Bid Function in Myeloid Homeostasis and Leukemogenesis

Bid 在骨髓稳态和白血病发生中的功能

• 批准号: 7121955
• 负责人: Sandra S Zinkel
• 金额: $ 13.03万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-30 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7121955
• 关键词: BCL2 gene /protein; apoptosis; biological signal transduction; carcinogenesis; comparative genomic hybridization; cytogenetics; flow cytometry; fluorescent in situ hybridization; genetically modified animals; histology; laboratory mouse; leukemia; myeloid stem cell; polymerase chain reaction; protein structure function

DESCRIPTION (provided by applicant): The BCL-2 family constitutes a crucial checkpoint in the cell death pathway. BID is a member of the "BH3-only" subset of this family and requires its conserved BH3 domain for its pro-apoptotic function. BID plays an important role in the apoptotic pathway downstream of death receptors such as TNF RI and Fas (1-7). Cleavage by caspase 8 and myristoylation serves as an activating molecular switch which facilitates targeting of BID to mitochondria(8) where it activates multidomain proapoptotic members such as BAK or BAX, mediating the release of cytochrome c and activation of downstream effector caspases (9). Bid-deficient mice are viable and develop normally, however hepatocytes are resistant to anti-Fas-induced hepatocellular apoptosis(10). BID thus plays an important role in mediating a mitochondrial amplification loop downstream of death receptors in certain cell types such as hepatocytes. Yet many other cells, including activated lymphocytes, are killed by Fas in in vitro assays, directly activating downstream effector caspases for the promotion of apoptosis(11). However, as Bid-deficient mice age or are challenged by chronic viral infection, we've discovered that BID is also singularly required in vivo to maintain homeostasis in so-called Type I cells including B cells, T cells, and the myelomonocytic lineage(12). As Bid-deficient mice age, they display a myeloid hyperplasia and then progress to Chronic myelomonocytic leukemia at high incidence. The founding family member, BCL-2 was cloned at the t(14:18) chromosomal breakpoint, the molecular hallmark of follicular B cell lymphoma establishing a new class of oncogenes in which the aberration is in cell death rather than proliferation(13-15). Transgenic mice over expressing BCL-2 in myeloid cells develop a myeloproliferative disorder, and when crossed with mice harboring a mutation in the Fas receptor, progress to AML, implicating a synergistic role for the Fas pathway and Bcl-2 in tumor suppression of the myeloid lineage(16). The role of pro-apoptotic members in normal myeloid homeostasis has not been well characterized. We propose that BID is the critical proapoptotic intermediate that mediates death receptor signaling in the myeloid lineage and that its inactivations promotes myeloid leukemogenesis by prolonging the life of these vulnerable cells, allowing accumulation of additional mutations. This single "BH3-only" protein therefore has potential to play a potent role in maintenance of normal myeloid homeostasis as well as tumor suppression. In this context, I propose the following specific aims: 1. Define the role of Bid in myeloid homeostasis. 2. Define the role of Bid in myeloid leukemogenesis. 3. Identify the secondary genetic changes that cooperate with loss of Bid in leukemogenesis.

描述（由申请人提供）：BCL-2 家族构成细胞死亡途径中的关键检查点。 BID 是该家族“仅 BH3”子集的成员，需要其保守的 BH3 结构域来发挥其促凋亡功能。 BID 在死亡受体（例如 TNF RI 和 Fas）下游的细胞凋亡途径中发挥着重要作用 (1-7)。 Caspase 8 的切割和肉豆蔻酰化充当激活分子开关，促进 BID 靶向线粒体 (8)，在线粒体中激活多域促凋亡成员，如 BAK 或 BAX，介导细胞色素 c 的释放和下游效应器 caspase 的激活 (9)。 Bid 缺陷小鼠能够存活并正常发育，但肝细胞对抗 Fas 诱导的肝细胞凋亡具有抵抗力 (10)。因此，BID 在介导某些细胞类型（如肝细胞）死亡受体下游的线粒体放大环中发挥着重要作用。然而，许多其他细胞，包括活化的淋巴细胞，在体外测定中被 Fas 杀死，直接激活下游效应器半胱天冬酶以促进细胞凋亡 (11)。然而，随着 Bid 缺陷小鼠年龄的增长或受到慢性病毒感染的挑战，我们发现 BID 在体内也是非常需要的，以维持所谓的 I 型细胞（包括 B 细胞、T 细胞和骨髓单核细胞谱系）的稳态。 12）。随着 Bid 缺陷小鼠年龄的增长，它们会表现出骨髓增生，然后以高发病率进展为慢性粒单核细胞白血病。创始家族成员 BCL-2 在 t(14:18) 染色体断点处被克隆，这是滤泡性 B 细胞淋巴瘤的分子标志，建立了一类新的癌基因，其中异常在于细胞死亡而不是增殖(13-15 ）。在骨髓细胞中过度表达 BCL-2 的转基因小鼠会出现骨髓增殖性疾病，当与 Fas 受体突变的小鼠杂交时，会进展为 AML，这表明 Fas 途径和 Bcl-2 在骨髓肿瘤抑制中具有协同作用血统(16)。促凋亡成员在正常骨髓稳态中的作用尚未得到很好的表征。我们认为，BID 是介导骨髓谱系中死亡受体信号传导的关键促凋亡中间体，其失活通过延长这些脆弱细胞的寿命来促进骨髓白血病的发生，从而允许额外突变的积累。因此，这种单一的“仅 BH3”蛋白有可能在维持正常骨髓稳态以及抑制肿瘤方面发挥重要作用。在此背景下，我提出以下具体目标： 1. 明确 Bid 在骨髓稳态中的作用。 2. 定义 Bid 在骨髓性白血病发生中的作用。 3. 确定在白血病发生过程中与 Bid 丢失相配合的继发性遗传变化。