Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Developmental Disability Center, 713-8 Kamiya, Kasugai, 480-0392, Japan.
Department of Neurochemistry, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Sci Rep. 2021 Nov 19;11(1):22568. doi: 10.1038/s41598-021-02123-3.
WDR45 plays an essential role in the early stage of autophagy. De novo heterozygous mutations in WDR45 have been known to cause β-propeller protein-associated neurodegeneration (BPAN), a subtype of neurodegeneration with brain iron accumulation (NBIA). Although BPAN patients display global developmental delay with intellectual disability, the neurodevelopmental pathophysiology of BPAN remains largely unknown. In the present study, we analyzed the physiological role of Wdr45 and pathophysiological significance of the gene abnormality during mouse brain development. Morphological and biochemical analyses revealed that Wdr45 is expressed in a developmental stage-dependent manner in mouse brain. Wdr45 was also found to be located in excitatory synapses by biochemical fractionation. Since WDR45 mutations are thought to cause protein degradation, we conducted acute knockdown experiments by in utero electroporation in mice to recapitulate the pathophysiological conditions of BPAN. Knockdown of Wdr45 caused abnormal dendritic development and synaptogenesis during corticogenesis, both of which were significantly rescued by co-expression with RNAi-resistant version of Wdr45. In addition, terminal arbors of callosal axons were less developed in Wdr45-deficient cortical neurons of adult mouse when compared to control cells. These results strongly suggest a pathophysiological significance of WDR45 gene abnormalities in neurodevelopmental aspects of BPAN.
WDR45 在自噬的早期阶段发挥着重要作用。已知 WDR45 的新生杂合突变会导致β-三叶螺旋蛋白相关神经退行性变（BPAN），这是一种具有脑铁积累的神经退行性变（NBIA）的亚型。尽管 BPAN 患者表现出全面的发育迟缓伴智力障碍，但 BPAN 的神经发育病理生理学仍知之甚少。在本研究中，我们分析了 Wdr45 在小鼠大脑发育过程中的生理作用和基因异常的病理生理意义。形态学和生化分析表明，Wdr45 在小鼠大脑中以发育阶段依赖性的方式表达。通过生化分级分离还发现 Wdr45 位于兴奋性突触中。由于认为 WDR45 突变会导致蛋白质降解，因此我们通过在体电穿孔在小鼠中进行急性敲低实验，以重现 BPAN 的病理生理条件。Wdr45 的敲低导致皮质发生过程中树突发育和突触发生异常，用 Wdr45 的 RNAi 抗性版本共表达可显著挽救这些异常。此外，与对照细胞相比，Wdr45 缺陷型成年小鼠皮质神经元中的胼胝体轴突终末树突发育不良。这些结果强烈表明 WDR45 基因异常在 BPAN 的神经发育方面具有病理生理意义。
