Table2_Pseudoautosomal Region 1 Overdosage Affects the Global Transcriptome in iPSCs From Patients With Klinefelter Syndrome and High-Grade X Chromosome Aneuploidies.docx

Klinefelter syndrome (KS) is the most prevalent aneuploidy in males and is characterized by a 47,XXY karyotype. Less frequently, higher grade sex chromosome aneuploidies (HGAs) can also occur. Here, using a paradigmatic cohort of KS and HGA induced pluripotent stem cells (iPSCs) carrying 49,XXXXY, 48,XXXY, and 47,XXY karyotypes, we identified the genes within the pseudoautosomal region 1 (PAR1) as the most susceptible to dosage-dependent transcriptional dysregulation and therefore potentially responsible for the progressively worsening phenotype in higher grade X aneuploidies. By contrast, the biallelically expressed non-PAR escape genes displayed high interclonal and interpatient variability in iPSCs and differentiated derivatives, suggesting that these genes could be associated with variable KS traits. By interrogating KS and HGA iPSCs at the single-cell resolution we showed that PAR1 and non-PAR escape genes are not only resilient to the X-inactive specific transcript (XIST)-mediated inactivation but also that their transcriptional regulation is disjointed from the absolute XIST expression level. Finally, we explored the transcriptional effects of X chromosome overdosage on autosomes and identified the nuclear respiratory factor 1 (NRF1) as a key regulator of the zinc finger protein X-linked (ZFX). Our study provides the first evidence of an X-dosage-sensitive autosomal transcription factor regulating an X-linked gene in low- and high-grade X aneuploidies.

克氏综合征（Klinefelter syndrome, KS）是男性群体中最常见的非整倍体（aneuploidy），以47,XXY核型（karyotype）为典型特征。更为罕见的是，亦可发生高级别性染色体非整倍体（higher grade sex chromosome aneuploidies, HGAs）。本研究依托包含49,XXXXY、48,XXXY及47,XXY核型的克氏综合征及高级别性染色体非整倍体诱导多能干细胞（induced pluripotent stem cells, iPSCs）典型队列，鉴定出假常染色体区域1（pseudoautosomal region 1, PAR1）内的基因最易受剂量依赖性转录失调（dosage-dependent transcriptional dysregulation）影响，提示该区域基因或参与高级别X染色体非整倍体的表型进行性加重过程。与之相对，双等位基因表达的非PAR逃逸基因（non-PAR escape genes）在诱导多能干细胞及其分化子代中表现出显著的克隆间与患者间异质性，提示此类基因或与克氏综合征的可变表型相关。本研究通过单细胞分辨率解析克氏综合征及高级别性染色体非整倍体诱导多能干细胞，证实PAR1基因与非PAR逃逸基因不仅可抵御X染色体失活特异性转录本（X-inactive specific transcript, XIST）介导的染色体失活，且其转录调控与XIST的绝对表达水平并无关联。最后，本研究探究了X染色体过量对常染色体的转录调控效应，并鉴定出核呼吸因子1（nuclear respiratory factor 1, NRF1）是X连锁锌指蛋白（zinc finger protein X-linked, ZFX）的关键调控因子。本研究首次提供证据表明，在低级别与高级别X染色体非整倍体中，存在X剂量敏感性常染色体转录因子调控X连锁基因的现象。