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Kikuchi A, Yamamoto H, Sato A, Matsumoto S. Wnt5a: its signalling, functions and implication in diseases. Acta Physiol (Oxf) 2012; 204:17-33. [PMID: 21518267 DOI: 10.1111/j.1748-1716.2011.02294.x] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Wnt5a is a representative ligand that activates the β-catenin-independent pathways. Because the β-catenin-independent pathway includes multiple signalling cascades in addition to the planar cell polarity and Ca(2+) pathway, Wnt5a regulates a variety of cellular functions, such as proliferation, differentiation, migration, adhesion and polarity. Consistent with the multiple functions of Wnt5a signalling, Wnt5a knockout mice show various phenotypes, including an inability to extend the embryonic anterior-posterior and proximal-distal axes in outgrowth tissues. Thus, many important roles of Wnt5a in developmental processes have been demonstrated. Moreover, recent reports suggest that the postnatal abnormalities in the Wnt5a signalling are involved in various diseases, such as cancer, inflammatory diseases and metabolic disorders. Therefore, Wnt5a and its signalling pathways could be important targets for the diagnosis and therapy for human diseases.
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Affiliation(s)
- A Kikuchi
- Department of Molecular Biology and Biochemistry, Graduate School of Medicine, Osaka University, Suita, Japan.
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Yamamoto Y, Takeshita H, Sawa H. Multiple Wnts redundantly control polarity orientation in Caenorhabditis elegans epithelial stem cells. PLoS Genet 2011; 7:e1002308. [PMID: 22022276 PMCID: PMC3192832 DOI: 10.1371/journal.pgen.1002308] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 08/08/2011] [Indexed: 01/22/2023] Open
Abstract
During development, cell polarization is often coordinated to harmonize tissue patterning and morphogenesis. However, how extrinsic signals synchronize cell polarization is not understood. In Caenorhabditis elegans, most mitotic cells are polarized along the anterior-posterior axis and divide asymmetrically. Although this process is regulated by a Wnt-signaling pathway, Wnts functioning in cell polarity have been demonstrated in only a few cells. We analyzed how Wnts control cell polarity, using compound Wnt mutants, including animals with mutations in all five Wnt genes. We found that somatic gonadal precursor cells (SGPs) are properly polarized and oriented in quintuple Wnt mutants, suggesting Wnts are dispensable for the SGPs' polarity, which instead requires signals from the germ cells. Thus, signals from the germ cells organize the C. elegans somatic gonad. In contrast, in compound but not single Wnt mutants, most of the six seam cells, V1–V6 (which are epithelial stem cells), retain their polarization, but their polar orientation becomes random, indicating that it is redundantly regulated by multiple Wnt genes. In contrast, in animals in which the functions of three Wnt receptors (LIN-17, MOM-5, and CAM-1) are disrupted—the stem cells are not polarized and divide symmetrically—suggesting that the Wnt receptors are essential for generating polarity and that they function even in the absence of Wnts. All the seam cells except V5 were polarized properly by a single Wnt gene expressed at the cell's anterior or posterior. The ectopic expression of posteriorly expressed Wnts in an anterior region and vice versa rescued polarity defects in compound Wnt mutants, raising two possibilities: one, Wnts permissively control the orientation of polarity; or two, Wnt functions are instructive, but which orientation they specify is determined by the cells that express them. Our results provide a paradigm for understanding how cell polarity is coordinated by extrinsic signals. Proper functions and development of organs often require the synchronized polarization of entire cell groups. How cells coordinate their polarity is poorly understood. One plausible model is that individual cells recognize extrinsic signal gradients that orient their polarity, although this has not been shown in any organism. In particular, although Wnt signaling is important for cell polarization, and Wnt signal gradients are important for the coordinated specification of cell fates, the Wnts' involvement in orienting cell polarity is unclear. In the nematode Caenorhabditis elegans, most asymmetrically dividing mitotic cells are polarized in the same anterior-posterior orientation. Here we show that multiple Wnt proteins redundantly control the proper orientation of cell polarity, but not for polarization per se, in a group of epithelial stem cells. In contrast, Wnt receptors are indispensable for cells to adopt a polarized phenotype. Most stem cells are properly oriented by Wnt genes that are expressed either at their anterior or posterior side. Surprisingly, Wnt signals can properly orient stem cell polarity, even when their source is changed from anterior to posterior or vice versa. Our results suggest the presence of novel mechanisms by which Wnt genes orient cell polarity.
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Affiliation(s)
- Yuko Yamamoto
- Laboratory for Cell Fate Decision, RIKEN, Center for Developmental Biology, Kobe, Japan
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Hisako Takeshita
- Laboratory for Cell Fate Decision, RIKEN, Center for Developmental Biology, Kobe, Japan
| | - Hitoshi Sawa
- Laboratory for Cell Fate Decision, RIKEN, Center for Developmental Biology, Kobe, Japan
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
- Multicellular Organization Laboratory, National Institute of Genetics, Mishima, Japan
- * E-mail:
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Chen L, Wang Z, Ghosh-Roy A, Hubert T, Yan D, O'Rourke S, Bowerman B, Wu Z, Jin Y, Chisholm AD. Axon regeneration pathways identified by systematic genetic screening in C. elegans. Neuron 2011; 71:1043-57. [PMID: 21943602 PMCID: PMC3183436 DOI: 10.1016/j.neuron.2011.07.009] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2011] [Indexed: 12/18/2022]
Abstract
The mechanisms underlying the ability of axons to regrow after injury remain poorly explored at the molecular genetic level. We used a laser injury model in Caenorhabditis elegans mechanosensory neurons to screen 654 conserved genes for regulators of axonal regrowth. We uncover several functional clusters of genes that promote or repress regrowth, including genes classically known to affect axon guidance, membrane excitability, neurotransmission, and synaptic vesicle endocytosis. The conserved Arf Guanine nucleotide Exchange Factor (GEF), EFA-6, acts as an intrinsic inhibitor of regrowth. By combining genetics and in vivo imaging, we show that EFA-6 inhibits regrowth via microtubule dynamics, independent of its Arf GEF activity. Among newly identified regrowth inhibitors, only loss of function in EFA-6 partially bypasses the requirement for DLK-1 kinase. Identification of these pathways significantly expands our understanding of the genetic basis of axonal injury responses and repair.
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Affiliation(s)
- Lizhen Chen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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LIN-44/Wnt directs dendrite outgrowth through LIN-17/Frizzled in C. elegans Neurons. PLoS Biol 2011; 9:e1001157. [PMID: 21949641 PMCID: PMC3176756 DOI: 10.1371/journal.pbio.1001157] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 08/10/2011] [Indexed: 11/19/2022] Open
Abstract
Nervous system function requires proper development of two functional and morphological domains of neurons, axons and dendrites. Although both these domains are equally important for signal transmission, our understanding of dendrite development remains relatively poor. Here, we show that in C. elegans the Wnt ligand, LIN-44, and its Frizzled receptor, LIN-17, regulate dendrite development of the PQR oxygen sensory neuron. In lin-44 and lin-17 mutants, PQR dendrites fail to form, display stunted growth, or are misrouted. Manipulation of temporal and spatial expression of LIN-44, combined with cell-ablation experiments, indicates that this molecule is patterned during embryogenesis and acts as an attractive cue to define the site from which the dendrite emerges. Genetic interaction between lin-44 and lin-17 suggests that the LIN-44 signal is transmitted through the LIN-17 receptor, which acts cell autonomously in PQR. Furthermore, we provide evidence that LIN-17 interacts with another Wnt molecule, EGL-20, and functions in parallel to MIG-1/Frizzled in this process. Taken together, our results reveal a crucial role for Wnt and Frizzled molecules in regulating dendrite development in vivo. Neurons have distinct compartments, which include axons and dendrites. Both of these compartments are essential for communication between neurons, as signals are received by dendrites and transmitted by axons. Although dendrites are vital for neural connectivity, very little is known about how they are formed. Here, we have investigated how dendrites develop in vivo by examining an oxygen sensory neuron (PQR) in the nematode C. elegans. Using a genetic approach, we have discovered that Wnt proteins, a group of highly conserved secreted morphogens, interact with their canonical Frizzled receptors to control the development of the PQR dendrite. We show that Wnt molecules act as attractive signals to determine the initiation and direction of dendrite outgrowth. Interestingly, Wnt proteins act specifically on the dendrite without affecting the axon, suggesting that outgrowth of the dendrite can be regulated by distinct processes that are independent of axon formation. We predict that similar mechanisms may be in place in other species owing to the conserved roles of Wnt and Frizzled molecules in development.
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Harterink M, Kim DH, Middelkoop TC, Doan TD, van Oudenaarden A, Korswagen HC. Neuroblast migration along the anteroposterior axis of C. elegans is controlled by opposing gradients of Wnts and a secreted Frizzled-related protein. Development 2011; 138:2915-24. [PMID: 21653614 PMCID: PMC3119304 DOI: 10.1242/dev.064733] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2011] [Indexed: 12/24/2022]
Abstract
The migration of neuroblasts along the anteroposterior body axis of C. elegans is controlled by multiple Wnts that act partially redundantly to guide cells to their precisely defined final destinations. How positional information is specified by this system is, however, still largely unknown. Here, we used a novel fluorescent in situ hybridization methods to generate a quantitative spatiotemporal expression map of the C. elegans Wnt genes. We found that the five Wnt genes are expressed in a series of partially overlapping domains along the anteroposterior axis, with a predominant expression in the posterior half of the body. Furthermore, we show that a secreted Frizzled-related protein is expressed at the anterior end of the body axis, where it inhibits Wnt signaling to control neuroblast migration. Our findings reveal that a system of regionalized Wnt gene expression and anterior Wnt inhibition guides the highly stereotypic migration of neuroblasts in C. elegans. Opposing expression of Wnts and Wnt inhibitors has been observed in basal metazoans and in the vertebrate neurectoderm. Our results in C. elegans support the notion that a system of posterior Wnt signaling and anterior Wnt inhibition is an evolutionarily conserved principle of primary body axis specification.
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Affiliation(s)
- Martin Harterink
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Dong hyun Kim
- Department of Physics and department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Teije C. Middelkoop
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Thang Dinh Doan
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Alexander van Oudenaarden
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
- Department of Physics and department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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Song S, Zhang B, Sun H, Li X, Xiang Y, Liu Z, Huang X, Ding M. A Wnt-Frz/Ror-Dsh pathway regulates neurite outgrowth in Caenorhabditis elegans. PLoS Genet 2010; 6:e1001056. [PMID: 20711352 PMCID: PMC2920835 DOI: 10.1371/journal.pgen.1001056] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 07/08/2010] [Indexed: 11/18/2022] Open
Abstract
One of the challenges to understand the organization of the nervous system has been to determine how axon guidance molecules govern axon outgrowth. Through an unbiased genetic screen, we identified a conserved Wnt pathway which is crucial for anterior-posterior (A/P) outgrowth of neurites from RME head motor neurons in Caenorhabditis elegans. The pathway is composed of the Wnt ligand CWN-2, the Frizzled receptors CFZ-2 and MIG-1, the co-receptor CAM-1/Ror, and the downstream component Dishevelled/DSH-1. Among these, CWN-2 acts as a local attractive cue for neurite outgrowth, and its activity can be partially substituted with other Wnts, suggesting that spatial distribution plays a role in the functional specificity of Wnts. As a co-receptor, CAM-1 functions cell-autonomously in neurons and, together with CFZ-2 and MIG-1, transmits the Wnt signal to downstream effectors. Yeast two-hybrid screening identified DSH-1 as a binding partner for CAM-1, indicating that CAM-1 could facilitate CWN-2/Wnt signaling by its physical association with DSH-1. Our study reveals an important role of a Wnt-Frz/Ror-Dsh pathway in regulating neurite A/P outgrowth.
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Affiliation(s)
- Song Song
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate School, Chinese Academy of Sciences, Beijing, China
| | - Bo Zhang
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate School, Chinese Academy of Sciences, Beijing, China
| | - Hui Sun
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xia Li
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yanhui Xiang
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- Graduate School, Chinese Academy of Sciences, Beijing, China
| | - Zhonghua Liu
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xun Huang
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Mei Ding
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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