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A mex3 homolog is required for differentiation during planarian stem cell lineage development.

Zhu SJ, Hallows SE, Currie KW, Xu C, Pearson BJ - Elife (2015)

Bottom Line: In this study, we used transcriptional profiling of irradiation-sensitive and irradiation-insensitive cell populations and RNA interference (RNAi) functional screening to uncover markers and regulators of postmitotic progeny.We also demonstrated the utility of using mex3-1(RNAi) animals to identify additional progenitor markers.These results identified mex3-1 as a cell fate regulator, broadly required for differentiation, and suggest that mex3-1 helps to mediate the balance between ASC self-renewal and commitment.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada.

ABSTRACT
Neoblasts are adult stem cells (ASCs) in planarians that sustain cell replacement during homeostasis and regeneration of any missing tissue. While numerous studies have examined genes underlying neoblast pluripotency, molecular pathways driving postmitotic fates remain poorly defined. In this study, we used transcriptional profiling of irradiation-sensitive and irradiation-insensitive cell populations and RNA interference (RNAi) functional screening to uncover markers and regulators of postmitotic progeny. We identified 32 new markers distinguishing two main epithelial progenitor populations and a planarian homolog to the MEX3 RNA-binding protein (Smed-mex3-1) as a key regulator of lineage progression. mex3-1 was required for generating differentiated cells of multiple lineages, while restricting the size of the stem cell compartment. We also demonstrated the utility of using mex3-1(RNAi) animals to identify additional progenitor markers. These results identified mex3-1 as a cell fate regulator, broadly required for differentiation, and suggest that mex3-1 helps to mediate the balance between ASC self-renewal and commitment.

No MeSH data available.


Related in: MedlinePlus

Gene expression analysis of candidate progeny genes with a prog-like expression pattern.Candidate progeny genes, which exhibited a prog-like expression pattern, were all assessed by WISH in irradiated worms (60 Gy) at the indicated time points. Genes were categorized as either early progeny or late progeny depending on whether they exhibited similar kinetics of down-regulation to prog-1/2 or AGAT-1/2/3, respectively. Genes, which are WThighXlow, are indicated in purple text. Scale bar, 200 μm.DOI:http://dx.doi.org/10.7554/eLife.07025.008
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fig2s2: Gene expression analysis of candidate progeny genes with a prog-like expression pattern.Candidate progeny genes, which exhibited a prog-like expression pattern, were all assessed by WISH in irradiated worms (60 Gy) at the indicated time points. Genes were categorized as either early progeny or late progeny depending on whether they exhibited similar kinetics of down-regulation to prog-1/2 or AGAT-1/2/3, respectively. Genes, which are WThighXlow, are indicated in purple text. Scale bar, 200 μm.DOI:http://dx.doi.org/10.7554/eLife.07025.008

Mentions: To begin our analysis of the top 100 X2-enriched transcripts and the top 20 WThighXlow transcripts, we performed whole-mount in situ hybridization (WISH) to elucidate gene expression patterns. We observed that 40/120 transcripts were either not detectable or not specific, and the remaining 80/120 genes could be binned into one of four categories (Figure 2A, Figure 2—figure supplement 1). One category (13/120) contained genes with the most intense expression in the bi-lobed brain and nervous system, with low levels of expression elsewhere in the body. A second group of genes (18/120) exhibited a predominantly stem cell-like expression pattern, with or without brain expression, which was confirmed by high expression in the X1 cell fraction (Figure 2A, Figure 2—figure supplement 1A, Supplementary file 2). A third subset of genes was expressed in a variety of distinct patterns including the gut, pharynx, peri-pharyngeal region, and neck (17/120) (Figure 2A, Figure 2—figure supplement 1A). Finally, the fourth and largest group (32/120) consisted of genes with an expression pattern highly similar to those of the known early and late progeny markers prog-1, prog-2, and AGAT-1, which are sub-epithelial across the entire animal with expression anterior to the photoreceptors (Figure 2A, Figure 2—figure supplement 2) (Eisenhoffer et al., 2008). This prog-like subset exhibited varying degrees of X2-enrichment, and some were highly expressed in the X1 population (Figure 1A, Supplementary file 2). Transcripts that displayed a prog-like pattern where BLAST did not identify significant similarity were named as postmitotic progeny (pmp's) with ascending numerals (e.g., pmp-3, pmp-4).10.7554/eLife.07025.006Figure 2.Expression analyses of candidate progeny genes.


A mex3 homolog is required for differentiation during planarian stem cell lineage development.

Zhu SJ, Hallows SE, Currie KW, Xu C, Pearson BJ - Elife (2015)

Gene expression analysis of candidate progeny genes with a prog-like expression pattern.Candidate progeny genes, which exhibited a prog-like expression pattern, were all assessed by WISH in irradiated worms (60 Gy) at the indicated time points. Genes were categorized as either early progeny or late progeny depending on whether they exhibited similar kinetics of down-regulation to prog-1/2 or AGAT-1/2/3, respectively. Genes, which are WThighXlow, are indicated in purple text. Scale bar, 200 μm.DOI:http://dx.doi.org/10.7554/eLife.07025.008
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507787&req=5

fig2s2: Gene expression analysis of candidate progeny genes with a prog-like expression pattern.Candidate progeny genes, which exhibited a prog-like expression pattern, were all assessed by WISH in irradiated worms (60 Gy) at the indicated time points. Genes were categorized as either early progeny or late progeny depending on whether they exhibited similar kinetics of down-regulation to prog-1/2 or AGAT-1/2/3, respectively. Genes, which are WThighXlow, are indicated in purple text. Scale bar, 200 μm.DOI:http://dx.doi.org/10.7554/eLife.07025.008
Mentions: To begin our analysis of the top 100 X2-enriched transcripts and the top 20 WThighXlow transcripts, we performed whole-mount in situ hybridization (WISH) to elucidate gene expression patterns. We observed that 40/120 transcripts were either not detectable or not specific, and the remaining 80/120 genes could be binned into one of four categories (Figure 2A, Figure 2—figure supplement 1). One category (13/120) contained genes with the most intense expression in the bi-lobed brain and nervous system, with low levels of expression elsewhere in the body. A second group of genes (18/120) exhibited a predominantly stem cell-like expression pattern, with or without brain expression, which was confirmed by high expression in the X1 cell fraction (Figure 2A, Figure 2—figure supplement 1A, Supplementary file 2). A third subset of genes was expressed in a variety of distinct patterns including the gut, pharynx, peri-pharyngeal region, and neck (17/120) (Figure 2A, Figure 2—figure supplement 1A). Finally, the fourth and largest group (32/120) consisted of genes with an expression pattern highly similar to those of the known early and late progeny markers prog-1, prog-2, and AGAT-1, which are sub-epithelial across the entire animal with expression anterior to the photoreceptors (Figure 2A, Figure 2—figure supplement 2) (Eisenhoffer et al., 2008). This prog-like subset exhibited varying degrees of X2-enrichment, and some were highly expressed in the X1 population (Figure 1A, Supplementary file 2). Transcripts that displayed a prog-like pattern where BLAST did not identify significant similarity were named as postmitotic progeny (pmp's) with ascending numerals (e.g., pmp-3, pmp-4).10.7554/eLife.07025.006Figure 2.Expression analyses of candidate progeny genes.

Bottom Line: In this study, we used transcriptional profiling of irradiation-sensitive and irradiation-insensitive cell populations and RNA interference (RNAi) functional screening to uncover markers and regulators of postmitotic progeny.We also demonstrated the utility of using mex3-1(RNAi) animals to identify additional progenitor markers.These results identified mex3-1 as a cell fate regulator, broadly required for differentiation, and suggest that mex3-1 helps to mediate the balance between ASC self-renewal and commitment.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada.

ABSTRACT
Neoblasts are adult stem cells (ASCs) in planarians that sustain cell replacement during homeostasis and regeneration of any missing tissue. While numerous studies have examined genes underlying neoblast pluripotency, molecular pathways driving postmitotic fates remain poorly defined. In this study, we used transcriptional profiling of irradiation-sensitive and irradiation-insensitive cell populations and RNA interference (RNAi) functional screening to uncover markers and regulators of postmitotic progeny. We identified 32 new markers distinguishing two main epithelial progenitor populations and a planarian homolog to the MEX3 RNA-binding protein (Smed-mex3-1) as a key regulator of lineage progression. mex3-1 was required for generating differentiated cells of multiple lineages, while restricting the size of the stem cell compartment. We also demonstrated the utility of using mex3-1(RNAi) animals to identify additional progenitor markers. These results identified mex3-1 as a cell fate regulator, broadly required for differentiation, and suggest that mex3-1 helps to mediate the balance between ASC self-renewal and commitment.

No MeSH data available.


Related in: MedlinePlus