Positional Information and Stem Cells Combine to Result in Planarian Regeneration

2021 ◽  
pp. a040717
Author(s):  
Peter W. Reddien
Keyword(s):  
Stem Cells ◽  
Positional Information ◽  
Planarian Regeneration

scholarly journals Symplastic communication spatially directs local auxin biosynthesis to maintain root stem cell niche in Arabidopsis

2017 ◽  
Vol 114 (15) ◽  
pp. 4005-4010 ◽  
Author(s):  
Yuting Liu ◽  
Meizhi Xu ◽  
Nengsong Liang ◽  
Yanghang Zheng ◽  
Qiaozhi Yu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Niche ◽  
Cell Communication ◽  
Positional Information ◽  
Auxin Biosynthesis ◽  
Root Tip ◽  
Quiescent Center ◽  
Stem Cell Maintenance ◽  
Cell Niche

Stem cells serve as the source of new cells for plant development. A group of stem cells form a stem cell niche (SCN) at the root tip and in the center of the SCN are slowly dividing cells called the quiescent center (QC). QC is thought to function as a signaling hub that inhibits differentiation of surrounding stem cells. Although it has been generally assumed that cell-to-cell communication provides positional information for QC and SCN maintenance, the tools for testing this hypothesis have long been lacking. Here we exploit a system that effectively blocks plasmodesmata (PD)-mediated signaling to explore how cell-to-cell communication functions in the SCN. We showed that the symplastic signaling between the QC and adjacent cells directs the formation of local auxin maxima and establishment of AP2-domain transcription factors, PLETHORA gradients. Interestingly we found symplastic signaling is essential for local auxin biosynthesis, which acts together with auxin polar transport to provide the guidance for local auxin enrichment. Therefore, we demonstrate the crucial role of cell-to-cell communication in the SCN maintenance and further uncover a mechanism by which symplastic signaling initiates and reinforces the positional information during stem cell maintenance via auxin regulation.

scholarly journals Efficient depletion of ribosomal RNA for RNA sequencing in planarians

2019 ◽  
Author(s):  
Iana V. Kim ◽  
Eric J. Ross ◽  
Sascha Dietrich ◽  
Kristina Döring ◽  
Alejandro Sánchez Alvarado ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ribosomal Rna ◽  
Cost Effective ◽  
Subtractive Hybridization ◽  
Mrna Levels ◽  
Rna Seq ◽  
Planarian Regeneration ◽  
Histone Mrnas ◽  
Transposon Activity ◽  
The Impact

AbstractBackgroundThe astounding regenerative abilities of planarian flatworms prompt a steadily growing interest in examining their molecular foundation. Planarian regeneration was found to require hundreds of genes and is hence a complex process. Thus, RNA interference followed by transcriptome-wide gene expression analysis by RNA-seq is a popular technique to study the impact of any particular planarian gene on regeneration. Typically, the removal of ribosomal RNA (rRNA) is the first step of all RNA-Seq library preparation protocols. To date, rRNA removal in planarians was primarily achieved by the enrichment of polyadenylated (poly(A)) transcripts. However, to better reflect transcriptome dynamics and to cover also non-poly(A) transcripts, a procedure for the targeted removal of rRNA in planarians is needed.ResultsIn this study, we describe a workflow for the efficient depletion of rRNA in the planarian model species S. mediterranea. Our protocol is based on subtractive hybridization using organism-specific probes. Importantly, the designed probes also deplete rRNA of other freshwater triclad families, a fact that considerably broadens the applicability of our protocol. We tested our approach on total RNA isolated stem cells (termed neoblasts) of S. mediterranea and compared ribodepleted libraries with publicly available poly(A)-enriched ones. Overall, mRNA levels after ribodepletion were consisted with poly(A) libraries. However, ribodepleted libraries revealed higher transcript levels for transposable elements and histone mRNAs that remained underrepresented in poly(A) libraries. As neoblasts experience high transposon activity this suggests that ribodepleted libraries better reflect the transcriptional dynamics of planarian stem cells. Furthermore, the presented ribodepletion procedure was successfully expanded to the removal of ribosomal RNA from the gram-negative bacterium Salmonella typhimurium.ConclusionsThe ribodepletion protocol presented here ensures the efficient rRNA removal from low input total planarian RNA, which can be further processed for RNA-Seq applications. Resulting libraries contain less than 2% rRNA. Moreover, for a cost-effective and efficient removal of rRNA prior to sequencing applications our procedure might be adapted to any prokaryotic or eukaryotic species of choice.

scholarly journals PI3K Plays an Essential Role in Planarian Regeneration and Tissue Maintenance

2021 ◽  
Vol 9 ◽  
Author(s):  
Hanxue Zheng ◽  
Hongbo Liu ◽  
Qian Xu ◽  
Wenjun Wang ◽  
Linfeng Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Adult Stem Cells ◽  
Apoptotic Cell ◽  
Wound Response ◽  
Pi3k Signaling ◽  
Loss Of Function ◽  
Planarian Regeneration ◽  
Spatiotemporal Expression ◽  
Dugesia Japonica

Phosphatidylinositol 3-kinase (PI3K) signaling plays a central role in various biological processes, and its abnormality leads to a broad spectrum of human diseases, such as cancer, fibrosis, and immunological disorders. However, the mechanisms by which PI3K signaling regulates the behavior of stem cells during regeneration are poorly understood. Planarian flatworms possess abundant adult stem cells (called neoblasts) allowing them to develop remarkable regenerative capabilities, thus the animals represent an ideal model for studying stem cells and regenerative medicine in vivo. In this study, the spatiotemporal expression pattern of Djpi3k, a PI3K ortholog in the planarian Dugesia japonica, was investigated and suggests its potential role in wound response and tissue regeneration. A loss-of-function study was conducted using small molecules and RNA interference technique, providing evidence that PI3K signaling is required for blastema regrowth and cilia maintenance during planarian regeneration and homeostasis. Interestingly, the mitotic and apoptotic responses to amputation are substantially abated in PI3K inhibitor-treated regenerating animals, while knockdown of Djpi3k alleviates the mitotic response and postpones the peak of apoptotic cell death, which may contribute to the varying degrees of regenerative defects induced by the pharmacological and genetic approaches. These observations reveal novel roles for PI3K signaling in the regulation of the cellular responses to amputation during planarian regeneration and provide insights for investigating the disease-related genes in the regeneration-competent organism in vivo.

scholarly journals Signaling gradients in surface dynamics as basis for planarian regeneration

2019 ◽  
Author(s):  
Arnd Scheel ◽  
Angela Stevens ◽  
Christoph Tenbrock
Keyword(s):  
Cell Differentiation ◽  
Stem Cell Differentiation ◽  
Positional Information ◽  
Surface Dynamics ◽  
Dynamic Boundary Conditions ◽  
Planarian Regeneration ◽  
Tissue Surface ◽  
Density Dynamics ◽  
Cutting Experiments ◽  
Positional Control

AbstractWe introduce and analyze a mathematical model for the regeneration of planarian flatworms. This system of differential equations incorporates dynamics of head and tail cells which express positional control genes that in turn translate into localized signals that guide stem cell differentiation. Orientation and positional information is encoded in the dynamics of a long range wnt-related signaling gradient. We motivate our model in relation to experimental data and demonstrate how it correctly reproduces cut and graft experiments. In particular, our system improves on previous models by preserving polarity in regeneration, over orders of magnitude in body size during cutting experiments and growth phases. Our model relies on tristability in cell density dynamics, between head, trunk, and tail. In addition, key to polarity preservation in regeneration, our system includes sensitivity of cell differentiation to gradients of wnt-related signals relative to the tissue surface. This process is particularly relevant in a small tissue layer close to wounds during their healing, and modeled here in a robust fashion through dynamic boundary conditions.

scholarly journals Clonogenic Neoblasts Are Pluripotent Adult Stem Cells That Underlie Planarian Regeneration

Science ◽  
2011 ◽  
Vol 332 (6031) ◽  
pp. 811-816 ◽  
Author(s):  
D. E. Wagner ◽  
I. E. Wang ◽  
P. W. Reddien
Keyword(s):  
Stem Cells ◽  
Adult Stem Cells ◽  
Planarian Regeneration

scholarly journals Efficient depletion of ribosomal RNA for RNA sequencing in planarians

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Iana V. Kim ◽  
Eric J. Ross ◽  
Sascha Dietrich ◽  
Kristina Döring ◽  
Alejandro Sánchez Alvarado ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ribosomal Rna ◽  
Cost Effective ◽  
Subtractive Hybridization ◽  
Mrna Levels ◽  
Rna Seq ◽  
Planarian Regeneration ◽  
Histone Mrnas ◽  
Transposon Activity ◽  
The Impact

Abstract Background The astounding regenerative abilities of planarian flatworms prompt steadily growing interest in examining their molecular foundation. Planarian regeneration was found to require hundreds of genes and is hence a complex process. Thus, RNA interference followed by transcriptome-wide gene expression analysis by RNA-seq is a popular technique to study the impact of any particular planarian gene on regeneration. Typically, the removal of ribosomal RNA (rRNA) is the first step of all RNA-seq library preparation protocols. To date, rRNA removal in planarians was primarily achieved by the enrichment of polyadenylated (poly(A)) transcripts. However, to better reflect transcriptome dynamics and to cover also non-poly(A) transcripts, a procedure for the targeted removal of rRNA in planarians is needed. Results In this study, we describe a workflow for the efficient depletion of rRNA in the planarian model species S. mediterranea. Our protocol is based on subtractive hybridization using organism-specific probes. Importantly, the designed probes also deplete rRNA of other freshwater triclad families, a fact that considerably broadens the applicability of our protocol. We tested our approach on total RNA isolated from stem cells (termed neoblasts) of S. mediterranea and compared ribodepleted libraries with publicly available poly(A)-enriched ones. Overall, mRNA levels after ribodepletion were consistent with poly(A) libraries. However, ribodepleted libraries revealed higher transcript levels for transposable elements and histone mRNAs that remained underrepresented in poly(A) libraries. As neoblasts experience high transposon activity this suggests that ribodepleted libraries better reflect the transcriptional dynamics of planarian stem cells. Furthermore, the presented ribodepletion procedure was successfully expanded to the removal of ribosomal RNA from the gram-negative bacterium Salmonella typhimurium. Conclusions The ribodepletion protocol presented here ensures the efficient rRNA removal from low input total planarian RNA, which can be further processed for RNA-seq applications. Resulting libraries contain less than 2% rRNA. Moreover, for a cost-effective and efficient removal of rRNA prior to sequencing applications our procedure might be adapted to any prokaryotic or eukaryotic species of choice.

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