Alpha-Globin expression: Post transcriptional mechanisms

珠蛋白mRNAs的高水平稳定性是血红蛋白合成和红细胞的主要决定因素 功能。红系分化过程中珠蛋白mRNAs选择性稳定的基础仍然存在 人们对此知之甚少。我们实验室正在使用人的ot-珠蛋白mRNA作为研究这一问题的模型。 在目前的资助期内进行的遗传、生化和体内表达研究表明， 序列特异性3‘UTRRNA-蛋白质(RNP)复合体(’C_Complex‘)在稳定ct-DNA中的中心作用 珠蛋白基因。通过富含C的结合基序的突变或通过阻断C_-复合体的失活 CtCP蛋白的结合导致ot-珠蛋白mRNA稳定性的递增损失。这种稳定性的丧失 可通过人工将ctCP拴在3‘非编码区上而完全恢复。C_CPS广泛分布于组织中， 提示a-复合体的红系限制性作用是由c_CP或c_CP的特定修饰决定的 到相互作用的RNP组件。CtCP的主要异构体分别定位于细胞核和 细胞质。有证据表明，etcps在ct-珠蛋白mrna稳定中的细胞质作用是 辅以单独的核功能(S)，参与促进c-珠蛋白mRNA的加工。这个 人c-珠蛋白mRNA选择性稳定的途径及其相互关系 本文将探讨ACPs在c_-珠蛋白基因表达中的核和胞质功能。 学习。 目的I.确定介导ct-珠蛋白mRNA稳定的复合体的相互作用。 目的II.确定α-珠蛋白mRNA稳定的机制(S)以及α-珠蛋白mRNA是如何 避免红系细胞的腐烂。 目的三.确定ctcp如何增强ct-珠蛋白转录本的核处理，以及这些 核事件与ACP介导的细胞质调控相结合。 这些研究将扩展我们先前在ct-珠蛋白基因表达方面的工作，定义新的 MRNA的衰退，并建立了一个协调的核质转录后调控的范例 红系基因的表达。

High-level stability of globin mRNAs is a major determinant of hemoglobin synthesis and erythrocyte function. The basis for selective stabilization of globin mRNAs during erythroid differentiation remains poorly understood. Our laboratory is using human ot-globin mRNA as a model for the study of this problem. Genetic, biochemical, and in vivo expression studies carried out over the present funding period point to a central role for a sequence-specific 3'UTR RNA-protein (RNP) complex ('c_ complex') in stabilizing ct- globin mRNA. Inactivation of the c_-complex by mutation of the C-rich binding motif or by blocking the binding of the ctCP protein results in an incremental loss of ot-globin mRNA stability. This loss of stability can be fully restored by artificially tethering ctCP to the 3'UTR. c_CPs are broadly distributed in tissues, suggesting that an erythroid- restricted role of the a-complex is dictated by specific modifications to c_CP or to interacting RNP components. The major ctCP isoforms are differentially localized in the nucleus and cytoplasm. Evidence suggests that the cytoplasmic role of etCPs in ct-globin mRNA stabilization is complemented by separate nuclear function(s) involved in enhancement of c_-globin mRNA processing. The pathways involved in selective stabilization of human c_-globin mRNA and the interrelationships between nuclear and cytoplasmic functions of aCPs in c_-globin gene expression will be explored in the proposed studies. Aim I. Identify interactions at the a complex that mediate ct-globin mRNA stabilization. Aim II. Define the mechanism(s) of _-globin mRNA stabilization and how a-globin mRNA evades decay in erythroid cells. Aim III. Determine how ctCPs enhance nuclear processing of ct-globin transcripts and how these nuclear events integrate with aCP-mediated cytoplasmic controls. These studies will extend our prior work on ct-globin gene expression, define novel pathways of mRNA decay, and establish a paradigm for coordinated nuclear and cytoplasmic post-transcriptional controls in erythroid gene expression.