Molecular Biology and Genetics Laboratory, Department of Biological Sciences, BITS Pilani Hyderabad Campus, Hyderabad 500078, India; Centre for Human Disease Research, BITS Pilani Hyderabad Campus, Hyderabad 500078, India.
Molecular Biology and Genetics Laboratory, Department of Biological Sciences, BITS Pilani Hyderabad Campus, Hyderabad 500078, India.
Int J Biochem Cell Biol. 2024 Apr;169:106535. doi: 10.1016/j.biocel.2024.106535. Epub 2024 Jan 26.
Hereditary Sensory and Autonomic Neuropathy Type 1E (HSAN1E) is a rare autosomal dominant neurological disorder due to missense mutations in DNA methyltransferase 1 (DNMT1). To investigate the nature of the dominant effect, we compared methylomes of transgenic R1 and R1 mouse embryonic stem cells (mESCs) overexpressing WT and the mutant mouse proteins respectively, with the R1 (wild-type) cells. In case of R1, 15 out of the 20 imprinting control regions were hypomethylated with transcript level dysregulation of multiple imprinted genes in ESCs and neurons. Non-imprinted regions, minor satellites, major satellites, LINE1 and IAP repeats were unaffected. These data mirror the specific imprinting defects associated with transient removal of DNMT1 in mESCs, deletion of the maternal-effect DNMT1o variant in preimplantation mouse embryos, and in part, reprogramming to naïve human iPSCs. This is the first DNMT1 mutation demonstrated to specifically affect Imprinting Control Regions (ICRs), and reinforces the differences in maintenance methylation of ICRs over non-imprinted regions. Consistent with nervous system abnormalities in the HSAN1E disorder and involvement of imprinted genes in normal development and neurogenesis, R1 cells showed dysregulated pluripotency and neuron marker genes, and yielded more slender, shorter, and extensively branched neurons. We speculate that R1 cells produce predominantly dimers containing mutant proteins, leading to a gradual and specific loss of ICR methylation during early human development.
遗传性感觉自主神经病 1E 型（HSAN1E）是一种罕见的常染色体显性遗传性神经疾病，由 DNA 甲基转移酶 1（DNMT1）的错义突变引起。为了研究显性效应的性质，我们比较了分别过表达 WT 和突变型小鼠蛋白的转基因 R1 和 R1 小鼠胚胎干细胞（mESC）的甲基组，与 R1（野生型）细胞进行比较。在 R1 中，20 个印迹控制区域中有 15 个出现低甲基化，多个印迹基因在 ESC 和神经元中的转录水平失调。非印迹区域、微卫星、大片段卫星、LINE1 和 IAP 重复序列不受影响。这些数据反映了与 mESC 中瞬时去除 DNMT1、小鼠胚胎前植入期母源效应 DNMT1o 变体缺失以及部分重编程为原始人类 iPSC 相关的特定印迹缺陷。这是第一个被证明专门影响印迹控制区（ICRs）的 DNMT1 突变，并且强化了 ICRs 与非印迹区域之间维持甲基化的差异。与 HSAN1E 疾病中的神经系统异常以及印迹基因在正常发育和神经发生中的参与一致，R1 细胞显示出失调的多能性和神经元标记基因，并且产生更多细长、短和广泛分支的神经元。我们推测，R1 细胞主要产生含有突变蛋白的二聚体，导致在人类早期发育过程中 ICR 甲基化逐渐且特异性丧失。
