Advances in geometric techniques for analyzing blebbing in chemotaxing Dictyostelium cells

Santiago, Zully; Loustau, John; Meretzky, David; Rawal, Devarshi; Brazill, Derrick

doi:10.1371/journal.pone.0211975

Cited by 7 publications

(26 citation statements)

References 26 publications

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“…We modified an in-house geometric platform [32] which extracts the boundary of 115 photographic images and renders them as objects in Cartesian space. Our modified 116 algorithm, in addition to the procedure outlined in [32], thins the cell boundary to a 117 width of one pixel (uses the Thinning function in Mathematica), implements a more 118 efficient algorithm for ordering boundary points, orients the boundary, and finally 119 applies a Gaussian convolution to smooth the boundary. The digitization of the 120 boundary into equally spaced points using B-splines, is also implemented more 121 efficiently.…”

Section: Edge Detection and Boundary Digitization 114mentioning

confidence: 99%

“…In our previous work [32] we applied the FindShortestTour function in Mathematica to 125 order the coordinates of boundary points. For cells with complex boundaries, this 126 function often failed to yield a reasonable ordering of the points.…”

Section: Ordering Boundary Nodes 124mentioning

confidence: 99%

“…Our membrane energy functional assumes a smooth parameteric representation of the 160 cell boundary from which derivatives are calculated. We achieved this paramterization 161 using B-splines, as described in our previous work [32] and employed finite differencing 162 to approximate the derivatives. In order to simplify the implementation of finite 163 difference schemes and reduce the local truncation error [33], we sought a partitioning of 164 the boundary into equally spaced points.…”

Section: Clockwise Orientation Of Boundary Nodes 139mentioning

confidence: 99%

“…81 Cells were starved for cAMP competency on filter pads using the method described 82 in [32]. 83 cyclic-AMP(cAMP) under agarose assay 84Two cAMP under agarose assays were used as described in [32], with minor 85 modifications, to mimic the confinement conditions cells experience in their natural 86 environment. The first under agarose assay was used to collect data on blebbing cells 87 for validating the nucleation site predictions of the membrane energy functional.…”

mentioning

confidence: 99%

“…This term accounts (Sigma-Aldrich). In this way, the membrane could be observed as a shadow within a red 91 background created by the Rhodamine-Dextran (see [32]). In the second assay, used for 92 myosin II localization, the agaros gel was not laced with Rhodamine B 93 isothiocyanate-Dextran.…”

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confidence: 99%

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A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

Asante-Asamani

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Rawal

et al. 2020

Preprint

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Blebs, pressure driven protrusions of the plasma membrane, facilitate the movement of cells such as the soil amoeba Dictyostelium discoideum and other eukaryotes such as white blood cells and cancer cells. Blebs initiate or nucleate when proteins connecting the membrane to the cortex detach, either as a result of a rupture of the cortex or as a direct consequence of a build up in hydrostatic pressure. While linker detachment resulting from excess hydrostatic pressure is well understood, the mechanism by which cells rupture their cortex in locations of bleb formation is not so clear. Consequently, existing predictive models of bleb site selection do not account for it. To resolve this, we propose a model for bleb initiation which combines the geometric forces on the cell cortex/membrane complex with the underlying activity of actin binding proteins. In our model gaps, resulting from a rupture of the cortex, form at locations of high membrane energy where an accumulation of myosin II helps to weaken the cortex. We validate this model in part through a membrane energy functional which combines stresses on the cell boundary from membrane tension, curvature, membrane-cortex linker tension with hydrostatic pressure. Application of this functional to microscopy images of chemotaxing Dictyostelium discoideum cells identifies bleb nucleation sites at the highest energy locations 96.7% of the time. Sensitivity analysis of the model components points to membrane tension and hydrostatic pressure, all of which are regulated by myosin II, as critical to model predictability. Furthermore, microscopy reveals discrete clusters of myosin II along the leading edge of the cell, with blebs emerging from 80% of these sites. Together, our findings suggest a critical role for myosin II in bleb initiation through the formation of gaps and provides a predictive mathematical model for quantitative studies of blebbing. Author summaryEukaryotic cells such as white blood cells and cancer cells have been observed to move by making spherical herniation of their plasma membrane, referred to as blebs. The precise mechanism by which cells select locations around their boundary to initiate blebs is unclear. We hypothesize that blebs initiate at locations of high membrane energy where an accumulation of myosin II helps to rupture the cortex and/or detach linker proteins. We test this hypothesis by formulating a free energy functional representation of membrane energy to predict where blebs will initiate. The functional March 16, 2020 1/19 accounts for geometric forces due to membrane tension, curvature and membrane-cortex linker tension as well as hydrostatic pressure. Application of the functional to data from the soil amoeba, Dictyostelium disodium, identifies blebs at the highest energy locations over 90% of the time. Sensitivity analysis of model components points to membrane tension and hydrostatic pressure, all influenced by myosin II, as major forces driving bleb initiation. Additionally, we observe clusters of myosin II at locations of bleb ...

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Section: Edge Detection and Boundary Digitization 114mentioning

confidence: 99%

Section: Ordering Boundary Nodes 124mentioning

confidence: 99%

Section: Clockwise Orientation Of Boundary Nodes 139mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

Asante-Asamani

Grange

Rawal

et al. 2020

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Unraveling Endothelial Cell Migration: Insights into Fundamental Forces, Inflammation, Biomaterial Applications, and Tissue Regeneration Strategies

Jerka,

Bonowicz,

Piekarska

et al. 2024

ACS Appl. Bio Mater.

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Cell migration is vital for many fundamental biological processes and human pathologies throughout our life. Dynamic molecular changes in the tissue microenvironment determine modifications of cell movement, which can be reflected either individually or collectively. Endothelial cell (EC) migratory adaptation occurs during several events and phenomena, such as endothelial injury, vasculogenesis, and angiogenesis, under both normal and highly inflammatory conditions. Several advantageous processes can be supported by biomaterials. Endothelial cells are used in combination with various types of biomaterials to design scaffolds promoting the formation of mature blood vessels within tissue engineered structures. Appropriate selection, in terms of scaffolding properties, can promote desirable cell behavior to varying degrees. An increasing amount of research could lead to the creation of the perfect biomaterial for regenerative medicine applications. In this review, we summarize the state of knowledge regarding the possible systems by which inflammation may influence endothelial cell migration. We also describe the fundamental forces governing cell motility with a specific focus on ECs. Additionally, we discuss the biomaterials used for EC culture, which serve to enhance the proliferative, proangiogenic, and promigratory potential of cells. Moreover, we introduce the mechanisms of cell movement and highlight the significance of understanding these mechanisms in the context of designing scaffolds that promote tissue regeneration.

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Interplay between myosin II and actin dynamics in chemotactic amoeba

et al. 2019

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The actin cytoskeleton and its response to external chemical stimuli is fundamental to the mechanobiology of eukaryotic cells and their functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin II. Based on a phase space embedding we have identified from experiments three phases in the cytoskeletal dynamics of starved Dictyostelium discoideum in response to a precisely controlled chemotactic stimulation. In the first two phases the dynamics of actin and myosin II in the cortex is uncoupled, while in the third phase the time scale for the recovery of cortical actin is determined by the myosin II dynamics. We report a theoretical model that captures the experimental observations quantitatively. The model predicts an increase in the optimal response time of actin with decreasing myosin II-actin coupling strength highlighting the role of myosin II in the robust control of cell contraction.

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Advances in geometric techniques for analyzing blebbing in chemotaxing Dictyostelium cells

Cited by 7 publications

References 26 publications

A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

Unraveling Endothelial Cell Migration: Insights into Fundamental Forces, Inflammation, Biomaterial Applications, and Tissue Regeneration Strategies

Interplay between myosin II and actin dynamics in chemotactic amoeba

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