The mechanics of the microenvironment continuously modulates cell functions like growth, survival, apoptosis, differentiation, and morphogenesis via cytoskeletal remodeling and actomyosin contractility 1 – 3 . Although all these processes consume energy 4 , 5 , it is unknown if and how cells adapt their metabolic activity to variable mechanical cues. Here, we report that transfer of human bronchial epithelial cells (HBECs) from stiff to soft substrates causes downregulation of glycolysis via proteasomal degradation of the rate-limiting metabolic enzyme phosphofructokinase (PFK). PFK degradation is triggered by stress fiber disassembly, which releases the PFK-targeting E3 ubiquitin ligase tripartite motif (TRIM)-containing protein 21 (TRIM21). Transformed non-small cell lung cancer cells (NSCLCs), which maintain high glycolytic rates regardless of changing environmental mechanics, retain PFK expression by downregulating TRIM21, and by sequestering residual TRIM21 on a stress fiber population that is insensitive to substrate stiffness. In sum, our data unveil a mechanism by which glycolysis responds to architectural features of the actomyosin cytoskeleton, thus coupling cell metabolism to the mechanical properties of the surrounding tissue. These processes enable normal cells to attune energy production in variable microenvironments, while the resistance of the cytoskeleton to respond to mechanical cues allows high glycolytic rates to persist in cancer cells despite constant alterations of the tumor tissue.

Many viruses deliver their genomes into the host cell nucleus for replication. However, the size restrictions of the nuclear pore complex (NPC), which regulates the passage of proteins, nucleic acids, and solutes through the nuclear envelope, require virus capsid uncoating before viral DNA can access the nucleus. We report a microtubule motor kinesin-1-mediated and NPC-supported mechanism of adenovirus uncoating. The capsid binds to the NPC filament protein Nup214 and kinesin-1 light-chain Klc1/2. The nucleoporin Nup358, which is bound to Nup214/Nup88, interacts with the kinesin-1 heavy-chain Kif5c to indirectly link the capsid to the kinesin motor. Kinesin-1 disrupts capsids docked at Nup214, which compromises the NPC and dislocates nucleoporins and capsid fragments into the cytoplasm. NPC disruption increases nuclear envelope permeability as indicated by the nuclear influx of large cytoplasmic dextran polymers. Thus, kinesin-1 uncoats viral DNA and compromises NPC integrity, allowing viral genomes nuclear access to promote infection.

Viral particle binding to plasma membrane receptors elicits virus motions, recruits signaling proteins, and triggers membrane bending and fission, finally resulting in endocytic virus uptake. Here we analyze how human adenovirus engages its receptor coxsackievirus adenovirus receptor (CAR) and coreceptor αv integrin to move on the plasma membrane. Virus binding to CAR through fiber knobs gave rise to diffusive motions and actomyosin-2-dependent drifts, while integrin-targeted viruses were spatially more confined. Diffusions, drifts, and confined motions were specifically observed with viral particles that were subsequently internalized. CAR-mediated drifts together with integrin binding supported fiber shedding from adenovirus particles, leading to exposure of the membrane-lytic internal virion protein VI and enhanced viral escape from endosomes. Our results show that adenovirus uncoating is initiated at the plasma membrane by CAR drifting motion and binding to immobile integrins.

SUMMARY Increased expression of vimentin intermediate filaments (VIF) enhances directed cell migration, but the mechanism behind VIF’s effect on motility is not understood. VIF interact with microtubules, whose organization contributes to polarity maintenance in migrating cells. Here we characterize the dynamic coordination of VIF and microtubule networks in wounded monolayers of Retinal Pigment Epithelial cells. By genome editing we fluorescently labelled endogenous vimentin and α-tubulin and we developed computational image analysis to delineate architecture and interactions of the two networks. Our results show that VIF assemble an ultrastructural copy of the previously polarized microtubule network. Because the VIF network is long-lived compared to the microtubule network, VIF template future microtubule growth along previous microtubule tracks, thus providing a feedback mechanism that maintains cell polarity. VIF knockdown prevents cells from polarizing and migrating properly during wound healing. We suggest that VIF’s templating function establishes a memory in microtubule organization that enhances persistence in cell polarization in general and migration in particular.