hnRNP A1 Selectively Interacts Through its Gly-rich Domain with Different RNA-binding Proteins

The heterogeneous nuclear RNP (hnRNP) A1 protein is one of the major pre-mRNA/mRNA binding proteins in eukaryotic cells and one of the most abundant proteins in the nucleus. It is localized to the nucleoplasm and it also shuttles between the nucleus and the cytoplasm. The amino acid sequence of A1 contains two RNP motif RNA-binding domains (RBDs) at the amino terminus and a glycine-rich domain at the carboxyl terminus. This configuration, designated 2x RBD-Gly, is representative of perhaps the largest family of hnRNP proteins. Unlike most nuclear proteins characterized so far, A1 (and most 2x RBD-Gly proteins) does not contain a recognizable nuclear localization signal (NLS). We have found that a segment of ca. 40 amino acids near the carboxyl end of the protein (designated M9) is necessary and sufficient for nuclear localization; attaching this segment to the bacterial protein beta-galactosidase or to pyruvate kinase completely localized these otherwise cytoplasmic proteins to the nucleus. The RBDs and another RNA binding motif found in the glycine-rich domain, the RGG box, are not required for A1 nuclear localization. M9 is a novel type of nuclear localization domain as it does not contain sequences similar to classical basic-type NLS. Interestingly, sequences similar to M9 are found in other nuclear RNA-binding proteins including hnRNP A2.

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In vivo and in vitro arginine methylation of RNA-binding proteins.

Molecular and Cellular Biology ◽

10.1128/mcb.15.5.2800 ◽

1995 ◽

Vol 15 (5) ◽

pp. 2800-2808 ◽

Cited By ~ 214

Author(s):

Q Liu ◽

G Dreyfuss

Keyword(s):

Hela Cells ◽

Posttranslational Modifications ◽

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Arginine Methylation ◽

Hnrnp A1 ◽

Arginine Residues

Heterogenous nuclear ribonucleoproteins (hnRNPs) bind pre-mRNAs and facilitate their processing into mRNAs. Many of the hnRNPs undergo extensive posttranslational modifications including methylation on arginine residues. hnRNPs contain about 65% of the total NG,NG-dimethylarginine found in the cell nucleus. The role of this modification is not known. Here we identify the hnRNPs that are methylated in HeLa cells and demonstrate that most of the pre-mRNA-binding proteins receive this modification. Using recombinant human hnRNP A1 as a substrate, we have partially purified and characterized a protein-arginine N-methyltransferase specific for hnRNPs from HeLa cells. This methyltransferase can methylate the same subset of hnRNPs in vitro as are methylated in vivo. Furthermore, it can also methylate other RNA-binding proteins that contain the RGG motif RNA-binding domain. This activity is evolutionarily conserved from lower eukaryotes to mammals, suggesting that methylation has a significant role in the function of RNA-binding proteins.

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Modulation of the expression of p16INK4a and p14ARF by hnRNP A1 and A2 RNA binding proteins: Implications for cellular senescence

Journal of Cellular Physiology ◽

10.1002/jcp.10147 ◽

2002 ◽

Vol 193 (1) ◽

pp. 19-25 ◽

Cited By ~ 27

Author(s):

Deguang Zhu ◽

Gang Xu ◽

Shanaz Ghandhi ◽

Karen Hubbard

Keyword(s):

Cellular Senescence ◽

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Hnrnp A1

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Structural basis for terminal loop recognition and processing of pri-miRNA-18a by hnRNP A1

10.1101/178855 ◽

2017 ◽

Cited By ~ 1

Author(s):

Hamed Kooshapur ◽

Nila Roy Choudhury ◽

Bernd Simon ◽

Max Mühlbauer ◽

Alexander Jussupow ◽

...

Keyword(s):

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Structural Basis ◽

Mirna Biogenesis ◽

Rna Recognition ◽

Hnrnp A1 ◽

Sequence Motifs ◽

Terminal Loop ◽

Recognition Motifs

Post-transcriptional mechanisms play a predominant role in the control of microRNA (miRNA) production. Recognition of the terminal loop of precursor miRNAs by RNA-binding proteins (RBPs) influences their processing; however, the mechanistic and structural basis for how levels of individual or subsets of miRNAs are regulated is mostly unexplored. We previously described a role for hnRNP A1, an RBP implicated in many aspects of RNA processing, as an auxiliary factor that promotes the Microprocessor-mediated processing of pri-mir-18a. Here, we reveal the mechanistic basis for this stimulatory role of hnRNP A1 by combining integrative structural biology with biochemical and functional assays. We demonstrate that hnRNP A1 forms a 1:1 complex with pri-mir-18a that involves binding of both RNA recognition motifs (RRMs) to cognate RNA sequence motifs in the conserved terminal loop of pri-mir-18a. Terminal loop binding induces an allosteric destabilization of base-pairing in the pri-mir-18a stem that promotes its down-stream processing. Our results highlight terminal loop RNA recognition by RNA-binding proteins as a general principle of miRNA biogenesis and regulation.

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PARylation regulates stress granule dynamics, phase separation, and neurotoxicity of disease-related RNA-binding proteins

10.1101/396465 ◽

2018 ◽

Cited By ~ 1

Author(s):

Yongjia Duan ◽

Aiying Du ◽

Jinge Gu ◽

Gang Duan ◽

Chen Wang ◽

...

Keyword(s):

Phase Separation ◽

Posttranslational Modifications ◽

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Binding Motif ◽

Hnrnp A1 ◽

Rnp Granules

SUMMARYMutations in RNA-binding proteins localized in ribonucleoprotein (RNP) granules, such as hnRNP A1 and TDP-43, promote aberrant protein aggregations, which are pathological hallmarks in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Protein posttranslational modifications (PTMs) are known to regulate RNP granules. In this study, we investigate the function of PARylation, an important PTM involved in DNA damage repair and cell death, in RNP-related neurodegeneration. We reveal that PARylation levels are a major regulator of the dynamic assembly-disassembly of RNP granules, and the disease-related RNPs such as hnRNP A1 and TDP-43 can both be PARylated and bind to PARylated proteins. We further identify the PARylation site of hnRNP A1 at K298, which controls the cytoplasmic translocation of hnRNP A1 in response to stress, as well as the PAR-binding motif (PBM) of hnRNP A1, which is required for the delivery and association of hnRNP A1 to stress granules. Moreover, we show that PAR not only dramatically enhances the liquid-liquid phase separation of hnRNP A1, but also promotes the co-phase separation of hnRNP A1 and TDP-43 in vitro and their interaction in vivo. Finally, we establish that both genetic and pharmacological inhibition of PARP mitigates hnRNP A1 and TDP-43-mediated neurotoxicity in cell and Drosophila models of ALS. Together, our findings indicate a novel and crucial role of PARylation in regulating the assembly and the dynamics of RNP granules, and dysregulation of PARylation may contribute to ALS disease pathogenesis.

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Roles of Plant Glycine-Rich RNA-Binding Proteins in Development and Stress Responses

International Journal of Molecular Sciences ◽

10.3390/ijms22115849 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5849

Author(s):

Liqun Ma ◽

Ke Cheng ◽

Jinyan Li ◽

Zhiqi Deng ◽

Chunjiao Zhang ◽

...

Keyword(s):

Stress Responses ◽

Binding Proteins ◽

Rna Binding ◽

Rna Binding Proteins ◽

Rna Recognition Motif ◽

Functional Roles ◽

Rich Domain ◽

C Terminus ◽

Cold Shock Domain ◽

Target Rna

In recent years, much progress has been made in elucidating the functional roles of plant glycine-rich RNA-binding proteins (GR-RBPs) during development and stress responses. Canonical GR-RBPs contain an RNA recognition motif (RRM) or a cold-shock domain (CSD) at the N-terminus and a glycine-rich domain at the C-terminus, which have been associated with several different RNA processes, such as alternative splicing, mRNA export and RNA editing. However, many aspects of GR-RBP function, the targeting of their RNAs, interacting proteins and the consequences of the RNA target process are not well understood. Here, we discuss recent findings in the field, newly defined roles for GR-RBPs and the actions of GR-RBPs on target RNA metabolism.

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