Genetic and molecular basis of hematopoietic abnormalities in ZTTK syndrome

项目摘要 患有罕见遗传病的人没有得到医学和研究界的关注。一 每两名被诊断患有罕见疾病的患者中就有一名是儿童，这意味着患者及其家人必须忍受 在孩子的一生中，与疾病进展有关的长期斗争。因此， 罕见疾病的临床/分子方面的研究将大大有益于年轻患者及其家庭。 SON是一种DNA和RNA结合蛋白，其作为RNA剪接因子和转录调节因子发挥双重作用。 阻遏物我们的研究小组最近发现了Zhu-Tokita-Takenouchi-Kim综合征（ZTTK综合征）， 一种罕见的遗传性疾病，伴有多器官异常，由基因组中的杂合功能丧失突变引起。 SON基因（SON haploinsufficiency）我们的研究和出版物在记录这一点方面发挥了关键作用 综合征的主要公共数据库，以促进临床诊断。作为支持ZTTK家庭的第一步 为了提高人们的意识，我们最近成立了一个官方基金会，ZTTK SON-Shine基金会。 我们最近的研究表明，许多患有ZTTK综合征的儿童患有各种造血系统疾病， 和免疫功能障碍，这有时会导致危及生命的败血症。要了解造血 由于ZTTK综合征相关的异常，我们已经产生了Son敲除（KO）的小鼠模型， 儿子单倍性不足。我们的初步数据表明，造血细胞中的完全Son KO导致 造血干细胞（HSC）扩增和胚胎致死。此外，我们还发现， 单倍不足导致谱系启动的多能祖细胞（MPPs）的比例异常， 巨核细胞-红细胞谱系引发的MPP的扩增和淋巴谱系引发的MPP的收缩， 这在胎儿肝脏造血过程中已经很明显，并且在成人骨髓造血过程中持续存在。 重要的是，我们的RNA测序分析显示，关键的染色质修饰基因是主要的目标 在早期造血干细胞和祖细胞（HSPC）中，Son单倍不足失调。 基于这些初步数据，我们的中心假设是，Son单倍不足直接和间接地 改变了关键染色质修饰剂的表达/剪接，从而共同重塑了 HSC和MPP的水平，并且这导致偏斜的谱系偏倚和HSC/MPP的功能输出受损。 为了验证这些假设，我们将研究Son单倍不足如何影响HSC的功能输出， 谱系引发的MPPs在体内（目的1），并将剖析潜在的分子机制，儿子 单倍不足导致HSPC异常（目的2）。成功完成这项拟议研究将 显著提高了我们对ZTTK综合征相关异常血液学特征认识， 将作为确定治疗策略的宝贵资源。最重要的是，这项研究将为 孩子们和他们的家人正在与这种罕见的疾病作斗争。

PROJECT SUMMARY Individuals with rare genetic diseases do not receive attention from the medical and research community. One out of two patients diagnosed with a rare disease is a child, meaning that patients and their families must endure long battles relating to disease progress throughout their child’s lifetime. Therefore, characterization of clinical/molecular aspects of rare diseases will greatly benefit young patients and their families. SON is a DNA- and RNA-binding protein that plays dual roles as an RNA splicing factor and a transcriptional repressor. Our research team recently identified Zhu-Tokita-Takenouchi-Kim syndrome (ZTTK syndrome), a rare genetic disease with multi-organ abnormalities caused by heterozygous loss-of-function mutations in the SON gene (SON haploinsufficiency). Our research and publication played a key role in documenting this syndrome in major public databases to facilitate clinical diagnosis. As a first step in supporting ZTTK families and promoting awareness, we recently launched an official foundation, the ZTTK SON-Shine Foundation. Our recent efforts revealed that many children with ZTTK syndrome experience various hematopoietic disorders and immune dysfunction, which sometimes leads to life-threatening sepsis. To understand the hematopoietic abnormalities associated with ZTTK syndrome, we have generated mouse models of Son knockout (KO) and Son haploinsufficiency. Our preliminary data demonstrated that complete Son KO in hematopoietic cells causes hematopoietic stem cell (HSC) expansion and embryonic lethality. Furthermore, we found that Son haploinsufficiency leads to abnormal proportions of lineage-primed multipotent progenitors (MPPs), with an expansion of megakaryocyte-erythroid lineage-primed MPPs and a shrinkage of lymphoid lineage-primed MPPs, which is already evident during fetal liver hematopoiesis and persists in adult hematopoiesis in the bone marrow. Importantly, our RNA-sequencing analyses revealed that critical chromatin modifier genes were the major targets dysregulated by Son haploinsufficiency in early stage hematopoietic stem and progenitor cells (HSPCs). Based on these preliminary data, our central hypothesis is that Son haploinsufficiency directly and indirectly alters the expression/splicing of key chromatin modifiers, which collectively reshapes chromatin status at the level of HSCs and MPPs, and this leads to skewed lineage bias and impaired functional output of HSCs/MPPs. To test these hypotheses, we will investigate how Son haploinsufficiency affects functional output of HSCs and lineage primed MPPs in vivo (Aim 1), and will dissect the underlying molecular mechanisms by which Son haploinsufficiency leads to HSPC abnormalities (Aim 2). Successful completion of this proposed study will significantly advance our knowledge about ZTTK syndrome-associated abnormal hematological features and will serve as a valuable resource to identify therapeutic strategies. Most importantly, this study will bring hope to children and their families battling this rare disease.