Biology subjects

Wehrle-Haller, B.

Publications and source records attributed to Wehrle-Haller, B..

4 recordsLinked to original sources

bioRxiv2023

Akt Drives TGF-beta-induced Over-secretion of DKK1 and Impairment of Cystic Fibrosis Airway Epithelium Polarity

Epithelial polarity is fundamental in maintaining barrier integrity and tissue protection. In cystic fibrosis (CF), apicobasal polarity of the airway epithelium is lost, resulting in increased apical fibronectin deposition and enhanced susceptibility to bacterial infections. Here we show that CFTR mutation in primary human airway epithelial cells (HAECs) and CFTR knockdown in a HAEC line promote the overexpression and over-secretion of TGF-{beta}1 and DKK1 when cultured at air-liquid interface (ALI). These dynamic changes result in hyperactivation of the TGF-{beta} pathway and inhibition of the Wnt pathway through degradation of {beta}-catenin leading to imbalanced proliferation and polarization. The abnormal interplay between TGF-{beta} and Wnt signaling pathways is further enhanced by aberrant Akt signaling. Pharmacological manipulation of TGF-{beta}, Wnt, and Akt pathways restored polarization of the CF epithelium. Our data shed new insights into the signaling pathways that fine-tune apicobasal polarization and also highlight new therapeutic strategies in preventing infections in CF HAECs.

cell biology↗

bioRxiv2023

New tools to study the interaction between integrins and latent TGFbeta1

Transforming growth factor beta (TGF{beta}) 1 regulates cell differentiation and proliferation in different physiological settings, but is also involved in fibrotic progression and protects tumors from the immune system. Integrin V{beta}6 has been shown to activate latent TGF{beta}1 by applying mechanical forces onto the latency-associated peptide (LAP). While the extracellular binding between V{beta}6 and LAP1 is well characterized, less is known about the cytoplasmic adaptations that enable V{beta}6 to apply such forces. Here, we generated new tools to facilitate the analysis of this interaction. We combined the integrin-binding part of LAP1 with a GFP and the Fc chain of human IgG. This chimeric protein, sLAP1, revealed a mechanical rearrangement of immobilized sLAP1 by V{beta}6 integrin. This unique interaction was not observed between sLAP1 and other integrins. We also analyzed V{beta}6 integrin binding to LAP2 and LAP3 by creating respective sLAPs. Compared to sLAP1, integrin V{beta}6 showed less binding to sLAP3 and no rearrangement. These observations indicate differences in the binding of V{beta}6 to LAP1 and LAP3 that have not been appreciated so far. Finally, V{beta}6-sLAP1 interaction was maintained even at strongly reduced cellular contractility, highlighting the special mechanical connection between V{beta}6 integrin and latent TGF{beta}1.

cell biology↗

bioRxiv2020

Molecular motion and tridimensional nanoscale localization of kindlin control integrin activation in focal adhesions

AO_SCPLOWBSTRACTC_SCPLOWFocal adhesions (FAs) initiate chemical and mechanical signals involved in cell polarity, migration, proliferation and differentiation. Super-resolution microscopy revealed that FAs are organized at the nanoscale into functional layers from the lower plasma membrane to the upper actin cytoskeleton. Yet, how FAs proteins are guided into specific nano-layers to promote interaction with given targets is unknown. Using single protein tracking, super-resolution microscopy and functional assays, we linked the molecular behavior and tridimensional nanoscale localization of kindlin with its function in integrin activation inside FAs. We show that immobilization of integrins in FAs depends on interaction with kindlin. Unlike talin, kindlin displayed free diffusion along the plasma membrane outside and inside FAs. We demonstrate that the kindlin Pleckstrin Homology domain promotes membrane diffusion and localization to the membrane-proximal integrin nano-layer, necessary for kindlin enrichment and function in FAs. Using kindlin-deficient cells, we show that kindlin membrane localization and diffusion are crucial for integrin activation during cell adhesion and spreading. Thus, kindlin uses a different route than talin to reach and activate integrins, providing a possible molecular basis for their complementarity during integrin activation.

cell biology↗

bioRxiv2017

Force-dependent ligand sensing enables αVβ3 integrin to differentiate between fibronectin and high-affinity ligands

V{beta}3 integrin recognizes multiple extracellular matrix proteins, including vitronectin (Vn) and fibronectin (Fn). However, cell experiments are frequently performed on homogenously coated substrates with only one integrin ligand present. Here, we employed binary-choice substrates of Fn and Vn to dissect V{beta}3 integrin-mediated binding to both ligands on the subcellular scale. Superresolution imaging revealed that V{beta}3 integrin preferred binding to Vn under various conditions. In contrast, binding to Fn required mechanical load on V{beta}3 integrin. Integrin mutations, structural analysis, and molecular dynamics simulations established a model where the extended-closed conformation of V{beta}3 integrin binds Vn but not Fn. Force-mediated hybrid domain swing-out characterizes the extended-open conformation needed for efficient Fn binding. Thus, force-dependent conformational changes in V{beta}3 integrin increase the number of available ligands and therefore the ligand promiscuity of this integrin. These findings for V{beta}3 integrin were shown to regulate cell migration and mechanotransduction differentially on Fn compared to Vn and therefore to regulate cell behavior.

cell biology↗