Genetic Approaches to Hemoglobin Switching

β-血红蛋白病和地中海贫血的健康负担是巨大的。增加的胎儿血红蛋白 (HbF)改善这些疾病的严重程度。虽然在理解方面取得了很大进展， 从γ-珠蛋白到β-珠蛋白的"血红蛋白开关"，这一关键发育过程的特定细胞内调节因子， 事件未知，无法在患者体内可靠操作开关。这项研究的重点是 新的血红蛋白转换方法依赖于遗传，而不是严格的生物化学或分子， 战略布局若干领域的进展表明，现在是采取新举措的有利时机。几 将采取独立但互补的办法。首先，整合基因组分析将是 应用于鉴定染色体位置Xp22处的特定基因座，该基因座先前已与F细胞连锁 其他研究者的作品。初步的计算机分析表明，候选基因的数量有限， 在这个区间内。候选人将通过使用高密度SNP的关联研究进行验证或排除， 高度可能的候选者的测序，以及在携带人免疫缺陷病毒的小鼠红系细胞中的功能研究。 β-珠蛋白基因座。目的是确定血红蛋白开关的第一个反式调节因子。二、高水平 HbF表达是罕见的儿童恶性肿瘤青少年髓性白血病的标志， 偶发或在努南综合征和I型神经纤维瘤病的背景下出现。一个共同特点 是PTPN11或神经纤维蛋白的突变，随后激活Ras途径。基于这些 根据临床观察，Ras活性增加刺激γ-珠蛋白产生的假设将是可行的。 通过对可用于这些研究的工程小鼠的研究来进行。如果拉斯 通路被验证为HbF表达的调节剂，这一发现将为考虑 影响患者血红蛋白转换的新治疗方法。与此同时， 新发现的血红蛋白转换因子zfp148将与Cantor博士合作研究 （项目4）。最后，将启动无偏见的基因筛选，以确定基因的表达， 促进或抑制γ-珠蛋白表达。将使用适当的"报告"小鼠红系细胞系， 全基因组siRNA和逆转录病毒插入诱变筛选。通过这些多学科 将发现血红蛋白转换的未被识别的调节剂的方法。

The health burden from beta-hemoglobinopathies and thalassemias is enormous. Increased fetal hemoglobin (HbF) ameliorates the severity of these disorders. While much progress has been made in an understanding of the "hemoglobin switch" from gamma- to beta-globin, specific intracellular regulators of this critical developmental event are unknown and the switch cannot be reliably manipulated in patients. This research is focused on new approaches to the hemoglobin switch that rely on genetic, rather than strictly biochemical or molecular, strategies. Progress in several areas suggests that the time is propitious for new initiatives. Several independent, but complementary, approaches will be taken. First, integrative genomic analysis will be applied to identify the specific locus at chromosome position Xp22 that has previously been linked to F-cell production by other investigators. Preliminary in silico analyses suggest a limited number of candidate genes within this interval. Candidates will be validated or excluded by association studies using high-density SNPs, sequencing of highly likely candidates, and functional studies in mouse erythroid cells harboring the human beta-globin locus. The aim is to identify the first trans-regulator of the hemoglobin switch. Second, high-level HbF expression is a hallmark of the rare pediatric malignancy juvenile myeloid leukemia, a disorder that arises sporadically or in the setting of Noonan's syndrome and neurofibromatosis type I. A common feature is mutation of PTPN11 or neurofibromin with consequent activation of the Ras pathway. Based on these clinical observations, the hypothesis that increased Ras activity stimulates gamma-globin production will be pursued through the study of engineered mice that have been made available for these studies. If the Ras pathway is validated as a modulator of HbF expression, this finding would open the way to consideration of new therapeutic approaches to influencing the hemoglobin switch in patients. In parallel, the potential role of the newly identified factor zfp148 in hemoglobin switching will be pursued in collaboration with Dr. Cantor (Project 4). Finally, unbiased genetic screens will be initiated to identify genes whose expression either promotes or inhibits gamma-globin expression. An appropriate "reporter" mouse erythroid cell line will be used in both genome-wide siRNA and retroviral insertional mutagenesis screens. Through these multidisciplinary approaches unrecognized regulators of the hemoglobin switch will be discovered.