Patched-1 Proapoptotic Activity Is Downregulated by Modification of K1413 by the E3 Ubiquitin-Protein Ligase Itchy Homolog
Patched-1 Proapoptotic Activity Is Downregulated by Modification of K1413 by the E3 Ubiquitin-Protein Ligase Itchy Homolog
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DOI：
10.1128/mcb.00960-14
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发表时间：
2014-10-01
影响因子：
5.3
通讯作者：
Riobo, Natalia A.
中科院分区：
文献类型：
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作者：
Chen, Xiaole L.;Chinchilla, Pilar;Riobo, Natalia A.
Hedgehog（Hh）受体Patched-1（PTCH 1）对抗Gli转录因子的激活并通过Gli非依赖性途径诱导细胞死亡。在这里，我们报告的C-末端结构域（CTD）的PTCH 1相互作用，并在K1413泛素化的E3泛素蛋白连接酶瘙痒同源物（痒），Nedd 4家族成员。瘙痒诱导K1413的泛素化、质膜上PTCH 1水平的降低和降解，从而在不存在Hh配体的情况下激活Gli转录活性。瘙痒的沉默稳定PTCH 1并增加其在质膜上的保留水平。在不存在Hh配体的情况下，Itch是优先的PTCH 1 E3连接酶，因为在其他7个Nedd 4家族成员中，只有含WW结构域的蛋白2（WWP 2）显示出次要的冗余作用。与瘙痒耗竭一样，泛素化位点（K1314 R）的突变导致PTCH 1在质膜上的积累，其半衰期延长，并通过半胱天冬酶-9的超活化增加细胞死亡。值得注意的是，瘙痒是PTCH 1在静息条件下稳定性的主要决定因素，但不是响应Sonic Hedgehog。总之，我们的研究结果表明，瘙痒是一个关键的调节配体独立的Gli激活和非经典的Hh信号的治理基础PTCH 1的内化和降解。
The Hedgehog (Hh) receptor Patched-1 (PTCH1) opposes the activation of Gli transcription factors and induces cell death through a Gli-independent pathway. Here, we report that the C-terminal domain (CTD) of PTCH1 interacts with and is ubiquitylated on K1413 by the E3 ubiquitin-protein ligase Itchy homolog (Itch), a Nedd4 family member. Itch induces the ubiquitylation of K1413, the reduction of PTCH1 levels at the plasma membrane, and degradation, activating Gli transcriptional activity in the absence of Hh ligands. Silencing of Itch stabilizes PTCH1 and increases its level of retention at the plasma membrane. Itch is the preferential PTCH1 E3 ligase in the absence of Hh ligands, since of the other seven Nedd4 family members, only WW domain-containing protein 2 (WWP2) showed a minor redundant role. Like Itch depletion, mutation of the ubiquitylation site (K1314R) resulted in the accumulation of PTCH1 at the plasma membrane, prolongation of its half-life, and increased cell death by hyperactivation of caspase-9. Remarkably, Itch is the main determinant of PTCH1 stability under resting conditions but not in response to Sonic Hedgehog. In conclusion, our findings reveal that Itch is a key regulator of ligand-independent Gli activation and noncanonical Hh signaling by the governance of basal PTCH1 internalization and degradation.