Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
Neuroscience Graduate Program, Vanderbilt University Nashville, Nashville, Tennessee, USA.
Clin Genet. 2021 Aug;100(2):176-186. doi: 10.1111/cge.13973. Epub 2021 Jun 2.
We report the case of a patient with severe progressive epilepsy and peripheral neuropathy and a novel de novo inactivating variant (p.E79X) in Protein Kinase D1 (PKD1). Using CRISPR/Cas9, we engineered the homologous variant in mice and showed that in the homozygote mouse, it recapitulated the patient peripheral nerve hypermyelination pathology. The lethality of the homozygote mouse prevented us from performing an assessment of locomotor behavior. The mutant heterozygote mouse; however, exhibited a significant increase in kainate-induced seizure activity over wild-type mice, supporting the hypothesis that the PKD1 variant is a candidate for the cause of the patient epilepsy. Because PKD1 was previously identified in a kinomic screen as an interacting partner of the K-Cl cotransporter 3 (KCC3), and since KCC3 is involved in peripheral nerve disease and brain hyperexcitability, one possible mechanism of action of PKD1 in disease is through KCC3. We show that catalytically inactive PKD1 stimulates KCC3 activity, consistent with tonic relief of inhibitory phosphorylation. Our findings implicate a novel role for PKD1 in the human nervous system, and uncover a mechanism that could serve as a potential target to promote nervous system myelination.
我们报告了一例患有严重进行性癫痫和周围神经病的患者，并发现其蛋白激酶 D1（PKD1）中存在一种新的从头失活变异体（p.E79X）。我们使用 CRISPR/Cas9 在小鼠中构建了同源变异体，并表明在纯合子小鼠中，它重现了患者周围神经过度髓鞘化的病理。纯合子小鼠的致死性使我们无法进行运动行为评估。然而，突变杂合子小鼠在红藻氨酸诱导的癫痫发作活动中显著增加，支持了 PKD1 变异体是患者癫痫病因的候选假设。因为 PKD1 先前在激酶组学筛选中被鉴定为 K-Cl 共转运蛋白 3（KCC3）的相互作用伙伴，并且 KCC3 参与周围神经疾病和大脑过度兴奋，PKD1 在疾病中的一种可能作用机制是通过 KCC3。我们表明，催化失活的 PKD1 刺激 KCC3 活性，与抑制性磷酸化的紧张缓解一致。我们的发现暗示 PKD1 在人类神经系统中具有新的作用，并揭示了一种可能作为促进神经系统髓鞘形成的潜在靶标的机制。
