1
|
Bell I, Khan H, Stutt N, Horn M, Hydzik T, Lum W, Rea V, Clapham E, Hoeg L, Van Raay TJ. Nkd1 functions downstream of Axin2 to attenuate Wnt signaling. Mol Biol Cell 2024; 35:ar93. [PMID: 38656801 PMCID: PMC11244159 DOI: 10.1091/mbc.e24-02-0059-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/10/2024] [Accepted: 04/19/2024] [Indexed: 04/26/2024] Open
Abstract
Wnt signaling is a crucial developmental pathway involved in early development as well as stem-cell maintenance in adults and its misregulation leads to numerous diseases. Thus, understanding the regulation of this pathway becomes vitally important. Axin2 and Nkd1 are widely utilized negative feedback regulators in Wnt signaling where Axin2 functions to destabilize cytoplasmic β-catenin, and Nkd1 functions to inhibit the nuclear localization of β-catenin. Here, we set out to further understand how Axin2 and Nkd1 regulate Wnt signaling by creating axin2gh1/gh1, nkd1gh2/gh2 single mutants and axin2gh1/gh1;nkd1gh2/gh2 double mutant zebrafish using sgRNA/Cas9. All three Wnt regulator mutants were viable and had impaired heart looping, neuromast migration defects, and behavior abnormalities in common, but there were no signs of synergy in the axin2gh1/gh1;nkd1gh2/gh2 double mutants. Further, Wnt target gene expression by qRT-PCR and RNA-seq, and protein expression by mass spectrometry demonstrated that the double axin2gh1/gh1;nkd1gh2/gh2 mutant resembled the nkd1gh2/gh2 phenotype demonstrating that Nkd1 functions downstream of Axin2. In support of this, the data further demonstrates that Axin2 uniquely alters the properties of β-catenin-dependent transcription having novel readouts of Wnt activity compared with nkd1gh2/gh2 or the axin2gh1/gh1;nkd1gh2/gh2 double mutant. We also investigated the sensitivity of the Wnt regulator mutants to exacerbated Wnt signaling, where the single mutants displayed characteristic heightened Wnt sensitivity, resulting in an eyeless phenotype. Surprisingly, this phenotype was rescued in the double mutant, where we speculate that cross-talk between Wnt/β-catenin and Wnt/Planar Cell Polarity pathways could lead to altered Wnt signaling in some scenarios. Collectively, the data emphasizes both the commonality and the complexity in the feedback regulation of Wnt signaling.
Collapse
Affiliation(s)
- Ian Bell
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Haider Khan
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Nathan Stutt
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Matthew Horn
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Teesha Hydzik
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Whitney Lum
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Victoria Rea
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Emma Clapham
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| | - Lisa Hoeg
- Department of Bioinformatics, University of Guelph, Guelph, Ontario, N1G 2W1 Canada
| | - Terence J. Van Raay
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1 Ontario, Canada
| |
Collapse
|
2
|
Clinical Significance of NKD Inhibitor of WNT Signaling Pathway 1 (NKD1) in Glioblastoma. Genet Res (Camb) 2023; 2023:1184101. [PMID: 36969985 PMCID: PMC10038739 DOI: 10.1155/2023/1184101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/23/2023] [Accepted: 01/30/2023] [Indexed: 03/19/2023] Open
Abstract
Introduction. As the most malignant type of gliomas, glioblastoma is characterized with disappointing prognosis. Here, we aimed to investigate expression and function of NKD inhibitor of Wnt signaling pathway 1 (NKD1), an antagonist of Wnt-beta-catenin signaling pathways, in glioblastoma. Methods. The mRNA level of NKD1 was firstly retrieved from TCGA glioma dataset to evaluate its correlation with clinical characteristics and its value in prognosis prediction. Then, its protein expression level in glioblastoma was tested by immunohistochemistry staining in a retrospectively cohort collected from our medical center (n = 66). Univariate and multivariate survival analyses were conducted to assess its effect on glioma prognosis. Two glioblastoma cell lines, U87 and U251, were used to further investigate the tumor-related role of NKD1 through overexpression strategy in combination with cell proliferation assays. Immune cell enrichment in glioblastoma and its correlation with NKD1 level was finally assessed using bioinformatics analyses. Results. NKD1 shows a lower expression level in glioblastoma compared to that in the normal brain or other glioma subtypes, which is independently correlated to a worse prognosis in both the TCGA cohort and our retrospective cohort. Overexpressing NKD1 in glioblastoma cell lines can significantly attenuate cell proliferation. In addition, expression of NKD1 in glioblastoma is negatively correlated to the T cell infiltration, indicating it may have crosstalk with the tumor immune microenvironment. Conclusions. NKD1 inhibits glioblastoma progression and its downregulated expression indicates a poor prognosis.
Collapse
|
3
|
Wu B, Woo JS, Sun Z, Srikanth S, Gwack Y. Ca 2+ Signaling Augmented by ORAI1 Trafficking Regulates the Pathogenic State of Effector T Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:1329-1340. [PMID: 35217583 PMCID: PMC8916982 DOI: 10.4049/jimmunol.2100871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/07/2022] [Indexed: 02/02/2023]
Abstract
Activation of the Ca2+ release-activated Ca2+ (CRAC) channel is crucial for T cell functions. It was recently shown that naked cuticle homolog 2 (NKD2), a signaling adaptor molecule, orchestrates trafficking of ORAI1, a pore subunit of the CRAC channels, to the plasma membrane for sustained activation of the CRAC channels. However, the physiological role of sustained Ca2+ entry via ORAI1 trafficking remains poorly understood. Using NKD2 as a molecular handle, we show that ORAI1 trafficking is crucial for sustained Ca2+ entry and cytokine production, especially in inflammatory Th1 and Th17 cells. We find that murine T cells cultured under pathogenic Th17-polarizing conditions have higher Ca2+ levels that are NKD2-dependent than those under nonpathogenic conditions. In vivo, deletion of Nkd2 alleviated clinical symptoms of experimental autoimmune encephalomyelitis in mice by selectively decreasing effector T cell responses in the CNS. Furthermore, we observed a strong correlation between NKD2 expression and proinflammatory cytokine production in effector T cells. Taken together, our findings suggest that the pathogenic effector T cell response demands sustained Ca2+ entry supported by ORAI1 trafficking.
Collapse
Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Zuoming Sun
- Department of Molecular Imaging and Therapy, Beckman Research Institute of City of Hope, Duarte, CA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| |
Collapse
|
4
|
Wu B, Woo JS, Vila P, Jew M, Leung J, Sun Z, Srikanth S, Gwack Y. NKD2 mediates stimulation-dependent ORAI1 trafficking to augment Ca 2+ entry in T cells. Cell Rep 2021; 36:109603. [PMID: 34433025 PMCID: PMC8435239 DOI: 10.1016/j.celrep.2021.109603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/21/2021] [Accepted: 08/03/2021] [Indexed: 01/19/2023] Open
Abstract
Sustained activation of the Ca2+-release-activated Ca2+ (CRAC) channel is pivotal for effector T cell responses. The mechanisms underlying this sustainability remain poorly understood. We find that plasma membrane localization of ORAI1, the pore subunit of CRAC channels, is limited in effector T cells, with a significant fraction trapped in intracellular vesicles. From a targeted screen, we identify an essential component of ORAI1+ vesicles, naked cuticle homolog 2 (NKD2). Mechanistically, NKD2, an adaptor molecule activated by signaling pathways downstream of T cell receptors, orchestrates trafficking and insertion of ORAI1+ vesicles to the plasma membrane. Together, our findings suggest that T cell receptor (TCR)-stimulation-dependent insertion of ORAI1 into the plasma membrane is essential for sustained Ca2+ signaling and cytokine production in T cells.
Collapse
Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Pamela Vila
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Olive View-UCLA Medical Center, 14445 Olive View Drive, Sylmar, CA 91342, USA
| | - Marcus Jew
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Jennifer Leung
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Zuoming Sun
- Department of Molecular Imaging & Therapy, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
| |
Collapse
|
5
|
Wang B, Rong X, Zhou Y, Liu Y, Sun J, Zhao B, Deng B, Lu L, Lu L, Li Y, Zhou J. Eukaryotic initiation factor 4A3 inhibits Wnt/β-catenin signaling and regulates axis formation in zebrafish embryos. Development 2021; 148:261699. [PMID: 33914867 DOI: 10.1242/dev.198101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/25/2021] [Indexed: 12/31/2022]
Abstract
A key step in the activation of canonical Wnt signaling is the interaction between β-catenin and Tcf/Lefs that forms the transcription activation complex and facilitates the expression of target genes. Eukaryotic initiation factor 4A3 (EIF4A3) is an ATP-dependent DEAD box-family RNA helicase and acts as a core subunit of the exon junction complex (EJC) to control a series of RNA post-transcriptional processes. In this study, we uncover that EIF4A3 functions as a Wnt inhibitor by interfering with the formation of β-catenin/Tcf transcription activation complex. As Wnt stimulation increases, accumulated β-catenin displaces EIF4A3 from a transcriptional complex with Tcf/Lef, allowing the active complex to facilitate the expression of target genes. In zebrafish embryos, eif4a3 depletion inhibited the development of the dorsal organizer and pattern formation of the anterior neuroectoderm by increasing Wnt/β-catenin signaling. Conversely, overexpression of eif4a3 decreased Wnt/β-catenin signaling and inhibited the formation of the dorsal organizer before gastrulation. Our results reveal previously unreported roles of EIF4A3 in the inhibition of Wnt signaling and the regulation of embryonic development in zebrafish.
Collapse
Affiliation(s)
- Bo Wang
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Xiaozhi Rong
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Yumei Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yunzhang Liu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Jiqin Sun
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Beibei Zhao
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Bei Deng
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Lei Lu
- Model Animal Research Center of Nanjing University and MOE Key Laboratory of Model Animals for Disease Study, 12 Xuefu Road, Pukou High-Tech Zone, Nanjing 210061, China
| | - Ling Lu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yun Li
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Jianfeng Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| |
Collapse
|
6
|
Fry E, Kim SK, Chigurapti S, Mika KM, Ratan A, Dammermann A, Mitchell BJ, Miller W, Lynch VJ. Functional Architecture of Deleterious Genetic Variants in the Genome of a Wrangel Island Mammoth. Genome Biol Evol 2021; 12:48-58. [PMID: 32031213 PMCID: PMC7094797 DOI: 10.1093/gbe/evz279] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2019] [Indexed: 12/21/2022] Open
Abstract
Woolly mammoths were among the most abundant cold-adapted species during the Pleistocene. Their once-large populations went extinct in two waves, an end-Pleistocene extinction of continental populations followed by the mid-Holocene extinction of relict populations on St. Paul Island ∼5,600 years ago and Wrangel Island ∼4,000 years ago. Wrangel Island mammoths experienced an episode of rapid demographic decline coincident with their isolation, leading to a small population, reduced genetic diversity, and the fixation of putatively deleterious alleles, but the functional consequences of these processes are unclear. Here, we show that a Wrangel Island mammoth genome had many putative deleterious mutations that are predicted to cause diverse behavioral and developmental defects. Resurrection and functional characterization of several genes from the Wrangel Island mammoth carrying putatively deleterious substitutions identified both loss and gain of function mutations in genes associated with developmental defects (HYLS1), oligozoospermia and reduced male fertility (NKD1), diabetes (NEUROG3), and the ability to detect floral scents (OR5A1). These data suggest that at least one Wrangel Island mammoth may have suffered adverse consequences from reduced population size and isolation.
Collapse
Affiliation(s)
- Erin Fry
- Department of Human Genetics, The University of Chicago
| | - Sun K Kim
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University
| | | | | | - Aakrosh Ratan
- Center for Public Health Genomics, University of Virginia
| | | | - Brian J Mitchell
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University
| | - Webb Miller
- Center for Comparative Genomics and Bioinformatics, Pennsylvania State University
| | - Vincent J Lynch
- Department of Biological Sciences, University at Buffalo, SUNY
| |
Collapse
|
7
|
Xue R, Lin W, Sun J, Watanabe M, Xu A, Araki M, Nasu Y, Tang Z, Huang P. The role of Wnt signaling in male reproductive physiology and pathology. Mol Hum Reprod 2021; 27:gaaa085. [PMID: 33543289 DOI: 10.1093/molehr/gaaa085] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/26/2020] [Indexed: 12/14/2022] Open
Abstract
Accumulating evidence has shown that Wnt signaling is deeply involved in male reproductive physiology, and malfunction of the signal path can cause pathological changes in genital organs and sperm cells. These abnormalities are diverse in manifestation and have been constantly found in the knockout models of Wnt studies. Nevertheless, most of the research solely focused on a certain factor in the Wnt pathway, and there are few reports on the overall relation between Wnt signals and male reproductive physiology. In our review, Wnt findings relating to the reproductive system were sought and summarized in terms of Wnt ligands, Wnt receptors, Wnt intracellular signals and Wnt regulators. By sorting out and integrating relevant functions, as well as underlining the controversies among different reports, our review aims to offer an overview of Wnt signaling in male reproductive physiology and pathology for further mechanistic studies.
Collapse
Affiliation(s)
- Ruizhi Xue
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- Department of Urology, Xiangya Hospital, Central South University, Changsha, China
| | - Wenfeng Lin
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Jingkai Sun
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- Department of Urology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Masami Watanabe
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Abai Xu
- Department of Urology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Motoo Araki
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yasutomo Nasu
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Zhengyan Tang
- Department of Urology, Xiangya Hospital, Central South University, Changsha, China
| | - Peng Huang
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- Department of Urology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
- Okayama Medical Innovation Center, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| |
Collapse
|
8
|
Gammons MV, Renko M, Flack JE, Mieszczanek J, Bienz M. Feedback control of Wnt signaling based on ultrastable histidine cluster co-aggregation between Naked/NKD and Axin. eLife 2020; 9:e59879. [PMID: 33025907 PMCID: PMC7581431 DOI: 10.7554/elife.59879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/06/2020] [Indexed: 12/20/2022] Open
Abstract
Feedback control is a universal feature of cell signaling pathways. Naked/NKD is a widely conserved feedback regulator of Wnt signaling which controls animal development and tissue homeostasis. Naked/NKD destabilizes Dishevelled, which assembles Wnt signalosomes to inhibit the β-catenin destruction complex via recruitment of Axin. Here, we discover that the molecular mechanism underlying Naked/NKD function relies on its assembly into ultra-stable decameric core aggregates via its conserved C-terminal histidine cluster (HisC). HisC aggregation is facilitated by Dishevelled and depends on accumulation of Naked/NKD during prolonged Wnt stimulation. Naked/NKD HisC cores co-aggregate with a conserved histidine cluster within Axin, to destabilize it along with Dishevelled, possibly via the autophagy receptor p62, which binds to HisC aggregates. Consistent with this, attenuated Wnt responses are observed in CRISPR-engineered flies and human epithelial cells whose Naked/NKD HisC has been deleted. Thus, HisC aggregation by Naked/NKD provides context-dependent feedback control of prolonged Wnt responses.
Collapse
Affiliation(s)
- Melissa V Gammons
- MRC Laboratory of Molecular Biology, Cambridge Biomedical CampusCambridgeUnited Kingdom
| | - Miha Renko
- MRC Laboratory of Molecular Biology, Cambridge Biomedical CampusCambridgeUnited Kingdom
| | - Joshua E Flack
- MRC Laboratory of Molecular Biology, Cambridge Biomedical CampusCambridgeUnited Kingdom
| | - Juliusz Mieszczanek
- MRC Laboratory of Molecular Biology, Cambridge Biomedical CampusCambridgeUnited Kingdom
| | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Cambridge Biomedical CampusCambridgeUnited Kingdom
| |
Collapse
|
9
|
Chen C, Zhang J, Ling J, Du Y, Hou Y. Nkd2 promotes the differentiation of dental follicle stem/progenitor cells into osteoblasts. Int J Mol Med 2018; 42:2403-2414. [PMID: 30106129 PMCID: PMC6192769 DOI: 10.3892/ijmm.2018.3822] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 08/10/2018] [Indexed: 12/05/2022] Open
Abstract
Dental follicle stem/progenitor cells have the potential to undergo osteogenesis. naked cuticle homolog 2 (Nkd2) is a signal-inducible feedback antagonist of the canonical Wnt signaling pathway. The purpose of the present study was to investigate the function of Nkd2 in the differentiation of dental follicle stem/progenitor cells (DFSCs) into osteoblasts. Immunohistochemistry, reverse transcription-quantitative polymerase chain reaction and western blotting were employed to detect Nkd2 expression in rat DFSCs. In addition, rat DFSCs (rDFSCs) were transfected with small interfering RNAs to examine the effect of Nkd2 on the differentiation of these cells into osteoblasts. Furthermore, the function of Nkd2 in the Wnt/β-catenin pathway in rDFSCs was investigated using β-catenin/T-cell factor luciferase activity assays and western blotting. It was revealed that the expression of Nkd2 was upregulated during the differentiation of rDFSCs into osteoblasts. Furthermore, osteoblast differentiation ability and Wnt/β-catenin pathway activity were significantly decreased in Nkd2-silenced rDFSCs compared with the si-NC group (P<0.05 and P<0.001, respectively). The results suggest that Nkd2 promotes the differentiation of rDFSCs into osteoblasts through Wnt/β-catenin signaling.
Collapse
Affiliation(s)
- Chanchan Chen
- Department of Stomatology, Shenzhen Children's Hospital, Shenzhen, Guangdong 518038, P.R. China
| | - Jianying Zhang
- Department of Operative Dentistry and Endodontics, Xiangya School of Stomatology, Xiangya Stomatological Hospital, Central South University, Changsha, Hu'nan 410083, P.R. China
| | - Junqi Ling
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Research Institute of Stomatology, Guangdong Province Key Laboratory of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| | - Yu Du
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Research Institute of Stomatology, Guangdong Province Key Laboratory of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| | - Yuluan Hou
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Research Institute of Stomatology, Guangdong Province Key Laboratory of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| |
Collapse
|
10
|
Rosmaninho P, Mükusch S, Piscopo V, Teixeira V, Raposo AA, Warta R, Bennewitz R, Tang Y, Herold-Mende C, Stifani S, Momma S, Castro DS. Zeb1 potentiates genome-wide gene transcription with Lef1 to promote glioblastoma cell invasion. EMBO J 2018; 37:e97115. [PMID: 29903919 PMCID: PMC6068449 DOI: 10.15252/embj.201797115] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 04/27/2018] [Accepted: 05/07/2018] [Indexed: 12/30/2022] Open
Abstract
Glioblastoma is the most common and aggressive brain tumor, with a subpopulation of stem-like cells thought to mediate its recurring behavior and therapeutic resistance. The epithelial-mesenchymal transition (EMT) inducing factor Zeb1 was linked to tumor initiation, invasion, and resistance to therapy in glioblastoma, but how Zeb1 functions at molecular level and what genes it regulates remain poorly understood. Contrary to the common view that EMT factors act as transcriptional repressors, here we show that genome-wide binding of Zeb1 associates with both activation and repression of gene expression in glioblastoma stem-like cells. Transcriptional repression requires direct DNA binding of Zeb1, while indirect recruitment to regulatory regions by the Wnt pathway effector Lef1 results in gene activation, independently of Wnt signaling. Amongst glioblastoma genes activated by Zeb1 are predicted mediators of tumor cell migration and invasion, including the guanine nucleotide exchange factor Prex1, whose elevated expression is predictive of shorter glioblastoma patient survival. Prex1 promotes invasiveness of glioblastoma cells in vivo highlighting the importance of Zeb1/Lef1 gene regulatory mechanisms in gliomagenesis.
Collapse
Affiliation(s)
- Pedro Rosmaninho
- Molecular Neurobiology Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Susanne Mükusch
- Institute of Neurology (Edinger Institute), Frankfurt University Medical School, Frankfurt, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Valerio Piscopo
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Vera Teixeira
- Molecular Neurobiology Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Alexandre Asf Raposo
- Molecular Neurobiology Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Rolf Warta
- Division of Experimental Neurosurgery, Department of Neurosurgery, University Hospital of Heidelberg, Heidelberg, Germany
| | - Romina Bennewitz
- Institute of Neurology (Edinger Institute), Frankfurt University Medical School, Frankfurt, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Yeman Tang
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Christel Herold-Mende
- Division of Experimental Neurosurgery, Department of Neurosurgery, University Hospital of Heidelberg, Heidelberg, Germany
| | - Stefano Stifani
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Stefan Momma
- Institute of Neurology (Edinger Institute), Frankfurt University Medical School, Frankfurt, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Diogo S Castro
- Molecular Neurobiology Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| |
Collapse
|
11
|
Marsden AN, Derry SW, Schneider I, Scott CA, Westfall TA, Brastrom LK, Shea MA, Dawson DV, Slusarski DC. The Nkd EF-hand domain modulates divergent wnt signaling outputs in zebrafish. Dev Biol 2018; 434:63-73. [PMID: 29180104 DOI: 10.1016/j.ydbio.2017.11.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/29/2017] [Accepted: 11/20/2017] [Indexed: 12/25/2022]
Abstract
Wnt proteins regulate diverse biological responses by initiating two general outcomes: β-catenin-dependent transcription and β-catenin-independent activation of signaling cascades, the latter including modulation of calcium and regulation of cytoskeletal dynamics (Planar Cell Polarity, PCP). It has been difficult to elucidate the mechanisms by which Wnt signals are directed to effect one or the other outcome due to shared signaling proteins between the β-catenin-dependent and -independent pathways, such as the Dishevelled binding protein Naked. While all Naked paralogs contain a putative calcium-binding domain, the EF-Hand, Drosophila Naked does not bind calcium. Here we find a lineage-specific evolutionary change within the Drosophila Naked EF-hand that is not shared with other insects or vertebrates. We demonstrate the necessary role of the EF-hand for Nkd localization changes in calcium fluxing cells and using in vivo assays, we identify a role for the zebrafish Naked EF-hand in PCP but not in β-catenin antagonism. In contrast, Drosophila-like Nkd does not function in PCP, but is a robust antagonist of Wnt/β-catenin signaling. This work reveals that the zebrafish Nkd1 EF-hand is essential to balance Wnt signaling inputs and modulate the appropriate outputs, while the Drosophila-like EF-Hand primarily functions in β-catenin signaling.
Collapse
Affiliation(s)
- Autumn N Marsden
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Sarah W Derry
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA; Drake University, Des Moines, IA 50311, USA
| | - Igor Schneider
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA; Instituto de Ciencias Biologicas, Universidade Federal do Para, Belem 66075-110, Brazil
| | - C Anthony Scott
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Trudi A Westfall
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Lindy K Brastrom
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Madeline A Shea
- Department of Biochemistry, University of Iowa, UA 52242, USA
| | - Deborah V Dawson
- Departments of Pediatric Dentistry&Biostatistics, University of Iowa, Iowa City 52242, USA
| | - Diane C Slusarski
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA.
| |
Collapse
|
12
|
Twaroski K, Mallanna SK, Jing R, DiFurio F, Urick A, Duncan SA. FGF2 mediates hepatic progenitor cell formation during human pluripotent stem cell differentiation by inducing the WNT antagonist NKD1. Genes Dev 2016; 29:2463-74. [PMID: 26637527 PMCID: PMC4691950 DOI: 10.1101/gad.268961.115] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Twaroski et al. identified naked cuticle homolog 1 (NKD1) as being directly regulated by FGFR activity during the transition from endoderm to hepatic progenitor cell. Loss of NKD1 suppresses the formation of hepatic progenitor cells from human induced pluripotent stem cells, and this phenotype can be rescued by using a pharmacological antagonist of canonical WNT signaling. Fibroblast growth factors (FGFs) are required to specify hepatic fate within the definitive endoderm through activation of the FGF receptors (FGFRs). While the signaling pathways involved in hepatic specification are well understood, the mechanisms through which FGFs induce hepatic character within the endoderm are ill defined. Here we report the identification of genes whose expression is directly regulated by FGFR activity during the transition from endoderm to hepatic progenitor cell. The FGFR immediate early genes that were identified include those encoding transcription factors, growth factors, and signaling molecules. One of these immediate early genes encodes naked cuticle homolog 1 (NKD1), which is a repressor of canonical WNT (wingless-type MMTV integration site) signaling. We show that loss of NKD1 suppresses the formation of hepatic progenitor cells from human induced pluripotent stem cells and that this phenotype can be rescued by using a pharmacological antagonist of canonical WNT signaling. We conclude that FGF specifies hepatic fate at least in large part by inducing expression of NKD1 to transiently suppress the canonical WNT pathway.
Collapse
Affiliation(s)
- Kirk Twaroski
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA
| | - Sunil K Mallanna
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, USA
| | - Ran Jing
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, USA
| | - Francesca DiFurio
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, USA
| | - Amanda Urick
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, USA
| | - Stephen A Duncan
- Department of Cell Biology, Neurobiology, and Anatomy, Program in Regenerative Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226, USA; Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, USA
| |
Collapse
|
13
|
Xu P, Zhang X, Ni W, Fan H, Xu J, Chen Y, Zhu J, Gu X, Yang L, Ni R, Chen B, Shi W. Upregulated HOXC8 Expression Is Associated with Poor Prognosis and Oxaliplatin Resistance in Hepatocellular Carcinoma. Dig Dis Sci 2015; 60:3351-63. [PMID: 26123838 DOI: 10.1007/s10620-015-3774-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/17/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. It is indispensable to understanding molecular mechanisms of HCC progression and to developing clinically useful biomarkers for this disease. AIM In this article, we examined whether HOXC8 was associated with the poor prognosis of hepatocellular carcinoma and explored the possible underlying mechanism. METHODS The HOXC8 and Ki67 expression levels in 86 patients with hepatocellular carcinoma were examined using immunohistochemistry. HOXC8 levels in HCC cells were downregulated by siRNA transfection. The cycle progression and cell proliferation status of HCC cells and the oxaliplatin effectiveness were evaluated by flow cytometry and CCK-8 assay. HOXC8, CyclinD1, PCNA, Nkd2, and cleaved caspase-3 levels were detected by western blot. RESULTS HOXC8 was upregulated in HCC tissues, compared with adjacent non-tumor ones. HOXC8 expression levels in 86 patients with hepatocellular carcinoma were positively correlated with histological grade. Univariate and multivariate survival analysis revealed that HOXC8 was a significant predictor for overall survival of HCC patients. HOXC8 siRNA knockdown delayed the G1-S phase transition, inhibited cell proliferation, and attenuated resistance to oxaliplatin. CONCLUSIONS HOXC8 promoted HCC proliferation and predicted poor prognosis. Furthermore, upregulated HOXC8 expression was associated with oxaliplatin resistance in hepatocellular carcinoma.
Collapse
Affiliation(s)
- Pan Xu
- Department of Radiotherapy, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, People's Republic of China
| | - Xiubing Zhang
- Department of Medical Oncology, the Second Peoples Hospital of Nan Tong, 43 Tangzha Xinglong Road, Nantong, 226002, Jiangsu Province, People's Republic of China
| | - Wenkai Ni
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, People's Republic of China
| | - Hui Fan
- Department of Medical Oncology, the Second Peoples Hospital of Nan Tong, 43 Tangzha Xinglong Road, Nantong, 226002, Jiangsu Province, People's Republic of China
| | - Jian Xu
- Department of Medical Oncology, the Second Peoples Hospital of Nan Tong, 43 Tangzha Xinglong Road, Nantong, 226002, Jiangsu Province, People's Republic of China
| | - Yongmei Chen
- Department of Medical Oncology, the Second Peoples Hospital of Nan Tong, 43 Tangzha Xinglong Road, Nantong, 226002, Jiangsu Province, People's Republic of China
| | - Jia Zhu
- Department of Pathogen Biology, Jiangsu Province Key Laboratory for Information and Molecular Drug Target, Nantong University, 9 Qiangyuan Road, Nantong, 226019, Jiangsu Province, People's Republic of China
| | - Xiaoling Gu
- Department of Pathogen Biology, Jiangsu Province Key Laboratory for Information and Molecular Drug Target, Nantong University, 9 Qiangyuan Road, Nantong, 226019, Jiangsu Province, People's Republic of China
| | - Linlin Yang
- Department of Pathogen Biology, Jiangsu Province Key Laboratory for Information and Molecular Drug Target, Nantong University, 9 Qiangyuan Road, Nantong, 226019, Jiangsu Province, People's Republic of China
| | - Runzhou Ni
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, People's Republic of China
| | - Buyou Chen
- Department of Radiotherapy, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, People's Republic of China.
| | - Weidong Shi
- Department of Medical Oncology, the Second Peoples Hospital of Nan Tong, 43 Tangzha Xinglong Road, Nantong, 226002, Jiangsu Province, People's Republic of China.
| |
Collapse
|
14
|
Larraguibel J, Weiss ARE, Pasula DJ, Dhaliwal RS, Kondra R, Van Raay TJ. Wnt ligand-dependent activation of the negative feedback regulator Nkd1. Mol Biol Cell 2015; 26:2375-84. [PMID: 25904337 PMCID: PMC4462952 DOI: 10.1091/mbc.e14-12-1648] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/16/2015] [Indexed: 02/02/2023] Open
Abstract
Nkd1, a negative feedback regulator of the Wnt pathway, localizes with Dvl2 to the putative Wnt signalosome, where it becomes activated by Wnt. Activated Nkd1 moves away from the membrane to become more cytosolic, where it interacts with β-catenin to prevent nuclear accumulation. Misregulation of Wnt signaling is at the root of many diseases, most notably colorectal cancer, and although we understand the activation of the pathway, we have a very poor understanding of the circumstances under which Wnt signaling turns itself off. There are numerous negative feedback regulators of Wnt signaling, but two stand out as constitutive and obligate Wnt-induced regulators: Axin2 and Nkd1. Whereas Axin2 behaves similarly to Axin in the destruction complex, Nkd1 is more enigmatic. Here we use zebrafish blastula cells that are responsive Wnt signaling to demonstrate that Nkd1 activity is specifically dependent on Wnt ligand activation of the receptor. Furthermore, our results support the hypothesis that Nkd1 is recruited to the Wnt signalosome with Dvl2, where it becomes activated to move into the cytoplasm to interact with β-catenin, inhibiting its nuclear accumulation. Comparison of these results with Nkd function in Drosophila generates a unified and conserved model for the role of this negative feedback regulator in the modulation of Wnt signaling.
Collapse
Affiliation(s)
- Jahdiel Larraguibel
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Alexander R E Weiss
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Daniel J Pasula
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Rasmeet S Dhaliwal
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Roman Kondra
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Terence J Van Raay
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| |
Collapse
|
15
|
Pallares LF, Harr B, Turner LM, Tautz D. Use of a natural hybrid zone for genomewide association mapping of craniofacial traits in the house mouse. Mol Ecol 2014; 23:5756-70. [PMID: 25319559 DOI: 10.1111/mec.12968] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/23/2014] [Accepted: 10/03/2014] [Indexed: 02/03/2023]
Abstract
The identification of the genes involved in morphological variation in nature is still a major challenge. Here, we explore a new approach: we combine 178 samples from a natural hybrid zone between two subspecies of the house mouse (Mus musculus domesticus and Mus musculus musculus), and high coverage of the genome (~ 145K SNPs) to identify loci underlying craniofacial shape variation. Due to the long history of recombination in the hybrid zone, high mapping resolution is anticipated. The combination of genomes from subspecies allows the mapping of both, variation within subspecies and inter-subspecific differences, thereby increasing the overall amount of causal genetic variation that can be detected. Skull and mandible shape were measured using 3D landmarks and geometric morphometrics. Using principal component axes as phenotypes, and a linear mixed model accounting for genetic relatedness in the mapping populations, we identified nine genomic regions associated with skull shape and 10 with mandible shape. High mapping resolution (median size of significant regions = 148 kb) enabled identification of single or few candidate genes in most cases. Some of the genes act as regulators or modifiers of signalling pathways relevant for morphological development and bone formation, including several with known craniofacial phenotypes in mice and humans. The significant associations combined explain 13% and 7% of the skull and mandible shape variation, respectively. In addition, a positive correlation was found between chromosomal length and proportion of variation explained. Our results suggest a complex genetic architecture for shape traits and support a polygenic model.
Collapse
Affiliation(s)
- Luisa F Pallares
- Max-Planck Institute for Evolutionary Biology, Plön, 24306, Germany
| | | | | | | |
Collapse
|
16
|
Stancikova J, Krausova M, Kolar M, Fafilek B, Svec J, Sedlacek R, Neroldova M, Dobes J, Horazna M, Janeckova L, Vojtechova M, Oliverius M, Jirsa M, Korinek V. NKD1 marks intestinal and liver tumors linked to aberrant Wnt signaling. Cell Signal 2014; 27:245-56. [PMID: 25446263 DOI: 10.1016/j.cellsig.2014.11.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 10/24/2014] [Accepted: 11/08/2014] [Indexed: 01/29/2023]
Abstract
The activity of the Wnt pathway undergoes complex regulation to ensure proper functioning of this principal signaling mechanism during development of adult tissues. The regulation may occur at several levels and includes both positive and negative feedback loops. In the present study we employed one of such negative feedback regulators, naked cuticle homolog 1 (Nkd1), to follow the Wnt pathway activity in the intestine and liver and in neoplasia originated in these organs. Using lineage tracing in transgenic mice we localized Nkd1 mRNA to the bottom parts of the small intestinal crypts and hepatocytes surrounding the central vein of the hepatic lobule. Furthermore, in two mouse models of intestinal tumorigenesis, Nkd1 expression levels were elevated in tumors when compared to healthy tissue. We utilized a collection of human intestinal polyps and carcinomas to confirm that NKD1 represents a robust marker of neoplastic growth. In addition, expression analysis of NKD1 in liver cancer showed that high expression levels of the gene distinguish a subclass of hepatocellular carcinomas related to aberrant Wnt signaling. Finally, our results were confirmed by bioinformatic analysis of large publicly available datasets that included gene expression profiling and high-throughput sequencing data of human colon and liver cancer specimens.
Collapse
Affiliation(s)
- Jitka Stancikova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic; Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2, Czech Republic
| | - Michaela Krausova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Michal Kolar
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Bohumil Fafilek
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Jiri Svec
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic; Second Department of Internal Medicine, Third Faculty of Medicine, Charles University, Prague, Srobarova 50, 100 34 Prague 10, Czech Republic
| | - Radislav Sedlacek
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Magdalena Neroldova
- Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Jan Dobes
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Monika Horazna
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Lucie Janeckova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Martina Vojtechova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic
| | - Martin Oliverius
- Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Milan Jirsa
- Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Vladimir Korinek
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083142 20 Prague 4, Czech Republic.
| |
Collapse
|
17
|
PAF and EZH2 induce Wnt/β-catenin signaling hyperactivation. Mol Cell 2013; 52:193-205. [PMID: 24055345 DOI: 10.1016/j.molcel.2013.08.028] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 04/26/2013] [Accepted: 08/09/2013] [Indexed: 11/20/2022]
Abstract
Fine control of Wnt signaling is essential for various cellular and developmental decision-making processes. However, deregulation of Wnt signaling leads to pathological consequences, one of which is cancer. Here, we identify a function of PAF, a component of translesion DNA synthesis, in modulating Wnt signaling. PAF is specifically overexpressed in colon cancer cells and intestinal stem cells and is required for colon cancer cell proliferation. In Xenopus laevis, ventrovegetal expression of PAF hyperactivates Wnt signaling, developing a secondary axis with β-catenin target gene upregulation. Upon Wnt signaling activation, PAF dissociates from PCNA and binds directly to β-catenin. Then, PAF recruits EZH2 to the β-catenin transcriptional complex and specifically enhances Wnt target gene transactivation, independently of EZH2's methyltransferase activity. In mice, conditional expression of PAF induces intestinal neoplasia via Wnt signaling hyperactivation. Our studies reveal an unexpected role of PAF in regulating Wnt signaling and propose a regulatory mechanism of Wnt signaling during tumorigenesis.
Collapse
|
18
|
Angonin D, Van Raay TJ. Nkd1 functions as a passive antagonist of Wnt signaling. PLoS One 2013; 8:e74666. [PMID: 24009776 PMCID: PMC3756965 DOI: 10.1371/journal.pone.0074666] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 08/05/2013] [Indexed: 12/22/2022] Open
Abstract
Wnt signaling is involved in many aspects of development and in the homeostasis of stem cells. Its importance is underscored by the fact that misregulation of Wnt signaling has been implicated in numerous diseases, especially colorectal cancer. However, how Wnt signaling regulates itself is not well understood. There are several Wnt negative feedback regulators, which are active antagonists of Wnt signaling, but one feedback regulator, Nkd1, has reduced activity compared to other antagonists, yet is still a negative feedback regulator. Here we describe our efforts to understand the role of Nkd1 using Wnt signaling compromised zebrafish mutant lines. In several of these lines, Nkd1 function was not any more active than it was in wild type embryos. However, we found that Nkd1’s ability to antagonize canonical Wnt/β-catenin signaling was enhanced in the Wnt/Planar Cell Polarity mutants silberblick (slb/wnt11) and trilobite (tri/vangl2). While slb and tri mutants do not display alterations in canonical Wnt signaling, we found that they are hypersensitive to it. Overexpression of the canonical Wnt/β-catenin ligand Wnt8a in slb or tri mutants resulted in dorsalized embryos, with tri mutants being much more sensitive to Wnt8a than slb mutants. Furthermore, the hyperdorsalization caused by Wnt8a in tri could be rescued by Nkd1. These results suggest that Nkd1 functions as a passive antagonist of Wnt signaling, functioning only when homeostatic levels of Wnt signaling have been breached or when Wnt signaling becomes destabilized.
Collapse
Affiliation(s)
- Diane Angonin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Terence J. Van Raay
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
| |
Collapse
|
19
|
Regard JB, Zhong Z, Williams BO, Yang Y. Wnt signaling in bone development and disease: making stronger bone with Wnts. Cold Spring Harb Perspect Biol 2012; 4:4/12/a007997. [PMID: 23209148 DOI: 10.1101/cshperspect.a007997] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The skeleton as an organ is widely distributed throughout the entire vertebrate body. Wnt signaling has emerged to play major roles in almost all aspects of skeletal development and homeostasis. Because abnormal Wnt signaling causes various human skeletal diseases, Wnt signaling has become a focal point of intensive studies in skeletal development and disease. As a result, promising effective therapeutic agents for bone diseases are being developed by targeting the Wnt signaling pathway. Understanding the functional mechanisms of Wnt signaling in skeletal biology and diseases highlights how basic and clinical studies can stimulate each other to push a quick and productive advancement of the entire field. Here we review the current understanding of Wnt signaling in critical aspects of skeletal biology such as bone development, remodeling, mechanotransduction, and fracture healing. We took special efforts to place fundamentally important discoveries in the context of human skeletal diseases.
Collapse
Affiliation(s)
- Jean B Regard
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | |
Collapse
|
20
|
Yan Q, Huang HL, Yao X, Li J, Li LQ, Zhong J, Min LS, Dai LC, Zheng SS. Novel functional proteins interact with midkine in hepatic cancer cells. Hepatobiliary Pancreat Dis Int 2012; 11:272-7. [PMID: 22672821 DOI: 10.1016/s1499-3872(12)60160-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Midkine is a heparin-binding growth factor that promotes the proliferation, survival, migration and differentiation of various target cells. Midkine plays an important role in tumorigenesis and tumor progression, and is overexpressed in many human malignant tumors. Patients with high tumor midkine expression frequently have a worse prognosis than those with low expression. The present study was designed to investigate the interaction network of midkine in hepatic cancer cells, and to elucidate its role in hepatocellular carcinoma. METHODS DNA encoding full-length midkine was cloned into pDBLeu vector to serve as bait in yeast two-hybrid screening to identify interacting proteins. Candidate proteins were examined on SC-Leu-Trp-His+3-AT (20 mmol/L) plates and assayed for X-gal activity, then sequenced and classified according to the GenBank. Finally, identified proteins were expressed by the in vitro expression system pCMVTnT, and protein interactions were confirmed by co-immunoprecipitation. RESULTS Using the yeast two-hybrid system, we found 6 proteins that interacted with midkine: NK-kappa-B inhibitor alpha (I-κ-B-alpha), Dvl-binding protein naked cuticle 2, granulin, latent active TGF-beta binding protein 3, latent active TGF-beta binding protein 4, and phospholipid scramblase 1. In vitro co-immunoprecipitation demonstrated that all identified proteins directly interacted with midkine. CONCLUSION The identification of midkine-interacting proteins in hepatic cancer cells indicates that midkine is a multifunctional factor that may participate in cell migration, differentiation, and proliferation, and is also associated with the multicellular response feedback during the development of hepatocellular carcinoma.
Collapse
Affiliation(s)
- Qiang Yan
- Zhejiang University School of Medicine, Hangzhou, China
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Eckalbar WL, Fisher RE, Rawls A, Kusumi K. Scoliosis and segmentation defects of the vertebrae. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 1:401-23. [PMID: 23801490 DOI: 10.1002/wdev.34] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The vertebral column derives from somites, which are transient paired segments of mesoderm that surround the neural tube in the early embryo. Somites are formed by a genetic mechanism that is regulated by cyclical expression of genes in the Notch, Wnt, and fibroblast growth factor (FGF) signaling pathways. These oscillators together with signaling gradients within the presomitic mesoderm help to set somitic boundaries and rostral-caudal polarity that are essential for the precise patterning of the vertebral column. Disruption of this mechanism has been identified as the cause of severe segmentation defects of the vertebrae in humans. These segmentation defects are part of a spectrum of spinal disorders affecting the skeletal elements and musculature of the spine, resulting in curvatures such as scoliosis, kyphosis, and lordosis. While the etiology of most disorders with spinal curvatures is still unknown, genetic and developmental studies of somitogenesis and patterning of the axial skeleton and musculature are yielding insights into the causes of these diseases.
Collapse
|
22
|
Filipovich A, Gehrke I, Poll-Wolbeck SJ, Kreuzer KA. Physiological inhibitors of Wnt signaling. Eur J Haematol 2011; 86:453-65. [PMID: 21342268 DOI: 10.1111/j.1600-0609.2011.01592.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Wnt signaling is crucial for cell proliferation and differentiation. It represents a complex network with mechanisms of self-regulation through positive and negative feedback. Recent increasing interest in this signaling pathway has led to the discovery of many new proteins that down-regulate Wnt activity. Here, we provide a short description of the most important and best-studied inhibitors, group them according to the target molecule within the Wnt cascade, and discuss their clinical potential. Although most of the inhibitors discussed here may also interact with proteins from other signaling pathways, we focus only on their ability to modulate Wnt signaling.
Collapse
|
23
|
Van Raay TJ, Fortino NJ, Miller BW, Ma H, Lau G, Li C, Franklin JL, Attisano L, Solnica-Krezel L, Coffey RJ. Naked1 antagonizes Wnt signaling by preventing nuclear accumulation of β-catenin. PLoS One 2011; 6:e18650. [PMID: 21490931 PMCID: PMC3072412 DOI: 10.1371/journal.pone.0018650] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 03/14/2011] [Indexed: 02/04/2023] Open
Abstract
Cyto-nuclear shuttling of β-catenin is at the epicenter of the canonical Wnt pathway and mutations in genes that result in excessive nuclear accumulation of β-catenin are the driving force behind the initiation of many cancers. Recently, Naked Cuticle homolog 1 (Nkd1) has been identified as a Wnt-induced intracellular negative regulator of canonical Wnt signaling. The current model suggests that Nkd1 acts between Disheveled (Dvl) and β-catenin. Here, we employ the zebrafish embryo to characterize the cellular and biochemical role of Nkd1 in vivo. We demonstrate that Nkd1 binds to β-catenin and prevents its nuclear accumulation. We also show that this interaction is conserved in mammalian cultured cells. Further, we demonstrate that Nkd1 function is dependent on its interaction with the cell membrane. Given the conserved nature of Nkd1, our results shed light on the negative feedback regulation of Wnt signaling through the Nkd1-mediated negative control of nuclear accumulation of β-catenin.
Collapse
Affiliation(s)
- Terence J. Van Raay
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail: (TJVR); (RJC)
| | - Nicholas J. Fortino
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Bryan W. Miller
- Department of Biochemistry and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Haiting Ma
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Garnet Lau
- Department of Biochemistry and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Cunxi Li
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jeffery L. Franklin
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Liliana Attisano
- Department of Biochemistry and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Lilianna Solnica-Krezel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Robert J. Coffey
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Veterans Affairs Medical Center, Nashville, Tennessee, United States of America
- * E-mail: (TJVR); (RJC)
| |
Collapse
|
24
|
Cadigan KM, Peifer M. Wnt signaling from development to disease: insights from model systems. Cold Spring Harb Perspect Biol 2010; 1:a002881. [PMID: 20066091 DOI: 10.1101/cshperspect.a002881] [Citation(s) in RCA: 222] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
One of the early surprises in the study of cell adhesion was the discovery that beta-catenin plays dual roles, serving as an essential component of cadherin-based cell-cell adherens junctions and also serving as the key regulated effector of the Wnt signaling pathway. Here, we review our current model of Wnt signaling and discuss how recent work using model organisms has advanced our understanding of the roles Wnt signaling plays in both normal development and in disease. These data help flesh out the mechanisms of signaling from the membrane to the nucleus, revealing new protein players and providing novel information about known components of the pathway.
Collapse
Affiliation(s)
- Ken M Cadigan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, USA
| | | |
Collapse
|
25
|
Zebrafish Nkd1 promotes Dvl degradation and is required for left-right patterning. Dev Biol 2010; 348:22-33. [PMID: 20858476 DOI: 10.1016/j.ydbio.2010.08.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 08/22/2010] [Accepted: 08/27/2010] [Indexed: 12/20/2022]
Abstract
The establishment of the left-right (LR) axis in zebrafish embryos relies on signals from the dorsal forerunner cells (DFC) and the Kupffer's vesicle (KV). While the Wnt signaling network influences many aspects of embryonic development, its precise role in LR patterning is still unclear. One branch of the Wnt network leads to stabilization of β-catenin and activation of downstream target genes. Other Wnt ligands appear to act independently of β-catenin to modulate calcium release and influence cell polarity. Central to regulation of β-catenin and coordination of convergent extension (CE) movements is Dishevelled (Dvl). Naked Cuticle (Nkd) binds Dvl and modulates β-catenin-dependent and independent Wnt signaling. Here, we analyze the expression patterns of three zebrafish Nkd homologs and find enriched expression of nkd1 in DFCs and KV. Dvl is degraded upon Nkd1 overexpression in zebrafish. Knockdown of Nkd1 specifically in the DFC results in β-catenin nuclear localization and transcriptional activation as well as alterations to DFC migration, KV formation, ciliogenesis and LR patterning. Furthermore, we identify asymmetric expression of the Nodal antagonist charon around the KV and show that Nkd1 knockdown impacts asymmetric charon expression. Our findings show that Nkd1 acts as a β-catenin antagonist in the DFCs necessary for LR patterning.
Collapse
|
26
|
Götze S, Wolter M, Reifenberger G, Müller O, Sievers S. Frequent promoter hypermethylation of Wnt pathway inhibitor genes in malignant astrocytic gliomas. Int J Cancer 2010; 126:2584-93. [PMID: 19847810 DOI: 10.1002/ijc.24981] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Aberrant activation of wingless (Wnt) signaling is involved in the pathogenesis of various cancers. Recent studies suggested a role of Wnt signaling in gliomas, the most common primary brain tumors. We investigated 70 gliomas of different malignancy grades for promoter hypermethylation in 8 genes encoding members of the secreted frizzled-related protein (SFRP1, SFRP2, SFRP4, SFRP5), dickkopf (DKK1, DKK3) and naked (NKD1, NKD2) families of Wnt pathway inhibitors. All tumors were additionally analyzed for mutations in exon 3 of the beta-catenin gene (CTNNB1). While none of the tumors carried CTNNB1 mutations, we found frequent promoter hypermethylation of Wnt pathway inhibitor genes, with at least one of these genes being hypermethylated in 6 of 16 diffuse astrocytomas (38%), 4 of 14 anaplastic astrocytomas (29%), 7 of 10 secondary glioblastomas (70%) and 23 of 30 primary glioblastomas (77%). Glioblastomas often demonstrated hypermethylation of 2 or more analyzed genes. Hypermethylation of SFRP1, SFRP2 and NKD2 each occurred in more than 40% of the primary glioblastomas, while DKK1 hypermethylation was found in 50% of secondary glioblastomas. Treatment of SFRP1-, SFRP5-, DKK1-, DKK3-, NKD1- and NKD2-hypermethylated U87-MG glioblastoma cells with 5-aza-2'-deoxycytidine and trichostatin A resulted in increased expression of each gene. Furthermore, SFRP1-hypermethylated gliomas showed significantly lower expression of the respective transcripts when compared with unmethylated tumors. Taken together, our results suggest an important role of epigenetic silencing of Wnt pathway inhibitor genes in astrocytic gliomas, in particular, in glioblastomas, with distinct patterns of hypermethylated genes distinguishing primary from secondary glioblastomas.
Collapse
Affiliation(s)
- Silke Götze
- Department of Structural Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| | | | | | | | | |
Collapse
|
27
|
Mutations in the human naked cuticle homolog NKD1 found in colorectal cancer alter Wnt/Dvl/beta-catenin signaling. PLoS One 2009; 4:e7982. [PMID: 19956716 PMCID: PMC2776356 DOI: 10.1371/journal.pone.0007982] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 10/19/2009] [Indexed: 12/27/2022] Open
Abstract
Background Mutation of Wnt signal antagonists Apc or Axin activates β-catenin signaling in many cancers including the majority of human colorectal adenocarcinomas. The phenotype of apc or axin mutation in the fruit fly Drosophila melanogaster is strikingly similar to that caused by mutation in the segment-polarity gene, naked cuticle (nkd). Nkd inhibits Wnt signaling by binding to the Dishevelled (Dsh/Dvl) family of scaffold proteins that link Wnt receptor activation to β-catenin accumulation and TCF-dependent transcription, but human NKD genes have yet to be directly implicated in cancer. Methodology/Principal Findings We identify for the first time mutations in NKD1 - one of two human nkd homologs - in a subset of DNA mismatch repair-deficient colorectal tumors that are not known to harbor mutations in other Wnt-pathway genes. The mutant Nkd1 proteins are defective at inhibiting Wnt signaling; in addition, the mutant Nkd1 proteins stabilize β-catenin and promote cell proliferation, in part due to a reduced ability of each mutant Nkd1 protein to bind and destabilize Dvl proteins. Conclusions/Significance Our data raise the hypothesis that specific NKD1 mutations promote Wnt-dependent tumorigenesis in a subset of DNA mismatch-repair-deficient colorectal adenocarcinomas and possibly other Wnt-signal driven human cancers.
Collapse
|
28
|
Lukas J, Mazna P, Valenta T, Doubravska L, Pospichalova V, Vojtechova M, Fafilek B, Ivanek R, Plachy J, Novak J, Korinek V. Dazap2 modulates transcription driven by the Wnt effector TCF-4. Nucleic Acids Res 2009; 37:3007-20. [PMID: 19304756 PMCID: PMC2685103 DOI: 10.1093/nar/gkp179] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A major outcome of the canonical Wnt/beta-catenin-signalling pathway is the transcriptional activation of a specific set of target genes. A typical feature of the transcriptional response induced by Wnt signalling is the involvement of Tcf/Lef factors that function in the nucleus as the principal mediators of signalling. Vertebrate Tcf/Lef proteins perform two well-characterized functions: in association with beta-catenin they activate gene expression, and in the absence of Wnt ligands they bind TLE/Groucho proteins to act as transcriptional repressors. Although the general characteristics of Tcf/Lef factors are well understood, the mechanisms that control their specific roles in various cellular backgrounds are much less defined. In this report we reveal that the evolutionary conserved Dazap2 protein functions as a TCF-4 interacting partner. We demonstrate that a short region proximal to the TCF-4 HMG box mediates the interaction and that all Tcf/Lef family members associate with Dazap2. Interestingly, knockdown of Dazap2 not only reduced the activity of Wnt signalling as measured by Tcf/beta-catenin reporters but additionally altered the expression of Wnt-signalling target genes. Finally, chromatin immunoprecipitation studies indicate that Dazap2 modulates the affinity of TCF-4 for its DNA-recognition motif.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Vladimir Korinek
- *To whom correspondence should be addressed. Tel:+4202 4106 3146; Fax:+4202 4447 2282;
| |
Collapse
|
29
|
Cinquin O. Understanding the somitogenesis clock: what's missing? Mech Dev 2007; 124:501-17. [PMID: 17643270 DOI: 10.1016/j.mod.2007.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2007] [Revised: 05/10/2007] [Accepted: 06/09/2007] [Indexed: 01/09/2023]
Abstract
The segmentation of vertebrate embryos depends on a complex genetic network that generates highly dynamic gene expression. Many of the elements of the network have been identified, but their interaction and their influence on segmentation remain poorly understood. A few mathematical models have been proposed to explain the dynamics of subsets of the network, but the mechanistic bases remain controversial. This review focuses on outstanding problems with the generation of somitogenesis clock oscillations, and the ways they could regulate segmentation. Proposals that oscillations are generated by a negative feedback loop formed by Lunatic fringe and Notch signaling are weighed against a model based on positive feedback, and the experimental basis for models of simple negative feedback involving Her/Hes genes or Wnt targets is evaluated. Differences are then made explicit between the many 'clock and wavefront' model variants that have been proposed to explain how the clock regulates segmentation. An understanding of the somitogenesis clock will require addressing experimentally the many questions that arise from the study of simple models.
Collapse
Affiliation(s)
- Olivier Cinquin
- Howard Hughes Medical Institute and Department of Biochemistry, University of Wisconsin - Madison, 433 Babcock Drive, Madison, WI 53706, USA.
| |
Collapse
|