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Wu Y, Devotta A, José-Edwards DS, Kugler JE, Negrón-Piñeiro LJ, Braslavskaya K, Addy J, Saint-Jeannet JP, Di Gregorio A. Xbp1 and Brachyury establish an evolutionarily conserved subcircuit of the notochord gene regulatory network. eLife 2022; 11:e73992. [PMID: 35049502 PMCID: PMC8803312 DOI: 10.7554/elife.73992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Gene regulatory networks coordinate the formation of organs and structures that compose the evolving body plans of different organisms. We are using a simple chordate model, the Ciona embryo, to investigate the essential gene regulatory network that orchestrates morphogenesis of the notochord, a structure necessary for the proper development of all chordate embryos. Although numerous transcription factors expressed in the notochord have been identified in different chordates, several of them remain to be positioned within a regulatory framework. Here, we focus on Xbp1, a transcription factor expressed during notochord formation in Ciona and other chordates. Through the identification of Xbp1-downstream notochord genes in Ciona, we found evidence of the early co-option of genes involved in the unfolded protein response to the notochord developmental program. We report the regulatory interplay between Xbp1 and Brachyury, and by extending these results to Xenopus, we show that Brachyury and Xbp1 form a cross-regulatory subcircuit of the notochord gene regulatory network that has been consolidated during chordate evolution.
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Affiliation(s)
- Yushi Wu
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Arun Devotta
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Diana S José-Edwards
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Jamie E Kugler
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Lenny J Negrón-Piñeiro
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Karina Braslavskaya
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | - Jermyn Addy
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
| | | | - Anna Di Gregorio
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
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2
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Riaz TA, Junjappa RP, Handigund M, Ferdous J, Kim HR, Chae HJ. Role of Endoplasmic Reticulum Stress Sensor IRE1α in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation. Cells 2020; 9:E1160. [PMID: 32397116 PMCID: PMC7290600 DOI: 10.3390/cells9051160] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/27/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022] Open
Abstract
Inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) is the most prominent and evolutionarily conserved unfolded protein response (UPR) signal transducer during endoplasmic reticulum functional upset (ER stress). A IRE1α signal pathway arbitrates yin and yang of cellular fate in objectionable conditions. It plays several roles in fundamental cellular physiology as well as in several pathological conditions such as diabetes, obesity, inflammation, cancer, neurodegeneration, and in many other diseases. Thus, further understanding of its molecular structure and mechanism of action during different cell insults helps in designing and developing better therapeutic strategies for the above-mentioned chronic diseases. In this review, recent insights into structure and mechanism of activation of IRE1α along with its complex regulating network were discussed in relation to their basic cellular physiological function. Addressing different binding partners that can modulate IRE1α function, UPRosome triggers different downstream pathways depending on the cellular backdrop. Furthermore, IRE1α are in normal cell activities outside the dominion of ER stress and activities under the weather of inflammation, diabetes, and obesity-related metaflammation. Thus, IRE1 as an ER stress sensor needs to be understood from a wider perspective for comprehensive functional meaning, which facilitates us with assembling future needs and therapeutic benefits.
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Affiliation(s)
- Thoufiqul Alam Riaz
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Raghu Patil Junjappa
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Mallikarjun Handigund
- Department of Laboratory Medicine, Jeonbuk National University, Medical School, Jeonju 54907, Korea;
| | - Jannatul Ferdous
- Department of Radiology and Research Institute of Clinical Medicine of Jeonbuk National University, Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Korea;
| | - Hyung-Ryong Kim
- College of Dentistry, Dankook University, Cheonan 31116, Korea
| | - Han-Jung Chae
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
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Jin Y, Weinstein DC. Pitx1 regulates cement gland development in Xenopus laevis through activation of transcriptional targets and inhibition of BMP signaling. Dev Biol 2018. [PMID: 29530451 DOI: 10.1016/j.ydbio.2018.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cement gland in Xenopus laevis has long been used as a model to study the interplay of cell signaling and transcription factors during embryogenesis. It has been shown that an intermediate level of Bone Morphogenetic Protein (BMP) signaling is essential for cement gland formation. In addition, several transcription factors have been linked to cement gland development. One of these, the homeodomain-containing protein Pitx1, can generate ectopic cement gland formation; however, the mechanisms underlying this process remain obscure. We report here, for the first time, a requirement for Pitx proteins in cement gland formation, in vivo: knockdown of both pitx1 and the closely related pitx2c inhibit endogenous cement gland formation. Pitx1 transcriptionally activates cement gland differentiation genes through both direct and indirect mechanisms, and functions as a transcriptional activator to inhibit BMP signaling. This inhibition, required for the expression of pitx genes, is partially mediated by Pitx1-dependent follistatin expression. Complete suppression of BMP signaling inhibits induction of cement gland markers by Pitx1; furthermore, we find that Pitx1 physically interacts with Smad1, an intracellular transducer of BMP signaling. We propose a model of cement gland formation in which Pitx1 limits local BMP signaling within the cement gland primordium, and recruits Smad1 to activate direct downstream targets.
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Affiliation(s)
- Ye Jin
- Program in Biology, The Graduate Center, The City University of New York, New York, NY 10016, USA
| | - Daniel C Weinstein
- Department of Biology, Queens College, The City University of New York, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
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Kupsco A, Schlenk D. Oxidative stress, unfolded protein response, and apoptosis in developmental toxicity. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:1-66. [PMID: 26008783 DOI: 10.1016/bs.ircmb.2015.02.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Physiological development requires precise spatiotemporal regulation of cellular and molecular processes. Disruption of these key events can generate developmental toxicity in the form of teratogenesis or mortality. The mechanism behind many developmental toxicants remains unknown. While recent work has focused on the unfolded protein response (UPR), oxidative stress, and apoptosis in the pathogenesis of disease, few studies have addressed their relationship in developmental toxicity. Redox regulation, UPR, and apoptosis are essential for physiological development and can be disturbed by a variety of endogenous and exogenous toxicants to generate lethality and diverse malformations. This review examines the current knowledge of the role of oxidative stress, UPR, and apoptosis in physiological development as well as in developmental toxicity, focusing on studies and advances in vertebrates model systems.
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Affiliation(s)
- Allison Kupsco
- Environmental Toxicology Program, University of California, Riverside, CA, USA
| | - Daniel Schlenk
- Environmental Toxicology Program, University of California, Riverside, CA, USA; Environmental Sciences, University of California, Riverside, CA, USA
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Shi W, Xu G, Wang C, Sperber SM, Chen Y, Zhou Q, Deng Y, Zhao H. Heat shock 70-kDa protein 5 (Hspa5) is essential for pronephros formation by mediating retinoic acid signaling. J Biol Chem 2015; 290:577-89. [PMID: 25398881 PMCID: PMC4281759 DOI: 10.1074/jbc.m114.591628] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 11/09/2014] [Indexed: 12/17/2022] Open
Abstract
Heat shock 70-kDa protein 5 (Hspa5), also known as binding immunoglobulin protein (Bip) or glucose-regulated protein 78 (Grp78), belongs to the heat shock protein 70 kDa family. As a multifunctional protein, it participates in protein folding and calcium homeostasis and serves as an essential regulator of the endoplasmic reticulum (ER) stress response. It has also been implicated in signal transduction by acting as a receptor or co-receptor residing at the plasma membrane. Its function during embryonic development, however, remains largely elusive. In this study, we used morpholino antisense oligonucleotides (MOs) to knock down Hspa5 activity in Xenopus embryos. In Hspa5 morphants, pronephros formation was strongly inhibited with the reduction of pronephric marker genes Lim homeobox protein 1 (lhx1), pax2, and β1 subunit of Na/K-ATPase (atp1b1). Pronephros tissue was induced in vitro by treating animal caps with all-trans-retinoic acid and activin. Depletion of Hspa5 in animal caps, however, blocked the induction of pronephros as well as reduced the expression of retinoic acid (RA)-responsive genes, suggesting that knockdown of Hspa5 attenuated RA signaling. Knockdown of Hspa5 in animal caps resulted in decreased expression of lhx1, a transcription factor directly regulated by RA signaling and essential for pronephros specification. Co-injection of Hspa5MO with lhx1 mRNA partially rescued the phenotype induced by Hspa5MO. These results suggest that the RA-Lhx1 signaling cascade is involved in Hspa5MO-induced pronephros malformation. This study shows that Hspa5, a key regulator of the unfolded protein response, plays an essential role in pronephros formation, which is mediated in part through RA signaling during early embryonic development.
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Affiliation(s)
- Weili Shi
- From the Key Laboratory for Regenerative Medicine, Ministry of Education, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (SAR), China
| | - Gang Xu
- School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Kowloon Tong, Hong Kong SAR, China
| | - Chengdong Wang
- From the Key Laboratory for Regenerative Medicine, Ministry of Education, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (SAR), China, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
| | - Steven M Sperber
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029-6574
| | - Yonglong Chen
- Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China, and
| | - Qin Zhou
- Division of Molecular Nephrology and Creative Training Center for Undergraduates, Ministry of Education Key Laboratory of Laboratory Medicine Diagnostics, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Yi Deng
- Department of Biology, South University of Science and Technology of China, Shenzhen 518055, China,
| | - Hui Zhao
- From the Key Laboratory for Regenerative Medicine, Ministry of Education, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (SAR), China, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China,
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Yuan L, Yu J, Li X, Feng J, Yin C, Wang X. IRE1α knockdown rescues tunicamycin-induced developmental defects and apoptosis in Xenopus laevis. J Biomed Res 2014; 28:275-81. [PMID: 25050111 PMCID: PMC4102841 DOI: 10.7555/jbr.28.20120075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/06/2012] [Accepted: 12/04/2013] [Indexed: 11/29/2022] Open
Abstract
Inositol requiring enzyme-1 (IRE1) is highly conserved from yeasts to humans. Upon endoplasmic reticulum (ER) stress, IRE1 activates X-box-binding protein 1 (XBP1) by unconventional splicing of XBP1 mRNA, which activates unfolded protein response (UPR) to restore ER homeostasis. In mice, IRE1α plays an essential role in extraembryonic tissues. However, its precise action during the early stage of development is unknown. In this study, the gain and loss-of-function analyses were used to investigate the function of Xenopus IRE1α (xIRE1α). The effects of xIRE1α during embryo development were detected with RT-PCR and whole mount in situ hybridization. ER stress was induced by tunicamycin. The apoptotic cells were measured by TUNNEL assays. Although both gain and loss of xIRE1α function had no significant effect on Xenopus embryogenesis, knockdown of xIRE1α could rescue tunicamycin-induced developmental defects and apoptosis. The finding indicates that xIRE1α is not required for embryogenesis but is required for tunicamycin-induced developmental defects and apoptosis in Xenopus laevis.
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Affiliation(s)
- Li Yuan
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
| | - Jin Yu
- Department of Hematology, Friendship hospital of yili kazakh prefecture, Yining, Xinjiang 835000, China.
| | - Xinxin Li
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
| | - Jiaojiao Feng
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
| | - Chenyang Yin
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
| | - Xinru Wang
- Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
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Yuan L, Li X, Feng J, Yin C, Yuan F, Wang X. IRE1α is essential for Xenopus pancreas development. J Biomed Res 2013; 28:123-31. [PMID: 24683410 PMCID: PMC3968283 DOI: 10.7555/jbr.28.20130076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 05/29/2013] [Accepted: 07/28/2013] [Indexed: 12/26/2022] Open
Abstract
Inositol requiring enzyme-1 (IRE1) is highly conserved from yeasts to humans. Upon the endoplasmic reticulum (ER) stress, IRE1 activates X-box-binding protein 1 (XBP1) by unconventionally splicing XBP1 mRNA, which activates the unfolded protein response (UPR) to restore ER homeostasis. In mice, IRE1α inactivity leads to embryonic death and IRE1α plays an essential role in extraembryonic tissues and the placenta. However, its precise action in the embryo proper is still unknown. In this study, the loss of function analysis was performed to investigate the function of Xenopus IRE1α (xIRE1α) during pancreas development. Firstly, the complete open reading frame of xIRE1α was amplified and the expression pattern was detected. The effects of Xenopus IRE1α and XBP1 during embryo development were detected with whole-mount in situ hybridization. The results demonstrated that xIRE1α was much closer to human IRE1α when compared with their sequence alignment. xIRE1α was expressed strongly in developing pancreas and the knockdown of xIRE1α inhibited the differentiation and specification of the pancreas. xIRE1α, which was required for cytoplasmic splicing of XBP1 pre-mRNA and XBP1MO, also showed inhibitory effects on pancreas development. These results suggest that xIRE1α is essential for pancreas development during embryogenesis and functions via the XBP1 dependent pathway.
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Affiliation(s)
- Li Yuan
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Xinxin Li
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Jiaojiao Feng
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Chenyang Yin
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Fang Yuan
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Xinru Wang
- Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
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Evolution of the unfolded protein response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2458-63. [PMID: 23369734 DOI: 10.1016/j.bbamcr.2013.01.016] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/07/2013] [Accepted: 01/13/2013] [Indexed: 01/05/2023]
Abstract
The unfolded protein response (UPR) is a network of signaling pathways that responds to stress in the endoplasmic reticulum (ER). The general output of the UPR is to upregulate genes involved in ER function, thus restoring and/or increasing the capacity of the ER to fold and process proteins. In parallel, many organisms have mechanisms for limiting the load on the ER by attenuating translation or degrading ER-targeted mRNAs. Despite broad conservation of these signaling pathways across eukaryotes, interesting variations demonstrate a variety of mechanisms for managing ER stress. How do early-diverging protozoa respond to stress when they lack traditional transcriptional regulation? What is the role of the ER stress sensor Ire1 in fungal species that are missing its main target? Here I describe how diverse species have optimized the UPR to fit their needs. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Guo J, Li XX, Feng JJ, Yin CY, Wang XJ, Wang N, Yuan L. Inositol-requiring enzyme 1α is required for gut development in Xenopus lavies embryos. World J Gastroenterol 2013; 19:227-234. [PMID: 23345945 PMCID: PMC3548012 DOI: 10.3748/wjg.v19.i2.227] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/19/2012] [Accepted: 12/17/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the role of inositol-requiring enzyme 1α (IRE1α) in gut development of Xenopus lavies embryos.
METHODS: Xenopus embryos were obtained with in vitro fertilization and cultured in 0.1 × MBSH. One and half nanogram of IRE1α, 1 ng of IRE1α-GR mRNA, 1 ng of IRE1αΔC-GR mRNA, and 50 ng of IRE1α morpholino oligonucleotide (MO) or XBP1(C)MO were injected into four blastomeres at 4-cell stage for scoring the phenotype and marker gene analysis. To rescue the effect of IRE1α MO, 1 ng of IRE1α-GR mRNA was co-injected with 50 ng of MO. For the activation of the GR-fusion proteins, dexamethasone was prepared as 5 mmol/L stock solutions in 100% ethanol and applied to the mRNA injected embryos at desired stages in a concentration of 10 μmol/L in 0.1 × MBSH. Embryos were kept in dexamethasone up to stage 41. Whole-mount in situ hybridization was used to determine specific gene expression, such as IRE1α, IRE1β, Xbra and Xsox17α. IRE1α protein expression during Xenopus embryogenesis was detected by Western blotting.
RESULTS: In the whole-mount in situ hybridization analysis, xenopus IRE1α and IRE1β showed quite different expression pattern during tadpole stage. The relatively higher expression of IRE1α was observed in the pancreas, and significant transcription of IRE1β was found in the liver. IRE1α protein could be detected at all developmental stages analyzed, from stage 1 to stage 42. Gain-of-function assay showed that IRE1α mRNA injected embryos at tailbud stage were nearly normal and the expression of the pan-mesodermal marker gene Xbra and the endodermal gene Xsox17α at stage 10.5 was not significantly changed in embryos injected with IRE1α mRNA as compared to uninjected control embryos. And at tadpole stage, the embryos injected with IRE1α-GR mRNA did not display overt phenotype, such as gut-coiling defect. Loss-of-function assay demonstrated that the IRE1α MO injected embryos were morphologically normal before the tailbud stages. We did not observe a significant change of mesodermal and endodermal marker gene expression, while after stage 40, about 80% of the MO injected embryos exhibited dramatic gut defects in which the guts did not coil, but other structures outside the gastrointestinal tract were relatively normal. To test if the phenotypes were specifically caused by the knockdown of IRE1α, a rescue experiment was performed by co-injection of IRE1α-GR mRMA with IRE1α MO. The data obtained demonstrated that the gut coiling defect was rescued. The deletion mutant of IRE1α was constructed, consisting of the N-terminal part without the C-terminal kinase and RNase domains named IRE1αΔC, to investigate the functional domain of IRE1α. Injection of IRE1αΔC-GR mRNA caused similar morphological alterations with gut malformation by interfering with the function of endogenous xIRE1α. In order to investigate if IRE1α/XBP1 pathway was involved in gut development, 50 ng of XBP1 MO was injected and the results showed that knockdown of XBP1 resulted in similar morphological alterations with gut-coiling defect at tadpole stage.
CONCLUSION: IRE1α is not required for germ layer formation but for gut development in Xenopus lavies and it may function via XBP1-dependent pathway.
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Abstract
The endoplasmic reticulum (ER) controls many important aspects of cellular function, including processing of secreted and membrane proteins, synthesis of membranes, and calcium storage. Maintenance of ER function is controlled through a network of signaling pathways collectively known as the unfolded protein response (UPR). The UPR balances the load of incoming proteins with the folding capacity of the ER and allows cells to adapt to situations that disrupt this balance. This disruption is referred to as ER stress. Although ER stress often arises in pathological situations, the UPR plays a central role in the normal development and function of cells specializing in secretion. Many aspects of this response are conserved broadly across eukaryotes; most organisms use some subset of a group of ER transmembrane proteins to signal to the nucleus and induce a broad transcriptional upregulation of genes involved in ER function. However, new developments in metazoans, plants, and fungi illustrate interesting variations on this theme. Here, we summarize mechanisms for detecting and counteracting ER stress, the role of the UPR in normal secretory cell function, and how these pathways vary across organisms and among different tissues and cell types.
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Affiliation(s)
- Kristin A Moore
- Department of Biology and the Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112-0840, USA
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Tanegashima K, Zhao H, Rebbert ML, Dawid IB. Coordinated activation of the secretory pathway during notochord formation in the Xenopus embryo. Development 2009; 136:3543-8. [PMID: 19793890 DOI: 10.1242/dev.036715] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We compared the transcriptome in the developing notochord of Xenopus laevis embryos with that of other embryonic regions. A coordinated and intense activation of a large set of secretory pathway genes was observed in the notochord, but not in notochord precursors in the axial mesoderm at early gastrula stage. The genes encoding Xbp1 and Creb3l2 were also activated in the notochord. These two transcription factors are implicated in the activation of secretory pathway genes during the unfolded protein response, where cells react to the stress of a build-up of unfolded proteins in their endoplasmic reticulum. Xbp1 and Creb3l2 are differentially expressed but not differentially activated in the notochord. Reduction of expression of Xbp1 or Creb3l2 by injection of antisense morpholinos led to strong deficits in notochord but not somitic muscle development. In addition, the expression of some, but not all, genes encoding secretory proteins was inhibited by injection of xbp1 morpholinos. Furthermore, expression of activated forms of Xbp1 or Creb3l2 in animal explants could activate a similar subset of secretory pathway genes. We conclude that coordinated activation of a battery of secretory pathway genes mediated by Xbp1 and Creb/ATF factors is a characteristic and necessary feature of notochord formation.
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Affiliation(s)
- Kosuke Tanegashima
- Laboratory of Molecular Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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