Characterization of innexin gene expression and functional roles of gap-junctional communication in planarian regeneration

Nogi, Taisaku; Levin, Michael

doi:10.1016/j.ydbio.2005.09.002

Cited by 149 publications

(159 citation statements)

References 95 publications

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“…Whole mount in situ hybridization experiments were performed according to (Umesono et al, 1997;Umesono et al, 1999) with minor modifications (Nogi and Levin, 2005). Color development of the alkaline phosphate-coniugated anti-DIG-antibody was carried out with a mixture of BCIP/NBT (Sigma).…”

Section: Methodsmentioning

confidence: 99%

Expression of a retinal homeobox (Rx) gene during planarian regeneration

Mannini¹,

Deri²,

Picchi³

et al. 2008

Int. J. Dev. Biol.

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Retinal homeobox (Rx) genes, with representatives in vertebrates and invertebrates, encode fundamental regulators of early eye and brain formation. Here we describe the spatiotemporal expression profile of a candidate planarian orthologue of Rx during regeneration in Dugesia japonica and Schmidtea mediterranea. Although low levels of Rx transcripts were found throughout the body of intact planarians, high levels of Rx expression were specific to regenerating tissue in both head and tail fragments. We also observed that Rx was never expressed in the simple rhabdomeric planarian eyes, supporting the notion that only formation of eyes that use the ciliary type of photoreceptors requires Rx function. KEY WORDS: paired-class homeobox gene, Rx, planarian, regeneration, eyeRx paired-type homeobox transcription factors have been isolated in several vertebrate and invertebrate species (Arendt et al., 2004; Bailey et al., 2004 and references therein;D'Aniello et al., 2006). A growing body of evidence suggests that Rx genes, early expressed in the anterior neural plate, are essential for the proliferation and specification of retina progenitor cells in chordates. In invertebrates, such as Drosophila, Rx does not seem to play a similar role. In fact, Drosophila Rx is not required for the formation of the visual system, but only for brain and clypeus development (Davis et al., 2003). In addition, an Rx ortholog of the annelid Platynereis has been found expressed in the ciliary photoreceptor cells of the brain, but not in the rhabdomeric photoreceptors of the larval and differentiating adult eyes (Arendt et al., 2004). Based on these observations, it has been proposed that an Rx ancestral function was related to the regulation of genes involved in brain development. During evolution, Rx genes became then essential for development of photoreceptors of ciliary type. No data are available on the function of Rx genes in a context different from the embryonic development, such as regeneration. Planarians (Platyhelminthes, Lophotrochozoa) offer a suitable model to investigate the role of Rx during regeneration. These organisms indeed can regenerate heads, including a complete brain, as well as other body parts in a short time, by virtue of the activity of adult stem cells, called neoblasts Saló 2006;Sánchez Alvarado, 2006). Planarian brain consists of two anterior cephalic ganglia connected to two ventral Int. J. Dev. Biol. 52: 1113-1117 (2008) nerve cords that run along the body (Cebrià, 2007). A pair of simple rhabdomeric eyes is generally located on its dorsal side. Despite the planarian central nervous system (CNS) seems quite simple at the morphological level, it possesses a functionally and molecularly complex structure (Cebrià, 2007 and references therein).We have cloned and sequenced the cDNA of a planarian Rx homolog in Dugesia japonica (GI strain) and Schmidtea mediterranea (asexual strain). Animals were maintained in autoclaved stream water at 18°C and starved for two weeks before being used in the experimen...

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Section: Methodsmentioning

confidence: 99%

Expression of a retinal homeobox (Rx) gene during planarian regeneration

Mannini¹,

Deri²,

Picchi³

et al. 2008

Int. J. Dev. Biol.

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“…Given the long phylogenetic history of gap junctions in metazoans (Fraser and Bode 1981;Potenza et al 2002;Starich et al 2003;Nogi and Levin 2005), it is not surprising that this method of cell-cell communication has been adapted to subserve a wide variety of physiological functions in different cell types. Many cell-and tissue-specific functions of GJIC have been brought to light by human mutations and targeted connexin gene deletion in mice (for reviews see White and Paul 1999;Gerido and White 2004;Dobrowolski and Willecke 2008).…”

Section: Specialized Functions Revealed By Connexin Mutations Human Mmentioning

confidence: 99%

Gap Junctions

Goodenough¹,

Paul²

2009

Cold Spring Harbor Perspectives in Biology

557

440

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“…Proteinase K treatment (20 µg/ml) was performed for 8 min on the asexual strain and for 12 min on the sexual strain. A triethanolamine treatment was performed as described by Nogi and Levin (2005). All the nascent probes were used to a concentration of 1ng/µl and the hybridizations were carried out at 55 °C for 17 hours.…”

Section: Whole-mount In Situ Hybridization Experimentsmentioning

confidence: 99%

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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Characterization of innexin gene expression and functional roles of gap-junctional communication in planarian regeneration

Cited by 149 publications

References 95 publications

Expression of a retinal homeobox (Rx) gene during planarian regeneration

Expression of a retinal homeobox (Rx) gene during planarian regeneration

Gap Junctions

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

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