Tandem Phosphorylation of Serines 221 and 318 by Protein Kinase Cδ Coordinates mRNA Binding and Nucleocytoplasmic Shuttling of HuR

Doller, Anke; Schlepckow, Kai; Schwalbe, Harald; Pfeilschifter, Josef; Eberhardt, W.

doi:10.1128/mcb.01373-09

Cited by 95 publications

(128 citation statements)

References 64 publications

(91 reference statements)

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“…On the other hand, PKC has been implicated in the stabilization of a variety of other mRNAs such as, p21, GAP-43 and IL-1β itself [19,20,22,23]. Importantly, PKC has been convincingly implicated in COX-2 mRNA stabilization in several recent studies [21,31,44,54,68] and, indirectly, in IL-6 mRNA stabilization in one older study [69]. In astrocytes, PKC was previously shown to be important for IL-6 induction after IL-1β [70].…”

Section: Discussionmentioning

confidence: 99%

IL-1β potently stabilizes IL-6 mRNA in human astrocytes

Spooren

Mestdagh

Rondou

et al. 2011

Biochemical Pharmacology

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Uncontrolled expression of IL-6 in the central nervous system is associated with neurodegenerative pathology and glioma development. Astrocytes are the predominant source of IL-6 in the central nervous system, and they are characteristically susceptible to synergistic IL-6 expression. Combined β-adrenergic and TNF-receptor triggering induces synergistic IL-6 expression in 1321N1 cells via a transcriptional enhancer mechanism. Here, we have investigated the molecular basis of the very potent "super"-synergistic IL-6 expression that is apparent after combined treatment of astrocytes with a β-adrenergic agonist, isoproterenol, and the inflammatory cytokines TNF-α and IL-1β. We found that IL-1β treatment strengthens the IL-6 synergy by inducing a distinct stabilization of IL-6 mRNA. Surprisingly, the mRNAstabilizing effect seems to be dependent on protein kinase C (PKC), but not on the prototypical mRNA-stabilizing kinase p38. Moreover, although the mRNA-binding protein HuR basally stabilizes IL-6 mRNA, the mRNA-stabilizing effect of IL-1β is independent of HuR. Our data using pharmacological inhibitors suggest PKC is an important modulator of IL-6 expression in the central nervous system and this might have therapeutic implications.

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Section: Discussionmentioning

confidence: 99%

IL-1β potently stabilizes IL-6 mRNA in human astrocytes

Spooren

Mestdagh

Rondou

et al. 2011

Biochemical Pharmacology

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“…The most studied modification of the HuR proteins is phosphorylation. It has been demonstrated that phosphorylation at specific serines or a threonine of HuR can lead to altered cellular localization of the protein and, in one case, can increase the RNA-binding affinity of HuR (Doller et al 2010;Srikantan and Gorospe 2012). One report indicated that heat shock induces ubiquitination of HuR at Lys 182, leading to degradation of HuR and decreased levels of HuR target mRNA abundance (Abdelmohsen et al 2009).…”

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confidence: 99%

The p97–UBXD8 complex destabilizes mRNA by promoting release of ubiquitinated HuR from mRNP

Zhou

Geng²,

Luo³

et al. 2013

Genes Dev.

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The assembly and disassembly of ribonucleoproteins (RNPs) are dynamic processes that control every step of RNA metabolism, including mRNA stability. However, our knowledge of how RNP remodeling is achieved is largely limited to RNA helicase functions. Here, we report a previously unknown mechanism that implicates the ATPase p97, a protein-remodeling machine, in the dynamic regulation of mRNP disassembly. We found that p97 and its cofactor, UBXD8, destabilize p21, MKP-1, and SIRT1, three established mRNA targets of the RNA-binding protein HuR, by promoting release of HuR from mRNA. Importantly, ubiquitination of HuR with a short K29 chain serves as the signal for release. When cells are subjected to stress conditions, the steady-state levels of HuR ubiquitination change, suggesting a new mechanism through which HuR mediates the stress response. Our studies reveal a new paradigm in RNA biology: nondegradative ubiquitin signaling-dependent disassembly of mRNP promoted by the p97-UBXD8 complex to control mRNA stability.[Keywords: HuR; mRNA stability; ubiquitin] Supplemental material is available for this article. RNA-binding proteins (RBPs) recognize specific cis-regulatory mRNA elements to form ribonucleoprotein (RNP) complexes, which control every aspect of the life of a mRNA from pre-mRNA processing to mRNA localization, translation, and turnover (Moore 2005;Keene 2007). A different array of proteins is loaded onto pre-mRNA/ mRNA during every step of post-transcriptional mRNA metabolism, making assembly and disassembly of mRNPs a highly dynamic process. Precise regulation of this process is essential, as failure to assemble or disassemble an appropriate mRNP complex leads to disruption of downstream events such as mRNA export, translation, and decay, which have direct impacts on gene expression (Hieronymus and Silver 2004;Keene 2010;Wilusz and Wilusz 2010). Despite its fundamental importance, our knowledge of mRNP remodeling is limited and mostly emerged from two types of studies involving either RNA helicases or individual protein factors that associate with a defined mRNP in a spatially and/or temporally regu- RNA helicases of the DEAD-box family are an important group of RNA-remodeling proteins. These proteins are ATPases that use ATP to unwind RNA duplexes and remodel RNA-protein complexes (Linder and Jankowsky 2011; Pyle 2011). Distinct RNA helicases play important roles in every step of RNA metabolism (Linder and Jankowsky 2011). However, given the central role of RNA molecules in every aspect of cellular metabolism, it is expected that other types of ATPases function as additional motor proteins in RNA metabolism. In this study, we describe a previously uncharacterized role of a member of the AAA (ATPases associated with diverse cellular activities) family of proteins, vasolin-containing protein (VCP)/p97 (also called cdc48 in yeast), in mRNA stability control.p97 is considered a protein-remodeling machine (Meyer et al. 2012). It has two ATPase domains, D1 and D2, and uses the energy of ATP hydrolysis to r...

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“…Upon HuR phosphorylation, different cellular responses have been described (Abdelmohsen, 2007 a,b;Doller et al 2008;Kim 2008a-c). Whereas the HuR capability for binding to RNA targets increases or decreases when Chk2 phosphorylates HuR at Ser88 or Ser100 residues, respectively (Abdelmohsen et al 2007b), the addition of a phosphate group to Ser158, Ser221 and Ser318 by PKC favors the cytoplasmic localization of HuR instead of the preferred nuclear localization of the protein (Doller et al 2008(Doller et al , 2009, along with an enhancement in the mRNA binding (Doller et al 2007). …”

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confidence: 99%

HuR thermal stability is dependent on domain binding and upon phosphorylation

2012

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Abstract:Human antigen R (HuR) is a multitasking RNA binding protein involved in posttranscriptional regulation by recognizing Adenine and uracile Rich Elements (AREs) placed at the 3′ untranslated regions of mRNAs. The modular architecture of the protein, which consists of two N-terminal RNA recognition motifs (RRMs) in tandem spaced from a third one by a nuclear-cytoplasmic shuttling sequence, controls stability of many mRNA targets, as well as their translation rates. A higher level of regulation comes from the fact that both localization and function of HuR is strictly regulated by phosphorylation. Here, we report how the thermal stability of RRM2 is decreased by the presence of RRM1, indicating that both domains are interacting in solution. In addition, even though no significant structural changes are observed among mutants of HuR RRM12 mimicking phosphorylated species, slight differences in stability are appreciable, which may explain the RNA binding activity of HuR.Response to Reviewers: See attachment. Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporation

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Tandem Phosphorylation of Serines 221 and 318 by Protein Kinase Cδ Coordinates mRNA Binding and Nucleocytoplasmic Shuttling of HuR

Cited by 95 publications

References 64 publications

IL-1β potently stabilizes IL-6 mRNA in human astrocytes

IL-1β potently stabilizes IL-6 mRNA in human astrocytes

The p97–UBXD8 complex destabilizes mRNA by promoting release of ubiquitinated HuR from mRNP

HuR thermal stability is dependent on domain binding and upon phosphorylation

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