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The mechanical properties of cells are dynamic, allowing them to adjust to different needs in different biological contexts. In recent years, advanced biophysical techniques have enabled the rapid, high-throughput assessment of single-cell mechanics, providing new insights into the regulation of the mechanical cell phenotype. However, the molecular mechanisms by which cells maintain and regulate their mechanical properties remain poorly understood. Here, we present a genome-scale RNA interference (RNAi) screen investigating the roles of kinase and phosphatase genes in regulating single-cell mechanics using Real-Time Fluorescence and Deformability Cytometry (RT-FDC).

The ribosome plays a central role in translating the genetic code into amino acid sequences during polypeptide synthesis. In each cycle of peptide elongation, the ribosome discriminates between correct and incorrect aminoacyl-tRNAs based on the codon present in its A-site. To ensure high fidelity, ribosomes employ multiple proofreading mechanisms that reduce the selection of incorrect aminoacyl-tRNAs. Initial proofreading of incorrect tRNAs (near-cognate or non-cognate) is well understood in prokaryotic ribosomes but incompletely understood in eukaryotic systems.

Collagen is a prevalent protein in the animalia kingdom, especially in mammals. It is abundant in all connective tissue such as bone or ligaments and thus it is subjected to substantial mechanical forces. Crosslinks play an essential role for the structural and mechanical integrity of collagen, determining its stiffness and rigidity. Until now, studies on collagen including crosslinks have either been confined to fully atomistic simulations, which are computationally intensive and restrict the accessible time and length scales, or to coarse-grained descriptions that do not resolve the force response on a residue-level and therefore do not consider the triple helical structure and the connectivity of crosslinks.

Nanopore-forming outer membrane proteins mediate the selective transport of peptides and small molecules in Gram-negative bacteria. In this work, we investigate how peptides are recognized by a truncated form of Vibrio harveyi chitoporin (VhChiPΔN-plug), which lacks the native N-terminal plug. Using electrophysiology black lipid membrane (BLM), we show that a synthetic peptide mimicking the N-plug binds selectively and directionally to VhChiPΔN-plug pores when applied from the trans (periplasmic) side, consistent with the native extracellular orientation of the plug.

The voltage-gated calcium channel CaV1.1 is the voltage sensor for skeletal muscle excitation-contraction (EC) coupling. Upon depolarization of the membrane, it rapidly triggers calcium release from the sarcoplasmic reticulum by conformational coupling to the type 1 ryanodine receptor. Strong depolarization further gives rise to slowly activating L-type calcium currents. Activation of these two processes at distinct voltages and with distinct kinetics is accomplished by the specific actions and properties of CaV1.1´s four voltage-sensing domains (VSDs).

Deformability cytometry (DC) is a powerful biophysical technique that enables cost-effective, high-throughput characterization of disease-associated changes in blood cell mechanics. Mechanical profiling of living white blood cells (WBCs) is particularly valuable due to their critical role in the immune response. However, reliably identifying and classifying WBC subtypes in a label-free manner remains a significant challenge. Until now, the analysis pipeline has relied on manual gating by trained experts, limiting scalability and reproducibility.

Understanding molecular diffusion within cells is crucial for gaining insights into cellular biophysical mechanisms. Despite its importance, achieving versatile mapping of such diffusion across whole cells remains challenging, as many live-cell measurement techniques including fluorescence recovery after photobleaching (FRAP) provide data only at discrete spatial locations due to experimental constraints. To overcome this limitation, we developed Probabilistic FRAP (Pro-FRAP), a novel approach that integrates FRAP with sequential Gaussian simulation (SGS), an advanced spatial statistical method incorporating probabilistic modeling to estimate diffusion in unmeasured regions.

Cell-scale curvature is a key regulator of cell migration, yet its quantitative effects and underlying mechanisms remain elusive. Here, we combine controlled in vitro experiments with a phenomenological theoretical framework to investigate the migration of fibroblasts (NIH3T3) and epithelial cells (MCF10A) on the inner concave surfaces of polydimethylsiloxane (PDMS) microcylinders across a wide range of cell-scale curvatures (∼0.01 per micron). We find that migration persistence positively correlates with mean speed across all curvatures, consistent with the universal speed-persistence coupling relation (UCSP) previously observed for cells migrating on 1D and 2D planar substrates, as well as for cells embedded in 3D environments.

In adherent cells, actomyosin contractility is regulated mainly by the RhoA signaling pathway, which can be controlled by optogenetics. To model the mechanochemical coupling in such systems, we introduce a finite element framework based on the discontinuous Galerkin method, which allows us to treat cell doublets, chains of cells and monolayers within the same conceptual framework. While the adherent cell layer is modeled as an actively contracting viscoelastic material on an elastic foundation, different models are considered for the Rho-pathway, starting with a simple linear chain that can be solved analytically and later including direct feedback that can be solved only numerically.

One sentence summary: Biophysical modeling demonstrates how tissue fluidity is a key regulator of the rate and accuracy of adhesion-based sorting.

It is a pleasure to share this issue honoring Watt W. Webb. Watt was a pioneering biophysicist whose legacy is both in his diverse contributions to the field and in his training and mentorship of a large number of contemporary biophysicists. Watt is best known in the biophysics community for two techniques that he co-developed with collaborators—fluorescence correlation spectroscopy (FCS) (1) and multiphoton microscopy (MPM) (2)—tools that are widely used at research institutions across the world today.

The cell nucleus is constantly subjected to forces under many fundamental biological processes, including confined cell migration, osmoregulation, and large-scale stresses across tissues during development. Biomolecular condensates, a class of subcellular structures without surrounding membranes, are responsive to external force perturbation, as seen in early work on germline p-granules nearly two decades ago. However, how external forces on cells impact physiological condensation at the subcellular level, and how condensates themselves can be mechanically active, is still an emerging area of research.