Cleavage of Armadillo/beta-catenin by the caspase DrICE in Drosophila apoptotic epithelial cells.
Cleavage of Armadillo/beta-catenin by the caspase DrICE in Drosophila apoptotic epithelial cells.
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DOI：
10.1186/1471-213x-9-15
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发表时间：
2009-02-20
影响因子：
--
通讯作者：
Müller HA
中科院分区：
文献类型：
--
作者：
Kessler T;Müller HA
在凋亡过程中，细胞通过半胱天冬酶协同切割细胞蛋白质而发生深刻的重组。在上皮组织中，凋亡细胞失去其顶端/基底极性并从上皮中挤出。我们使用果蝇胚胎作为一个系统来研究细胞凋亡过程中粘附小带的成分的调节。由于Armadillo/β-连环蛋白（Arm）是钙粘蛋白介导的粘附的主要调节因子，因此我们分析了Arm蛋白水解在细胞凋亡中的机制。我们定义了早期和晚期凋亡阶段，发现凋亡早期Dα-catenin保持相对稳定，而Arm和DE-钙粘蛋白水平强烈降低。臂被切割的半胱天冬酶在胚胎提取物中，我们提供的证据表明，半胱天冬酶-3同源物drICE切割臂在体外和体内。通过drICE切割产生稳定的蛋白质片段，其在细胞凋亡早期保持与质膜相关。为了进一步理解胱天蛋白酶介导的Arm切割的作用，我们检查了潜在的胱天蛋白酶切割位点，发现drICE在蛋白质N-末端结构域中的独特DQVD基序处切割Arm。Arm中的drICE切割位点的突变导致蛋白质在体外和体内不被切割。此外，我们提供的证据表明，臂的切割在细胞凋亡期间从质膜去除DE-钙粘蛋白中起作用。本研究确定了果蝇凋亡细胞中Arm的半胱天冬酶切割的特异性。我们的数据表明，N-末端截断臂的半胱天冬酶是进化保守的，因此可能提供一个主要的机制参与在凋亡过程中的粘附连接的解体。
During apoptosis cells become profoundly restructured through concerted cleavage of cellular proteins by caspases. In epithelial tissues, apoptotic cells loose their apical/basal polarity and are extruded from the epithelium. We used the Drosophila embryo as a system to investigate the regulation of components of the zonula adherens during apoptosis. Since Armadillo/beta-catenin (Arm) is a major regulator of cadherin-mediated adhesion, we analyzed the mechanisms of Arm proteolysis in apoptosis. We define early and late apoptotic stages and find that early in apoptosis Dα-catenin remains relatively stable, while Arm and DE-cadherin protein levels are strongly reduced. Arm is cleaved by caspases in embryo extracts and we provide evidence that the caspase-3 homolog drICE cleaves Arm in vitro and in vivo. Cleavage by drICE creates a stable protein fragment that remains associated with the plasma membrane early in apoptosis. To further understand the role of caspase-mediated cleavage of Arm, we examined potential caspase cleavage sites and found that drICE cleaves Arm at a unique DQVD motif in the N-terminal domain of the protein. Mutation of the drICE cleavage site in Arm results in a protein that is not cleaved in vitro and in vivo. Furthermore we provide evidence that cleavage of Arm plays a role in the removal of DE-cadherin from the plasma membrane during apoptosis. This study defines the specificity of caspase cleavage of Arm in Drosophila apoptotic cells. Our data suggest that N-terminal truncation of Arm by caspases is evolutionarily conserved and thus might provide a principal mechanism involved in the disassembly of adherens junctions during apoptosis.