Spermidine promotes adipogenesis of 3T3-L1 cells by preventing interaction of ANP32 with HuR and PP2A

2013 ◽  
Vol 453 (3) ◽  
pp. 467-474 ◽  
Author(s):  
Mervi T. Hyvönen ◽  
Taina Koponen ◽  
Janne Weisell ◽  
Marko Pietilä ◽  
Alex R. Khomutov ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Rna Binding ◽  
Binding Protein ◽  
Cytoplasmic Localization ◽  
Polyamine Biosynthesis ◽  
Polyamine Analogues ◽  
Enhancer Binding Protein ◽  
Phosphatase 2A ◽  
Nuclear Phosphoprotein ◽  
Factor C

We have shown previously that the polyamine spermidine is indispensable for differentiation of 3T3-L1 preadipocytes. In the present study, we examined the mechanism of spermidine function by using the polyamine biosynthesis inhibitor α-difluoromethylornithine in combination with the metabolically stable polyamine analogues γ-methylspermidine or (R,R)-α,ω-bismethylspermine. At the early phase of differentiation, spermidine-depleted 3T3-L1 cells showed decreased translation of the transcription factor C/EBPβ (CCAAT/enhancer-binding protein β), decreased PP2A (protein phosphatase 2A) activity and increased cytoplasmic localization of the RNA-binding protein HuR (human antigen R). The amount of HuR bound to C/EBPβ mRNA was reduced, whereas the amount of bound CUGBP2, an inhibitor of C/EBPβ translation, was increased. ANP32 (acidic nuclear phosphoprotein 32) proteins, which are known PP2A inhibitors and HuR ligands, bound more PP2A and HuR in spermidine-depleted than in control cells, whereas immunodepletion of ANP32 proteins from the lysate of spermidine-depleted cells restored PP2A activity. Taken together, our data shows that spermidine promotes C/EBPβ translation in differentiating 3T3-L1 cells, and that this process is controlled by the interaction of ANP32 with HuR and PP2A.

scholarly journals Protein Phosphatase 2A and Cdc7 Kinase Regulate the DNA Unwinding Element-binding Protein in Replication Initiation

2014 ◽  
Vol 289 (52) ◽  
pp. 35987-36000 ◽  
Author(s):  
Yanzhe Gao ◽  
Jianhong Yao ◽  
Sumeet Poudel ◽  
Eric Romer ◽  
Lubna Abu-Niaaj ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Binding Protein ◽  
Protein Phosphatase 2A ◽  
Replication Initiation ◽  
Dna Unwinding ◽  
Element Binding Protein ◽  
Phosphatase 2A ◽  
Cdc7 Kinase

scholarly journals RNA-Binding Protein HuR Is Required for Stabilization of SLC11A1 mRNA and SLC11A1 Protein Expression

2005 ◽  
Vol 25 (18) ◽  
pp. 8139-8149 ◽  
Author(s):  
Yong Zhong Xu ◽  
Sergio Di Marco ◽  
Imed Gallouzi ◽  
Marek Rola-Pleszczynski ◽  
Danuta Radzioch
Keyword(s):  
Posttranscriptional Regulation ◽  
Macrophage Activation ◽  
Rna Binding ◽  
Binding Protein ◽  
Mrna Level ◽  
Rna Binding Protein ◽  
Cytoplasmic Localization ◽  
Differentiated Cells ◽  
Undifferentiated Cells ◽  
Solute Carrier

ABSTRACT The solute carrier family 11 member 1 (SLC11A1, formerly NRAMP1) gene is associated with infectious and autoimmune diseases and plays an important role in macrophage activation. Human SLC11A1 mRNA contains an AU-rich element (ARE) within the 3′ untranslated region; however, its role in the regulation of SLC11A1 gene expression has not been elucidated. Here we analyze the expression of SLC11A1 in human monocytes and HL-60 cells and then use HL-60 cells as a model to determine whether RNA-binding protein HuR is associated with the ARE and involved in SLC11A1 mRNA turnover. Our results demonstrate a binding of HuR to the SLC11A1 ARE in phorbol myristate acetate (PMA)-differentiated cells dramatically increased compared to that in undifferentiated cells. Interestingly, PMA-induced accumulation of cytoplasmic HuR occurs in parallel with an increase in the binding of HuR to SLC11A1 ARE and with an increase in the SLC11A1 mRNA level. This suggests that HuR's cytoplasmic localization plays an important role in the regulation of SLC11A1 expression. We also observe that down-regulation of HuR expression by RNA interference (RNAi) results in a decrease in SLC11A1 expression which can be restored by the addition of recombinant HuR protein to the RNAi-treated cells. Finally, we show that HuR overexpression in HL-60 cells significantly increases the SLC11A1 mRNA stability. Taken together, our data demonstrate that HuR is a key mediator of posttranscriptional regulation and expression of the SLC11A1 gene.

scholarly journals The RNA-binding protein QKI5 is a direct target of C/EBPα and delays macrophage differentiation

2012 ◽  
Vol 23 (9) ◽  
pp. 1628-1635 ◽  
Author(s):  
Haiyan Fu ◽  
Guodong Yang ◽  
Mengying Wei ◽  
Li Liu ◽  
Liang Jin ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Macrophage Differentiation ◽  
Endogenous Expression ◽  
Enhancer Binding Protein ◽  
Reporter Assays ◽  
Direct Target ◽  
Site Blocking

Differentiated macrophages are essential for the innate immune system; however, the molecular mechanisms underlying the generation of macrophages remain largely unknown. Here we show that the RNA-binding protein QKI, mainly QKI-5, is transcriptionally activated in the early differentiated monocytic progenitors when CCAAT/enhancer-binding protein (C/EBP) α is expressed. The forced expression of C/EBPα increases the endogenous expression of QKI. Chromatin immunoprecipitation analysis and reporter assays further confirm that C/EBPα activates the transcription of QKI, primarily by binding to the distal C/EBPα-binding site. Blocking the induction of QKI using RNA interference enhances the expression of endogenous CSF1R and facilitates macrophage differentiation. Further study of the mechanism reveals that QKI-5 facilitates the degradation of CSF1R mRNA by interacting with the distal QRE in the 3′ untranslated region. In summary, we show that in committed macrophage progenitors, C/EBPα-activated QKI-5 negatively regulates macrophage differentiation by down-regulating CSF1R expression, forming a negative feedback loop during macrophage differentiation.

scholarly journals Characterization of Staufen 1 ribonucleoprotein complexes

2004 ◽  
Vol 384 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Cornelia BRENDEL ◽  
Monika REHBEIN ◽  
Hans-Jürgen KREIENKAMP ◽  
Friedrich BUCK ◽  
Dietmar RICHTER ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Protein Phosphatase 1 ◽  
Cell Fractionation ◽  
Dependent Manner ◽  
Ribonucleoprotein Complexes ◽  
Ribonucleoprotein Particles ◽  
Purification Protocol

In Drosophila oocytes and neuroblasts, the double-stranded RNA binding protein Staufen assembles into ribonucleoprotein particles, which mediate cytoplasmic mRNA trafficking and translation. Two different mammalian orthologues also appear to reside in distinct RNA-containing particles. To date, relatively little is known about the molecular composition of Staufen-containing ribonucleoprotein complexes. Here, we have used a novel one-step affinity purification protocol to identify components of Staufen 1-containing particles. Whereas the nucleocytoplasmic RNA-binding protein nucleolin is linked to Staufen in an RNA-dependent manner, the association of protein phosphatase 1, the microtubule-dependent motor protein kinesin and several components of the large and small ribosomal subunits with Staufen ribonucleoprotein complexes is RNA-independent. Notably, all these components do not co-purify with a second RNA-binding protein, hnRNPK (heterogeneous ribonucleoprotein K), demonstrating the high specificity of the purification protocol. Furthermore, pull-down and immunoprecipitation experiments suggest a direct interaction between Staufen 1 and the ribosomal protein P0 in vitro as well as in cells. In cell fractionation and sucrose gradient assays, Staufen co-fractionates with intact ribosomes and polysomes, but not with the isolated 40 S ribosomal subunit. Taken together, these findings imply that, in the cytoplasm of mammalian cells, an association with the ribosomal P-stalk protein P0 recruits Staufen 1 into ribosome-containing ribonucleoprotein particles, which also contain kinesin, protein phosphatase 1 and nucleolin.

scholarly journals Regulated Nuclear-Cytoplasmic Localization of CCAAT/ Enhancer-binding Protein δ in Osteoblasts

2001 ◽  
Vol 276 (18) ◽  
pp. 15354-15361 ◽  
Author(s):  
Julia Billiard ◽  
Yutaka Umayahara ◽  
Kristine Wiren ◽  
Michael Centrella ◽  
Thomas L. McCarthy ◽  
...  
Keyword(s):  
Binding Protein ◽  
Cytoplasmic Localization ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein
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