The RNA-Binding Protein Rasputin/G3BP Enhances the Stability and Translation of Its Target mRNAs

The stability of mRNA is one of the key factors governing the regulation of eukaryotic gene expression and function. Human antigen R (HuR) is an RNA-binding protein that regulates the stability, translation, and nucleus-to-cytoplasm shuttling of its target mRNAs. While HuR is normally localized within the nucleus, it has been shown that HuR binds mRNAs in the nucleus and then escorts the mRNAs to the cytoplasm where HuR protects them from degradation. It contains several RNA recognition motifs, which specifically bind to adenylate and uridylate-rich regions within the 3’-untranslated region of the target mRNA to mediate its effect. Many of the HuR target mRNAs encode proteins important for cell growth, tumorigenesis, angiogenesis, tumor inflammation, invasion and metastasis. HuR overexpression is known to correlate well with high-grade malignancy and poor prognosis in many tumor types. Thus, HuR has emerged as an attractive drug target for cancer therapy. Novel small molecule HuR inhibitors have been identified by high throughput screening and new formulations for targeted delivery of HuR siRNA to tumor cells have been developed with promising anticancer activity. This review summarizes the significant role of HuR in cancer development, progression, and poor treatment response. We will discuss the potential and challenges of targeting HuR therapeutically.

Download Full-text

RNA–Binding Protein HuD as a Versatile Factor in Neuronal and Non–Neuronal Systems

Biology ◽

10.3390/biology10050361 ◽

2021 ◽

Vol 10 (5) ◽

pp. 361

Author(s):

Myeongwoo Jung ◽

Eun-Kyung Lee

Keyword(s):

Gene Expression ◽

Neural Plasticity ◽

Molecular Mechanisms ◽

Neuronal Development ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Novel Treatments ◽

Target Mrnas ◽

Neuronal Systems

HuD (also known as ELAVL4) is an RNA–binding protein belonging to the human antigen (Hu) family that regulates stability, translation, splicing, and adenylation of target mRNAs. Unlike ubiquitously distributed HuR, HuD is only expressed in certain types of tissues, mainly in neuronal systems. Numerous studies have shown that HuD plays essential roles in neuronal development, differentiation, neurogenesis, dendritic maturation, neural plasticity, and synaptic transmission by regulating the metabolism of target mRNAs. However, growing evidence suggests that HuD also functions as a pivotal regulator of gene expression in non–neuronal systems and its malfunction is implicated in disease pathogenesis. Comprehensive knowledge of HuD expression, abundance, molecular targets, and regulatory mechanisms will broaden our understanding of its role as a versatile regulator of gene expression, thus enabling novel treatments for diseases with aberrant HuD expression. This review focuses on recent advances investigating the emerging role of HuD, its molecular mechanisms of target gene regulation, and its disease relevance in both neuronal and non–neuronal systems.

Download Full-text

The Putative RNA-Binding Protein Nrp1 Promotes the Loading of Kinesin-14/Klp2 to the Mitotic Spindle and Is Sequestered Into Heat-Induced Protein Aggregates in Fission Yeast

10.20944/preprints202103.0452.v1 ◽

2021 ◽

Author(s):

Masashi Yukawa ◽

Mitsuki Ohishi ◽

Yusuke Yamada ◽

Takashi Toda

Keyword(s):

Fission Yeast ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Protein Aggregates ◽

Associated Proteins ◽

Spindle Microtubules ◽

The Stability ◽

And Function ◽

Post Transcriptional Regulation

Cells form a bipolar spindle during mitosis to ensure accurate chromosome segregation. Proper spindle architecture is established by a set of kinesin motors and microtubule-associated proteins. In most eukaryotes, kinesin-5 motors are essential for this process, and genetic or chemical inhibition of their activity leads to the emergence of monopolar spindles and cell death. However, these deficiencies can be rescued by simultaneous inactivation of kinesin-14 motors, as they counteract kinesin-5. We conducted detailed genetic analyses in fission yeast to understand the mechanisms driving spindle assembly in the absence of kinesin-5. Here we show that deletion of the nrp1 gene, which encodes a putative RNA-binding protein with unknown function, can rescue temperature sensitivity caused by cut7-22, a fission yeast kinesin-5 mutant. Interestingly, kinesin-14/Klp2 levels on the spindles in the cut7 mutants were significantly reduced by the nrp1 deletion, although the total levels of Klp2 and the stability of spindle microtubules remained unaffected. Moreover, RNA-binding motifs of Nrp1 are essential for its cytoplasmic localization and function. We have also found that a portion of Nrp1 is spatially and functionally sequestered by chaperone-based protein aggregates upon mild heat stress and limits cell division at high temperatures. We propose that Nrp1 might be involved in post-transcriptional regulation through its RNA-binding ability to promote the loading of Klp2 on the spindle microtubules.

Download Full-text

Identification and Functional Outcome of mRNAs Associated with RNA-Binding Protein TIA-1

Molecular and Cellular Biology ◽

10.1128/mcb.25.21.9520-9531.2005 ◽

2005 ◽

Vol 25 (21) ◽

pp. 9520-9531 ◽

Cited By ~ 156

Author(s):

Isabel López de Silanes ◽

Stefanie Galbán ◽

Jennifer L. Martindale ◽

Xiaoling Yang ◽

Krystyna Mazan-Mamczarz ◽

...

Keyword(s):

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Cellular Damage ◽

Necrosis Factor Alpha ◽

Target Mrnas ◽

Common Motif ◽

Tnf Α ◽

Cox 2 ◽

Rna Complexes

ABSTRACT The RNA-binding protein TIA-1 (T-cell intracellular antigen 1) functions as a posttranscriptional regulator of gene expression and aggregates to form stress granules following cellular damage. TIA-1 was previously shown to bind mRNAs encoding tumor necrosis factor alpha (TNF-α) and cyclooxygenase 2 (COX-2), but TIA-1 target mRNAs have not been systematically identified. Here, immunoprecipitation (IP) of TIA-1-RNA complexes, followed by microarray-based identification and computational analysis of bound transcripts, was used to elucidate a common motif present among TIA-1 target mRNAs. The predicted TIA-1 motif was a U-rich, 30- to 37-nucleotide (nt)-long bipartite element forming loops of variable size and a bent stem. The TIA-1 motif was found in the TNF-α and COX-2 mRNAs and in 3,019 additional UniGene transcripts (∼3% of the UniGene database), localizing preferentially to the 3′ untranslated region. The interactions between TIA-1 and target transcripts were validated by IP of endogenous mRNAs, followed by reverse transcription and PCR-mediated detection, and by pulldown of biotinylated RNAs, followed by Western blotting. Further studies using RNA interference revealed that TIA-1 repressed the translation of bound mRNAs. In summary, we report a signature motif present in mRNAs that associate with TIA-1 and provide support to the notion that TIA-1 represses the translation of target transcripts.

Download Full-text

The RNA-binding protein, Rasputin/G3BP, enhances the stability and translation of its target mRNAs

10.1101/2020.01.21.913079 ◽

2020 ◽

Author(s):

John D. Laver ◽

Jimmy Ly ◽

Allison K. Winn ◽

Angelo Karaiskakis ◽

Sichun Lin ◽

...

Keyword(s):

Microarray Analysis ◽

Rna Binding ◽

Rna Binding Proteins ◽

Rna Binding Protein ◽

Stress Granules ◽

Direct Role ◽

Target Mrnas ◽

Core Components ◽

The Stability

SUMMARYG3BP RNA-binding proteins are important components of stress granules (SGs). Here we analyze the role of Drosophila G3BP, Rasputin (RIN), in unstressed cells, where RIN is not SG associated. Immunoprecipitation followed by microarray analysis identified over 550 mRNAs that copurify with RIN. The mRNAs found in SGs are long and translationally silent. In contrast, we find that RIN-bound mRNAs, which encode core components of the transcription, splicing and translation machinery, are short, stable and highly translated. We show that RIN is associated with polysomes and provide evidence for a direct role for RIN and its human homologs in stabilizing and upregulating the translation of their target mRNAs. We propose that when cells are stressed the resulting incorporation of RIN/G3BPs into SGs sequesters them away from their short target mRNAs. This would downregulate the expression of these transcripts, even though they are not incorporated into stress granules.

Download Full-text

Studying RNA-Binding Protein Interactions with Target mRNAs in Eukaryotic Cells: Native Ribonucleoprotein Immunoprecipitation (RIP) Assays

Methods in Molecular Biology - Nuclear Bodies and Noncoding RNAs ◽

10.1007/978-1-4939-2253-6_14 ◽

2014 ◽

pp. 239-246 ◽

Cited By ~ 9

Author(s):

Joseph A. Cozzitorto ◽

Masaya Jimbo ◽

Saswati Chand ◽

Fernando Blanco ◽

Shruti Lal ◽

...

Keyword(s):

Protein Interactions ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Eukaryotic Cells ◽

Target Mrnas

Download Full-text

RNPC1, an RNA-binding protein and a target of the p53 family, is required for maintaining the stability of the basal and stress-induced p21 transcript

Genes & Development ◽

10.1101/gad.1463306 ◽

2006 ◽

Vol 20 (21) ◽

pp. 2961-2972 ◽

Cited By ~ 89

Author(s):

L. Shu ◽

W. Yan ◽

X. Chen

Keyword(s):

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

P53 Family ◽

The Stability

Download Full-text

Polyamines Regulate the Stability of Activating Transcription Factor-2 mRNA through RNA-binding Protein HuR in Intestinal Epithelial Cells

Molecular Biology of the Cell ◽

10.1091/mbc.e07-07-0675 ◽

2007 ◽

Vol 18 (11) ◽

pp. 4579-4590 ◽

Cited By ~ 55

Author(s):

Lan Xiao ◽

Jaladanki N. Rao ◽

Tongtong Zou ◽

Lan Liu ◽

Bernard S. Marasa ◽

...

Keyword(s):

Transcription Factor ◽

Rna Binding ◽

Binding Protein ◽

Critical Role ◽

Rna Binding Protein ◽

Gene Promoter ◽

Protein Levels ◽

Ribonucleoprotein Complexes ◽

Activating Transcription Factor ◽

The Stability

Maintenance of intestinal mucosal epithelial integrity requires polyamines that modulate the expression of various genes involved in cell proliferation and apoptosis. Recently, polyamines were shown to regulate the subcellular localization of the RNA-binding protein HuR, which stabilizes its target transcripts such as nucleophosmin and p53 mRNAs. The activating transcription factor-2 (ATF-2) mRNA encodes a member of the ATF/CRE-binding protein family of transcription factors and was computationally predicted to be a target of HuR. Here, we show that polyamines negatively regulate ATF-2 expression posttranscriptionally and that polyamine depletion stabilizes ATF-2 mRNA by enhancing the interaction of the 3′-untranslated region (UTR) of ATF-2 with cytoplasmic HuR. Decreasing cellular polyamines by inhibiting ornithine decarboxylase (ODC) with α-difluoromethylornithine increased the levels of ATF-2 mRNA and protein, whereas increasing polyamines by ectopic ODC overexpression repressed ATF-2 expression. Polyamine depletion did not alter transcription via the ATF-2 gene promoter but increased the stability of ATF-2 mRNA. Increased cytoplasmic HuR in polyamine-deficient cells formed ribonucleoprotein complexes with the endogenous ATF-2 mRNA and specifically bound to 3′-UTR of ATF-2 mRNA on multiple nonoverlapping 3′-UTR segments. Adenovirus-mediated HuR overexpression elevated ATF-2 mRNA and protein levels, whereas HuR silencing rendered the ATF-2 mRNA unstable and prevented increases in ATF-2 mRNA and protein. Furthermore, inhibition of ATF-2 expression prevented the increased resistance of polyamine-deficient cells to apoptosis induced by treatment with tumor necrosis factor-α and cycloheximide. These results indicate that polyamines modulate the stability of ATF-2 mRNA by altering cytoplasmic HuR levels and that polyamine-modulated ATF-2 expression plays a critical role in regulating epithelial apoptosis.

Download Full-text