Desmoplakin assembly dynamics in four dimensions

Abstract

The intermediate filament (IF)–binding protein desmoplakin (DP) is essential for desmosome function and tissue integrity, but its role in junction assembly is poorly understood. Using time-lapse imaging, we show that cell–cell contact triggers three temporally overlapping phases of DP-GFP dynamics: (1) the de novo appearance of punctate fluorescence at new contact zones after as little as 3 min; (2) the coalescence of DP and the armadillo protein plakophilin 2 into discrete cytoplasmic particles after as little as 15 min; and (3) the cytochalasin-sensitive translocation of cytoplasmic particles to maturing borders, with kinetics ranging from 0.002 to 0.04 μm/s. DP mutants that abrogate or enhance association with IFs exhibit delayed incorporation into junctions, altering particle trajectory or increasing particle pause times, respectively. Our data are consistent with the idea that DP assembles into nascent junctions from both diffusible and particulate pools in a temporally overlapping series of events triggered by cell–cell contact and regulated by actin and DP–IF interactions.

Plakoglobin-dependent regulation of keratinocyte APOPTOSIS by Rnd3

“…Cytoplasmic desmoplakin I/II staining was also observed in both cell lines but was increased in Rnd3-depleted cells. This cytoplasmic desmoplakin I/II staining is indicative of the formation of nonmembrane bound desmoplakin I/II-containing particles that are known to translocate to sites of cell-cell adhesion before being incorporated into maturing desmosomes (Godsel et al, 2005). Consistent with our observation that long-term treatment of keratinocytes with Y-27632 results in decreased Rnd3 expression (Fig.…”

“…Whilst desmosomes are well-studied structures, relatively little is known about how their assembly is regulated. There is evidence that the translocation of cytoplasmic non-membrane bound desmoplakincontaining particles to desmosomes is an actin-dependent process (Godsel et al, 2005). One possible mechanism whereby Rnd3 might regulate desmosomes is through RhoA-dependent regulation of the actin cytoskeleton and activation of RhoA has been shown to accelerate the initial translocation of desmoplakin I/II to desmosomes, although sustained RhoA activity compromised desmosomal maturation (Godsel et al, 2010).…”

Carboxyl Terminus of Plakophilin-1 Recruits It to Plasma Membrane, whereas Amino Terminus Recruits Desmoplakin and Promotes Desmosome Assembly

“…However, the mechanisms that regulate the assembly of this junction are poorly understood. The plakophilin family of desmosomal plaque proteins has recently been shown to play important roles in assembly and maintenance of the desmosome (15,18,39). In this study, we sought to examine the role of plakophilin-1 in desmosome assembly.…”

Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets

“…The recruitment of desmoplakin to cell borders occurs in three phases and both microfilaments and IFs are involved in targeting of cytoplasmic particles containing desmoplakin and plakophilin-2 to maturing borders. Specific DP mutants that either increase or abrogate the association of DP with keratins delayed incorporation of DP particles into junctions (Godsel et al, 2005). Furthermore, in A431 epithelial cells, an inducible expression of desmoplakin N-terminal domain severs the connection of IFs to desmosomes and results in dissociation of epithelial sheets subjected to mechanical stress (Huen et al, 2002).…”