Biology subjects

Cabe, J. I.

Publications and source records attributed to Cabe, J. I..

5 recordsLinked to original sources

bioRxiv2023

Vinculin is Essential For Sustaining Normal Levels of Endogenous Force Transmission at Cell-Cell Contacts

Transmission of cell-generated (i.e., endogenous) tension at cell-cell contacts is crucial for tissue shape changes during morphogenesis and adult tissue repair in tissues like epithelia. E-cadherin-based adhesions at cell-cell contacts are the primary means by which endogenous tension is transmitted between cells. The E-cadherin-{beta}-catenin--catenin complex mechanically couples to the actin cytoskeleton (and thereby the contractile machinery of the cell) both directly and indirectly. However, the key adhesion constituents required for substantial endogenous force transmission at these adhesions in cell-cell contacts are unclear. Due to the role of -catenin as a mechanotransducer that recruits vinculin at cell-cell contacts, we expected -catenin to be essential for the high levels of force transmission normally sustained. Instead, using the traction force imbalance method to determine the inter-cellular force at a single cell-cell contact between cell pairs, we found that it is vinculin that is essential for high endogenous force transmission. Our results constrain the potential mechanical pathways of force transmission at cell-cell contacts and suggest that vinculin can transmit forces at E-cadherin adhesions independent of -catenin, possibly through {beta}-catenin. Furthermore, we tested the ability of cell-cell contacts to withstand external stretch and found that vinculin is essential to maintain cell-cell contact stability under external forces as well.

biophysics↗

bioRxiv2023

α-Catenin Dependent E-cadherin Adhesion Dynamics as Revealed by an Accelerated Force Ramp

Tissue remodeling and shape changes often rely on force-induced cell rearrangements occurring via cell-cell contact dynamics. Epithelial cell-cell contact shape changes are particularly dependent upon E-cadherin adhesion dynamics which are directly influenced by cell-generated and external forces. While both the mobility of E-cadherin adhesions and their adhesion strength have been reported before, it is not clear how these two aspects of E-cadherin adhesion dynamics are related. Here, using magnetic pulling cytometry, we applied an accelerated force ramp on the E-cadherin adhesion between an E-cadherin-coated magnetic microbead and an epithelial cell to ascertain this relationship. Our approach enables the determination of the adhesion strength and force-dependent mobility of individual adhesions, which revealed a direct correlation between these key characteristics. Since -catenin has previously been reported to play a role in both E-cadherin mobility and adhesion strength when studied independently, we also probed epithelial cells in which -catenin has been knocked out. We found that, in the absence of -catenin, E-cadherin adhesions not only had lower adhesion strength, as expected, but were also more mobile. We observed that -catenin was required for the recovery of strained cell-cell contacts and propose that the adhesion strength and force-dependent mobility of E-cadherin adhesions act in tandem to regulate cell-cell contact homeostasis. Our approach introduces a method which relates the force-dependent adhesion mobility to adhesion strength and highlights the morphological role played by -catenin in E-cadherin adhesion dynamics.

biophysics↗

bioRxiv2023

Coupling During Collective Cell Migration is Controlled by a Vinculin Mechanochemical Switch

Collective cell migration (CCM) plays important roles in development, physiological, and pathological processes. A key feature of CCM is the dynamic mechanical coupling between cells, which enables both long-range coordination and local rearrangements. This coupling requires the ability of cell adhesions to adapt to forces. Recent efforts have identified key proteins and implicated cellular-scale mechanical properties, but how key proteins give rise to these larger-scale mechanical processes is unclear. Using force-sensitive biosensors, cell migration assays, and molecular clutch models, we sought a molecular understanding of adhesion strengthening that could bridge this gap. We found that the mechanical linker protein vinculin bears substantial loads at AJs, FAs, and in the cytoplasm during epithelial sheet migration, and we identified a switch-like residue on vinculin that regulates its conformation and loading at the AJs during CCM. In vinculin KO-rescue, this switch jointly controlled the speed and coupling length-scale of CCM, which suggested changes in adhesion-based friction. To test this, we developed molecularly detailed friction clutch models of the FA and AJ. They show that open, loaded vinculin increases friction in adhesive structures, with larger affects observed in AJs. Thus, this work elucidates how load-bearing linker proteins can be regulated to alter mechanical properties of cells and enable rapid tuning of mechanical coupling in CCM.

cell biology↗

bioRxiv2022

Loss of mechanical homeostasis drives epithelial acinar eversion

Epithelial cells lining a gland and cells grown in a soft extracellular matrix polarize with apical proteins exposed to the lumen and basal proteins in contact with the extracellular matrix. Alterations to polarity, including an apical-out polarity, occur in human cancers. While some aberrant polarity states may result from altered protein trafficking, recent observations of an extraordinary tissue-level inside-out unfolding suggest an alternate pathway for altered polarity. Because mechanical alterations are common in human cancer including an upregulation of RhoA mediated actomyosin tension in acinar epithelia, we explored whether perturbing mechanical homeostasis could cause apical-out eversion. Acinar eversion was robustly induced by direct activation of RhoA in normal and tumor epithelial acini, or indirect activation of RhoA through blockage of {beta}1 integrins, disruption of the LINC complex, oncogenic Ras activation, or Rac1 inhibition. Furthermore, laser ablation of a portion of the untreated acinus was sufficient to induce eversion. Analyses of acini revealed high curvature and low phosphorylated myosin in the apical cell surfaces relative to the basal surfaces. A vertex-based mathematical model which balances tension at cell-cell interfaces revealed a five-fold greater basal cell surface tension relative to the apical cell surface tension. The model suggests that the difference in surface energy between the apical and basal surfaces is the driving force for acinar eversion. Our findings raise the possibility that a loss of mechanical homeostasis may cause apical-out polarity states in human cancers.

biophysics↗

bioRxiv2022

Nuclear lamina strain states revealed by intermolecular force biosensor

Nuclear lamins have been considered to be an important structural element of the nucleus. The nuclear lamina is thought both to shield DNA from excessive mechanical forces and to transmit mechanical forces onto the DNA. However, to date there is not yet a technical approach to directly measure mechanical forces on nuclear lamins at the protein level. To overcome this limitation, we developed a nanobody-based intermolecular tension FRET biosensor capable of measuring the mechanical strain of lamin filaments. Using this sensor, we were able to show that the nuclear lamina is subjected to significant force. These forces are dependent on nuclear volume, actomyosin contractility, functional LINC complex, chromatin condensation state, cell cycle, and EMT. Interestingly, large forces were also present on nucleoplasmic lamins, indicating that these lamins may also have an important mechanical role in the nucleus. Overall, we demonstrate that nanobody-based approach allows construction of novel force biosensors for mechanobiology studies.

biophysics↗