VE-cadherin and desmoplakin are assembled into dermal microvascular endothelial intercellular junctions: A pivotal role for plakoglobin in the recruitment of desmoplakin to intercellular junctions

Abstract

Vascular endothelial cells assemble adhesive intercellular junctions comprising a unique cadherin, VE-cadherin, which is coupled to the actin cytoskeleton through cytoplasmic interactions with plakoglobin, beta-catenin and alpha -catenin. However, the potential linkage between VE-cadherin and the vimentin intermediate filament cytoskeleton is not well characterized. Recent evidence indicates that lymphatic and vascular endothelial cells express desmoplakin, a cytoplasmic desmosomal protein that attaches intermediate filaments to the plasma membrane in epithelial cells. In the present study, desmoplakin was localized to intercellular junctions in human dermal microvascular endothelial cells. To determine if VE-cadherin could associate with desmoplakin, VE-cadherin, plakoglobin, and a desmoplakin amino-terminal polypeptide (DP-NTP) were co-expressed in L-cell fibroblasts. In the presence of VE-cadherin, both plakoglobin and DP-NTP were recruited to cell-cell borders. Interestingly, beta-catenin could not substitute for plakoglobin in the recruitment of DP-NTP to cell borders, and DP-NTP bound to plakoglobin but not beta-catenin in the yeast two-hybrid system. In addition, DP-NTP colocalized at cell-cell borders with alpha-catenin in the L-cell lines, and endogenous desmoplakin and alpha-catenin colocalized in cultured dermal microvascular endothelial cells. This is in striking contrast to epithelial cells, where desmoplakin and alpha -+catenin are restricted to desmosomes and adherens junctions, respectively. These results suggest that endothelial cells assemble unique junctional complexes that couple VE-cadherin to both the actin and intermediate filament cytoskeleton.

Impact of Vimentin on Regulation of Cell Signaling and Matrix Remodeling

“…In the collective cell migration that is seen in certain wound healing sites, reduced vimentin expression (along with nestin) diminishes the abundance of actin stress fibers parallel to the wound and promotes stress fiber formation perpendicular to the wound; these changes impact retrograde actin flow and the ability of cells to translocate ( De Pascalis et al, 2018 ). In epithelial cells that express vimentin, VIFs are a component of junctional complexes that couple VE-cadherin to actin filaments, the IF cytoskeleton ( Kowalczyk et al, 1998 ) and to FAs ( Tsuruta and Jones, 2003 ; Kreis et al, 2005 ; Terriac et al, 2017 ), where VIFs bind to integrin-enriched matrix adhesions ( Ivaska et al, 2007 ).…”

Cell−Cell Junctions of Dermal Microvascular Endothelial Cells Contain Tight and Adherens Junction Proteins in Spatial Proximity

“…To address the question of whether the HMEC-1 junctions containing tight and adherens junction markers in spatial proximity are linked to the cytoskeleton, the different immunoprecipitations were also probed for the presence of actin and tubulin. Since an actin association of microvascular VE-cadherin has already been reported (26), only examples for anti-ZO-1 and anti-occludin immunoprecipitations revealing a coprecipitation of actin are shown (Figure 6). Likewise, ZO-1 and occluding antibodies coprecipitate actin following in vivo cross-linking of MDCK monocytes (Figure 5A), whereas tubulin is found neither in the HMEC-1 nor in the MDCK immunoprecipitations (not shown).…”

Glycomimetic affinity-enrichment proteomics identifies partners for a clinically-utilized iminosugar

“…32 Junction plakoglobin (JUP, desmoplakin 3) is a junctional plaque protein involved in the formation of desmosomes and tight junctions. 34 Mice with impaired ability to form tight junctions (e.g. Epas1 -/-) display higher testicular oxygen levels, which interferes with spermatogenesis.…”