Lou Guiyu, Zhao Yuanyin, Zhao Huiru, Zhang Yuwei, Hao Bingtao, Qin Litao, Liu Hongyan, Liao Shixiu
Henan Provincial People's Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People's Hospital of Zhengzhou University, Zhengzhou, China.
Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Army Medical University, Chongqing, China.
Front Genet. 2023 Aug 25;14:1216592. doi: 10.3389/fgene.2023.1216592. eCollection 2023.
Spondyloepiphyseal dysplasia tarda (SEDT) is a condition involving late-onset, X-linked recessive skeletal dysplasia caused by mutations in the gene. In this paper, we identified a novel nonsense variant in a SEDT pedigree and analyzed the function of the variant in an attempt to explain the new pathogenesis of the TRAPPC2 protein in SEDT. Briefly, DNA and RNA samples from the peripheral blood of SEDT individuals were prepared. The causative variant in the Chinese SEDT family was identified by clinic whole-exome sequencing analysis. Then, we observed the mRNA expression of in patients and the mutant TRAPPC2 level and analyzed the protein stability and subcellular distribution by cell fluorescence and Western blotting. We also investigated the effect of knockdown on the expression and secretion of COL2A1 in SW1353 cells or primary human chondrocytes. Herein, we found a nonsense variant, c.91A>T, of the gene in the pedigree. mRNA expression levels were significantly decreased in the available peripheral blood cell samples of two affected patients. An study showed that the mutant plasmid exhibited significantly lower mRNA and protein of , and the mutant protein changed its membrane distribution. knockdown resulted in decreased expression and collagen II secretions. Our data indicate that the novel nonsense variant, c.91A>T, of the gene is the cause of SEDT in this pedigree. The variant results in a lowered expression of TRAPPC2 and then affects the expression and collagen II secretions, which may explain the mechanism of loss of function of the variant.
迟发性脊椎骨骺发育不良（SEDT）是一种涉及迟发性、X连锁隐性骨骼发育不良的疾病，由该基因的突变引起。在本文中，我们在一个SEDT家系中鉴定出一种新的无义变异，并分析了该变异的功能，试图解释TRAPPC2蛋白在SEDT中的新发病机制。简要地说，制备了SEDT个体外周血的DNA和RNA样本。通过临床全外显子测序分析确定了中国SEDT家系中的致病变异。然后，我们观察了患者中该基因的mRNA表达以及突变型TRAPPC2水平，并通过细胞荧光和蛋白质印迹分析了蛋白质稳定性和亚细胞分布。我们还研究了该基因敲低对SW1353细胞或原代人软骨细胞中COL2A1表达和分泌的影响。在此，我们在该家系中发现了该基因的一个无义变异c.91A>T。在两名受影响患者可用的外周血细胞样本中，该基因的mRNA表达水平显著降低。一项研究表明，突变体质粒的该基因mRNA和蛋白质水平显著降低，且突变蛋白的膜分布发生了变化。该基因敲低导致该基因表达和胶原蛋白II分泌减少。我们的数据表明，该基因的新无义变异c.91A>T是该家系中SEDT的病因。该变异导致TRAPPC2表达降低，进而影响该基因表达和胶原蛋白II分泌，这可能解释了该变异功能丧失的机制。
