cells, as a powerful model system to study many aspects of stem cell biology and regeneration. In particular we wish to investigate the regulatory role miRNAs may have in planarian stem cell self renewal, proliferation and differentiation. Here, we characterized the differential spatial patterns of expression of miRNAs in whole and regenerating planarians by in situ hybridization to nascent miRNA transcripts. These miRNA expression patterns are the first which have been determined for a Lophotrocozoan animal. We have characterized the expression patterns of 42 miRNAs in adult planarians, constituting a complete range of tissue specific expression patterns. We also followed miRNA expression during planarian regeneration. The majority of planarian miRNAs were expressed either in areas where stem cells (neoblasts) are located and/or in the nervous system. Some miRNAs were definitively expressed in stem cells and dividing cells as confirmed by in situ hybridisation after irradiation. We also found miRNAs to be expressed in germ stem cells of the sexual strain. Together, these data suggest an important role for miRNAs in stem cell regulation and in neural cell differentiation in planarians.

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Section: Discussionmentioning

confidence: 95%

Diverse miRNA spatial expression patterns suggest important roles in homeostasis and regeneration in planarians

González‐Estévez¹,

Arseni²,

Thambyrajah³

et al. 2009

Int. J. Dev. Biol.

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“…Fixed parenchyma cells establish intercellular gap junctions with neoblasts 22 and these gap junctions are required for neoblast maintenance. 23 This may provide an explanation for how resources are supplied to neoblasts from autophagic cells. As regeneration proceeds, many cells will be superfluous or in the wrong place as symmetry and proportions are restored and many cells of different organs will undergo cell death in order to scale to the new proportions.…”

Section: Autophagy Enters the Game: A New Possible Scenario For Morphmentioning

confidence: 99%

Gtdap-1and the Role of Autophagy During Planarian Regeneration and Starvation

González‐Estévez¹,

Felix²,

Aboobaker³

et al. 2007

Autophagy

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“…Prominent among them were the homologues of the genes piwi, vasa, nanos, pumilio, tudor, bruno, MCM2, pcna, cyclin B, cbc, innexin, and many other found in microarrays studies and transcriptome and proteomic analyses (for further details see Reddien et al, 2005;Rossi et al, 2007;Oviedo and Levin, 2007;Eisenhoffer et al, 2008;Fernández-Taboada et al, 2011). These markers were used in the first single-cell simultaneous analysis of gene expression and cell cycle state of neoblasts using FACS and real-time PCR (Hayashi et al, 2010).…”

Section: Last Developments and The End Of The Storymentioning

confidence: 99%

“…A third, more physiological approach, is to look for systemic signals that mediate short-range and long-range cues involved to control from axial polarity to neoblast homeostasis. The recent finding of gap junction proteins (innexins) specific for neoblasts and for nerve cells (Oviedo and Levin, 2007), together with the importance of nervous system integrity to transmit inhibitory signals from anterior to posterior regions to avoid duplication of existing structures, highlights the importance of those signals, whatever they turn out to be, to regulate stem cell behaviour in adult organisms (Oviedo et al, 2010). Last but not least, the known effects of several ions, the role of ion channel proteins (Nogi et al, 2009), the plethora of neuropeptides and their agonists and antagonists on neoblast proliferation (Saló and Baguñà, 1986; reviewed in Baguñà et al, 1990), and of several signalling pathways (Wnt, BMP, Notch,..) acting on neoblast determination to specify axial polarity and regional identities (Gurley and Sanchez Alvarado, 2008;Reddien, 2011), also deserve further analyses.…”

Section: The Logic Of Neoblast Lineage and Its Proliferative Controlmentioning

confidence: 99%

The planarian neoblast: the rambling history of its origin and some current black boxes

Baguñà¹

2012

Int. J. Dev. Biol.

145

111

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First described by Randolph in 1897, the nature and main features of planarian neoblasts have a long rambling history. While their morphologically undifferentiated features have long been recognized, their origin and actual role during regeneration have been highly debated. Here I summarize the main stages of this rambling history: 1) undifferentiated, wandering cells of uncertain origin with a main, albeit undefined, role in regeneration (1890-1940s); 2) quiescent, undifferentiated cells whose main function is to build the blastema during regeneration, an idea which culminated in the 'neoblast theory' of the French School (1940-1960); 3) neoblasts as temporal, undifferentiated cells arising by dedifferentiation from differentiated cells (the 'cell dedifferentiation theory'; 1960-1980s); 4) a new paradigm, starting in the late 1970s-early 1980s, that brought together the role of neoblasts as the main cell for regeneration, with its more important role as somatic stem cells for the daily wear and tear of tissues and as the source of germ cells; and 5) more recent developments that culminate in the report of rescuing lethally irradiated planarians by injection of single neoblasts, which makes of neoblasts an unrivaled toti-, pluripotent somatic stem cell system in the Animal Kingdom. I finally discuss some "black boxes" regarding neoblasts which still baffle us, namely their phylogenetic and ontogenetic origins, their role in body size control, how their pool is regulated during growth and degrowth, the logic of their proliferative control, and some 'old' long-sought missing tools. KEY WORDS: planarian, neoblast, totipotency, dedifferentiation, stem cell A general overview of cell potency during developmentThe developmental potential of cells within embryos, and by extension in adult organisms has been one of the biggest riddles in Developmental Biology. A large amount of observations and experiments soon made clear that egg cells and early blastomeres in most phyla are totipotent cells (cells able to give rise to all cell types including germ cells). It also became evident that as development goes on, such potentialities, however ample, become restricted. After the morula stage in mammals, cells of the inner cell mass and from the outer trophoblasts are no longer totipotent but pluripotent (able to give rise to cell types of all three germ layers or to the placenta, respectively). Later, embryonic germ layers segregate. Embryonic outer cells (ectoderm), give rise to several epidermal derivatives together with central nervous system and neural crest cell types but not to any embryonic inner cells, or endoderm derivatives, and vice versa. Such cells are considered multipotent (able to give rise to several cell types). The final stage, the adult Int. J. Dev. Biol. 56: [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] doi: 10.1387/ijdb.113463jb organism, is formed of thousands, millions, billions, or trillions of cells of different types (over 200-300 in complex vertebrates) patter...

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smedinx-11is a planarian stem cell gap junction gene required for regeneration and homeostasis

Cited by 104 publications

References 53 publications

Diverse miRNA spatial expression patterns suggest important roles in homeostasis and regeneration in planarians

Diverse miRNA spatial expression patterns suggest important roles in homeostasis and regeneration in planarians

Gtdap-1and the Role of Autophagy During Planarian Regeneration and Starvation

The planarian neoblast: the rambling history of its origin and some current black boxes

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