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In epithelia, breakdown of tensional homeostasis is closely associated with E-cadherin dysfunction and disruption of tissue function and integrity. In this study, we investigated the effect of E-cadherin mutations affecting distinct protein domains on tensional homeostasis of gastric cancer cells. We used micropattern traction microscopy to measure temporal fluctuations of cellular traction forces in AGS cells transfected with the wild-type E-cadherin or with variants affecting the extracellular, the juxtamembrane, and the intracellular domains of the protein. We focused on the dynamic aspect of tensional homeostasis, namely the ability of cells to maintain a consistent level of tension, with low temporal variability around a set point. Cells were cultured on hydrogels micropatterned with different extracellular matrix (ECM) proteins to test whether the ECM adhesion impacts cell behavior. A combination of Fibronectin and Vitronectin was used as a substrate that promotes the adhesive ability of E-cadherin dysfunctional cells, whereas Collagen VI was used to test an unfavorable ECM condition. Our results showed that mutations affecting distinct E-cadherin domains influenced differently cell tensional homeostasis, and pinpointed the juxtamembrane and intracellular regions of E-cadherin as the key players in this process. Furthermore, Fibronectin and Vitronectin might modulate cancer cell behavior towards tensional homeostasis.

Drs Humphrey and Cyron wrote a commentary regarding our review article entitled “Tensional homeostasis at different length scales” that was published in Soft Matter , 2020, 16 , 6946–6963. These authors brought up some valid concerns to which we would like to respond. Their first concern is related to our remark regarding equations that we used to describe homeostasis in blood vessels, where we stated that those equations were limited only to linearly elastic materials. We were wrong, and we agree with the authors that these equations hold for all cylindrical vessels regardless of their material properties. Their second concern is related to tensional homeostasis at the subcellular level. Drs Humphrey and Cyron disagree with our substantiated claim that tensional homeostasis breaks down at the level of focal adhesions (FAs) of a living cell. In our reply, we provided several pieces of evidence that demonstrate that tensional homeostasis depends upon FA size, FA maturity and FA force dynamics and thus, tensional homeostasis cannot hold in all FAs across a cell. In summary, we are grateful for the opportunity to reply to the commentary of Drs Humphrey and Cyron. Moreover, we are excited that this topic has become an important focusmore »in the biomechanics and mechanobiology communities, and we feel strongly that critical feedback is necessary to move this field forward.« less

Honeybees are renowned for their perfectly hexagonal honeycomb, hailed as the pinnacle of biological architecture for its ability to maximize storage area while minimizing building material. However, in natural nests, workers must regularly transition between different cell sizes, merge inconsistent combs, and optimize construction in constrained geometries. These spatial obstacles pose challenges to workers building perfect hexagons, but it is unknown to what extent workers act as architects versus simple automatons during these irregular building scenarios. Using automated image analysis to extract the irregularities in natural comb building, we show that some building configurations are more difficult for the bees than others, and that workers overcome these challenges using a combination of building techniques, such as: intermediate-sized cells, regular motifs of irregular shapes, and gradual modifications of cell tilt. Remarkably, by anticipating these building challenges, workers achieve high-quality merges using limited local sensing, on par with analytical models that require global optimization. Unlike automatons building perfectly replicated hexagons, these building irregularities showcase the active role that workers take in shaping their nest and the true architectural abilities of honeybees.

Tumour progression relies on the ability of cancer cells to penetrate and invade neighbouring tissues. E-cadherin loss is associated with increased cell invasion in gastric carcinoma, and germline mutations of the E-cadherin gene are causative of hereditary diffuse gastric cancer. Although E-cadherin dysfunction impacts cell–cell adhesion, cell dissemination also requires an imbalance of adhesion to the extracellular matrix (ECM).

To identify ECM components and receptors relevant for adhesion of E-cadherin dysfunctional cells, we implemented a novel ECM microarray platform coupled with molecular interaction networks. The functional role of putative candidates was determined by combining micropattern traction microscopy, protein modulation and in vivo approaches, as well as transcriptomic data of 262 gastric carcinoma samples, retrieved from the cancer genome atlas (TCGA).

Here, we show that E-cadherin mutations induce an abnormal interplay of cells with specific components of the ECM, which encompasses increased traction forces and Integrin β1 activation. Integrin β1 synergizes with E-cadherin dysfunction, promoting cell scattering and invasion. The significance of the E-cadherin-Integrin β1 crosstalk was validated inDrosophilamodels and found to be consistent with evidence from human gastric carcinomas, where increased tumour grade and poor survival are associated with low E-cadherin and high Integrin β1 levels.

Integrin β1 ismore »a key mediator of invasion in carcinomas with E-cadherin impairment and should be regarded as a biomarker of poor prognosis in gastric cancer.

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Tensional homeostasis is a phenomenon of fundamental importance in mechanobiology. It refers to the ability of organs, tissues, and cells to respond to external disturbances by maintaining a homeostatic (set point) level of mechanical stress (tension). It is well documented that breakdown in tensional homeostasis is the hallmark of progression of diseases, including cancer and atherosclerosis. In this review, we surveyed quantitative studies of tensional homeostasis with the goal of providing characterization of this phenomenon across a broad range of length scales, from the organ level to the subcellular level. We considered both static and dynamics approaches that have been used in studies of this phenomenon. Results that we found in the literature and that we obtained from our own investigations suggest that tensional homeostasis is an emergent phenomenon driven by collective rheostatic mechanisms associated with focal adhesions, and by a collective action of cells in multicellular forms, whose impact on tensional homeostasis is cell type-dependent and cell microenvironment-dependent. Additionally, the finding that cadherins, adhesion molecules that are important for formation of cell–cell junctions, promote tensional homeostasis even in single cells, demonstrates their relevance as a signaling moiety.

In complex societies, individuals’ roles are reflected by interactions with other conspecifics. Honey bees (Apis mellifera) generally change tasks as they age, but developmental trajectories of individuals can vary drastically due to physiological and environmental factors. We introduce a succinct descriptor of an individual’s social network that can be obtained without interfering with the colony. This ‘network age’ accurately predicts task allocation, survival, activity patterns, and future behavior. We analyze developmental trajectories of multiple cohorts of individuals in a natural setting and identify distinct developmental pathways and critical life changes. Our findings suggest a high stability in task allocation on an individual level. We show that our method is versatile and can extract different properties from social networks, opening up a broad range of future studies. Our approach highlights the relationship of social interactions and individual traits, and provides a scalable technique for understanding how complex social systems function.

Textbooks shape teaching and learning in introductory biology and highlight scientists as potential role models who are responsible for significant discoveries. We explore a potential demographic mismatch between the scientists featured in textbooks and the students who use textbooks to learn core concepts in biology. We conducted a demographic analysis by extracting hundreds of human names from common biology textbooks and assessing the binary gender and race of featured scientists. We found that the most common scientists featured in textbooks are white men. However, women and scientists of colour are increasingly represented in contemporary scientific discoveries. In fact, the proportion of women highlighted in textbooks has increased in lockstep with the proportion of women in the field, indicating that textbooks are matching a changing demographic landscape. Despite these gains, the scientists portrayed in textbooks are not representative of their target audience—the student population. Overall, very few scientists of colour were highlighted, and projections suggest it could take multiple centuries at current rates before we reach inclusive representation. We call upon textbook publishers to expand upon the scientists they highlight to reflect the diverse population of learners in biology.