scholarly journals Emerging Roles for 3′ UTRs in Neurons

2020 ◽  
Vol 21 (10) ◽  
pp. 3413
Author(s):  
Bongmin Bae ◽  
Pedro Miura

The 3′ untranslated regions (3′ UTRs) of mRNAs serve as hubs for post-transcriptional control as the targets of microRNAs (miRNAs) and RNA-binding proteins (RBPs). Sequences in 3′ UTRs confer alterations in mRNA stability, direct mRNA localization to subcellular regions, and impart translational control. Thousands of mRNAs are localized to subcellular compartments in neurons—including axons, dendrites, and synapses—where they are thought to undergo local translation. Despite an established role for 3′ UTR sequences in imparting mRNA localization in neurons, the specific RNA sequences and structural features at play remain poorly understood. The nervous system selectively expresses longer 3′ UTR isoforms via alternative polyadenylation (APA). The regulation of APA in neurons and the neuronal functions of longer 3′ UTR mRNA isoforms are starting to be uncovered. Surprising roles for 3′ UTRs are emerging beyond the regulation of protein synthesis and include roles as RBP delivery scaffolds and regulators of alternative splicing. Evidence is also emerging that 3′ UTRs can be cleaved, leading to stable, isolated 3′ UTR fragments which are of unknown function. Mutations in 3′ UTRs are implicated in several neurological disorders—more studies are needed to uncover how these mutations impact gene regulation and what is their relationship to disease severity.

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Junnan Fang

Centrosomes, functioning as microtubule organizing centers, are composed of a proteinaceous matrix of pericentriolar material (PCM) that surrounds a pair of centrioles. Drosophila Pericentrin (Pcnt)-like protein (PLP) is a key component of the centrosome that serves as a scaffold for PCM assembly. The disruption of plp in Drosophila results in embryonic lethality, while the deregulation of Pcnt in humans is associated with MOPD II and Trisomy 21.We recently found plp mRNA localizes to Drosophila embryonic centrosomes. While RNA is known to associate with centrosomes in diverse cell types, the elements required for plp mRNA localization to centrosomes remains completely unknown. Additionally, how plp translation is regulated to accommodate rapid cell divisions during early embryogenesis is unclear. RNA localization coupled with translational control is a conserved mechanism that functions in diverse cellular processes. Control of mRNA localization and translation is mediated by RNA-binding proteins (RBPs). We find PLP protein expression is specifically promoted by an RNA-binding protein, Orb, during embryogenesis; moreover, plp mRNA interacts with Orb. Importantly, we find overexpression of full-length PLP can rescue cell division defects and embryonic lethality caused by orb depletion. We aim to uncover the mechanisms underlying embryonic plp mRNA localization and function and how Orb regulates plp translation.


2020 ◽  
Vol 29 (R1) ◽  
pp. R89-R99
Author(s):  
Deivid Carvalho Rodrigues ◽  
Marat Mufteev ◽  
James Ellis

Abstract The methyl-CpG-binding protein 2 (MECP2) is a critical global regulator of gene expression. Mutations in MECP2 cause neurodevelopmental disorders including Rett syndrome (RTT). MECP2 exon 2 is spliced into two alternative messenger ribonucleic acid (mRNA) isoforms encoding MECP2-E1 or MECP2-E2 protein isoforms that differ in their N-termini. MECP2-E2, isolated first, was used to define the general roles of MECP2 in methyl-deoxyribonucleic acid (DNA) binding, targeting of transcriptional regulatory complexes, and its disease-causing impact in RTT. It was later found that MECP2-E1 is the most abundant isoform in the brain and its exon 1 is also mutated in RTT. MECP2 transcripts undergo alternative polyadenylation generating mRNAs with four possible 3′untranslated region (UTR) lengths ranging from 130 to 8600 nt. Together, the exon and 3′UTR isoforms display remarkable abundance disparity across cell types and tissues during development. These findings indicate discrete means of regulation and suggest that protein isoforms perform non-overlapping roles. Multiple regulatory programs have been explored to explain these disparities. DNA methylation patterns of the MECP2 promoter and first intron impact MECP2-E1 and E2 isoform levels. Networks of microRNAs and RNA-binding proteins also post-transcriptionally regulate the stability and translation efficiency of MECP2 3′UTR isoforms. Finally, distinctions in biophysical properties in the N-termini between MECP2-E1 and E2 lead to variable protein stabilities and DNA binding dynamics. This review describes the steps taken from the discovery of MECP2, the description of its key functions, and its association with RTT, to the emergence of evidence revealing how MECP2 isoforms are differentially regulated at the transcriptional, post-transcriptional and post-translational levels.


2021 ◽  
Vol 12 ◽  
Author(s):  
Lindsey V. Soles ◽  
Yongsheng Shi

The majority of eukaryotic genes produce multiple mRNA isoforms by using alternative poly(A) sites in a process called alternative polyadenylation (APA). APA is a dynamic process that is highly regulated in development and in response to extrinsic or intrinsic stimuli. Mis-regulation of APA has been linked to a wide variety of diseases, including cancer, neurological and immunological disorders. Since the first example of APA was described 40 years ago, the regulatory mechanisms of APA have been actively investigated. Conventionally, research in this area has focused primarily on the roles of regulatory cis-elements and trans-acting RNA-binding proteins. Recent studies, however, have revealed important functions for epigenetic mechanisms, including DNA and histone modifications and higher-order chromatin structures, in APA regulation. Here we will discuss these recent findings and their implications for our understanding of the crosstalk between epigenetics and mRNA 3'-end processing.


2020 ◽  
Vol 21 (8) ◽  
pp. 2981
Author(s):  
Zemfira N. Karamysheva ◽  
Sneider Alexander Gutierrez Guarnizo ◽  
Andrey L. Karamyshev

Leishmaniasis represents a serious health problem worldwide and drug resistance is a growing concern. Leishmania parasites use unusual mechanisms to control their gene expression. In contrast to many other species, they do not have transcriptional regulation. The lack of transcriptional control is mainly compensated by post-transcriptional mechanisms, including tight translational control and regulation of mRNA stability/translatability by RNA-binding proteins. Modulation of translation plays a major role in parasite survival and adaptation to dramatically different environments during change of host; however, our knowledge of fine molecular mechanisms of translation in Leishmania remains limited. Here, we review the current progress in our understanding of how changes in the translational machinery promote parasite differentiation during transmission from a sand fly to a mammalian host, and discuss how translational reprogramming can contribute to the development of drug resistance.


2021 ◽  
Vol 8 ◽  
Author(s):  
Alejandro Velázquez-Cruz ◽  
Blanca Baños-Jaime ◽  
Antonio Díaz-Quintana ◽  
Miguel A. De la Rosa ◽  
Irene Díaz-Moreno

Cell signaling mechanisms modulate gene expression in response to internal and external stimuli. Cellular adaptation requires a precise and coordinated regulation of the transcription and translation processes. The post-transcriptional control of mRNA metabolism is mediated by the so-called RNA-binding proteins (RBPs), which assemble with specific transcripts forming messenger ribonucleoprotein particles of highly dynamic composition. RBPs constitute a class of trans-acting regulatory proteins with affinity for certain consensus elements present in mRNA molecules. However, these regulators are subjected to post-translational modifications (PTMs) that constantly adjust their activity to maintain cell homeostasis. PTMs can dramatically change the subcellular localization, the binding affinity for RNA and protein partners, and the turnover rate of RBPs. Moreover, the ability of many RBPs to undergo phase transition and/or their recruitment to previously formed membrane-less organelles, such as stress granules, is also regulated by specific PTMs. Interestingly, the dysregulation of PTMs in RBPs has been associated with the pathophysiology of many different diseases. Abnormal PTM patterns can lead to the distortion of the physiological role of RBPs due to mislocalization, loss or gain of function, and/or accelerated or disrupted degradation. This Mini Review offers a broad overview of the post-translational regulation of selected RBPs and the involvement of their dysregulation in neurodegenerative disorders, cancer and other pathologies.


Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2836
Author(s):  
Rebecca M. Sena ◽  
Jeffery L. Twiss ◽  
Amy S. Gardiner ◽  
Michela Dell’Orco ◽  
David N. Linsenbardt ◽  
...  

The neuronal Hu/ELAV-like proteins HuB, HuC and HuD are a class of RNA-binding proteins that are crucial for proper development and maintenance of the nervous system. These proteins bind to AU-rich elements (AREs) in the untranslated regions (3′-UTRs) of target mRNAs regulating mRNA stability, transport and translation. In addition to these cytoplasmic functions, Hu proteins have been implicated in alternative splicing and alternative polyadenylation in the nucleus. The purpose of this study was to identify transcriptome-wide effects of HuD deletion on both of these nuclear events using RNA sequencing data obtained from the neocortex of Elavl4–/– (HuD KO) mice. HuD KO affected alternative splicing of 310 genes, including 17 validated HuD targets such as Cbx3, Cspp1, Snap25 and Gria2. In addition, deletion of HuD affected polyadenylation of 53 genes, with the majority of significantly altered mRNAs shifting towards usage of proximal polyadenylation signals (PAS), resulting in shorter 3′-UTRs. None of these genes overlapped with those showing alternative splicing events. Overall, HuD KO had a greater effect on alternative splicing than polyadenylation, with many of the affected genes implicated in several neuronal functions and neuropsychiatric disorders.


2006 ◽  
Vol 84 (4) ◽  
pp. 572-580 ◽  
Author(s):  
Douglas G. Muench ◽  
Nam-Il Park

The cytoskeleton plays an important role in numerous cellular processes, including subcellular mRNA localization and translation. Several examples of mRNA localization have emerged in plant cells, and these appear to function in protein targeting, the establishment of polarity, and cell-to-cell trafficking. The identification of several cytoskeleton-associated RNA-binding proteins in plant cells has made available candidate proteins that mediate the interaction between mRNA and the cytoskeleton, and possibly play a role in mRNA localization and translational control. We propose a model that links mRNA–microtubule interactions to translational autoregulation, a process that may assist in the efficient and regulated binding of proteins to microtubules.


2016 ◽  
Vol 57 (2) ◽  
pp. F29-F34 ◽  
Author(s):  
Ayse Elif Erson-Bensan

Our understanding of the extent of microRNA-based gene regulation has expanded in an impressive pace over the past decade. Now, we are beginning to better appreciate the role of 3′-UTR (untranslated region) cis-elements which harbor not only microRNA but also RNA-binding protein (RBP) binding sites that have significant effect on the stability and translational rate of mRNAs. To add further complexity, alternative polyadenylation (APA) emerges as a widespread mechanism to regulate gene expression by producing shorter or longer mRNA isoforms that differ in the length of their 3′-UTRs or even coding sequences. Resulting shorter mRNA isoforms generally lack cis-elements where trans-acting factors bind, and hence are differentially regulated compared with the longer isoforms. This review focuses on the RBPs involved in APA regulation and their action mechanisms on APA-generated isoforms. A better understanding of the complex interactions between APA and RBPs is promising for mechanistic and clinical implications including biomarker discovery and new therapeutic approaches.


Author(s):  
Yi Zhang ◽  
Lian Liu ◽  
Qiongzi Qiu ◽  
Qing Zhou ◽  
Jinwang Ding ◽  
...  

AbstractOccurring in over 60% of human genes, alternative polyadenylation (APA) results in numerous transcripts with differing 3’ends, thus greatly expanding the diversity of mRNAs and of proteins derived from a single gene. As a key molecular mechanism, APA is involved in various gene regulation steps including mRNA maturation, mRNA stability, cellular RNA decay, and protein diversification. APA is frequently dysregulated in cancers leading to changes in oncogenes and tumor suppressor gene expressions. Recent studies have revealed various APA regulatory mechanisms that promote the development and progression of a number of human diseases, including cancer. Here, we provide an overview of four types of APA and their impacts on gene regulation. We focus particularly on the interaction of APA with microRNAs, RNA binding proteins and other related factors, the core pre-mRNA 3’end processing complex, and 3’UTR length change. We also describe next-generation sequencing methods and computational tools for use in poly(A) signal detection and APA repositories and databases. Finally, we summarize the current understanding of APA in cancer and provide our vision for future APA related research.


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