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1.
Cell ; 175(1): 200-211.e13, 2018 09 20.
Artículo en Inglés | MEDLINE | ID: mdl-30146160

RESUMEN

Much of our understanding of chromosome segregation is based on cell culture systems. Here, we examine the importance of the tissue environment for chromosome segregation by comparing chromosome segregation fidelity across several primary cell types in native and nonnative contexts. We discover that epithelial cells have increased chromosome missegregation outside of their native tissues. Using organoid culture systems, we show that tissue architecture, specifically integrin function, is required for accurate chromosome segregation. We find that tissue architecture enhances the correction of merotelic microtubule-kinetochore attachments, and this is especially important for maintaining chromosome stability in the polyploid liver. We propose that disruption of tissue architecture could underlie the widespread chromosome instability across epithelial cancers. Moreover, our findings highlight the extent to which extracellular context can influence intrinsic cellular processes and the limitations of cell culture systems for studying cells that naturally function within a tissue.


Asunto(s)
Inestabilidad Cromosómica/fisiología , Segregación Cromosómica/fisiología , Epitelio/fisiología , Animales , Agregación Celular/fisiología , Técnicas de Cultivo de Célula/métodos , Cromosomas/fisiología , Células Epiteliales/fisiología , Femenino , Cinetocoros/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Microtúbulos/metabolismo , Mitosis , Organoides/fisiología , Huso Acromático/metabolismo , Huso Acromático/fisiología
2.
Nature ; 617(7962): 747-754, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37165189

RESUMEN

While early multicellular lineages necessarily started out as relatively simple groups of cells, little is known about how they became Darwinian entities capable of sustained multicellular evolution1-3. Here we investigate this with a multicellularity long-term evolution experiment, selecting for larger group size in the snowflake yeast (Saccharomyces cerevisiae) model system. Given the historical importance of oxygen limitation4, our ongoing experiment consists of three metabolic treatments5-anaerobic, obligately aerobic and mixotrophic yeast. After 600 rounds of selection, snowflake yeast in the anaerobic treatment group evolved to be macroscopic, becoming around 2 × 104 times larger (approximately mm scale) and about 104-fold more biophysically tough, while retaining a clonal multicellular life cycle. This occurred through biophysical adaptation-evolution of increasingly elongate cells that initially reduced the strain of cellular packing and then facilitated branch entanglements that enabled groups of cells to stay together even after many cellular bonds fracture. By contrast, snowflake yeast competing for low oxygen5 remained microscopic, evolving to be only around sixfold larger, underscoring the critical role of oxygen levels in the evolution of multicellular size. Together, this research provides unique insights into an ongoing evolutionary transition in individuality, showing how simple groups of cells overcome fundamental biophysical limitations through gradual, yet sustained, multicellular evolution.


Asunto(s)
Aclimatación , Evolución Biológica , Agregación Celular , Saccharomyces cerevisiae , Modelos Biológicos , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/metabolismo , Anaerobiosis , Aerobiosis , Oxígeno/análisis , Oxígeno/metabolismo , Forma de la Célula , Agregación Celular/fisiología
3.
EMBO J ; 40(14): e107500, 2021 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-34046916

RESUMEN

The Staphylococcal Bap proteins sense environmental signals (such as pH, [Ca2+ ]) to build amyloid scaffold biofilm matrices via unknown mechanisms. We here report the crystal structure of the aggregation-prone region of Staphylococcus aureus Bap which adopts a dumbbell-shaped fold. The middle module (MM) connecting the N-terminal and C-terminal lobes consists of a tandem of novel double-Ca2+ -binding motifs involved in cooperative interaction networks, which undergoes Ca2+ -dependent order-disorder conformational switches. The N-terminal lobe is sufficient to mediate amyloid aggregation through liquid-liquid phase separation and maturation, and subsequent biofilm formation under acidic conditions. Such processes are promoted by disordered MM at low [Ca2+ ] but inhibited by ordered MM stabilized by Ca2+ binding, with inhibition efficiency depending on structural integrity of the interaction networks. These studies illustrate a novel protein switch in pathogenic bacteria and provide insights into the mechanistic understanding of Bap proteins in modulation of functional amyloid and biofilm formation, which could be implemented in the anti-biofilm drug design.


Asunto(s)
Amiloide/metabolismo , Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/metabolismo , Calcio/metabolismo , Agregación Celular/fisiología
4.
PLoS Comput Biol ; 20(5): e1012089, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38743660

RESUMEN

Cell rearrangements are fundamental mechanisms driving large-scale deformations of living tissues. In three-dimensional (3D) space-filling cell aggregates, cells rearrange through local topological transitions of the network of cell-cell interfaces, which is most conveniently described by the vertex model. Since these transitions are not yet mathematically properly formulated, the 3D vertex model is generally difficult to implement. The few existing implementations rely on highly customized and complex software-engineering solutions, which cannot be transparently delineated and are thus mostly non-reproducible. To solve this outstanding problem, we propose a reformulation of the vertex model. Our approach, called Graph Vertex Model (GVM), is based on storing the topology of the cell network into a knowledge graph with a particular data structure that allows performing cell-rearrangement events by simple graph transformations. Importantly, when these same transformations are applied to a two-dimensional (2D) polygonal cell aggregate, they reduce to a well-known T1 transition, thereby generalizing cell-rearrangements in 2D and 3D space-filling packings. This result suggests that the GVM's graph data structure may be the most natural representation of cell aggregates and tissues. We also develop a Python package that implements GVM, relying on a graph-database-management framework Neo4j. We use this package to characterize an order-disorder transition in 3D cell aggregates, driven by active noise and we find aggregates undergoing efficient ordering close to the transition point. In all, our work showcases knowledge graphs as particularly suitable data models for structured storage, analysis, and manipulation of tissue data.


Asunto(s)
Agregación Celular , Modelos Biológicos , Agregación Celular/fisiología , Biología Computacional , Algoritmos , Humanos , Animales , Simulación por Computador , Programas Informáticos
5.
Blood ; 135(10): 755-765, 2020 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-31971571

RESUMEN

Storage lesion-induced, red cell-derived microvesicles (RBC-MVs) propagate coagulation by supporting the assembly of the prothrombinase complex. It has also been reported that RBC-MVs initiate coagulation via the intrinsic pathway. To elucidate the mechanism(s) of RBC-MV-induced coagulation activation, the ability of storage lesion-induced RBC-MVs to activate each zymogen of the intrinsic pathway was assessed in a buffer system. Simultaneously, the thrombin generation (TG) assay was used to assess their ability to initiate coagulation in plasma. RBC-MVs directly activated factor XII (FXII) or prekallikrein, but not FXI or FIX. RBC-MVs initiated TG in normal pooled plasma and in FXII- or FXI-deficient plasma, but not in FIX-deficient plasma, suggesting an alternate pathway that bypasses both FXII and FXI. Interestingly, RBC-MVs generated FIXa in a prekallikrein-dependent manner. Similarly, purified kallikrein activated FIX in buffer and initiated TG in normal pooled plasma, as well as FXII- or FXI-deficient plasma, but not FIX-deficient plasma. Dual inhibition of FXIIa by corn trypsin inhibitor and kallikrein by soybean trypsin inhibitor was necessary for abolishing RBC-MV-induced TG in normal pooled plasma, whereas kallikrein inhibition alone was sufficient to abolish TG in FXII- or FXI-deficient plasma. Heating RBC-MVs at 60°C for 15 minutes or pretreatment with trypsin abolished TG, suggesting the presence of MV-associated proteins that are essential for contact activation. In summary, RBC-MVs activate both FXII and prekallikrein, leading to FIX activation by 2 independent pathways: the classic FXIIa-FXI-FIX pathway and direct kallikrein activation of FIX. These data suggest novel mechanisms by which RBC transfusion mediates inflammatory and/or thrombotic outcomes.


Asunto(s)
Coagulación Sanguínea/fisiología , Micropartículas Derivadas de Células/fisiología , Eritrocitos/ultraestructura , Factor IX/metabolismo , Pruebas de Coagulación Sanguínea , Agregación Celular/fisiología , Comunicación Celular/fisiología , Humanos , Transducción de Señal/fisiología
6.
PLoS Comput Biol ; 17(1): e1008617, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33471791

RESUMEN

Multicellular organization is particularly vulnerable to conflicts between different cell types when the body forms from initially isolated cells, as in aggregative multicellular microbes. Like other functions of the multicellular phase, coordinated collective movement can be undermined by conflicts between cells that spend energy in fuelling motion and 'cheaters' that get carried along. The evolutionary stability of collective behaviours against such conflicts is typically addressed in populations that undergo extrinsically imposed phases of aggregation and dispersal. Here, via a shift in perspective, we propose that aggregative multicellular cycles may have emerged as a way to temporally compartmentalize social conflicts. Through an eco-evolutionary mathematical model that accounts for individual and collective strategies of resource acquisition, we address regimes where different motility types coexist. Particularly interesting is the oscillatory regime that, similarly to life cycles of aggregative multicellular organisms, alternates on the timescale of several cell generations phases of prevalent solitary living and starvation-triggered aggregation. Crucially, such self-organized oscillations emerge as a result of evolution of cell traits associated to conflict escalation within multicellular aggregates.


Asunto(s)
Evolución Biológica , Agregación Celular/fisiología , Movimiento Celular/fisiología , Modelos Biológicos , Biología Computacional , Dictyostelium/citología , Dictyostelium/fisiología
7.
PLoS Comput Biol ; 17(8): e1008576, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34398883

RESUMEN

Cell sorting, whereby a heterogeneous cell mixture segregates and forms distinct homogeneous tissues, is one of the main collective cell behaviors at work during development. Although differences in interfacial energies are recognized to be a possible driving source for cell sorting, no clear consensus has emerged on the kinetic law of cell sorting driven by differential adhesion. Using a modified Cellular Potts Model algorithm that allows for efficient simulations while preserving the connectivity of cells, we numerically explore cell-sorting dynamics over very large scales in space and time. For a binary mixture of cells surrounded by a medium, increase of domain size follows a power-law with exponent n = 1/4 independently of the mixture ratio, revealing that the kinetics is dominated by the diffusion and coalescence of rounded domains. We compare these results with recent numerical studies on cell sorting, and discuss the importance of algorithmic differences as well as boundary conditions on the observed scaling.


Asunto(s)
Adhesión Celular/fisiología , Agregación Celular/fisiología , Modelos Biológicos , Algoritmos , Animales , Fenómenos Biofísicos , Movimiento Celular/fisiología , Biología Computacional , Simulación por Computador , Humanos , Cinética , Análisis de la Célula Individual/estadística & datos numéricos , Tensión Superficial
8.
PLoS Comput Biol ; 17(11): e1009011, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34758019

RESUMEN

The first stage of the metastatic cascade often involves motile cells emerging from a primary tumor either as single cells or as clusters. These cells enter the circulation, transit to other parts of the body and finally are responsible for growth of secondary tumors in distant organs. The mode of dissemination is believed to depend on the EMT nature (epithelial, hybrid or mesenchymal) of the cells. Here, we calculate the cluster size distribution of these migrating cells, using a mechanistic computational model, in presence of different degree of EMT-ness of the cells; EMT is treated as given rise to changes in their active motile forces (µ) and cell-medium surface tension (Γ). We find that, for (µ > µmin, Γ > 1), when the cells are hybrid in nature, the mean cluster size, [Formula: see text], where µmin increases with increase in Γ. For Γ ≤ 0, [Formula: see text], the cells behave as completely mesenchymal. In presence of spectrum of hybrid states with different degree of EMT-ness (motility) in primary tumor, the cells which are relatively more mesenchymal (higher µ) in nature, form larger clusters, whereas the smaller clusters are relatively more epithelial (lower µ). Moreover, the heterogeneity in µ is comparatively higher for smaller clusters with respect to that for larger clusters. We also observe that more extended cell shapes promote the formation of smaller clusters. Overall, this study establishes a framework which connects the nature and size of migrating clusters disseminating from a primary tumor with the phenotypic composition of the tumor, and can lead to the better understanding of metastasis.


Asunto(s)
Modelos Biológicos , Metástasis de la Neoplasia/patología , Neoplasias/patología , Adhesión Celular/fisiología , Agregación Celular/fisiología , Movimiento Celular/fisiología , Biología Computacional , Simulación por Computador , Transición Epitelial-Mesenquimal/fisiología , Humanos , Metástasis de la Neoplasia/fisiopatología , Siembra Neoplásica , Neoplasias/fisiopatología , Células Neoplásicas Circulantes/patología
9.
PLoS Comput Biol ; 17(11): e1009576, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34748539

RESUMEN

Advances in genetic engineering technologies have allowed the construction of artificial genetic circuits, which have been used to generate spatial patterns of differential gene expression. However, the question of how cells can be programmed, and how complex the rules need to be, to achieve a desired tissue morphology has received less attention. Here, we address these questions by developing a mathematical model to study how cells can collectively grow into clusters with different structural morphologies by secreting diffusible signals that can influence cellular growth rates. We formulate how growth regulators can be used to control the formation of cellular protrusions and how the range of achievable structures scales with the number of distinct signals. We show that a single growth inhibitor is insufficient for the formation of multiple protrusions but may be achieved with multiple growth inhibitors, and that other types of signals can regulate the shape of protrusion tips. These examples illustrate how our approach could potentially be used to guide the design of regulatory circuits for achieving a desired target structure.


Asunto(s)
Proliferación Celular/fisiología , Forma de la Célula/fisiología , Técnicas de Reprogramación Celular/métodos , Modelos Biológicos , Animales , Agregación Celular/fisiología , Comunicación Celular/fisiología , Extensiones de la Superficie Celular/fisiología , Técnicas de Reprogramación Celular/estadística & datos numéricos , Biología Computacional , Simulación por Computador , Redes Reguladoras de Genes , Ingeniería Genética/métodos , Ingeniería Genética/estadística & datos numéricos , Inhibidores de Crecimiento/fisiología , Humanos , Morfogénesis/fisiología , Biología Sintética
10.
J Neurochem ; 158(3): 766-778, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34107054

RESUMEN

Trans-active response DNA-binding protein of 43 kDa (TDP-43) promotes tau mRNA instability and tau exon 10 inclusion. Aggregation of phosphorylated TDP-43 is associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration. Casein kinase 1ε (CK1ε) phosphorylates TDP-43 at multiple sites, enhances its cytoplasmic aggregation, and modulates its function in tau mRNA processing. To determine roles of TDP-43 site-specific phosphorylation in its localization, aggregation, and function in tau mRNA processing, TDP-43 was mutated to alanine or aspartic acid at Ser379, Ser403/404, or Ser409/410 to block or mimic phosphorylation. Site-specific phosphorylation of TDP-43 and its mutants by CK1ε was studied in vitro and in cultured cells. Cytoplasmic and nuclear TDP-43 and phospho-TDP-43 were analyzed by western blots. Aggregation of TDP-43 was assessed by immunostaining and level of radioimmunoprecipitation assay buffer-insoluble TDP-43. Green florescent protein tailed with tau 3'-untranslated region and mini-tau gene pCI/SI9-LI10 were used to study tau mRNA stability and alternative splicing of tau exon 10. We found that phospho-blocking mutations of TDP-43 at Ser379, Ser403/404, or Ser409/410 were not effectively phosphorylated by CK1ε. Compared with TDP-43, higher level of phosphorylated TDP-43 in the cytoplasm was observed. Phospho-mimicking mutations at these sites enhanced cytoplasmic aggregation of TDP-43. Green florescent protein expression was not inhibited by phospho-blocking mutants of TDP-43, but tau exon 10 inclusion was further enhanced by phospho-blocking mutations at Ser379 and Ser403/404. Phosphorylation of TDP-43 at Ser379, Ser403/404, or Ser409/410 primes its phosphorylation by CK1ε, promotes TDP-43 cytoplasmic aggregation, and modulates its function in tau mRNA processing in site-specific manner.


Asunto(s)
Empalme Alternativo/fisiología , Citoplasma/metabolismo , Proteínas de Unión al ADN/metabolismo , Exones/fisiología , Estabilidad del ARN/fisiología , Proteínas tau/metabolismo , Anciano , Anciano de 80 o más Años , Animales , Agregación Celular/fisiología , Proteínas de Unión al ADN/genética , Femenino , Lóbulo Frontal/metabolismo , Células HEK293 , Células HeLa , Humanos , Masculino , Ratones , Fosforilación/fisiología , Proteínas tau/genética
11.
Fish Shellfish Immunol ; 114: 229-237, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33979692

RESUMEN

The freshwater aquifers of the Indo-Gangetic plains support rich biodiversity which is under the threat of arsenic contamination. The filter feeding bivalve mollusc Lamellidens marginalis is a sessile and sentinel resident of these freshwater habitats. In the present study, the classical cell behaviours of adhesion and aggregation were monitored in the circulating haemocytes of the freshwater bivalve under the exposure of sodium arsenite (NaAsO2) at sublethal concentrations in controlled laboratory conditions for a maximum time-span of sixteen days. The toxic metalloid significantly inhibited non-self adhesion, inter-haemocyte interactions and haemocyte aggregation in a dose and time dependent manner. The natural occurrence of the filopods on the haemocytes was significantly diminished in the bivalves exposed to the inorganic arsenite. Moreover, a significant fall in the kinetics of phagocytosis index and haemocyte adhesion was observed under the in vitro exposure to NaAsO2. Compromised non-self adhesion, cell-cell aggregation and phagocytosis of non-self particles by the bivalve haemocytes probably indicate susceptible immunological status of the bivalve. Such vulnerable immunity of the bivalve probably signifies the nature of imminent threat to the freshwater ecosystem as a whole under inorganic arsenite exposure. The findings would be helpful to design bivalve haemocyte based inexpensive biomonitoring tool to assess the health of freshwater ecosystem under potential arsenic threat.


Asunto(s)
Arsénico/toxicidad , Bivalvos/citología , Adhesión Celular/fisiología , Agregación Celular/fisiología , Hemocitos/fisiología , Fagocitosis/fisiología , Animales , Arseniatos/toxicidad , Contaminantes Químicos del Agua/toxicidad
12.
Dev Biol ; 454(1): 44-51, 2019 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-31220433

RESUMEN

The zebrafish kidney regenerates after injury by development of new nephrons from resident adult kidney stem cells. Although adult kidney progenitor cells have been characterized by transplantation and single cell RNA seq, signals that stimulate new nephron formation are not known. Here we demonstrate that fibroblast growth factors and FGF signaling is rapidly induced after kidney injury and that FGF signaling is required for recruitment of progenitor cells to sites of new nephron formation. Chemical or dominant negative blockade of Fgfr1 prevented formation of nephron progenitor cell aggregates after injury and during kidney development. Implantation of FGF soaked beads induced local aggregation of lhx1a:EGFP  â€‹+ â€‹kidney progenitor cells. Our results reveal a previously unexplored role for FGF signaling in recruitment of renal progenitors to sites of new nephron formation and suggest a role for FGF signaling in maintaining cell adhesion and cell polarity in newly forming kidney epithelia.


Asunto(s)
Factores de Crecimiento de Fibroblastos/metabolismo , Nefronas/metabolismo , Células Madre/citología , Células Madre Adultas/metabolismo , Animales , Agregación Celular/fisiología , Riñón/citología , Riñón/metabolismo , Organogénesis , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/metabolismo , Regeneración/fisiología , Transducción de Señal/fisiología , Células Madre/metabolismo , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismo
13.
Biochem Biophys Res Commun ; 523(2): 398-404, 2020 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-31870546

RESUMEN

The role of protein kinase N1 (PKN1) in cell aggregation and spheroid formation was investigated using mouse embryonic fibroblasts (MEFs) deficient in kinase activity caused by a point mutation (T778A) in the activation loop. Wild type (WT) MEFs formed cell aggregates within a few hours in suspension cultures placed in poly-2-hydroxyethylmethacrylate (poly-HEMA) coated flat-bottom dishes. By contrast, PKN1[T778A] (PKN1 T778A/T778A homozygous knock-in) MEFs showed significantly delayed aggregate formation and higher susceptibility to cell death. Video analysis of suspension cultures revealed decreased cell motility and lesser frequency of cell-cell contact in PKN1[T778A] MEFs compared to that in WT MEFs. Aggregate formation of PKN1[T778A] MEFs was compensated by shaking the cell suspension. When cultured in U-shaped ultra-low attachment well plates, initially larger-sized and loosely packed aggregates of WT MEFs underwent compaction resulting in a single round spheroid. On the other hand, image-based quantitative analysis of PKN1[T778A] MEFs revealed irregular compaction with decreased roundness, solidity, and sphericity within 24 h. Flow cytometry of PKN1[T778A] MEFs revealed decreased surface-expression of N-cadherin and integrins α5 and αV. These results suggest that kinase activity of PKN1 controls cell aggregation and spheroid compaction in MEF suspension culture, possibly by regulating the cell migration and cell-surface expression of N-cadherin and integrins.


Asunto(s)
Proteína Quinasa C/metabolismo , Animales , Cadherinas/metabolismo , Agregación Celular/fisiología , Membrana Celular/metabolismo , Supervivencia Celular/fisiología , Células Cultivadas , Fibroblastos/citología , Fibroblastos/enzimología , Técnicas de Sustitución del Gen , Integrina alfa5/metabolismo , Integrina alfaV/metabolismo , Ratones , Ratones Mutantes , Mutación Puntual , Proteína Quinasa C/deficiencia , Proteína Quinasa C/genética , Esferoides Celulares/citología , Esferoides Celulares/enzimología
14.
Cell Immunol ; 353: 104129, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32473470

RESUMEN

BENTA (B cell Expansion with NF-κB and T cell Anergy) is a novel lymphoproliferative disorder caused by germline, gain-of-function (GOF) mutations in the lymphocyte-restricted scaffolding protein CARD11. Similar somatic CARD11 mutations are found in lymphoid malignancies such as diffuse large B cell lymphoma (DLBCL). Normally, antigen receptor (AgR) engagement converts CARD11 into an active conformation that nucleates a signalosome required for IκB kinase (IKK) activation and NF-κB nuclear translocation. However, GOF CARD11 mutants drive constitutive NF-κB activity without AgR stimulation. Here we show that unlike wild-type CARD11, GOF CARD11 mutants can form large, peculiar cytosolic protein aggregates we term mCADS (mutant CARD11 dependent shells). MALT1 and phospho-IKK are reliably colocalized with mCADS, indicative of active signaling. Moreover, endogenous mCADS are detectable in ABC-DLBCL lines harboring similar GOF CARD11 mutations. The unique aggregation potential of GOF CARD11 mutants may represent a novel therapeutic target for treating BENTA or DLBCL.


Asunto(s)
Proteínas Adaptadoras de Señalización CARD/genética , Agregación Celular/fisiología , Mutación con Ganancia de Función , Guanilato Ciclasa/genética , Proteínas Reguladoras de la Apoptosis/metabolismo , Proteínas Adaptadoras de Señalización CARD/metabolismo , Guanilato Ciclasa/metabolismo , Humanos , Quinasa I-kappa B/metabolismo , Células Jurkat , Activación de Linfocitos , Linfocitos/metabolismo , Linfocitos/fisiología , Linfoma de Células B Grandes Difuso/genética , Linfoma de Células B Grandes Difuso/metabolismo , Linfoma de Células B Grandes Difuso/patología , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/metabolismo , FN-kappa B/metabolismo , Transducción de Señal
15.
Biotechnol Bioeng ; 117(10): 3136-3149, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32579299

RESUMEN

Protein homeostasis is critical for cellular function, as loss of homeostasis is attributed to aging and the accumulation of unwanted proteins. Human mesenchymal stem cells (MSCs) have shown promising therapeutic potential due to their impressive abilities to secrete inflammatory modulators, angiogenic, and regenerative cytokines. However, there exists the problem of human MSC expansion with compromised therapeutic quality. Duringin vitro expansion, human MSCs are plated on stiff plastics and undergo culture adaptation, which results in aberrant proliferation, shifts in metabolism, and decreased autophagic activity. It has previously been shown that three-dimensional (3D) aggregation can reverse some of these alterations by heightening autophagy and recovering the metabolic state back to a naïve phenotype. To further understand the proteostasis in human MSC culture, this study investigated the effects of 3D aggregation on the human MSC proteome to determine the specific pathways altered by aggregation. The 3D aggregates and 2D cultures of human MSCs derived from bone marrow (bMSC) and adipose tissue (ASC) were analyzed along with differentiated human dermal fibroblasts (FB). The proteomics analysis showed the elevated eukaryotic initiation factor 2 pathway and the upregulated activity of the integrated stress response (ISR) in 3D aggregates. Specific protein quantification further determined that bMSC and ASC responded to ISR, while FB did not. 3D aggregation significantly increased the ischemic survival of bMSCs and ASCs. Perturbation of ISR with small molecules salubrinal and GSK2606414 resulted in differential responses of bMSC, ASC, and FB. This study indicates that aggregation-based preconditioning culture holds the potential for improving the therapeutic efficacy of expanded human MSCs via the establishment of ISR and homeostasis.


Asunto(s)
Tejido Adiposo/citología , Médula Ósea/metabolismo , Técnicas de Cultivo de Célula/métodos , Células Madre Mesenquimatosas/citología , Agregación Celular/fisiología , Proliferación Celular , Células Cultivadas , Humanos , Células Madre Mesenquimatosas/metabolismo , Estrés Fisiológico
16.
PLoS Comput Biol ; 15(12): e1007459, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31825952

RESUMEN

Single and collective cell dynamics, cell shape changes, and cell migration can be conveniently represented by the Cellular Potts Model, a computational platform based on minimization of a Hamiltonian. Using the fact that a force field is easily derived from a scalar energy (F = -∇H), we develop a simple algorithm to associate effective forces with cell shapes in the CPM. We predict the traction forces exerted by single cells of various shapes and sizes on a 2D substrate. While CPM forces are specified directly from the Hamiltonian on the cell perimeter, we approximate the force field inside the cell domain using interpolation, and refine the results with smoothing. Predicted forces compare favorably with experimentally measured cellular traction forces. We show that a CPM model with internal signaling (such as Rho-GTPase-related contractility) can be associated with retraction-protrusion forces that accompany cell shape changes and migration. We adapt the computations to multicellular systems, showing, for example, the forces that a pair of swirling cells exert on one another, demonstrating that our algorithm works equally well for interacting cells. Finally, we show forces exerted by cells on one another in classic cell-sorting experiments.


Asunto(s)
Forma de la Célula/fisiología , Modelos Biológicos , Algoritmos , Fenómenos Biofísicos , Adhesión Celular/fisiología , Agregación Celular/fisiología , Comunicación Celular/fisiología , Movimiento Celular/fisiología , Biología Computacional , Simulación por Computador , Humanos , Transducción de Señal/fisiología
17.
Bull Math Biol ; 82(2): 20, 2020 01 22.
Artículo en Inglés | MEDLINE | ID: mdl-31970500

RESUMEN

Cancer is a complex phenomenon, and the sheer variation in behaviour across different types renders it difficult to ascertain underlying biological mechanisms. Experimental approaches frequently yield conflicting results for myriad reasons, and mathematical modelling of cancer is a vital tool to explore what we cannot readily measure, and ultimately improve treatment and prognosis. Like experiments, models are underpinned by certain biological assumptions, variation of which can lead to divergent predictions. An outstanding and important question concerns contact inhibition of proliferation (CIP), the observation that proliferation ceases when cells are spatially confined by their neighbours. CIP is a characteristic of many healthy adult tissues, but it remains unclear to which extent it holds in solid tumours, which exhibit regions of hyper-proliferation, and apparent breakdown of CIP. What precisely occurs in tumour tissue remains an open question, which mathematical modelling can help shed light on. In this perspective piece, we explore the implications of different hypotheses and available experimental evidence to elucidate the implications of these scenarios. We also outline how erroneous conclusions about the nature of tumour growth may be arrived at by looking selectively at biological data in isolation, and how this might be circumvented.


Asunto(s)
Modelos Biológicos , Neoplasias/patología , Animales , Agregación Celular/fisiología , Proliferación Celular/fisiología , Simulación por Computador , Inhibición de Contacto/fisiología , Humanos , Conceptos Matemáticos , Neoplasias/fisiopatología , Esferoides Celulares/patología , Células Tumorales Cultivadas
18.
Phys Biol ; 16(4): 046006, 2019 06 04.
Artículo en Inglés | MEDLINE | ID: mdl-31042683

RESUMEN

Cellular self-assembly and organization are fundamental steps for the development of biological tissues. In this paper, within the framework of a cellular automata model, we address how an ordered tissue pattern spontaneously emerges from a randomly migrating single cell population without the influence of any external cues. This model is based on the active motility of cells and their ability to reorganize due to cell-cell cohesivity as observed in experiments. Our model successfully emulates the formation of nascent clusters and also predicts the temporal evolution of aggregates that leads to the compact tissue structures. Moreover, the simulations also capture several dynamical properties of growing aggregates, such as, the rate of cell aggregation and non-monotonic growth of the aggregate area which show a good agreement with the existing experimental observations. We further investigate the time evolution of the cohesive strength, and the compactness of aggregates, and also study the ruggedness of the growing structures by evaluating the fractal dimension to get insights into the complexity of tumorous tissue growth which were hitherto unexplored.


Asunto(s)
Simulación por Computador , Modelos Biológicos , Algoritmos , Adhesión Celular/fisiología , Agregación Celular/fisiología , Línea Celular , Microambiente Celular , Cinética
19.
Cytotherapy ; 21(10): 1033-1048, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31537468

RESUMEN

Human mesenchymal stem cells (hMSCs) have been shown to enhance stroke lesion recovery by mediating inflammation and tissue repair through secretion of trophic factors. However, low cell survival and reduced primitive stem cell function of culture-expanded hMSCs are the major challenges limiting hMSC therapeutic efficacy in stroke treatment. In this study, we report the effects of short-term preconditioning of hMSCs via three-dimensional (3D) aggregation on stroke lesion recovery after intra-arterial (IA) transplantation of 3D aggregate-derived hMSCs (Agg-D hMSCs) in a transient middle cerebral artery occlusion (MCAO) stroke model. Compared with two-dimensional (2D) monolayer culture, Agg-D hMSCs exhibited increased resistance to ischemic stress, secretory function and therapeutic outcome. Short-term preconditioning via 3D aggregation reconfigured hMSC energy metabolism and altered redox cycle, which activated the PI3K/AKT pathway and enhanced resistance to in vitro oxidative stress. Analysis of transplanted hMSCs in MCAO rats using ultra-high-field magnetic resonance imaging at 21.1 T showed increased hMSC persistence and stroke lesion reduction by sodium (23Na) imaging in the Agg-D hMSC group compared with 2D hMSC control. Behavioral analyses further revealed functional improvement in MCAO animal treated with Agg-D hMSCs compared with saline control. Together, the results demonstrated the improved outcome for Agg-D hMSCs in the MCAO model and suggest short-term 3D aggregation as an effective preconditioning strategy for hMSC functional enhancement in stroke treatment.


Asunto(s)
Supervivencia de Injerto/fisiología , Infarto de la Arteria Cerebral Media/terapia , Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/fisiología , Accidente Cerebrovascular/terapia , Adulto , Animales , Agregación Celular/fisiología , Células Cultivadas , Humanos , Infarto de la Arteria Cerebral Media/patología , Masculino , Trasplante de Células Madre Mesenquimatosas/métodos , Persona de Mediana Edad , Ratas , Ratas Sprague-Dawley , Accidente Cerebrovascular/patología , Resultado del Tratamiento , Adulto Joven
20.
PLoS Comput Biol ; 14(12): e1006645, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-30589836

RESUMEN

Chirality in shape and motility can evolve rapidly in microbes and cancer cells. To determine how chirality affects cell fitness, we developed a model of chiral growth in compact aggregates such as microbial colonies and solid tumors. Our model recapitulates previous experimental findings and shows that mutant cells can invade by increasing their chirality or switching their handedness. The invasion results either in a takeover or stable coexistence between the mutant and the ancestor depending on their relative chirality. For large chiralities, the coexistence is accompanied by strong intermixing between the cells, while spatial segregation occurs otherwise. We show that the competition within the aggregate is mediated by bulges in regions where the cells with different chiralities meet. The two-way coupling between aggregate shape and natural selection is described by the chiral Kardar-Parisi-Zhang equation coupled to the Burgers' equation with multiplicative noise. We solve for the key features of this theory to explain the origin of selection on chirality. Overall, our work suggests that chirality could be an important ecological trait that mediates competition, invasion, and spatial structure in cellular populations.


Asunto(s)
Agregación Celular/fisiología , Modelos Biológicos , Movimiento Celular/fisiología , Polaridad Celular/fisiología , Proliferación Celular/fisiología , Forma de la Célula/fisiología , Biología Computacional , Simulación por Computador , Humanos , Microbiota/fisiología , Invasividad Neoplásica/patología , Invasividad Neoplásica/fisiopatología , Neoplasias/patología , Neoplasias/fisiopatología , Procesos Estocásticos
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