Competitive binding of CUGBP1 and HuR to occludin mRNA controls its translation and modulates epithelial barrier function

Yu, Tina; Rao, Jaladanki N.; Zou, Tongtong; Liu, Lan; Xiao, Lan; Ouyang, Ming; Cao, Shan; Gorospe, Myriam; Wang, Jianying

doi:10.1091/mbc.e12-07-0531

Cited by 68 publications

(99 citation statements)

References 58 publications

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“…Given the HCV RNA binding property of HuR, we hypothesized that it might indirectly modulate replication by influencing the binding of other proteins (such as La and PTB) regulating HCV replication at the 3= UTR. In fact, the ability of HuR to participate in such regulatory networks has been demonstrated in a few contexts, such as promotion of HIF-1␣ mRNA translation through cooperative binding with PTB (53) and promotion of occludin mRNA translation by HuR through displacement of CUGBP1 (54). Our studies demonstrate cooperative binding of La and HuR to the HCV 3= UTR as well as competitive binding of HuR and PTB.…”

Section: Discussionsupporting

confidence: 51%

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Shwetha

Kumar

Mullick

et al. 2015

J Virol

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HuR is a ubiquitous, RNA binding protein that influences the stability and translation of several cellular mRNAs. Here, we report a novel role for HuR, as a regulator of proteins assembling at the 3= untranslated region (UTR) of viral RNA in the context of hepatitis C virus (HCV) infection. HuR relocalizes from the nucleus to the cytoplasm upon HCV infection, interacts with the viral polymerase (NS5B), and gets redistributed into compartments of viral RNA synthesis. Depletion in HuR levels leads to a significant reduction in viral RNA synthesis. We further demonstrate that the interaction of HuR with the 3= UTR of the viral RNA affects the interaction of two host proteins, La and polypyrimidine tract binding protein (PTB), at this site. HuR interacts with La and facilitates La binding to the 3= UTR, enhancing La-mediated circularization of the HCV genome and thus viral replication. In addition, it competes with PTB for association with the 3= UTR, which might stimulate viral replication. Results suggest that HuR influences the formation of a cellular/viral ribonucleoprotein complex, which is important for efficient initiation of viral RNA replication. Our study unravels a novel strategy of regulation of HCV replication through an interplay of host and viral proteins, orchestrated by HuR. IMPORTANCE Hepatitis C virus (HCV) is highly dependent on various host factors for efficient replication of the viral RNA.Here, we have shown how a host factor (HuR) migrates from the nucleus to the cytoplasm and gets recruited in the protein complex assembling at the 3= untranslated region (UTR) of HCV RNA. At the 3= UTR, it facilitates circularization of the viral genome through interaction with another host factor, La, which is critical for replication. Also, it competes with the host protein PTB, which is a negative regulator of viral replication. Results demonstrate a unique strategy of regulation of HCV replication by a host protein through alteration of its subcellular localization and interacting partners. The study has advanced our knowledge of the molecular mechanism of HCV replication and unraveled the complex interplay between the host factors and viral RNA that could be targeted for therapeutic interventions. Hepatitis C virus (HCV) was discovered in 1989 as a major cause of chronic non-A non-B hepatitis (1). HCV is an enveloped positive-strand RNA virus classified in the Hepacivirus genus within the Flaviviridae family. The single-stranded uncapped 9.6-kb RNA codes for a long polyprotein of ϳ3,000 amino acids which is then processed to structural and nonstructural proteins. The RNA genome is flanked by the 5= and 3= untranslated regions (UTRs), which are essential for translation and replication of the viral RNA. The viral proteins are synthesized by internal ribosome entry site (IRES)-mediated translation. These proteins initiate extensive remodeling of the intracellular membranes to create a detergent-resistant scaffold for viral replication, termed as the "membranous web" (2). The progeny viral genomes a...

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Section: Discussionsupporting

confidence: 51%

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Shwetha

Kumar

Mullick

et al. 2015

J Virol

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“…Moreover, CUGBP1 silencing by transfection with siRNA targeting the Cugbp1 mRNA (siCUGBP1) led to increased IGF2R expression. These specific siCUGBP1 nucleotides showed high specificity with the Cugbp1 mRNA and low toxicity, as described previously (25,26). The levels of CUGBP1 protein decreased by Ͼ95% at 48 h after transfection of siCUGBP1, whereas the levels of IGF2R protein increased by ϳ2-fold (n ϭ 3; P Ͻ 0.05) compared with those in cells transfected with control siRNA (C-siRNA) (Fig.…”

Section: Regulation Of Igf2r Translation By Mir-195 and Cugbp1supporting

confidence: 82%

“…However, its potential role as a regulator of IGF receptor expression is unknown. In addition, CUGBP1 has also recently emerged as a master regulator of gut epithelial homeostasis by modulating IEC proliferation, apoptosis, and cell-to-cell interaction (18,25,26), and low levels of CUGBP1 in mice are associated with crypt hyperplasia in the small intestine (27). Given the presence of sites for predicted binding of miR-195 and CUGBP1 in the Igf2r mRNA, we tested the possibility that miR-195 and CUGBP1 jointly regulate IGF2R expression.…”

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confidence: 99%

Cooperative Repression of Insulin-Like Growth Factor Type 2 Receptor Translation by MicroRNA 195 and RNA-Binding Protein CUGBP1

Zhang

Xiao

et al. 2017

Molecular and Cellular Biology

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Insulin-like growth factor type 2 (IGF2) receptor (IGF2R) recognizes mannose 6-phosphate-containing molecules and IGF2 and plays an important role in many pathophysiological processes, including gut mucosal adaptation. However, the mechanisms that control cellular IGF2R abundance are poorly known. MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) critically regulate gene expression programs in mammalian cells by modulating the stability and translation of target mRNAs. Here we report that miRNA 195 (miR-195) and RBP CUG-binding protein 1 (CUGBP1) jointly regulate IGF2R expression at the posttranscriptional level in intestinal epithelial cells. Both miR-195 and CUGBP1 interacted with the 3= untranslated region (3=-UTR) of Igf2r mRNA, and the association of CUGBP1 with Igf2r mRNA enhanced miR-195 binding to Igf2r mRNA. Ectopically expressed CUGBP1 and miR-195 repressed IGF2R translation cooperatively without altering the stability of Igf2r mRNA. Importantly, the miR-195-and CUGBP1-repressed levels of cellular IGF2R led to a disruption in the structure of the trans-Golgi network. These findings indicate that IGF2R expression is controlled posttranscriptionally by two factors that associate with Igf2r mRNA and suggest that miR-195 and CUGBP1 dampen IGF signaling by inhibiting IGF2R translation.KEYWORDS insulin superfamily, posttranscriptional regulation, trans-Golgi network, intestinal epithelial cells, RNA-binding proteins, noncoding RNAs M ucosal regeneration/adaptation is an essential process in gut homeostasis and tightly regulated by numerous factors, including insulin-like growth factor type 1 (IGF1) and IGF2 (1, 2). Two structurally distinct types of receptors, the IGF1 receptor (IGF1R) and IGF2R, specifically interact with IGF1 and IGF2 as ligands and regulate diverse biological functions such as cell proliferation, differentiation, and apoptosis (3, 4). Like the insulin receptor, IGF1R is a heterotetrameric transmembrane receptor tyrosine kinase, and its activation results in autophosphorylation of tyrosine residues in the intracellular ␤-subunits, thus initiating the phosphatidylinositol 3-kinase (PI3) kinase/AKT and/or mitogen-activated protein (MAP) kinase signaling cascade (5). In contrast, IGF2R is a single-transmembrane-domain protein and binds IGF2 with greater affinity than IGF1, although it does not accept insulin as a ligand (4, 6). IGF2R also recognizes, via distinct sites, mannose-6-phosphate (M6P)-containing molecules and can therefore associate with other growth factors and cytokines (4). The majority of IGF2R is localized in the trans-Golgi network (TGN) and endosomal compartments and, to a lesser extent, on the cell surface (6). A subpopulation of the IGF2R on the plasma membrane regulates IGF2 internalization and various M6P-containing ligands for their

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“…Interestingly, the Cyp19a1 3= UTR represses the expression of the reporter gene at the protein level in a CELF1-dependent manner, but not at the mRNA level. This suggests that CELF1 represses the translation of Cyp19a1, in accordance with known properties of CELF1 (10,(16)(17)(18)(19). These results in HeLa cells seem to contradict the in vivo results, as we detected high levels of Cyp19a1 mRNA in Celf1 Ϫ/Ϫ testes (Fig.…”

Section: Discussionsupporting

confidence: 57%

“…In the nucleus, it controls pre-mRNA alternative splicing (11,12). In the cytoplasm, it targets bound mRNAs for rapid decay (13,14) and/or modulates their translation (15)(16)(17)(18)(19). The cytoplasmic functions are probably mediated by interactions with molecular partners, like the poly(A) nuclease PARN (20) or the translation initiation complex eIF2 (21).…”

mentioning

confidence: 99%

Hypogonadism Associated with Cyp19a1 (Aromatase) Posttranscriptional Upregulation in Celf1 Knockout Mice

Boulanger

Cibois

Viet

et al. 2015

Molecular and Cellular Biology

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CELF1 is a multifunctional RNA-binding protein that controls several aspects of RNA fate. The targeted disruption of the Celf1 gene in mice causes male infertility due to impaired spermiogenesis, the postmeiotic differentiation of male gametes. Here, we investigated the molecular reasons that underlie this testicular phenotype. By measuring sex hormone levels, we detected low concentrations of testosterone in Celf1-null mice. We investigated the effect of Celf1 disruption on the expression levels of steroidogenic enzyme genes, and we observed that Cyp19a1 was upregulated. Cyp19a1 encodes aromatase, which transforms testosterone into estradiol. Administration of testosterone or the aromatase inhibitor letrozole partly rescued the spermiogenesis defects, indicating that a lack of testosterone associated with excessive aromatase contributes to the testicular phenotype. In vivo and in vitro interaction assays demonstrated that CELF1 binds to Cyp19a1 mRNA, and reporter assays supported the conclusion that CELF1 directly represses Cyp19a1 translation. We conclude that CELF1 downregulates Cyp19a1 (Aromatase) posttranscriptionally to achieve high concentrations of testosterone compatible with spermiogenesis completion. We discuss the implications of these findings with respect to reproductive defects in men, including patients suffering from isolated hypogonadotropic hypogonadism and myotonic dystrophy type I.

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Competitive binding of CUGBP1 and HuR to occludin mRNA controls its translation and modulates epithelial barrier function

Abstract: The present study shows that RNA-binding proteins CUGBP1 and HuR jointly regulate the translation of occludin and play a crucial role in the maintenance of tight junction integrity.

Cited by 68 publications

References 58 publications

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3′ Untranslated Region and Enhances Hepatitis C Virus Replication

Cooperative Repression of Insulin-Like Growth Factor Type 2 Receptor Translation by MicroRNA 195 and RNA-Binding Protein CUGBP1

Hypogonadism Associated with Cyp19a1 (Aromatase) Posttranscriptional Upregulation in Celf1 Knockout Mice

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