Biology subjects

Mattheyses, A. L.

Publications and source records attributed to Mattheyses, A. L..

9 recordsLinked to original sources

bioRxiv2026

The Desmoplakin Hinge Domain Confers a Reversible Conformational Change in Response to Acute External Force

Desmosomes provide mechanical integrity to tissues that experience strain, yet how mechanical force is sensed and distributed within the desmosomal plaque remains poorly understood. Here we identify the hinge within the desmoplakin (DP) head domain is required for repositioning the DP tail in response to acute uniaxial mechanical stretch. This repositioning occurs within 30 seconds of applied stretch and reverses with release, indicating a dynamic reversible switch rather than a stable structural transition. We show this hinge-dependent repositioning correlates with the propagation of mechanical force to the desmosomal cadherins, consistent with the hinge's role in buffering tension at the cadherin interface during mechanical loading. Deletion or shortening of the hinge abolishes the stretch-induced response and compromises desmosome mechanical integrity. The repositioning of the DP tail in the calcium-dependent to hyper-adhesive transition was not impacted by alterations to the hinge, demonstrating that DP repositioning due to acute force or adhesive state is mechanistically distinct. Together, these findings define a reversible, hinge-dependent mechanotransduction pathway through which DP senses and relays mechanical force within the desmosome. This mechanism could act as a mechanical buffer by reducing the impulse of forces on the cadherins, and play a central role in mechanical resilience.

cell biology↗

bioRxiv2026

N-cadherin orientational order decreases with mechanical load at cardiomyocyte adherens junctions

Adherens junctions physically connect neighboring cells and are built around classical cadherins, homophilic transmembrane proteins that link to the actin cytoskeleton. Classical cadherins can organize into ordered arrays in vitro, but whether they do so in cells remains to be established. Here, we use fluorescence polarization microscopy to show that the classical cadherin N-cadherin is orientationally ordered at cardiomyocyte cell-cell junctions. Whereas the desmosomal cadherin desmoglein 2 was similarly ordered across junction types, N-cadherin order was spatially heterogeneous. Order was lowest where organized myofibrils terminate at high-load, vinculin-enriched axial junctions and highest at low-load, vinculin-poor lateral junctions. This inverse relationship between order and mechanical load suggests that robust cadherin-mediated adhesion does not require ectodomain order. Our findings provide evidence that a classical cadherin is orientationally ordered in cells and show that mechanically active adhesions adopt distinct organizational strategies according to local mechanical demands. Summary StatementAt cardiomyocyte junctions, N-cadherin is ordered where mechanical load is low but disordered where load is high, suggesting that cadherin organization adapts to local force conditions.

cell biology↗

bioRxiv2025

Super-Resolution Imaging Reveals Stretch-Induced Architectural Rearrangement of Desmoplakin in Desmosomes

Desmosomes (DSMs) are intercellular junctions essential for providing mechanical resilience to tissues, particularly the epidermis. Desmoplakin (DP) is a key DSM protein which anchors plaque proteins to keratins, thereby ensuring tissue integrity under mechanical stress. Clinically, DP mutations impair keratinocyte adhesion and structural integrity, leading to skin fragility disorders. However, how mechanical forces influence DSM architecture is poorly understood. We hypothesized that physiological stretch could alter DP architecture in DSMs. To test this, we subjected normal human epidermal keratinocytes (NHEKs) and DP-knockout human keratinocytes expressing either DPI-mEGFP, DP1a-mEGFP, or DP2-mEGFP to mechanical stretch using the Flexcell system (13% uniaxial strain for 30 minutes). Direct stochastic optical reconstruction microscopy (dSTORM) was used to visualize DP architecture with 20 nm resolution. We found mechanical stretch significantly increased the distance between DP cytoplasmic tails compared to static controls across all cell lines. In contrast, there was no significant change in the N-terminal head domain under stretch, highlighting the tail domain as the primary site of mechanical adaptation. This work enhances our understanding of how DSMs and DP isoforms respond to biomechanical forces, revealing that the C-term of DP undergoes a strain-induced conformational shift, reorganizing the DSM architecture in response to physiological stress. Ultimately, elucidating the spatial and biomechanical behavior of DP will deepen our understanding of its contribution to dermatological health and disease.

cell biology↗

bioRxiv2025

The role of actin dynamics in vesicle formation during clathrin mediated endocytosis

Clathrin-mediated endocytosis (CME) is an important internalization route for macromolecules, lipids, and membrane receptors in eukaryotic cells. During CME, the plasma membrane invaginates and pinches off forming a clathrin coated vesicle. We previously identified heterogeneity in this process with clathrin coated vesicles forming though multiple routes including simultaneous clathrin accumulation and membrane invagination (constant curvature; CCM) as well as membrane bending after accumulation of flat clathrin (flat to curved; FTC). The architectural dynamics of vesicle formation could be influenced by osmotic or confining pressure, membrane stiffness, fluid force, or cytoskeletal arrangement. Whether these biophysical factors regulate the heterogeneity of vesicle formation dynamics is not well understood. To address this, we investigated the interconnected roles of actin and membrane tension in CME using simultaneous two-wavelength axial ratiometry (STAR) microscopy with nanometer-scale axial resolution. First, we treated Cos-7 cells with latrunculin A (LatA) to inhibit actin polymerization and found the total number of clathrin coated vesicles increased significantly, short-lifetime curved events especially. The proportion of vesicles formed following the FTC model was reduced, the membrane curved sooner after clathrin recruitment, and vesicles were less stable in the x-y plane compared to control. Next, we disrupted actin branching by inhibiting Arp2/3 with CK-869. We found an increased delay between membrane invagination and clathrin recruitment, reduced number of curved events, increased vesicle stability and an increase in the FTC model compared to control. As loss of actin filaments also reduces membrane tension, we treated Cos7 with high osmolality to decrease membrane tension and observed similar result with LatA treated group except vesicle stability stayed unchanged. This suggested the increased curved events in LatA groups may result from reduced membrane tension. We conclude actin polymerization promotes FTC while actin branching promotes vesicle formation though the CCM.

cell biology↗

bioRxiv2025

The Desmoglein 2 interactome in primary neonatal cardiomyocytes

Mechanical coupling and chemical communication between cardiomyocytes are facilitated through a specialized adhesive structure known as the intercalated disc (ICD). The ICD is essential for heart organization and contraction. Yet, the network of adhesion, adaptor, and signaling proteins that form the ICD remains poorly defined. Here, we combined proximity labeling and quantitative mass spectrometry to identify proteins associated with the desmosomal cadherin, Desmoglein 2 (DSG2), in cultured neonatal cardiomyocytes. We identified over 300 proteins in the DSG2 interactome; half of which are shared with the N-cadherin (CDH2) interactome in cardiomyocytes. Proteins unique to DSG2 include the gap junction protein connexin 43 and the plakin family of cytolinker proteins. Comparison of the cardiomyocyte DSG2 interactome with the interactomes of desmosomal proteins from epithelia revealed only a small number of shared proteins. In cardiomyocytes, plakoglobin (JUP) and plakophilin 2 (PKP2) were the most abundant shared proteins between the DSG2 and CDH2 interactomes. PKP2 is a dynamic protein whose membrane recruitment in cardiomyocytes is tension-dependent. Our analysis of the DSG2 interactome provides a critical new dimension to the proteomic atlas of the essential molecular complexes required for cardiomyocyte adhesion.

cell biology↗

bioRxiv2025

Desmoplakin tail domain position in the desmosomal plaque is isoform dependent

Desmoplakin (DP) is the anchoring subunit of desmosomes, macromolecular junctions that provide mechanical integrity to the skin and heart. DP has three isoforms, DPI, DPIa, and DPII that arise from alternative splicing. The isoforms are structurally identical excluding the length of their central rod domain. As desmosomes are macromolecular complexes, the precise arrangement of their component proteins, or architecture, is essential to maintain physiological function. Alterations of the tissue-specific expression of DP isoforms underlies rare human diseases impacting the skin and heart. Overall DP is oriented with its head domain closest to the plasma membrane and tail domain extending into the cytosol. However, the differences in the architecture of the DP isoforms within the desmosomal plaque remains unknown. Here, we sought to define the architectural arrangement of each DP isoform. To address this, we utilized direct stochastic optical reconstruction microscopy (dSTORM) and analysis of DP KO HaCaT cells stably expressing DPI, DPIa, or DPII with a C-terminal mEGFP tag. Our results show the DP head domain position in the desmosomal plaque is isoform independent and the DP tail domain position correlates with rod length. The tail domain of DPI, the isoform with the longest rod, is furthest from the plasma membrane and that of DPII, the isoform with the shortest rod, is closest. We propose a variable tail location model to describe the architectural arrangement of each isoform. In this model, the DP isoforms are arranged with their rod domains parallel at an angle between 21{degrees} to 25{degrees} from the plasma membrane. These results provide valuable insight into the role of DP isoforms in desmosomal architecture and function.

cell biology↗

bioRxiv2024

Fluidic shear stress alters clathrin dynamics and vesicle formation in endothelial cells

Endothelial cells (ECs) experience a variety of highly dynamic mechanical stresses. Among others, cyclic stretch and increased plasma membrane tension inhibit clathrin-mediated endocytosis (CME) in non-ECs cells. How ECs overcome such unfavorable, from biophysical perspective, conditions and maintain CME remains elusive. Previously, we have used simultaneous two-wavelength axial ratiometry (STAR) microscopy to show that endocytic dynamics are similar between statically cultured human umbilical vein endothelial cells (HUVECs) and fibroblast-like Cos-7 cells. Here we asked whether biophysical stresses generated by blood flow could favor one mechanism of clathrin-coated vesicle formation to overcome environment present in vasculature. We used our data processing platform - DrSTAR - to examine if clathrin dynamics are altered in HUVECs grown under fluidic sheer stress (FSS). Surprisingly, we found that FSS led to an increase in clathrin dynamics. In HUVECs grown under FSS we observed a 2.3-fold increase in clathrin-coated vesicle formation and a 1.9-fold increase in non-productive flat clathrin lattices compared to cells grown in static conditions. The curvature-positive events had significantly delayed curvature initiation in flow-stimulated cells, highlighting a shift toward flat-to-curved clathrin transitions in vesicle formation. Overall, our findings indicate that clathrin dynamics and CCV formation can be modulated by the local physiological environment and represents an important regulatory mechanism. SignificanceTargeted nanomedicine holds a great promise of improved drug bioavailability and specificity. While some cargoes must cross the blood-tissue barrier, the understanding of endocytic pathways in the context of vasculature is limited, which is an obstacle to targeted nanomedicine delivery. In this pilot study we show that the physiological local vascular environment must be considered in the context of internalization of growth factors, membrane proteins, therapeutics, or pathogens. Studies in non-ECs or ECs not cultured under fluidic shear stress do not properly recapitulate clathrin dynamics and will lead to incorrect conclusions.

cell biology↗

bioRxiv2023

Sialylation of EGFR by ST6GAL1 induces receptor activation and modulates trafficking dynamics

Aberrant glycosylation is a hallmark of a cancer cell. One prevalent alteration is an enrichment in 2,6-linked sialylation of N-glycosylated proteins, a modification directed by the ST6GAL1 sialyltransferase. ST6GAL1 is upregulated in many malignancies including ovarian cancer. Prior studies have shown that the addition of 2,6 sialic acid to the Epidermal Growth Factor Receptor (EGFR) activates this receptor, although the mechanism was largely unknown. To investigate the role of ST6GAL1 in EGFR activation, ST6GAL1 was overexpressed in the OV4 ovarian cancer line, which lacks endogenous ST6GAL1, or knocked down in the OVCAR-3 and OVCAR-5 ovarian cancer lines, which have robust ST6GAL1 expression. Cells with high expression of ST6GAL1 displayed increased activation of EGFR and its downstream signaling targets, AKT and NF{kappa}B. Using biochemical and microscopy approaches, including Total Internal Reflection Fluorescence (TIRF) microscopy, we determined that the 2,6 sialylation of EGFR promoted its dimerization and higher order oligomerization. Additionally, ST6GAL1 activity was found to modulate EGFR trafficking dynamics following EGF-induced receptor activation. Specifically, EGFR sialylation enhanced receptor recycling to the cell surface following activation while simultaneously inhibiting lysosomal degradation. 3D widefield deconvolution microscopy confirmed that in cells with high ST6GAL1 expression, EGFR exhibited greater co-localization with Rab11 recycling endosomes and reduced co-localization with LAMP1-positive lysosomes. Collectively, our findings highlight a novel mechanism by which 2,6 sialylation promotes EGFR signaling by facilitating receptor oligomerization and recycling.

cell biology↗

bioRxiv2018

The Desmosome is a Mesoscale Lipid Raft-Like Membrane Domain

Desmogleins are cadherin family adhesion molecules essential for epidermal integrity. Previous studies have shown that desmogleins associate with lipid rafts, but the significance of this association was not clear. Here, we report that the desmoglein transmembrane domain (TMD) is the primary determinant of raft association. Further, we identify a novel mutation in the DSG1 TMD (G562R) that causes severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome. Molecular modeling predicts that this G to R mutation shortens the DSG1 TMD, and experiments directly demonstrate that this mutation compromises both lipid raft association and desmosome incorporation. Finally, cryo-electron tomography (cryo-ET) indicates that the lipid bilayer within the desmosome is ~10% thicker than adjacent regions of the plasma membrane. These findings suggest that differences in bilayer thickness influence the organization of adhesion molecules within the epithelial plasma membrane, with cadherin TMDs recruited to the desmosome via establishment of a specialized mesoscale lipid raft-like membrane domain.

cell biology↗