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Elul T, Lim J, Hanton K, Lui A, Jones K, Chen G, Chong C, Dao S, Rawat R. Cannabinoid 1 Receptor CBIR regulates growth cone filopodia and axon dispersion in the optic tract of
Xenopus laevis
tadpoles. Eur J Neurosci 2022; 55:989-1001. [DOI: 10.1111/ejn.15603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/10/2021] [Accepted: 01/05/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Tamira Elul
- Touro University California Vallejo California US
| | - John Lim
- Touro University California Vallejo California US
| | | | - Austin Lui
- Touro University California Vallejo California US
| | - Kenton Jones
- Touro University California Vallejo California US
| | - George Chen
- Touro University California Vallejo California US
| | | | - Sophia Dao
- Touro University California Vallejo California US
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Jin T, Peng G, Wu E, Mendiratta S, Elul T. N-terminal and central domains of APC function to regulate branch number, length and angle in developing optic axonal arbors in vivo. Brain Res 2018; 1697:34-44. [PMID: 29856981 DOI: 10.1016/j.brainres.2018.05.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 05/07/2018] [Accepted: 05/28/2018] [Indexed: 11/24/2022]
Abstract
During formation of neuronal circuits, axons navigate long distances to reach their target locations in the brain. When axons arrive at their target tissues, in many cases, they extend collateral branches and/or terminal arbors that serve to increase the number of synaptic connections they make with target neurons. Here, we investigated how Adenomatous Polyposis Coli (APC) regulates terminal arborization of optic axons in living Xenopus laevis tadpoles. The N-terminal and central domains of APC that regulate the microtubule cytoskeleton and stability of β-catenin in the Wnt pathway, were co-expressed with GFP in individual optic axons, and their terminal arbors were then imaged in tectal midbrains of intact tadpoles. Our data show that the APCNTERM and APCβ-cat domains both decreased the mean number, and increased the mean length, of branches in optic axonal arbors relative to control arbors in vivo. Additional analysis demonstrated that expression of the APCNTERM domain increased the average bifurcation angle of branching in optic axonal arbors. However, the APCβ-cat domain did not significantly affect the mean branch angle of arbors in tecta of living tadpoles. These data suggest that APC N-terminal and central domains both modulate number and mean length of branches optic axonal arbors in a compensatory manner, but also define a specific function for the N-terminal domain of APC in regulating branch angle in optic axonal arbors in vivo. Our findings establish novel mechanisms for the multifunctional protein APC in shaping terminal arbors in the visual circuit of the developing vertebrate brain.
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Affiliation(s)
- Taegun Jin
- Touro University California, Vallejo, CA, United States
| | - Gregory Peng
- Touro University California, Vallejo, CA, United States
| | - Esther Wu
- Touro University California, Vallejo, CA, United States
| | | | - Tamira Elul
- Touro University California, Vallejo, CA, United States.
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Dar MS, Singh P, Mir RA, Dar MJ. Βeta-catenin N-terminal domain: An enigmatic region prone to cancer causing mutations. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:122-133. [PMID: 28927523 DOI: 10.1016/j.mrrev.2017.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 12/21/2022]
Abstract
The Wnt/β-catenin is a highly conserved signaling pathway involved in cell fate decisions during various stages of development. Dysregulation of canonical Wnt/β-catenin signaling has been associated with various diseases including cancer. β-Catenin, the central component of canonical Wnt signaling pathway, is a multi-functional protein playing both structural and signaling roles. β-Catenin is composed of three distinct domains: N-terminal domain, C-terminal domain and a central armadillo repeat domain. N-terminal domain of β-catenin harbours almost all of the cancer causing mutations, thus deciphering its critical structural and functional roles offers great potential in cancer detection and therapy. Here, in this review, we have collected information from pharmacological analysis, bio-physical and structural studies, molecular modeling, in-vivo and in-vitro assays, and transgenic animal experiments employing various N-terminal domain variants of β-catenin to discuss the interaction of β-catenin with its binding partners that specifically interact with this domain and the implications of these interactions on signaling, cell fate determination, and in tumorigenesis. A thorough understanding of interactions between β-catenin and its binding partners will enable us to more effectively understand how β-catenin switches between its multiple roles, and will lead to the development of specific assays for the identification of small molecules as chemotherapeutic agents to treat diseases, including cancer and neurological disorders, where Wnt/β-catenin signaling is dysregulated.
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Affiliation(s)
- Mohd Saleem Dar
- Academy of Scientific and Innovative Research (AcSIR), New Delhi, India; Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, J&K, India
| | - Paramjeet Singh
- Academy of Scientific and Innovative Research (AcSIR), New Delhi, India; Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, J&K, India
| | - Riyaz A Mir
- Department of Biochemistry, All India Institute of Medical Sciences (AIIMS), Ansari Nagar, New Delhi, India
| | - Mohd Jamal Dar
- Academy of Scientific and Innovative Research (AcSIR), New Delhi, India; Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, J&K, India.
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Patel A, Bains A, Millet R, Elul T. Visualizing Morphogenesis with the Processing Programming Language. THE JOURNAL OF BIOCOMMUNICATION 2017; 41:e4. [PMID: 36405413 PMCID: PMC9138804 DOI: 10.5210/jbc.v41i1.7314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We used Processing, a visual artists' programming language developed at MIT Media Lab, to simulate cellular mechanisms of morphogenesis - the generation of form and shape in embryonic tissues. Based on observations of in vivo time-lapse image sequences, we created animations of neural cell motility responsible for elongating the spinal cord, and of optic axon branching dynamics that establish primary visual connectivity. These visual models underscore the significance of the computational decomposition of cellular dynamics underlying morphogenesis.
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Yang C, Li X, Wang C, Fu S, Li H, Guo Z, Zhao S, Lin J. N-cadherin regulates beta-catenin signal and its misexpression perturbs commissural axon projection in the developing chicken spinal cord. J Mol Histol 2016; 47:541-554. [PMID: 27650519 DOI: 10.1007/s10735-016-9698-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/14/2016] [Indexed: 12/31/2022]
Abstract
N-cadherin is a calcium-sensitive cell adhesion molecule that plays an important role in the formation of the neural circuit and the development of the nervous system. In the present study, we investigated the function of N-cadherin in cell-cell connection in vitro with HEK293T cells, and in commissural axon projections in the developing chicken spinal cord using in ovo electroporation. Cell-cell connections increased with N-cadherin overexpression in HEK293T cells, while cell contacts disappeared after co-transfection with an N-cadherin-shRNA plasmid. The knockdown of N-cadherin caused the accumulation of β-catenin in the nucleus, supporting the notion that N-cadherin regulates β-catenin signaling in vitro. Furthermore, N-cadherin misexpression perturbed commissural axon projections in the spinal cord. The overexpression of N-cadherin reduced the number of axons that projected alongside the contralateral margin of the floor plate, and formed intermediate longitudinal commissural axons. In contrast, the knockdown of N-cadherin perturbed commissural axon projections significantly, affecting the projections alongside the contralateral margin of the floor plate, but did not affect intermediate longitudinal commissural axons. Taken together, these findings suggest that N-cadherin regulates commissural axon projections in the developing chicken spinal cord.
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Affiliation(s)
- Ciqing Yang
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, 453003, China.,Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang, 453003, China
| | - Xiaoying Li
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, 453003, China
| | - Congrui Wang
- Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang, 453003, China
| | - Sulei Fu
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, 453003, China
| | - Han Li
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, 453003, China.,Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200, Bertam, Penang, Malaysia
| | - Zhikun Guo
- Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang, 453003, China
| | - Shanting Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China
| | - Juntang Lin
- College of Life Science and Technology, Xinxiang Medical University, Xinxiang, 453003, China. .,Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang, 453003, China. .,Institute of Anatomy I, Jena University Hospital, 07743, Jena, Germany.
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McFarlane S, Lom B. The Xenopus retinal ganglion cell as a model neuron to study the establishment of neuronal connectivity. Dev Neurobiol 2012; 72:520-36. [PMID: 21634016 DOI: 10.1002/dneu.20928] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Neurons receive inputs through their multiple branched dendrites and pass this information on to the next neuron via long axons, which branch within the target. The shape the neuron acquires is thus the key to its proper functioning in the neural circuit in which it participates. Both axons and dendrites grow in a directed fashion to their target partner neurons by responding to a large number of molecular cues in the milieu through which they extend. They then go through the process of synaptogenesis, first choosing a neuron on which to synapse, and then the appropriate subcellular location. How a neuron acquires its unique shape, establishes and modifies appropriate synaptic connectivity, and the molecular signals involved, are key questions in developmental neurobiology. Such questions of nervous system wiring are being pursued actively with a variety of different animal models and neuron types, each with its own unique advantages. Among these, the developing retinal ganglion cell (RGC) of the South African clawed frog, Xenopus laevis, has proven particularly fruitful for revealing the secrets of how axons and dendrites acquire their final morphology and connectivity. In this review, we describe how this system can be used to understand the multiple molecular events that instruct the incorporation of RGCs into the neural circuit that controls vision.
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Affiliation(s)
- Sarah McFarlane
- Department of Cell Biology and Anatomy, University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada.
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Pratt T, Davey JW, Nowakowski TJ, Raasumaa C, Rawlik K, McBride D, Clinton M, Mason JO, Price DJ. The expression and activity of β-catenin in the thalamus and its projections to the cerebral cortex in the mouse embryo. BMC Neurosci 2012; 13:20. [PMID: 22360971 PMCID: PMC3347985 DOI: 10.1186/1471-2202-13-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 02/23/2012] [Indexed: 11/10/2022] Open
Abstract
Background The mammalian thalamus relays sensory information from the periphery to the cerebral cortex for cognitive processing via the thalamocortical tract. The thalamocortical tract forms during embryonic development controlled by mechanisms that are not fully understood. β-catenin is a nuclear and cytosolic protein that transduces signals from secreted signaling molecules to regulate both cell motility via the cytoskeleton and gene expression in the nucleus. In this study we tested whether β-catenin is likely to play a role in thalamocortical connectivity by examining its expression and activity in developing thalamic neurons and their axons. Results At embryonic day (E)15.5, the time when thalamocortical axonal projections are forming, we found that the thalamus is a site of particularly high β-catenin mRNA and protein expression. As well as being expressed at high levels in thalamic cell bodies, β-catenin protein is enriched in the axons and growth cones of thalamic axons and its growth cone concentration is sensitive to Netrin-1. Using mice carrying the β-catenin reporter BAT-gal we find high levels of reporter activity in the thalamus. Further, Netrin-1 induces BAT-gal reporter expression and upregulates levels of endogenous transcripts encoding β-actin and L1 proteins in cultured thalamic cells. We found that β-catenin mRNA is enriched in thalamic axons and its 3'UTR is phylogenetically conserved and is able to direct heterologous mRNAs along the thalamic axon, where they can be translated. Conclusion We provide evidence that β-catenin protein is likely to be an important player in thalamocortcial development. It is abundant both in the nucleus and in the growth cones of post-mitotic thalamic cells during the development of thalamocortical connectivity and β-catenin mRNA is targeted to thalamic axons and growth cones where it could potentially be translated. β-catenin is involved in transducing the Netrin-1 signal to thalamic cells suggesting a mechanism by which Netrin-1 guides thalamocortical development.
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Affiliation(s)
- Thomas Pratt
- Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, Scotland, UK.
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Vacik T, Stubbs JL, Lemke G. A novel mechanism for the transcriptional regulation of Wnt signaling in development. Genes Dev 2011; 25:1783-95. [PMID: 21856776 DOI: 10.1101/gad.17227011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Axial patterning of the embryonic brain requires a precise balance between canonical Wnt signaling, which dorsalizes the nervous system, and Sonic hedgehog (Shh), which ventralizes it. The ventral anterior homeobox (Vax) transcription factors are induced by Shh and ventralize the forebrain through a mechanism that is poorly understood. We therefore sought to delineate direct Vax target genes. Among these, we identify an extraordinarily conserved intronic region within the gene encoding Tcf7l2, a key mediator of canonical Wnt signaling. This region functions as a Vax2-activated internal promoter that drives the expression of dnTcf7l2, a truncated Tcf7l2 isoform that cannot bind β-catenin and that therefore acts as a potent dominant-negative Wnt antagonist. Vax2 concomitantly activates the expression of additional Wnt antagonists that cooperate with dnTcf7l2. Specific elimination of dnTcf7l2 in Xenopus results in headless embryos, a phenotype consistent with a fundamental role for this regulator in forebrain development.
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Affiliation(s)
- Tomas Vacik
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037, USA
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