Exchange of molecular and cellular information: a hybrid model that integrates stem cell divisions and key regulatory interactions

AbstractStem cells give rise to the entirety of cells within an organ. Maintaining stem cell identity and coordinately regulating stem cell divisions is crucial for proper development. In plants, mobile proteins, such as WOX5 and SHR, regulate divisions in the root stem cell niche (SCN). However, how these proteins coordinately function to establish systemic behavior is not well understood. We propose a non-cell autonomous role for WOX5 in the CEI and identify a regulator, AN3/GIF1, that coordinates CEI divisions. Here we show with a multiscale hybrid model integrating ODEs and agent-based modeling that QC and CEI divisions have different dynamics. Specifically, by combining continuous models to describe regulatory networks and agent-based rules, we model systemic behavior, which led us to predict cell-type-specific expression dynamics of SHR, SCR, WOX5, AN3, and CYCD6;1, and experimentally validate CEI cell divisions. Conclusively, our results show an interdependency between CEI and QC divisions.Thumbnail image

Download Full-text

A hybrid model connecting regulatory interactions with stem cell divisions in the root

Quantitative Plant Biology ◽

10.1017/qpb.2021.1 ◽

2021 ◽

Vol 2 ◽

Author(s):

Lisa Van den Broeck ◽

Ryan J. Spurney ◽

Adam P. Fisher ◽

Michael Schwartz ◽

Natalie M. Clark ◽

...

Keyword(s):

Stem Cell ◽

Hybrid Model ◽

Regulatory Networks ◽

Quiescent Center ◽

Specific Expression ◽

Agent Based ◽

Cell Divisions ◽

Cell Type Specific Expression ◽

Stem Cell Divisions ◽

Cell Niche

Abstract Stem cells give rise to the entirety of cells within an organ. Maintaining stem cell identity and coordinately regulating stem cell divisions is crucial for proper development. In plants, mobile proteins, such as WUSCHEL-RELATED HOMEOBOX 5 (WOX5) and SHORTROOT (SHR), regulate divisions in the root stem cell niche. However, how these proteins coordinately function to establish systemic behaviour is not well understood. We propose a non-cell autonomous role for WOX5 in the cortex endodermis initial (CEI) and identify a regulator, ANGUSTIFOLIA (AN3)/GRF-INTERACTING FACTOR 1, that coordinates CEI divisions. Here, we show with a multi-scale hybrid model integrating ordinary differential equations (ODEs) and agent-based modeling that quiescent center (QC) and CEI divisions have different dynamics. Specifically, by combining continuous models to describe regulatory networks and agent-based rules, we model systemic behaviour, which led us to predict cell-type-specific expression dynamics of SHR, SCARECROW, WOX5, AN3 and CYCLIND6;1, and experimentally validate CEI cell divisions. Conclusively, our results show an interdependency between CEI and QC divisions.

Download Full-text

Week-long imaging of cell divisions in the Arabidopsis root meristem

10.1101/268102 ◽

2018 ◽

Author(s):

Ramin Rahni ◽

Kenneth D. Birnbaum

Keyword(s):

Stem Cell ◽

Cell Division ◽

Stem Cell Niche ◽

Root Meristem ◽

Imaging Method ◽

Fluorescent Reporters ◽

Cell Divisions ◽

4D Imaging ◽

Root Stem Cell ◽

Cell Niche

AbstractCharacterizing the behaviors of dynamic systems requires capturing them with high temporal and spatial resolution. Owing to its transparency and genetic tractability, theArabidopsis thalianaroot lends itself well to live imaging when combined with cell and tissue-specific fluorescent reporters. We developed a novel 4D imaging method that utilizes simple confocal microscopy and readily available components to track cell divisions in the root stem cell niche and surrounding region for up to one week. This new setup allows us to finely analyze meristematic cell division rates that lead to patterning. Using this method, we performed a direct measurement of cell division intervals within and around the root stem cell niche. The results reveal a short, steep gradient of cell division in proximal stem cells, with progressively more rapid cell division rates from QC, to cells in direct contact with the QC (initials), to their immediate daughters, after which division rates appear to become more homogeneous. These results provide a baseline to study how perturbations in signaling could affect cell division patterns in the root meristem.

Download Full-text