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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

mex3-1 RNAi depletes progeny without impairing stem cell proliferation.(A) Lineage markers labeling stem cells (piwi-1), early (prog-1, prog-2), and late (AGAT-1) progeny were assessed by WISH after RNAi. Shown are a late time point after one RNAi feeding and a late time point with multiple RNAi feeds, when health decline is evident. (B) Detailed time course analysis of early (prog-2) and late (AGAT-1, pmp-11) progeny marker down-regulation after mex3-1 RNAi. Scale bars, 200 μm. (C) FACS analysis with Hoechst staining of mex3-1(RNAi) animals 9 days after RNAi. FACS plots from one run are shown on the left; right table indicates proportion of X1 and X2 populations of all runs.DOI:http://dx.doi.org/10.7554/eLife.07025.014
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fig4s1: mex3-1 RNAi depletes progeny without impairing stem cell proliferation.(A) Lineage markers labeling stem cells (piwi-1), early (prog-1, prog-2), and late (AGAT-1) progeny were assessed by WISH after RNAi. Shown are a late time point after one RNAi feeding and a late time point with multiple RNAi feeds, when health decline is evident. (B) Detailed time course analysis of early (prog-2) and late (AGAT-1, pmp-11) progeny marker down-regulation after mex3-1 RNAi. Scale bars, 200 μm. (C) FACS analysis with Hoechst staining of mex3-1(RNAi) animals 9 days after RNAi. FACS plots from one run are shown on the left; right table indicates proportion of X1 and X2 populations of all runs.DOI:http://dx.doi.org/10.7554/eLife.07025.014

Mentions: To ascertain which step(s) in stem cell lineage progression were aberrant after mex3-1 knockdown, we performed WISH analysis to follow stem cell and postmitotic prog-1/2+ and AGAT-1+ progeny population dynamics after RNAi was initiated. Knockdown of mex3-1 leads to a rapid decline of the two progeny populations but not of stem cells (Figure 4A, Figure 4—figure supplement 1A), with the majority of progeny gene expression lost by 6 days after RNAi (Figure 4—figure supplement 1B). We assessed the expression of additional newly identified epithelial progenitor markers as well and observed that all were similarly abolished, supporting the loss of these two progeny types (Figure 4B).10.7554/eLife.07025.013Figure 4.RNAi against mex3-1 selectively affects progeny markers and causes hyper-proliferation.


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)

mex3-1 RNAi depletes progeny without impairing stem cell proliferation.(A) Lineage markers labeling stem cells (piwi-1), early (prog-1, prog-2), and late (AGAT-1) progeny were assessed by WISH after RNAi. Shown are a late time point after one RNAi feeding and a late time point with multiple RNAi feeds, when health decline is evident. (B) Detailed time course analysis of early (prog-2) and late (AGAT-1, pmp-11) progeny marker down-regulation after mex3-1 RNAi. Scale bars, 200 μm. (C) FACS analysis with Hoechst staining of mex3-1(RNAi) animals 9 days after RNAi. FACS plots from one run are shown on the left; right table indicates proportion of X1 and X2 populations of all runs.DOI:http://dx.doi.org/10.7554/eLife.07025.014
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4507787&req=5

fig4s1: mex3-1 RNAi depletes progeny without impairing stem cell proliferation.(A) Lineage markers labeling stem cells (piwi-1), early (prog-1, prog-2), and late (AGAT-1) progeny were assessed by WISH after RNAi. Shown are a late time point after one RNAi feeding and a late time point with multiple RNAi feeds, when health decline is evident. (B) Detailed time course analysis of early (prog-2) and late (AGAT-1, pmp-11) progeny marker down-regulation after mex3-1 RNAi. Scale bars, 200 μm. (C) FACS analysis with Hoechst staining of mex3-1(RNAi) animals 9 days after RNAi. FACS plots from one run are shown on the left; right table indicates proportion of X1 and X2 populations of all runs.DOI:http://dx.doi.org/10.7554/eLife.07025.014
Mentions: To ascertain which step(s) in stem cell lineage progression were aberrant after mex3-1 knockdown, we performed WISH analysis to follow stem cell and postmitotic prog-1/2+ and AGAT-1+ progeny population dynamics after RNAi was initiated. Knockdown of mex3-1 leads to a rapid decline of the two progeny populations but not of stem cells (Figure 4A, Figure 4—figure supplement 1A), with the majority of progeny gene expression lost by 6 days after RNAi (Figure 4—figure supplement 1B). We assessed the expression of additional newly identified epithelial progenitor markers as well and observed that all were similarly abolished, supporting the loss of these two progeny types (Figure 4B).10.7554/eLife.07025.013Figure 4.RNAi against mex3-1 selectively affects progeny markers and causes hyper-proliferation.

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