Kozłowska Emilia, Ciołak Agata, Adamek Grażyna, Szcześniak Julia, Fiszer Agnieszka
Department of Medical Biotechnology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznań, 61-704, Poland.
Department of Neuronal Cell Biology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznań, 61-704, Poland.
Cell Biosci. 2025 Jul 9;15(1):100. doi: 10.1186/s13578-025-01443-5.
Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the HTT gene, which results in a long polyglutamine tract in the huntingtin protein (HTT). One of the earliest key molecular mechanisms underlying HD pathogenesis is transcriptional dysregulation, which is already present in the developing brain. In this study, we searched for networks of deregulated RNAs crucial for initial transcriptional changes in HD- and HTT-deficient neuronal cells.
RNA-seq (including small RNAs) was used to analyze a set of isogenic human neural stem cells. The results were validated using additional methods, rescue experiments, and in the medium spiny neuron-like cells. We observed numerous changes in gene expression and substantial dysregulation of miRNA expression in HD and HTT-knockout (HTT-KO) cell lines. The overlapping set of genes upregulated in both HD and HTT-KO cells was enriched in genes associated with DNA binding and the regulation of transcription. We observed substantial upregulation of the following transcription factors: TWIST1, SIX1, TBX1, TBX15, MSX2, MEOX2 and FOXD1. Moreover, we identified miRNAs that were consistently deregulated in HD and HTT-KO cells, including miR-214, miR-199, and miR-9. These miRNAs may function in the network that regulates TWIST1 and HTT expression via a regulatory feed-forward loop in HD.
On the basis of overlapping changes in the mRNA and miRNA profiles of HD and HTT-KO cell lines, we propose that transcriptional deregulation in HD at early neuronal stages is largely caused by a deficiency of properly functioning HTT rather than a typical gain-of-function mechanism.
亨廷顿舞蹈症（HD）是一种神经退行性疾病，由HTT基因中CAG重复序列的扩增引起，这导致亨廷顿蛋白（HTT）中出现长的多聚谷氨酰胺序列。HD发病机制的最早关键分子机制之一是转录失调，这种失调在发育中的大脑中就已存在。在本研究中，我们寻找了在HD和HTT缺陷型神经元细胞中对初始转录变化至关重要的失调RNA网络。
RNA测序（包括小RNA）用于分析一组同基因人类神经干细胞。使用其他方法、拯救实验以及在中等棘状神经元样细胞中对结果进行了验证。我们在HD和HTT基因敲除（HTT-KO）细胞系中观察到基因表达的大量变化以及miRNA表达的显著失调。在HD和HTT-KO细胞中上调的重叠基因集富含与DNA结合和转录调控相关的基因。我们观察到以下转录因子的大量上调：TWIST1、SIX1、TBX1、TBX15、MSX2、MEOX2和FOXD1。此外，我们鉴定出在HD和HTT-KO细胞中持续失调的miRNA，包括miR-214、miR-199和miR-9。这些miRNA可能在通过HD中的调节前馈环调节TWIST1和HTT表达的网络中发挥作用。
基于HD和HTT-KO细胞系的mRNA和miRNA谱的重叠变化，我们提出HD早期神经元阶段的转录失调很大程度上是由功能正常的HTT缺乏引起的，而不是典型的功能获得机制。
