scholarly journals Regulation of Early Lymphocyte Development via mRNA Decay Catalyzed by the CCR4-NOT Complex

2021 ◽  
Vol 12 ◽  
Author(s):  
Taishin Akiyama ◽  
Tadashi Yamamoto

Development of lymphocytes is precisely regulated by various mechanisms. In addition to transcriptional rates, post-transcriptional regulation of mRNA abundance contributes to differentiation of lymphocytes. mRNA decay is a post-transcriptional mechanism controlling mRNA abundance. The carbon catabolite repression 4 (CCR4)-negative on TATA-less (NOT) complex controls mRNA longevity by catalyzing mRNA deadenylation, which is the rate-limiting step in the mRNA decay pathway. mRNA decay, regulated by the CCR4-NOT complex, is required for differentiation of pro-B to pre-B cells and V(D)J recombination in pro-B cells. In this process, it is likely that the RNA-binding proteins, ZFP36 ring finger protein like 1 and 2, recruit the CCR4-NOT complex to specific target mRNAs, thereby inducing cell quiescence of pro-B cells. A recent study showed that the CCR4-NOT complex participates in positive selection of thymocytes. Mechanistically, the CCR4-NOT deadenylase complex inhibits abnormal apoptosis by reducing the expression level of mRNAs encoding pro-apoptotic proteins, which are otherwise up-regulated during positive selection. We discuss mechanisms regulating CCR4-NOT complex-dependent mRNA decay in lymphocyte development and selection.

2021 ◽  
Author(s):  
Eun Seon Kim ◽  
Chang Geon Chung ◽  
Jeong Hyang Park ◽  
Byung Su Ko ◽  
Sung Soon Park ◽  
...  

Abstract RNA-binding proteins (RBPs) play essential roles in diverse cellular processes through post-transcriptional regulation of RNAs. The subcellular localization of RBPs is thus under tight control, the breakdown of which is associated with aberrant cytoplasmic accumulation of nuclear RBPs such as TDP-43 and FUS, well-known pathological markers for amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). Here, we report in Drosophila model for ALS/FTD that nuclear accumulation of a cytoplasmic RBP, Staufen, may be a new pathological feature. We found that in Drosophila C4da neurons expressing PR36, one of the arginine-rich dipeptide repeat proteins (DPRs), Staufen accumulated in the nucleus in Importin- and RNA-dependent manner. Notably, expressing Staufen with exogenous NLS—but not with mutated endogenous NLS—potentiated PR-induced dendritic defect, suggesting that nuclear-accumulated Staufen can enhance PR toxicity. PR36 expression increased Fibrillarin staining in the nucleolus, which was enhanced by heterozygous mutation of stau (stau+/−), a gene that codes Staufen. Furthermore, knockdown of fib, which codes Fibrillarin, exacerbated retinal degeneration mediated by PR toxicity, suggesting that increased amount of Fibrillarin by stau+/− is protective. Stau+/− also reduced the amount of PR-induced nuclear-accumulated Staufen and mitigated retinal degeneration and rescued viability of flies expressing PR36. Taken together, our data show that nuclear accumulation of Staufen in neurons may be an important pathological feature contributing to the pathogenesis of ALS/FTD.


eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Ling-Yu Liu ◽  
Xi Long ◽  
Ching-Po Yang ◽  
Rosa L Miyares ◽  
Ken Sugino ◽  
...  

Temporal patterning is a seminal method of expanding neuronal diversity. Here we unravel a mechanism decoding neural stem cell temporal gene expression and transforming it into discrete neuronal fates. This mechanism is characterized by hierarchical gene expression. First, Drosophila neuroblasts express opposing temporal gradients of RNA-binding proteins, Imp and Syp. These proteins promote or inhibit chinmo translation, yielding a descending neuronal gradient. Together, first and second-layer temporal factors define a temporal expression window of BTB-zinc finger nuclear protein, Mamo. The precise temporal induction of Mamo is achieved via both transcriptional and post-transcriptional regulation. Finally, Mamo is essential for the temporally defined, terminal identity of α’/β’ mushroom body neurons and identity maintenance. We describe a straightforward paradigm of temporal fate specification where diverse neuronal fates are defined via integrating multiple layers of gene regulation. The neurodevelopmental roles of orthologous/related mammalian genes suggest a fundamental conservation of this mechanism in brain development.


2019 ◽  
Vol 97 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Laura P.M.H. de Rooij ◽  
Derek C.H. Chan ◽  
Ava Keyvani Chahi ◽  
Kristin J. Hope

Normal hematopoiesis is sustained through a carefully orchestrated balance between hematopoietic stem cell (HSC) self-renewal and differentiation. The functional importance of this axis is underscored by the severity of disease phenotypes initiated by abnormal HSC function, including myelodysplastic syndromes and hematopoietic malignancies. Major advances in the understanding of transcriptional regulation of primitive hematopoietic cells have been achieved; however, the post-transcriptional regulatory layer that may impinge on their behavior remains underexplored by comparison. Key players at this level include RNA-binding proteins (RBPs), which execute precise and highly coordinated control of gene expression through modulation of RNA properties that include its splicing, polyadenylation, localization, degradation, or translation. With the recent identification of RBPs having essential roles in regulating proliferation and cell fate decisions in other systems, there has been an increasing appreciation of the importance of post-transcriptional control at the stem cell level. Here we discuss our current understanding of RBP-driven post-transcriptional regulation in HSCs, its implications for normal, perturbed, and malignant hematopoiesis, and the most recent technological innovations aimed at RBP–RNA network characterization at the systems level. Emerging evidence highlights RBP-driven control as an underappreciated feature of primitive hematopoiesis, the greater understanding of which has important clinical implications.


2021 ◽  
Vol 22 (21) ◽  
pp. 11963
Author(s):  
Noof Aloufi ◽  
Aeshah Alluli ◽  
David H. Eidelman ◽  
Carolyn J. Baglole

Chronic obstructive pulmonary disease (COPD) is an incurable and prevalent respiratory disorder that is characterized by chronic inflammation and emphysema. COPD is primarily caused by cigarette smoke (CS). CS alters numerous cellular processes, including the post-transcriptional regulation of mRNAs. The identification of RNA-binding proteins (RBPs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) as main factors engaged in the regulation of RNA biology opens the door to understanding their role in coordinating physiological cellular processes. Dysregulation of post-transcriptional regulation by foreign particles in CS may lead to the development of diseases such as COPD. Here we review current knowledge about post-transcriptional events that may be involved in the pathogenesis of COPD.


Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4505
Author(s):  
Hilde Sundvold

An increased understanding of low-density lipoprotein receptor (LDLR) and its regulation may facilitate drug development for the treatment of hypercholesterolemia. Triciribine (TCN), which is a highly selective AKT inhibitor, increases the stability of LDLR mRNA downstream of extracellular signal-regulated kinase (ERK) in human hepatoma cells (HepG2). Here, a candidate approach was used in order to determine whether the RNA-binding proteins (RBPs) ZFP36 ring finger protein like 1 (ZFP36L1) and Hu antigen R (HuR) play a role in TCN-mediated stabilization of LDLR mRNA. The depletion of HuR led to a reduction of LDLR mRNA stability, an event that was more pronounced in TCN-treated cells. TCN was found to induce the translocation of nuclear HuR to cytoplasm in an ERK-dependent manner. ZFP36L1 depletion increased the stability of LDLR mRNA consistent with its destabilizing role. However, in contrast to HuR, TCN had no effect on LDLR mRNA turnover in ZFP36L1-depleted cells. TCN induced the phosphorylation of ZFP36L1 in an ERK/RSK-dependent manner and promoted its dissociation from the CCR4-NOT complex. In sum, these data suggest that TCN utilizes ERK signaling to increase the activity of HuR and inhibit ZFP36L1 to stabilize LDLR mRNA in HepG2 cells.


2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Tracey W. Chan ◽  
Ting Fu ◽  
Jae Hoon Bahn ◽  
Hyun-Ik Jun ◽  
Jae-Hyung Lee ◽  
...  

Abstract Background RNA editing generates modifications to the RNA sequences, thereby increasing protein diversity and shaping various layers of gene regulation. Recent studies have revealed global shifts in editing levels across many cancer types, as well as a few specific mechanisms implicating individual sites in tumorigenesis or metastasis. However, most tumor-associated sites, predominantly in noncoding regions, have unknown functional relevance. Results Here, we carry out integrative analysis of RNA editing profiles between epithelial and mesenchymal tumors, since epithelial-mesenchymal transition is a key paradigm for metastasis. We identify distinct editing patterns between epithelial and mesenchymal tumors in seven cancer types using TCGA data, an observation further supported by single-cell RNA sequencing data and ADAR perturbation experiments in cell culture. Through computational analyses and experimental validations, we show that differential editing sites between epithelial and mesenchymal phenotypes function by regulating mRNA abundance of their respective genes. Our analysis of RNA-binding proteins reveals ILF3 as a potential regulator of this process, supported by experimental validations. Consistent with the known roles of ILF3 in immune response, epithelial-mesenchymal differential editing sites are enriched in genes involved in immune and viral processes. The strongest target of editing-dependent ILF3 regulation is the transcript encoding PKR, a crucial player in immune and viral response. Conclusions Our study reports widespread differences in RNA editing between epithelial and mesenchymal tumors and a novel mechanism of editing-dependent regulation of mRNA abundance. It reveals the broad impact of RNA editing in cancer and its relevance to cancer-related immune pathways.


Author(s):  
Marialaura Amadio ◽  
Giovanni Scapagnini ◽  
Sergio Davinelli ◽  
Vittorio Calabrese ◽  
Stefano Govoni ◽  
...  

2015 ◽  
Vol 6 ◽  
Author(s):  
Elke Van Assche ◽  
Sandra Van Puyvelde ◽  
Jos Vanderleyden ◽  
Hans P. Steenackers

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