scholarly journals A nuclear localization domain in the hnRNP A1 protein.

1995 ◽  
Vol 129 (3) ◽  
pp. 551-560 ◽  
Author(s):  
H Siomi ◽  
G Dreyfuss

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.

1996 ◽  
Vol 259 (3) ◽  
pp. 337-348 ◽  
Author(s):  
Luca Cartegni ◽  
Mariacaterina Maconi ◽  
Elena Morandi ◽  
Fabio Cobianchi ◽  
Silvano Riva ◽  
...  

1995 ◽  
Vol 108 (2) ◽  
pp. 545-555 ◽  
Author(s):  
F. Weighardt ◽  
G. Biamonti ◽  
S. Riva

hnRNP A1 (34 kDa) is an RNA binding protein consisting of two tandemly arranged RNA binding domains C-terminally linked to a glycine-rich auxiliary domain (2 × RBD-Gly). A1 belongs to the set of polypeptides that bind nascent hnRNA in the nucleus to form the so called hnRNP complexes. These complexes seem to be involved both in pre-mRNA processing and in the nuclear export of mRNA. In fact A1, along with other hnRNP proteins, is exported from the nucleus probably bound to mRNA and is immediately re-imported. A1 nuclear re-import, which requires active transcription, is not mediated by a canonical nuclear localisation signal (NLS). To identify the determinants of A1 subcellular localisation we developed an expression vector for studying the localisation, in transiently transfected cells, of the different structural motifs of A1 fused to a small reporter protein (chloramphenicol acetyltransferase, CAT; 26 kDa). We demonstrate that a 30 amino acid sequence in the glycine-rich domain (YNDFGNYNNQSSNFGPMKGGNFGGRSSGPY), which bears no resemblance to canonical NLS, is necessary and sufficient to target the protein to the nucleus. Our data suggest that this targeting sequence might act by mediating the interaction of A1 with a NLS-containing nuclear import complex. On the other hand, the nuclear export of A1 requires at least one RNA binding domain in accord with the hypothesis that A1 exits from the nucleus bound to mRNA. We propose a mechanism for the nucleo-cytoplasmic shuttling of A1 that envisages a specific role for the different structural domains and can explain the dependence of nuclear import from active transcription.


2010 ◽  
Vol 30 (10) ◽  
pp. 2552-2562 ◽  
Author(s):  
Courtney M. Van Dusen ◽  
Lily Yee ◽  
Lisa M. McNally ◽  
Mark T. McNally

ABSTRACT Heterogeneous nuclear ribonucleoprotein (hnRNP) H and F are members of a closely related subfamily of hnRNP proteins that are implicated in many aspects of RNA processing. hnRNP H and F are alternative splicing factors for numerous U2- and U12-dependent introns. The proteins have three RNA binding domains and two glycine-rich domains and localize to both the nucleus and cytoplasm, but little is known about which domains govern subcellular localization or splicing activity. We show here that the central glycine-tyrosine-arginine-rich (GYR) domain is responsible for nuclear localization, and a nonclassical nuclear localization signal (NLS) was mapped to a short, highly conserved sequence whose activity was compromised by point mutations. Glutathione S-transferase (GST) pulldown assays demonstrated that the hnRNP H NLS interacts with the import receptor transportin 1. Finally, we show that hnRNP H/F are transcription-dependent shuttling proteins. Collectively, the results suggest that hnRNP H and F are GYR domain-dependent shuttling proteins whose posttranslational modifications may alter nuclear localization and hence function.


2018 ◽  
Author(s):  
Yongjia Duan ◽  
Aiying Du ◽  
Jinge Gu ◽  
Gang Duan ◽  
Chen Wang ◽  
...  

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.


2021 ◽  
Author(s):  
Simon H. Stitzinger ◽  
Salma Sohrabi-Jahromi ◽  
Johannes Söding

AbstractNumerous cellular processes rely on the binding of proteins with high affinity to specific sets of RNAs. Yet most RNA binding domains display low specificity and affinity, to the extent that for most RNA-binding domains, the enrichment of the best binding motif measured by high-throughput RNA SELEX or RNA bind-n-seq is usually below 10-fold, dramatically lower than that of DNA-binding domains. Here, we develop a thermodynamic model to predict the binding affinity for proteins with any number of RNA-binding domains given the affinities of their isolated domains. For the four proteins in which affinities for individual domains have been measured the model predictions are in good agreement with experimental values. The model gives insight into how proteins with multiple RNA-binding domains can reach affinities and specificities orders of magnitude higher than their individual domains. Our results contribute towards resolving the conundrum of missing specificity and affinity of RNA binding proteins and underscore the need for bioinformatic methods that can learn models for multi-domain RNA binding proteins from high-throughput in-vitro and in-vivo experiments.


2021 ◽  
Vol 9 (3) ◽  
pp. 34
Author(s):  
Thomas E. Forman ◽  
Brenna J. C. Dennison ◽  
Katherine A. Fantauzzo

Cranial neural crest (NC) cells delaminate from the neural folds in the forebrain to the hindbrain during mammalian embryogenesis and migrate into the frontonasal prominence and pharyngeal arches. These cells generate the bone and cartilage of the frontonasal skeleton, among other diverse derivatives. RNA-binding proteins (RBPs) have emerged as critical regulators of NC and craniofacial development in mammals. Conventional RBPs bind to specific sequence and/or structural motifs in a target RNA via one or more RNA-binding domains to regulate multiple aspects of RNA metabolism and ultimately affect gene expression. In this review, we discuss the roles of RBPs other than core spliceosome components during human and mouse NC and craniofacial development. Where applicable, we review data on these same RBPs from additional vertebrate species, including chicken, Xenopus and zebrafish models. Knockdown or ablation of several RBPs discussed here results in altered expression of transcripts encoding components of developmental signaling pathways, as well as reduced cell proliferation and/or increased cell death, indicating that these are common mechanisms contributing to the observed phenotypes. The study of these proteins offers a relatively untapped opportunity to provide significant insight into the mechanisms underlying gene expression regulation during craniofacial morphogenesis.


1993 ◽  
Vol 13 (10) ◽  
pp. 6114-6123
Author(s):  
M J Matunis ◽  
E L Matunis ◽  
G Dreyfuss

The expression of RNA polymerase II transcripts can be regulated at the posttranscriptional level by RNA-binding proteins. Although extensively characterized in metazoans, relatively few RNA-binding proteins have been characterized in the yeast Saccharomyces cerevisiae. Three major proteins are cross-linked by UV light to poly(A)+ RNA in living S. cerevisiae cells. These are the 72-kDa poly(A)-binding protein and proteins of 60 and 50 kDa (S.A. Adam, T.Y. Nakagawa, M.S. Swanson, T. Woodruff, and G. Dreyfuss, Mol. Cell. Biol. 6:2932-2943, 1986). Here, we describe the 60-kDa protein, one of the major poly(A)+ RNA-binding proteins in S. cerevisiae. This protein, PUB1 [for poly(U)-binding protein 1], was purified by affinity chromatography on immobilized poly(rU), and specific monoclonal antibodies to it were produced. UV cross-linking demonstrated that PUB1 is bound to poly(A)+ RNA (mRNA or pre-mRNA) in living cells, and it was detected primarily in the cytoplasm by indirect immunofluorescence. The gene for PUB1 was cloned and sequenced, and the sequence was found to predict a 51-kDa protein with three ribonucleoprotein consensus RNA-binding domains and three glutamine- and asparagine-rich auxiliary domains. This overall structure is remarkably similar to the structures of the Drosophila melanogaster elav gene product, the human neuronal antigen HuD, and the cytolytic lymphocyte protein TIA-1. Each of these proteins has an important role in development and differentiation, potentially by affecting RNA processing. PUB1 was found to be nonessential in S. cerevisiae by gene replacement; however, further genetic analysis should reveal important features of this class of RNA-binding proteins.


2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jeetayu Biswas ◽  
Vivek L. Patel ◽  
Varun Bhaskar ◽  
Jeffrey A. Chao ◽  
Robert H. Singer ◽  
...  

Abstract The IGF2 mRNA-binding proteins (ZBP1/IMP1, IMP2, IMP3) are highly conserved post-transcriptional regulators of RNA stability, localization and translation. They play important roles in cell migration, neural development, metabolism and cancer cell survival. The knockout phenotypes of individual IMP proteins suggest that each family member regulates a unique pool of RNAs, yet evidence and an underlying mechanism for this is lacking. Here, we combine systematic evolution of ligands by exponential enrichment (SELEX) and NMR spectroscopy to demonstrate that the major RNA-binding domains of the two most distantly related IMPs (ZBP1 and IMP2) bind to different consensus sequences and regulate targets consistent with their knockout phenotypes and roles in disease. We find that the targeting specificity of each IMP is determined by few amino acids in their variable loops. As variable loops often differ amongst KH domain paralogs, we hypothesize that this is a general mechanism for evolving specificity and regulation of the transcriptome.


2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Dustin Haskell ◽  
Anna Zinovyeva

Abstract MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) regulate gene expression at the post-transcriptional level, but the extent to which these key regulators of gene expression coordinate their activities and the precise mechanisms of this coordination are not well understood. RBPs often have recognizable RNA binding domains that correlate with specific protein function. Recently, several RBPs containing K homology (KH) RNA binding domains were shown to work with miRNAs to regulate gene expression, raising the possibility that KH domains may be important for coordinating with miRNA pathways in gene expression regulation. To ascertain whether additional KH domain proteins functionally interact with miRNAs during Caenorhabditis elegans development, we knocked down twenty-four genes encoding KH-domain proteins in several miRNA sensitized genetic backgrounds. Here, we report that a majority of the KH domain-containing genes genetically interact with multiple miRNAs and Argonaute alg-1. Interestingly, two KH domain genes, predicted splicing factors sfa-1 and asd-2, genetically interacted with all of the miRNA mutants tested, whereas other KH domain genes showed genetic interactions only with specific miRNAs. Our domain architecture and phylogenetic relationship analyses of the C. elegans KH domain-containing proteins revealed potential groups that may share both structure and function. Collectively, we show that many C. elegans KH domain RBPs functionally interact with miRNAs, suggesting direct or indirect coordination between these two classes of post-transcriptional gene expression regulators.


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