Oxman Elias, Li Huili, Wang Hong-Yan, Zohn Irene E
Center for Genetic Medicine Research, Children's Research Institute, Children's National Research and Innovation Campus, Children's National Hospital, Washington, DC, 20012, USA.
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA.
Hum Genet. 2024 Mar;143(3):263-277. doi: 10.1007/s00439-024-02647-4. Epub 2024 Mar 7.
Neural tube defects (NTDs) are severe malformations of the central nervous system that arise from failure of neural tube closure. HECTD1 is an E3 ubiquitin ligase required for cranial neural tube closure in mouse models. NTDs in the Hectd1 mutant mouse model are due to the failure of cranial mesenchyme morphogenesis during neural fold elevation. Our earlier research has linked increased extracellular heat shock protein 90 (eHSP90) secretion to aberrant cranial mesenchyme morphogenesis in the Hectd1 model. Furthermore, overexpression of HECTD1 suppresses stress-induced eHSP90 secretion in cell lines. In this study, we report the identification of five rare HECTD1 missense sequence variants in NTD cases. The variants were found through targeted next-generation sequencing in a Chinese cohort of 352 NTD cases and 224 ethnically matched controls. We present data showing that HECTD1 is a highly conserved gene, extremely intolerant to loss-of-function mutations and missense changes. To evaluate the functional consequences of NTD-associated missense variants, functional assays in HEK293T cells were performed to examine protein expression and the ability of HECTD1 sequence variants to suppress eHSP90 secretion. One NTD-associated variant (A1084T) had significantly reduced expression in HEK293T cells. All five NTD-associated variants (p.M392V, p.T801I, p.I906V, p.A1084T, and p.P1835L) reduced regulation of eHSP90 secretion by HECTD1, while a putative benign variant (p.P2474L) did not. These findings are the first association of HECTD1 sequence variation with NTDs in humans.
神经管缺陷（NTDs）是中枢神经系统的严重畸形，由神经管闭合失败引起。在小鼠模型中，HECTD1是颅神经管闭合所需的一种E3泛素连接酶。Hectd1突变小鼠模型中的NTDs是由于神经褶抬高过程中颅间充质形态发生失败所致。我们早期的研究将细胞外热休克蛋白90（eHSP90）分泌增加与Hectd1模型中异常的颅间充质形态发生联系起来。此外，HECTD1的过表达抑制细胞系中应激诱导的eHSP90分泌。在本研究中，我们报告了在NTD病例中鉴定出5种罕见的HECTD1错义序列变异。这些变异是通过靶向二代测序在一个由352例NTD病例和224例种族匹配对照组成的中国队列中发现的。我们提供的数据表明，HECTD1是一个高度保守的基因，对功能丧失突变和错义变化极度不耐受。为了评估与NTD相关的错义变异的功能后果，在HEK293T细胞中进行了功能测定，以检测蛋白质表达以及HECTD1序列变异抑制eHSP90分泌的能力。一种与NTD相关的变异（A1084T）在HEK293T细胞中的表达显著降低。所有5种与NTD相关变异（p.M392V、p.T801I、p.I906V、p.A1084T和p.P1835L）均降低了HECTD1对eHSP90分泌的调节作用，而一种假定的良性变异（p.P2474L）则没有。这些发现首次将HECTD1序列变异与人类NTDs联系起来。
