Cleavage and Shedding of E-cadherin after Induction of Apoptosis

Abstract

Apoptotic cell death induces dramatic molecular changes in cells, becoming apparent on the structural level as membrane blebbing, condensation of the cytoplasm and nucleus, and loss of cell-cell contacts. The activation of caspases is one of the fundamental steps during programmed cell death. Here we report a detailed analysis of the fate of the Ca 2؉ -dependent cell adhesion molecule E-cadherin in apoptotic epithelial cells and show that during apoptosis fragments of Ecadherin with apparent molecular masses of 24, 29, and 84 kDa are generated by two distinct proteolytic activities. In addition to a caspase-3-mediated cleavage releasing the cytoplasmic domain of E-cadherin, a metalloproteinase sheds the extracellular domain from the cell surface during apoptosis. Immunofluorescence analysis confirmed that concomitant with the disappearance of E-cadherin staining at the cell surface, the E-cadherin cytoplasmic domain accumulates in the cytosol. In the presence of inhibitors of caspase-3 and/or metalloproteinases, cleavage of E-cadherin was almost completely blocked. The simultaneous cleavage of the intracellular and extracellular domains of E-cadherin may provide a highly efficient mechanism to disrupt cadherin-mediated cell-cell contacts in apoptotic cells, a prerequisite for cell rounding and exit from the epithelium.The crucial role of apoptosis during development and for tissue homeostasis of multicellular organisms is well established (1). Malfunctions of the death program and its control mechanisms often result in prenatal death during development and contribute to immune and neuronal diseases or cancer in the adult organism (2-4). The central mechanism of this cell death machinery is a proteolytic cascade mediated by the caspase family of cysteine proteinases (5, 6), which specifically cleave their substrates after aspartate residues. Caspases are synthesized as inactive proenzymes. After initiation of the apoptotic program these proenzymes are processed by two proteolytic events, generating a large subunit and a small subunit that form a heterodimer. The association of two heterodimers results in the formation of the active enzyme containing two catalytic sites (7,8). Depending on their position in the proteolytic cascade, caspase family members are divided into upstream initiator caspases and downstream effector caspases.The activation of this caspase cascade leads to the specific cleavage of substrate proteins and finally results in the morphological changes becoming apparent in apoptotic cells. The identification of an increasing number of caspase substrates has revealed different classes of cellular proteins that are cleaved during the effector phase of apoptosis. A set of substrate proteins is represented by proteins that protect living cells from apoptosis, e.g. ICAD/DFF45 (9, 10) and Bcl-2 (11, 12). Nuclear envelope proteins (e.g. lamin A and B (13-15) and LAP2 and Nup153 (16) (27)) and DNA repair (DNA-PK CS ) and of the splicing machinery (U1-70K) is assumed to support the disruption of structural...

Cleavage of MAGI-1, a tight junction PDZ protein, by caspases is an important step for cell-cell detachment in apoptosis

“…MAGI-1 itself has been shown to localise to tight and adherens junctions [28], where it interacts with the β-catenin-E-cadherin complex [26], with the synaptopodin and alphaactinin-4 actin binding proteins [28], and with the JAM4 cell adhesion protein [29]. β-catenin was the first protein involved in regulating cell contact that was shown to be cleaved by caspases during apoptosis [6] and E-cadherin is also known to be cleaved by caspases during apoptosis [12]. The data presented here demonstrates that MAGI-1 cleavage occurs at a similar time as β-catenin and E-cadherin cleavage during apoptosis (Figs.…”

“…Similarly, caspase activity (DEVD-ase activity) was largely increased (~ 10-fold after 16 h; data not shown). Cleavage of E-cadherin, which is an important player in establishing and maintaining cell-cell contacts (for review [37]), and which is a known caspase target [12], was also followed during UV irradiation-induced apoptosis. The first cleavage products were also observed 4 h post induction of apoptosis ( Fig.…”

“…Several of them have already been shown to be cleaved by caspases, among them: β-catenin, plakoglobin [6][7][8], α-fodrin [9], actin [10], gelsolin [11], E-cadherin [12], focal adhesion kinase [13], desmosomal plaque proteins [14], the tight junction proteins ZO-1, ZO-2 and occludin, [15] and also hDLG, a constituent of adherens junctions in epithelial and endothelial cells [16].…”

The specific fates of tight junction proteins in apoptotic epithelial cells

“…During recent years a number of caspase substrates have been identified. Among these, cytoskeletal proteins and regulators (Brancolini et al, 1995;Jaenicke et al, 1998) and components of cell-cell adhesion complexes such as cadherins (Herren et al, 1998;Schmeiser and Grand, 1999;Steinhusen et al, 2001) and catenins (Brancolini et al, 1998;Schmeiser et al, 1998;Steinhusen et al, 2000) contribute to the disruption of the cytoarchitecture. Furthermore, we recently showed that desmosomal proteins are targeted by caspases .…”

E-cadherin in canine mast cell tumors: Decreased expression and altered subcellular localization in Grade 3 tumors

“…The mechanisms that lead to the loss of E-cadherin expression in the cell membrane are still unclear. The disruption of cell-to-cell adhesion might be mediated by several factors, such as digestion by proteases (Lochter et al, 1997;Steinhusen et al, 2001), transcriptional repression (Batlle et al, 2000;Cano et al, 2000;Yap et al, 2007), endocytosis (Fujita et al, 2002), mutations in the E-cadherin gene (Oda et al, 1994;Saito et al, 2001) and methylation of E-cadherin promoter (Yoshiura et al, 1995).…”