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Hanqian Mao, John J McMahon, Yi-Hsuan Tsai, Zefeng Wang, Debra L Silver
The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling...
September 2016: PLoS Genetics
Kazuhiro Fukumura, Shunichi Wakabayashi, Naoyuki Kataoka, Hiroshi Sakamoto, Yutaka Suzuki, Kenta Nakai, Akila Mayeda, Kunio Inoue
The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon-exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT-PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression...
2016: International Journal of Molecular Sciences
J J McMahon, E E Miller, D L Silver
Post-transcriptional mRNA metabolism has emerged as a critical regulatory nexus in proper development and function of the nervous system. In particular, recent studies highlight roles for the exon junction complex (EJC) in neurodevelopment. The EJC is an RNA binding complex composed of 3 core proteins, EIF4A3 (DDX48), RBM8A (Y14), and MAGOH, and is a major hub of post-transcriptional regulation. Following deposition onto mRNA, the EJC serves as a platform for the binding of peripheral factors which together regulate splicing, nonsense mediated decay, translation, and RNA localization...
April 9, 2016: International Journal of Developmental Neuroscience
Ming-Hui Zhao, Shuang Liang, Nam-Hyung Kim, Xiang-Shun Cui
Several germ cell-specific transcription factors essential for ovarian formation and folliculogenesis have been identified and studied. However, their function during early embryo development has been poorly explored. In this study, we investigated the role of mixed-lineage leukemia protein 2 (MLL2) in the development of porcine preimplantation embryos. To explore the function of MLL2 in porcine embryo development, expression and localization of MLL2 were assessed by qRT-PCR and immunofluorescence assays. Results showed that expression of MLL2 was significantly reduced after the four-cell stage...
June 2016: In Vitro Cellular & Developmental Biology. Animal
Rafal S Sobota, Catherine M Stein, Nuri Kodaman, Laura B Scheinfeldt, Isaac Maro, Wendy Wieland-Alter, Robert P Igo, Albert Magohe, LaShaunda L Malone, Keith Chervenak, Noemi B Hall, Chawangwa Modongo, Nicola Zetola, Mecky Matee, Moses Joloba, Alain Froment, Thomas B Nyambo, Jason H Moore, William K Scott, Timothy Lahey, W Henry Boom, C Fordham von Reyn, Sarah A Tishkoff, Giorgio Sirugo, Scott M Williams
Immunosuppression resulting from HIV infection increases the risk of progression to active tuberculosis (TB) both in individuals newly exposed to Mycobacterium tuberculosis (MTB) and in those with latent infections. We hypothesized that HIV-positive individuals who do not develop TB, despite living in areas where it is hyperendemic, provide a model of natural resistance. We performed a genome-wide association study of TB resistance by using 581 HIV-positive Ugandans and Tanzanians enrolled in prospective cohort studies of TB; 267 of these individuals developed active TB, and 314 did not...
March 3, 2016: American Journal of Human Genetics
Louis-Jan Pilaz, John J McMahon, Emily E Miller, Ashley L Lennox, Aussie Suzuki, Edward Salmon, Debra L Silver
Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny...
January 6, 2016: Neuron
Donghua Zou, Colleen McSweeney, Aswathy Sebastian, Derrick James Reynolds, Fengping Dong, Yijing Zhou, Dazhi Deng, Yonggang Wang, Long Liu, Jun Zhu, Jizhong Zou, Yongsheng Shi, Istvan Albert, Yingwei Mao
BACKGROUND: Nonsense mediated mRNA decay (NMD) is an RNA surveillance mechanism that controls RNA stability and ensures the speedy degradation of erroneous and unnecessary transcripts. This mechanism depends on several core factors in the exon junction complex (EJC), eIF4A3, RBM8a, Magoh, and BTZ, as well as peripheral factors to distinguish premature stop codons (PTCs) from normal stop codons in transcripts. Recently, emerging evidence has indicated that NMD factors are associated with neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability (ID)...
2015: Neural Development
Holly R Ramage, G Renuka Kumar, Erik Verschueren, Jeffrey R Johnson, John Von Dollen, Tasha Johnson, Billy Newton, Priya Shah, Julie Horner, Nevan J Krogan, Melanie Ott
Hepatitis C virus (HCV) is a leading cause of liver disease, but insight into virus-host interactions remains limited. We systematically used affinity purification/mass spectrometry to define the host interactions of all ten HCV proteins in hepatoma cells. We combined these studies with RNAi knockdown of corresponding genes using a two-step scoring approach to generate a map of 139 high-confidence HCV-host protein-protein interactions. We found mitochondrial proteins highly involved in HCV infection and characterized an interaction between the viral core protein and host protein within bgcn homolog (WIBG)...
January 22, 2015: Molecular Cell
Zhen Wang, Valentine Murigneux, Hervé Le Hir
BACKGROUND: The exon junction complex (EJC) is a dynamic multi-protein complex deposited onto nuclear spliced mRNAs upstream of exon-exon junctions. The four core proteins, eIF4A3, Magoh, Y14 and MLN51, are stably bound to mRNAs during their lifecycle, serving as a binding platform for other nuclear and cytoplasmic proteins. Recent evidence has shown that the EJC is involved in the splicing regulation of some specific events in both Drosophila and mammalian cells. RESULTS: Here, we show that knockdown of EJC core proteins causes widespread alternative splicing changes in mammalian cells...
2014: Genome Biology
Yasuhito Ishigaki, Yuka Nakamura, Takanori Tatsuno, Shaofu Ma, Naohisa Tomosugi
The RNA-binding protein 8A (RBM8A)-mago-nashi homolog, proliferation-associated (Magoh) complex is a component of the exon junction complex (EJC) required for mRNA metabolism involving nonsense-mediated mRNA decay (NMD). RBM8A is a phosphorylated protein that plays some roles in NMD. However, the detailed status and mechanism of the phosphorylation of RBM8A is not completely understood. Therefore, in this study, we analyzed in detail RBM8A phosphorylation in human cells. Accordingly, analysis of the phosphorylation status of RBM8A protein in whole-cell lysates by using Phos-tag gels revealed that the majority of endogenous RBM8A was phosphorylated throughout the cell-cycle progression...
April 2015: Experimental Biology and Medicine
Nicolas Cougot, Elisabeth Daguenet, Aurélie Baguet, Annie Cavalier, Daniel Thomas, Pascale Bellaud, Alain Fautrel, Florence Godey, Edouard Bertrand, Catherine Tomasetto, Reynald Gillet
Metastatic lymph node 51 (MLN51, also known as CASC3) is a core component of the exon junction complex (EJC), which is loaded onto spliced mRNAs and plays an essential role in determining their fate. Unlike the three other EJC core components [eIF4AIII, Magoh and Y14 (also known as RBM8A)], MLN51 is mainly located in the cytoplasm, where it plays a key role in the assembly of stress granules. In this study, we further investigated the cytoplasmic role of MLN51. We show that MLN51 is a new component of processing bodies (P-bodies)...
November 1, 2014: Journal of Cell Science
John J McMahon, Lei Shi, Debra L Silver
Magoh encodes a core component of the exon junction complex (EJC), which binds mRNA and regulates mRNA metabolism. Magoh is highly expressed in proliferative tissues during development. EJC components have been implicated in several developmental disorders including TAR syndrome, Richieri-Costa-Pereira syndrome, and intellectual disability. Existing germline null Magoh mice are embryonic lethal as homozygotes and perinatal lethal as heterozygotes, precluding detailed analysis of embryonic and postnatal functions...
August 2014: Genesis: the Journal of Genetics and Development
Yasuhito Ishigaki, Yuka Nakamura, Takanori Tatsuno, Mitsumasa Hashimoto, Takeo Shimasaki, Kuniyoshi Iwabuchi, Naohisa Tomosugi
RBM8A (Y14) contains an RNA-binding motif and forms a tight heterodimer with Magoh. The heterodimer is known to be a member of the exon junction complex that forms on mRNA before export and it is required for mRNA metabolism processes such as splicing, mRNA export and nonsense-mediated mRNA decay. Recently, deficient cellular proliferation has been observed in RBM8A- or Magoh-depleted cells. These results prompted us to study the role of RBM8A in cell cycle progression of human tumour cells. The depletion of RBM8A in A549 cells resulted in poor cell survival and the accumulation of mitotic cells...
August 1, 2013: Experimental Biology and Medicine
Yasuhito Ishigaki, Yuka Nakamura, Takanori Tatsuno, Mitsumasa Hashimoto, Kuniyoshi Iwabuchi, Naohisa Tomosugi
RBM8A (Y14) is carrying RNA-binding motif and forms the tight heterodimer with MAGOH. The heterodimer is known to be a member of exon junction complex on exporting mRNA and is required for mRNA metabolisms such as splicing, mRNA export and nonsense-mediated mRNA decay. Almost all RBM8A-MAGOH complexes localize in nucleoplasm and shuttle between nuclei and cytoplasm for RNA metabolism. Recently, the abnormality of G2/M transition and aberrant centrosome regulation in RBM8A- or MAGOH-deficient cells has been reported...
January 2014: Histochemistry and Cell Biology
Kusum K Singh, Laurens Wachsmuth, Andreas E Kulozik, Niels H Gehring
The exon junction complex (EJC) participates in the regulation of many post-transcriptional steps of gene expression. EJCs are deposited on messenger RNAs (mRNAs) during splicing and their core consists of eIF4A3, MLN51, Y14, and MAGOH. Here, we show that two genes encoding MAGOH paralogs (referred to as MAGOH and MAGOHB) are expressed in mammals. In macrophages, the expression of MAGOHB, but not MAGOH mRNA, increases rapidly after LPS stimulation. Both MAGOH proteins interact with other EJC components, incorporate into mRNA-bound EJCs, and activate nonsense-mediated decay...
August 2013: RNA Biology
Kang-Bin Im, Ute Schmidt, Moon-Sik Kang, Ji-Young Lee, Felix Bestvater, Malte Wachsmuth
To quantify more precisely and more reliably diffusion and reaction properties of biomolecules in living cells, a novel closed description in 3D of both the bleach and the post-bleach segment of fluorescence recovery after photobleaching (FRAP) data acquired at a point, i.e., a diffraction-limited observation area, termed point FRAP, is presented. It covers a complete coupled reaction-diffusion scheme for mobile molecules undergoing transient or long-term immobilization because of binding. We assess and confirm the feasibility with numerical solutions of the differential equations...
September 2013: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
Sumihito Togi, Kaname Shiga, Ryuta Muromoto, Masaya Kato, Yuki Souma, Yuichi Sekine, Shigeyuki Kon, Kenji Oritani, Tadashi Matsuda
Although Y14 is known to be a component of the exon junction complex, we previously reported that Y14 regulates IL-6-induced STAT3 activation. In this study, we showed that endogenous Y14 positively regulated TNF-α-induced IL-6 expression in HeLa cells. Small interfering RNA-mediated Y14-knockdown reduced TNF-α-induced and NF-κB-mediated transcriptional activity, phosphorylation/degradation of IκBα, and nuclear localization of NF-κB/p65. As in the case of IL-6 stimuli, Y14 enhanced TNF-α-induced STAT3 phosphorylation, which is important for its nuclear retention...
August 1, 2013: Journal of Immunology: Official Journal of the American Association of Immunologists
Sapna Varia, Divya Potabathula, Zhihui Deng, Athanasios Bubulya, Paula A Bubulya
Transcription of protein-coding genes in mammalian cells is coordinated with pre-mRNA processing as well as the assembly and nuclear export of mRNPs. Btf (BCLAF1) and TRAP150 (THRAP3) were previously reported to associate with in vitro spliced mRNPs and also as a part of the spliceosome, suggesting they are involved in pre-mRNA processing. Btf and TRAP150 are serine-arginine-rich (SR) proteins with significant sequence similarity, but the extent of their functional overlap is not yet clear. We show that both Btf and TRAP150 localize at a constitutively active β-tropomyosin (BTM) reporter minigene locus in mammalian cells...
May 2013: Nucleus
Alexandre Jose Christino Quaresma, Rachel Sievert, Jeffrey A Nickerson
UAP56, ALY/REF, and NXF1 are mRNA export factors that sequentially bind at the 5' end of a nuclear mRNA but are also reported to associate with the exon junction complex (EJC). To screen for signal transduction pathways regulating mRNA export complex assembly, we used fluorescence recovery after photobleaching to measure the binding of mRNA export and EJC core proteins in nuclear complexes. The fraction of UAP56, ALY/REF, and NXF1 tightly bound in complexes was reduced by drug inhibition of the phosphatidylinositide 3-kinase (PI3 kinase)/AKT pathway, as was the tightly bound fraction of the core EJC proteins eIF4A3, MAGOH, and Y14...
April 2013: Molecular Biology of the Cell
Debra L Silver, Karen E Leeds, Hun-Way Hwang, Emily E Miller, William J Pavan
Melanoblasts are a population of neural crest-derived cells that generate the pigment-producing cells of our body. Defective melanoblast development and function underlies many disorders including Waardenburg syndrome and melanoma. Understanding the genetic regulation of melanoblast development will help elucidate the etiology of these and other neurocristopathies. Here we demonstrate that Magoh, a component of the exon junction complex, is required for normal melanoblast development. Magoh haploinsufficient mice are hypopigmented and exhibit robust genetic interactions with the transcription factor, Sox10...
March 15, 2013: Developmental Biology
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