scholarly journals Single-molecule imaging of mRNA localization and regulation during the integrated stress response

2018 ◽  
Author(s):  
Johannes H. Wilbertz ◽  
Franka Voigt ◽  
Ivana Horvathova ◽  
Gregory Roth ◽  
Yinxiu Zhan ◽  
...  

AbstractBiological phase transitions form membrane-less organelles that generate distinct cellular environments. How molecules are partitioned between these compartments and the surrounding cellular space and the functional consequence of this localization is not well understood. Here, we report the localization of mRNA to stress granules(SGs) and processing bodies(PBs), which are distinct biomolecular condensates, and its effect on translation and mRNA degradation during the integrated stress response. Using single mRNA imaging in living human cells, we find that the interactions of mRNAs with SGs and PBs have different dynamics and that specific RNA binding proteins can anchor mRNAs within these compartments. During recovery from stress, mRNAs that were within SGs and PBs are translated and degraded at similar rates as their cytosolic counterparts.

2019 ◽  
Vol 73 (5) ◽  
pp. 946-958.e7 ◽  
Author(s):  
Johannes H. Wilbertz ◽  
Franka Voigt ◽  
Ivana Horvathova ◽  
Gregory Roth ◽  
Yinxiu Zhan ◽  
...  

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 11 (1) ◽  
Author(s):  
Deepika Vasudevan ◽  
Sarah D. Neuman ◽  
Amy Yang ◽  
Lea Lough ◽  
Brian Brown ◽  
...  

Abstract The Integrated Stress Response (ISR) helps metazoan cells adapt to cellular stress by limiting the availability of initiator methionyl-tRNA for translation. Such limiting conditions paradoxically stimulate the translation of ATF4 mRNA through a regulatory 5′ leader sequence with multiple upstream Open Reading Frames (uORFs), thereby activating stress-responsive gene expression. Here, we report the identification of two critical regulators of such ATF4 induction, the noncanonical initiation factors eIF2D and DENR. Loss of eIF2D and DENR in Drosophila results in increased vulnerability to amino acid deprivation, susceptibility to retinal degeneration caused by endoplasmic reticulum (ER) stress, and developmental defects similar to ATF4 mutants. eIF2D requires its RNA-binding motif for regulation of 5′ leader-mediated ATF4 translation. Consistently, eIF2D and DENR deficient human cells show impaired ATF4 protein induction in response to ER stress. Altogether, our findings indicate that eIF2D and DENR are critical mediators of ATF4 translational induction and stress responses in vivo.


2012 ◽  
Vol 40 (6) ◽  
pp. 1416-1420 ◽  
Author(s):  
Mary W. McCaffrey ◽  
Andrew J. Lindsay

Mammals express three class V myosins. Myosin Va is widely expressed, but enriched in the brain, testes and melanocytes, myosin Vb is expressed ubiquitously, and myosin Vc is believed to be epithelium-specific. Myosin Va is the best characterized of the three and plays a key role in the transport of cargo to the plasma membrane. Its cargo includes cell-surface receptors, pigment and organelles such as the endoplasmic reticulum. It is also emerging that RNA and RNA-BPs (RNA-binding proteins) make up another class of myosin Va cargo. It has long been established that the yeast class V myosin, Myo4p, transports mRNAs along actin cables into the growing bud, and now several groups have reported a similar role for class V myosins in higher eukaryotes. Myosin Va has also been implicated in the assembly and maintenance of P-bodies (processing bodies), cytoplasmic foci that are involved in mRNA storage and degradation. The present review examines the evidence that myosin Va plays a role in the transport and turnover of mRNA.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lulu Deng ◽  
Long Li ◽  
Cheng Zou ◽  
Chengchi Fang ◽  
Changchun Li

Many increasing documents have proved that alternative polyadenylation (APA) events with different polyadenylation sites (PAS) contribute to posttranscriptional regulation. However, little is known about the detailed molecular features of PASs and its role in porcine fast and slow skeletal muscles through microRNAs (miRNAs) and RNA binding proteins (RBPs). In this study, we combined single-molecule real-time sequencing and Illumina RNA-seq datasets to comprehensively analyze polyadenylation in pigs. We identified a total of 10,334 PASs, of which 8734 were characterized by reference genome annotation. 32.86% of PAS-associated genes were determined to have more than one PAS. Further analysis demonstrated that tissue-specific PASs between fast and slow muscles were enriched in skeletal muscle development pathways. In addition, we obtained 1407 target genes regulated by APA events through potential binding 69 miRNAs and 28 RBPs in variable 3′ UTR regions and some are involved in myofiber transformation. Furthermore, the de novo motif search confirmed that the most common usage of canonical motif AAUAAA and three types of PASs may be related to the strength of motifs. In summary, our results provide a useful annotation of PASs for pig transcriptome and suggest that APA may serve as a role in fast and slow muscle development under the regulation of miRNAs and RBPs.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sundararaghavan Pattabiraman ◽  
Gajendra Kumar Azad ◽  
Triana Amen ◽  
Shlomi Brielle ◽  
Jung Eun Park ◽  
...  

Abstract Vimentin is one of the first cytoplasmic intermediate filaments to be expressed in mammalian cells during embryogenesis, but its role in cellular fitness has long been a mystery. Vimentin is acknowledged to play a role in cell stiffness, cell motility, and cytoplasmic organization, yet it is widely considered to be dispensable for cellular function and organismal development. Here, we show that Vimentin plays a role in cellular stress response in differentiating cells, by recruiting aggregates, stress granules, and RNA-binding proteins, directing their elimination and asymmetric partitioning. In the absence of Vimentin, pluripotent embryonic stem cells fail to differentiate properly, with a pronounced deficiency in neuronal differentiation. Our results uncover a novel function for Vimentin, with important implications for development, tissue homeostasis, and in particular, stress response.


2016 ◽  
Vol 310 (1) ◽  
pp. C54-C65 ◽  
Author(s):  
Ting-Xi Yu ◽  
Bei-Lin Gu ◽  
Jun-Kai Yan ◽  
Jie Zhu ◽  
Wei-Hui Yan ◽  
...  

The effectiveness and stability of epithelial barrier depend on apical junctional complexes, which consist of tight junctions (TJs) and adherens junctions (AJs). E-cadherin is the primary component of AJs, and it is essential for maintenance of cell-to-cell interactions and regulates the epithelial barrier. However, the exact mechanism underlying E-cadherin expression, particularly at the posttranscriptional level, remains largely unknown. RNA-binding proteins CUG-binding protein 1 (CUGBP1) and HU antigen R (HuR) are highly expressed in the intestinal epithelial tissues and modulate the stability and translation of target mRNAs. Here, we present evidence that CUGBP1 and HuR interact directly with the 3′-untranslated region of E-cadherin mRNA and regulate E-cadherin translation. CUGBP1 overexpression in Caco-2 cells inhibited E-cadherin translation by increasing the recruitment of E-cadherin mRNA to processing bodies (PBs), thus resulting in an increase in paracellular permeability. Overexpression of HuR exhibited an opposite effect on E-cadherin expression by preventing the translocation of E-cadherin mRNA to PBs and therefore prevented CUGBP1-induced repression of E-cadherin expression. Elevation of HuR also abolished the CUGBP1-induced epithelial barrier dysfunction. These findings indicate that CUGBP1 and HuR negate each other's effects in regulating E-cadherin translation by altering the recruitment of E-cadherin mRNA to PBs and play an important role in the regulation of intestinal barrier integrity under various pathophysiological conditions.


2013 ◽  
Vol 24 (2) ◽  
pp. 85-99 ◽  
Author(s):  
Ting-Xi Yu ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Lan Liu ◽  
Lan Xiao ◽  
...  

RNA-binding proteins CUG-binding protein 1 (CUGBP1) and HuR are highly expressed in epithelial tissues and modulate the stability and translation of target mRNAs. Here we present evidence that CUGBP1 and HuR jointly regulate the translation of occludin and play a crucial role in the maintenance of tight junction (TJ) integrity in the intestinal epithelial cell monolayer. CUGBP1 and HuR competed for association with the same occludin 3′-untranslated region element and regulated occludin translation competitively and in opposite directions. CUGBP1 overexpression decreased HuR binding to occludin mRNA, repressed occludin translation, and compromised the TJ barrier function, whereas HuR overexpression inhibited CUGBP1 association with occludin mRNA and promoted occludin translation, thereby enhancing the barrier integrity. Repression of occludin translation by CUGBP1 was due to the colocalization of CUGBP1 and tagged occludin RNA in processing bodies (P-bodies), and this colocalization was prevented by HuR overexpression. These findings indicate that CUGBP1 represses occludin translation by increasing occludin mRNA recruitment to P-bodies, whereas HuR promotes occludin translation by blocking occludin mRNA translocation to P-bodies via the displacement of CUGBP1.


2012 ◽  
Vol 23 (1) ◽  
pp. 151-162 ◽  
Author(s):  
Yu-Hong Cui ◽  
Lan Xiao ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Lan Liu ◽  
...  

microRNAs (miRNAs) and RNA-binding proteins (RBPs) jointly regulate gene expression at the posttranscriptional level and are involved in many aspects of cellular functions. The RBP CUG-binding protein 1 (CUGBP1) destabilizes and represses the translation of several target mRNAs, but the exact mechanism that regulates CUGBP1 abundance remains elusive. In this paper, we show that miR-503, computationally predicted to associate with three sites of the CUGBP1 mRNA, represses CUGBP1 expression. Overexpression of an miR-503 precursor (pre-miR-503) reduced the de novo synthesis of CUGBP1 protein, whereas inhibiting miR-503 by using an antisense RNA (antagomir) enhanced CUGBP1 biosynthesis and elevated its abundance; neither intervention changed total CUGBP1 mRNA levels. Studies using heterologous reporter constructs revealed a greater repressive effect of miR-503 through the CUGBP1 coding region sites than through the single CUGBP1 3′-untranslated region target site. CUGBP1 mRNA levels in processing bodies (P-bodies) increased in cells transfected with pre-miR-503, while silencing P-body resident proteins Ago2, RCK, or LSm4 decreased miR-503–mediated repression of CUGBP1 expression. Decreasing the levels of cellular polyamines reduced endogenous miR-503 levels and promoted CUGBP1 expression, an effect that was prevented by ectopic miR-503 overexpression. Repression of CUGBP1 by miR-503 in turn altered the expression of CUGBP1 target mRNAs and thus increased the sensitivity of intestinal epithelial cells to apoptosis. These findings identify miR-503 as both a novel regulator of CUGBP1 expression and a modulator of intestinal epithelial homoeostasis.


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