Abstract

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 alpha-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 ('alpha- complex') in stabilizing alpha globin mRNA. Inactivation of the alpha-complex by mutation of the C-rich binding motif or by blocking the binding of the alphaCP protein results in an incremental loss of alpha-globin mRNA stability. This loss of stability can be fully restored by artificially tethering alphaCP to the 3'UTR. AlphaCPs are broadly distributed in tissues, suggesting that an erythroid- restricted role of the a-complex is dictated by specific modifications to alphaCP or to interacting RNP components. The major alphaCP isoforms are differentially localized in the nucleus and cytoplasm. Evidence suggests that the cytoplasmic role of alphaCPs in alpha-globin mRNA stabilization is complemented by separate nuclear function(s) involved in enhancement of alpha-globin mRNA processing. The pathways involved in selective stabilization of human alpha-globin mRNA and the interrelationships between nuclear and cytoplasmic functions of alphaCPs in alpha-globin gene expression will be explored in the proposed studies.
Aim I. Identify interactions at the alpha complex that mediate alpha-globin mRNA stabilization.
Aim II. Define the mechanism(s) of alpha-globin mRNA stabilization and how alpha-globin mRNA evades decay in erythroid cells.
Aim III. Determine how alphaCPs enhance nuclear processing of alpha-globin transcripts and how these nuclear events integrate with alphaCP-mediated cytoplasmic controls. These studies will extend our prior work on alpha-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. ? ?

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37HL065449-09
Application #
7487410
Study Section
Erythrocyte and Leukocyte Biology Study Section (ELB)
Program Officer
Qasba, Pankaj
Project Start
2000-09-05
Project End
2009-08-31
Budget Start
2008-09-01
Budget End
2009-08-31
Support Year
9
Fiscal Year
2008
Total Cost
$338,242
Indirect Cost

  Institution

Name
University of Pennsylvania
Department
Genetics
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104

  Publications

Ghanem, Louis R; Kromer, Andrew; Silverman, Ian M et al. (2016) The Poly(C) Binding Protein Pcbp2 and Its Retrotransposed Derivative Pcbp1 Are Independently Essential to Mouse Development. Mol Cell Biol 36:304-19
Kini, Hemant K; Kong, Jian; Liebhaber, Stephen A (2014) Cytoplasmic poly(A) binding protein C4 serves a critical role in erythroid differentiation. Mol Cell Biol 34:1300-9
Ghanem, Louis R; Chatterji, Priya; Liebhaber, Stephen A (2014) Specific enrichment of the RNA-binding proteins PCBP1 and PCBP2 in chief cells of the murine gastric mucosa. Gene Expr Patterns 14:78-87
Harper, Sandra L; Sriswasdi, Sira; Tang, Hsin-Yao et al. (2013) The common hereditary elliptocytosis-associated *-spectrin L260P mutation perturbs erythrocyte membranes by stabilizing spectrin in the closed dimer conformation. Blood 122:3045-53
Ji, Xinjun; Wan, Ji; Vishnu, Melanie et al. (2013) ?CP Poly(C) binding proteins act as global regulators of alternative polyadenylation. Mol Cell Biol 33:2560-73
Natsuizaka, Mitsuteru; Naganuma, Seiji; Kagawa, Shingo et al. (2012) Hypoxia induces IGFBP3 in esophageal squamous cancer cells through HIF-1?-mediated mRNA transcription and continuous protein synthesis. FASEB J 26:2620-30
Ji, Xinjun; Kong, Jian; Liebhaber, Stephen A (2011) An RNA-protein complex links enhanced nuclear 3' processing with cytoplasmic mRNA stabilization. EMBO J 30:2622-33
Vishnu, Melanie R; Sumaroka, Marina; Klein, Peter S et al. (2011) The poly(rC)-binding protein alphaCP2 is a noncanonical factor in X. laevis cytoplasmic polyadenylation. RNA 17:944-56
Chiefari, Eusebio; Iiritano, Stefania; Paonessa, Francesco et al. (2010) Pseudogene-mediated posttranscriptional silencing of HMGA1 can result in insulin resistance and type 2 diabetes. Nat Commun 1:40
Kini, Hemant K; Vishnu, Melanie R; Liebhaber, Stephen A (2010) Too much PABP, too little translation. J Clin Invest 120:3090-3

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