The X-linked intellectual disability gene product and E3 ubiquitin ligase KLHL15 degrades doublecortin proteins to constrain neuronal dendritogenesis.
The X-linked intellectual disability gene product and E3 ubiquitin ligase KLHL15 degrades doublecortin proteins to constrain neuronal dendritogenesis.
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DOI：
10.1074/jbc.ra120.016210
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Strack S
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作者：
Song J;Merrill RA;Usachev AY;Strack S
适当的大脑发育和功能需要精细控制的蛋白质周转机制，而蛋白质稳态相关基因的破坏是神经发育障碍的常见原因。Kelch-like 15（KLHL 15）是一种含有cullin 3的E3泛素连接酶的底物适配器，KLHL 15基因突变最近被描述为严重X连锁智力残疾的原因。在这里，我们使用生物信息学的方法来确定一个家庭的神经元微管相关蛋白KLHL 15基板，这本身是至关重要的早期大脑发育。我们生物化学验证doublecortin（DCX），也是一种X-连锁疾病蛋白，doublecortin样激酶1和2作为真正的KLHL 15相互作用，并映射KLHL 15相互作用区域的串联DCX结构域。与两个先前确定的KLHL 15底物共享，在第二个DCX结构域的C-末端边缘的FRY三肽对于KLHL 15介导的DCX和双皮质素样激酶1和2的泛素化以及随后的蛋白酶体降解是必需的。相反，沉默内源性KLHL 15显着稳定这些含DCX结构域的蛋白质，并延长其半衰期。在功能上，在WT DCX存在下KLHL 15的过表达降低了培养的海马神经元的树突复杂性，而表达FRY突变DCX的神经元对KLHL 15具有抗性。总的来说，我们的研究结果强调了E3泛素连接酶接头KLHL 15在神经元微管相关蛋白的蛋白质稳定中的重要性，并确定了对哺乳动物神经系统发育重要的调控网络。
Proper brain development and function requires finely controlled mechanisms for protein turnover, and disruption of genes involved in proteostasis is a common cause of neurodevelopmental disorders. Kelch-like 15 (KLHL15) is a substrate adaptor for cullin3-containing E3 ubiquitin ligases, and KLHL15 gene mutations were recently described as a cause of severe X-linked intellectual disability. Here, we used a bioinformatics approach to identify a family of neuronal microtubule-associated proteins as KLHL15 substrates, which are themselves critical for early brain development. We biochemically validated doublecortin (DCX), also an X-linked disease protein, and doublecortin-like kinase 1 and 2 as bona fide KLHL15 interactors and mapped KLHL15 interaction regions to their tandem DCX domains. Shared with two previously identified KLHL15 substrates, a FRY tripeptide at the C-terminal edge of the second DCX domain is necessary for KLHL15-mediated ubiquitination of DCX and doublecortin-like kinase 1 and 2 and subsequent proteasomal degradation. Conversely, silencing endogenous KLHL15 markedly stabilizes these DCX domain-containing proteins and prolongs their half-life. Functionally, overexpression of KLHL15 in the presence of WT DCX reduces dendritic complexity of cultured hippocampal neurons, whereas neurons expressing FRY-mutant DCX are resistant to KLHL15. Collectively, our findings highlight the critical importance of the E3 ubiquitin ligase adaptor KLHL15 in proteostasis of neuronal microtubule-associated proteins and identify a regulatory network important for development of the mammalian nervous system.