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1.
bioRxiv ; 2024 Jun 19.
Article in English | MEDLINE | ID: mdl-38826314

ABSTRACT

During embryonic development, diverse cell types coordinate to form functionally complex tissues. Exemplifying this process, the trigeminal ganglion emerges from the condensation of two distinct precursor cell populations, cranial placodes and neural crest, with neuronal differentiation of the former preceding the latter. While the dual origin of the trigeminal ganglion has been understood for decades, the molecules orchestrating formation of the trigeminal ganglion from these precursors remain relatively obscure. Initial assembly of the trigeminal ganglion is mediated by cell adhesion molecules, including neural cadherin (N-cadherin), which is required by placodal neurons to properly condense with other neurons and neural crest cells. Whether N-cadherin is required for later growth and target innervation by trigeminal ganglion neurons, however, is unknown. To this end, we depleted N-cadherin from chick trigeminal placode cells and uncovered decreases in trigeminal ganglion size, nerve growth, and target innervation in vivo at later developmental stages. Furthermore, blocking N-cadherin-mediated adhesion prevented axon extension in some placode-derived trigeminal neurons in vitro . This indicates the existence of neuronal subtypes that may have unique requirements for N-cadherin for outgrowth, and points to this subset of placodal neurons as potential pioneers that serve as templates for additional axon outgrowth. Neurite complexity was also decreased in neural crest-derived neurons in vitro in response to N-cadherin knockdown in placode cells. Collectively, these findings reveal persistent cell autonomous and non-cell autonomous functions for N-cadherin, thus highlighting the critical role of N-cadherin in mediating reciprocal interactions between neural crest and placode neuronal derivatives during trigeminal ganglion development. Significance Statement: Our findings are significant because they demonstrate how neurons derived from two distinct cell populations, neural crest and placode cells, coordinate the outgrowth of their axons in time and space to generate the trigeminal ganglion using the cell adhesion molecule N-cadherin. Notably, our results provide evidence for the existence of subpopulations of neurons within the trigeminal ganglion that differentially require N-cadherin to facilitate axon outgrowth, and hint at the possibility that trigeminal pioneer neurons are derived from placode cells while followers arise from both placode and neural crest cells. These studies provide new insight into trigeminal gangliogenesis that will likely be translatable to other cranial ganglia and vertebrate species.

2.
J Proteome Res ; 22(10): 3264-3274, 2023 Oct 06.
Article in English | MEDLINE | ID: mdl-37616547

ABSTRACT

The epithelial-to-mesenchymal transition (EMT) and migration of cranial neural crest cells within the midbrain are critical processes that permit proper craniofacial patterning in the early embryo. Disruptions in these processes not only impair development but also lead to various diseases, underscoring the need for their detailed understanding at the molecular level. The chick embryo has served historically as an excellent model for human embryonic development, including cranial neural crest cell EMT and migration. While these developmental events have been characterized transcriptionally, studies at the protein level have not been undertaken to date. Here, we applied mass spectrometry (MS)-based proteomics to establish a deep proteomics profile of the chick midbrain region during early embryonic development. Our proteomics method combines optimal lysis conditions, offline fractionation, separation on a nanopatterned stationary phase (µPAC) using nanoflow liquid chromatography, and detection using quadrupole-ion trap-Orbitrap tribrid high-resolution tandem MS. Identification of >5900 proteins and >450 phosphoproteins in this study marks the deepest coverage of the chick midbrain proteome to date. These proteins have known roles in pathways related to neural crest cell EMT and migration such as signaling, proteolysis/extracellular matrix remodeling, and transcriptional regulation. This study offers valuable insight into important developmental processes occurring in the midbrain region and demonstrates the utility of proteomics for characterization of tissue microenvironments during chick embryogenesis.

3.
J Dev Biol ; 11(1)2023 Feb 19.
Article in English | MEDLINE | ID: mdl-36810460

ABSTRACT

The trigeminal ganglion contains the cell bodies of sensory neurons comprising cranial nerve V, which relays information related to pain, touch, and temperature from the face and head to the brain. Like other cranial ganglia, the trigeminal ganglion is composed of neuronal derivatives of two critical embryonic cell types, neural crest and placode cells. Neurogenesis within the cranial ganglia is promoted by Neurogenin 2 (Neurog2), which is expressed in trigeminal placode cells and their neuronal derivatives, and transcriptionally activates neuronal differentiation genes such as Neuronal Differentiation 1 (NeuroD1). Little is known, however, about the role of Neurog2 and NeuroD1 during chick trigeminal gangliogenesis. To address this, we depleted Neurog2 and NeuroD1 from trigeminal placode cells with morpholinos and demonstrated that Neurog2 and NeuroD1 influence trigeminal ganglion development. While knockdown of both Neurog2 and NeuroD1 affected innervation of the eye, Neurog2 and NeuroD1 had opposite effects on ophthalmic nerve branch organization. Taken together, our results highlight, for the first time, functional roles for Neurog2 and NeuroD1 during chick trigeminal gangliogenesis. These studies shed new light on the molecular mechanisms underlying trigeminal ganglion formation and may also provide insight into general cranial gangliogenesis and diseases of the peripheral nervous system.

4.
Elife ; 112022 06 17.
Article in English | MEDLINE | ID: mdl-35713404

ABSTRACT

Familial dysautonomia (FD) is a sensory and autonomic neuropathy caused by mutations in elongator complex protein 1 (ELP1). FD patients have small trigeminal nerves and impaired facial pain and temperature perception. These signals are relayed by nociceptive neurons in the trigeminal ganglion, a structure that is composed of both neural crest- and placode-derived cells. Mice lacking Elp1 in neural crest derivatives ('Elp1 CKO') are born with small trigeminal ganglia, suggesting Elp1 is important for trigeminal ganglion development, yet the function of Elp1 in this context is unknown. We demonstrate that Elp1, expressed in both neural crest- and placode-derived neurons, is not required for initial trigeminal ganglion formation. However, Elp1 CKO trigeminal neurons exhibit abnormal axon outgrowth and deficient target innervation. Developing nociceptors expressing the receptor TrkA undergo early apoptosis in Elp1 CKO, while TrkB- and TrkC-expressing neurons are spared, indicating Elp1 supports the target innervation and survival of trigeminal nociceptors. Furthermore, we demonstrate that specific TrkA deficits in the Elp1 CKO trigeminal ganglion reflect the neural crest lineage of most TrkA neurons versus the placodal lineage of most TrkB and TrkC neurons. Altogether, these findings explain defects in cranial gangliogenesis that may lead to loss of facial pain and temperature sensation in FD.


Subject(s)
Dysautonomia, Familial , Animals , Dysautonomia, Familial/genetics , Dysautonomia, Familial/metabolism , Facial Pain/metabolism , Mice , Neural Crest/metabolism , Neurons/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Trigeminal Ganglion
5.
F1000Res ; 11: 741, 2022.
Article in English | MEDLINE | ID: mdl-36128560

ABSTRACT

Background: Arising at distinct positions in the head, the cranial ganglia are crucial for integrating various sensory inputs. The largest of these ganglia is the trigeminal ganglion, which relays pain, touch and temperature information through its three primary nerve branches to the central nervous system. The trigeminal ganglion and its nerves are composed of derivatives of two critical embryonic cell types, neural crest cells and placode cells, that migrate from different anatomical locations, coalesce together, and differentiate to form trigeminal sensory neurons and supporting glia. While the dual cellular origin of the trigeminal ganglion has been known for over 60 years, molecules expressed by neural crest cells and placode cells that regulate initial ganglion assembly remain obscure. Prior studies revealed the importance of cell surface cadherin proteins during early trigeminal gangliogenesis, with Cadherin-7 and neural cadherin (N-cadherin) expressed in neural crest cells and placode cells, respectively. Although cadherins typically interact in a homophilic ( i.e., like) fashion, the presence of different cadherins expressed in neural crest cells and placode cells raises the question as to whether heterophilic cadherin interactions may also be occurring. Given this, the aim of the study was to understand whether Cadherin-7 and N-cadherin were interacting during initial trigeminal ganglion formation. Methods: To assess potential interactions between Cadherin-7 and N-cadherin, we used biochemistry and innovative imaging assays conducted in vitro and in vivo, including in the forming chick trigeminal ganglion. Results: Our data revealed a physical interaction between Cadherin-7 and N-cadherin. Conclusions: These studies identify a new molecular basis by which neural crest cells and placode cells can aggregate in vivo to build the trigeminal ganglion during embryogenesis.


Subject(s)
Cadherins , Neural Crest , Trigeminal Ganglion , Animals , Cadherins/metabolism , Neural Crest/metabolism , Neurons/metabolism , Trigeminal Ganglion/metabolism , Chick Embryo
7.
Am J Med Genet A ; 185(6): 1932-1939, 2021 06.
Article in English | MEDLINE | ID: mdl-33660912

ABSTRACT

The Society for Craniofacial Genetics and Developmental Biology (SCGDB) held its 43rd annual meeting in a virtual format on October 19-20, 2020. The SCGDB meeting included the presentation of the SCGDB Distinguished Scientists in Craniofacial Research Awards to Marilyn Jones and Kerstin Ludwig and four scientific sessions on the molecular regulation of craniofacial development, craniofacial morphogenesis, translational craniofacial biology, and signaling during craniofacial development. The meeting also included workshops on career development, NIH/NIDCR funding, and the utility of the FaceBase database, as well as two poster sessions. Over 190 attendees from 21 states, representing over 50 different scientific institutions, participated. This diverse group of scientists included cell biologists, developmental biologists, and clinical geneticists. While in-person interactions were missed due to the virtual meeting format imposed by the COVID-19 pandemic, the meeting platform provided ample opportunities for participant interactions and discussions, thus strengthening the community.


Subject(s)
Craniofacial Abnormalities/genetics , Developmental Biology , Animals , COVID-19 , Congresses as Topic/organization & administration , Craniofacial Abnormalities/embryology , Genetics, Medical , Humans , Pandemics , Societies, Medical/organization & administration , Societies, Scientific/organization & administration , Videoconferencing
8.
Am J Med Genet A ; 182(7): 1555-1561, 2020 07.
Article in English | MEDLINE | ID: mdl-32352199

ABSTRACT

The Society for Craniofacial Genetics and Developmental Biology (SCGDB) 42nd Annual Meeting was held at the MD Anderson Cancer Center in Houston, Texas from October 14-15, 2019. The SCGDB meeting included scientific sessions on the molecular regulation of craniofacial development, cell biology of craniofacial development, signaling during craniofacial development, translational craniofacial biology, and for the first time, a career development workshop. Over a one hundred attendees from 21 states, and representing over 50 different scientific institutions, participated. The diverse group of scientists included cell and developmental biologists and clinical geneticists, promoting excellent discussions about molecular pathways guiding abnormal cell behaviors and the resultant morphological changes to craniofacial development. The results were high-quality science and a welcoming environment for trainees interested in craniofacial biology.


Subject(s)
Craniofacial Abnormalities/genetics , Developmental Biology , Animals , Awards and Prizes , Career Choice , Gene Expression Regulation, Developmental , Humans , Mice , Neural Crest/pathology , Neural Crest/physiology , Societies, Scientific , Xenopus/genetics , Xenopus/growth & development
9.
J Cell Sci ; 133(4)2020 02 20.
Article in English | MEDLINE | ID: mdl-31964703

ABSTRACT

Gap junctions are intercellular channels between cells that facilitate cell-cell communication. Connexin 43 (Cx43; also known as GJA1), the predominant gap junction protein in vertebrates, is expressed in premigratory cranial neural crest cells and is maintained throughout the neural crest cell epithelial-to-mesenchymal transition (EMT), but its function in these cells is unknown. To this end, we used a combination of in vivo and ex vivo experiments to assess gap junction formation, and Cx43 function, in chick cranial neural crest cells. Our results demonstrate that gap junctions exist between premigratory and migratory cranial neural crest cells and depend on Cx43 for their function. In the embryo, Cx43 knockdown just prior to EMT delays the emergence of Cx43-depleted neural crest cells from the neural tube, but these cells eventually successfully emigrate and join the migratory stream. This delay can be rescued by introduction of full-length Cx43 into Cx43-depleted cells. Furthermore, Cx43 depletion reduces the size of the premigratory neural crest cell domain through an early effect on neural crest cell specification. Collectively, these data identify new roles for Cx43 in chick cranial neural crest cell development.


Subject(s)
Connexin 43 , Neural Crest , Animals , Cell Differentiation , Connexin 43/genetics , Connexins , Gap Junctions , Neural Tube
10.
Semin Cell Dev Biol ; 100: 177-185, 2020 04.
Article in English | MEDLINE | ID: mdl-31727473

ABSTRACT

Neural crest cells have the extraordinary task of building much of the vertebrate body plan, including the craniofacial cartilage and skeleton, melanocytes, portions of the heart, and the peripheral nervous system. To execute these developmental programs, stationary premigratory neural crest cells first acquire the capacity to migrate through an extensive process known as the epithelial-to-mesenchymal transition. Once motile, neural crest cells must traverse a complex environment consisting of other cells and the protein-rich extracellular matrix in order to get to their final destinations. Herein, we will highlight some of the main molecular machinery that allow neural crest cells to first exit the neuroepithelium and then later successfully navigate this intricate in vivo milieu. Collectively, these extracellular and intracellular factors mediate the appropriate migration of neural crest cells and allow for the proper development of the vertebrate embryo.


Subject(s)
Cell Movement , Extracellular Matrix/metabolism , Neural Crest/cytology , Animals , Neural Crest/metabolism
11.
Am J Med Genet A ; 179(5): 864-869, 2019 05.
Article in English | MEDLINE | ID: mdl-30793834

ABSTRACT

The mission of the Society for Craniofacial Genetics and Developmental Biology (SCGDB) is to promote education, research, and communication about normal and abnormal development of the tissues and organs of the head. The SCGDB welcomes as members undergraduate students, graduate students, postdoctoral researchers, medical and dental practitioners, scientists, and academicians who possess an interest in craniofacial biology. Each year our members come together to share their novel findings, build upon, and challenge current knowledge of craniofacial biology.


Subject(s)
Craniofacial Abnormalities/diagnosis , Craniofacial Abnormalities/etiology , Craniofacial Abnormalities/therapy , Developmental Biology , Genetic Association Studies , Genetic Predisposition to Disease , Humans , Models, Biological , Organogenesis
12.
Genesis ; 57(1): e23264, 2019 01.
Article in English | MEDLINE | ID: mdl-30461190

ABSTRACT

The cranial trigeminal ganglia play a vital role in the peripheral nervous system through their relay of sensory information from the vertebrate head to the brain. These ganglia are generated from the intermixing and coalescence of two distinct cell populations: cranial neural crest cells and placodal neurons. Trigeminal ganglion assembly requires the formation of cadherin-based adherens junctions within the neural crest cell and placodal neuron populations; however, the molecular composition of these adherens junctions is still unknown. Herein, we aimed to define the spatio-temporal expression pattern and function of Cadherin-7 during early chick trigeminal ganglion formation. Our data reveal that Cadherin-7 is expressed exclusively in migratory cranial neural crest cells and is absent from trigeminal neurons. Using molecular perturbation experiments, we demonstrate that modulation of Cadherin-7 in neural crest cells influences trigeminal ganglion assembly, including the organization of neural crest cells and placodal neurons within the ganglionic anlage. Moreover, alterations in Cadherin-7 levels lead to changes in the morphology of trigeminal neurons. Taken together, these findings provide additional insight into the role of cadherin-based adhesion in trigeminal ganglion formation, and, more broadly, the molecular mechanisms that orchestrate the cellular interactions essential for cranial gangliogenesis.


Subject(s)
Avian Proteins/metabolism , Cadherins/metabolism , Neural Crest/metabolism , Neurons/metabolism , Trigeminal Ganglion/metabolism , Adherens Junctions/metabolism , Animals , Avian Proteins/genetics , Cadherins/genetics , Chick Embryo , Neural Crest/embryology , Neurogenesis , Trigeminal Ganglion/cytology , Trigeminal Ganglion/embryology
13.
Dev Biol ; 444 Suppl 1: S237-S251, 2018 12 01.
Article in English | MEDLINE | ID: mdl-29958899

ABSTRACT

During epithelial-to-mesenchymal transitions (EMTs), chick cranial neural crest cells simultaneously delaminate from the basement membrane and segregate from the epithelia, in part, via multiple protease-mediated mechanisms. Proteolytic processing of Cadherin-6B (Cad6B) in premigratory cranial neural crest cells by metalloproteinases not only disassembles cadherin-based junctions but also generates shed Cad6B ectodomains or N-terminal fragments (NTFs) that may possess additional roles. Here we report that Cad6B NTFs promote delamination by enhancing local extracellular proteolytic activity around neural crest cells undergoing EMT en masse. During EMT, Cad6B NTFs of varying molecular weights are observed, indicating that Cad6B may be cleaved at different sites by A Disintegrin and Metalloproteinases (ADAMs) 10 and 19 as well as by other matrix metalloproteinases (MMPs). To investigate Cad6B NTF function, we first generated NTF constructs that express recombinant NTFs with similar relative mobilities to those NTFs shed in vivo. Overexpression of either long or short Cad6B NTFs in premigratory neural crest cells reduces laminin and fibronectin levels within the basement membrane, which then facilitates precocious neural crest cell delamination. Zymography assays performed with supernatants of neural crest cell explants overexpressing Cad6B long NTFs demonstrate increased MMP2 activity versus controls, suggesting that Cad6B NTFs promote delamination through a mechanism involving MMP2. Interestingly, this increase in MMP2 does not involve up-regulation of MMP2 or its regulators at the transcriptional level but instead may be attributed to a physical interaction between shed Cad6B NTFs and MMP2. Taken together, these results highlight a new function for Cad6B NTFs and provide insight into how cadherins regulate cellular delamination during normal developmental EMTs as well as aberrant EMTs that underlie human disease.


Subject(s)
Avian Proteins/physiology , Cadherins/physiology , Epithelial-Mesenchymal Transition/physiology , Neural Crest/metabolism , Animals , Avian Proteins/genetics , Avian Proteins/metabolism , CHO Cells , Cadherins/metabolism , Cell Adhesion , Cell Differentiation , Cell Movement , Chick Embryo , Chickens/metabolism , Cricetulus , Epithelial-Mesenchymal Transition/genetics , Epithelium/metabolism , Extracellular Matrix/metabolism , Extracellular Matrix/physiology , Fibronectins/physiology , Gene Expression Regulation, Developmental/genetics , Laminin/metabolism , Laminin/physiology , Matrix Metalloproteinase 2/physiology , Neural Crest/embryology , Neural Crest/physiology , Peptides/metabolism , Proteolysis , Skull/metabolism , Tight Junctions/physiology , Transcriptional Activation
14.
Genesis ; 56(6-7): e23095, 2018 06.
Article in English | MEDLINE | ID: mdl-29476604

ABSTRACT

ADAM metalloproteases have been shown to play critical roles during development. In this review, we will describe functional evidence that implicates ADAM proteins during the genesis, migration and differentiation of neural crest cells. We will restrict our analysis to the transmembrane ADAMs as other reviews have addressed the role of extracellular metalloproteases (Christian et al. [2013] Critical Reviews in Biochemistry and Molecular Biology 48:544-560). This review will describe advances that have been obtained mainly through the use of two vertebrate model systems, the frog, and avian embryos. The role of the principal substrates of ADAMs, the cadherins, has been extensively described in other reviews, most recently in (Cousin [1997] Mechanisms of Development 148:79-88; Taneyhill and Schiffmacher [2017] Genesis, 55). The function of ADAMs in the migration of other cell types, including the immune system, wound healing and cancer has been described previously in (Dreymueller et al. [2017] Mediators of Inflammation 2017: 9621724). Our goal is to illustrate both the importance of ADAMs in controlling neural crest behavior and how neural crest cells have helped us understand the molecular interactions, substrates, and functions of ADAM proteins in vivo.


Subject(s)
ADAM Proteins/metabolism , ADAM Proteins/physiology , Neural Crest/embryology , Animals , Cell Differentiation , Cell Movement , Humans , Membrane Proteins/metabolism , Neural Crest/metabolism , Organogenesis , Protein Transport , Xenopus/metabolism , Xenopus Proteins/metabolism
15.
Gene Expr Patterns ; 27: 67-75, 2018 01.
Article in English | MEDLINE | ID: mdl-29126985

ABSTRACT

During embryogenesis, a single cell develops into new tissues and organs that are made up of a number of different cell types. The assembly of the trigeminal ganglion (cranial nerve V), an important component of the peripheral nervous system, typifies this process. The trigeminal ganglia perform key sensory functions, including sensing pain and touch in the face, and arise from cells of two different progenitor populations, the neural crest and the cranial placodes. One question that remains poorly understood is how these two populations of cells interact with each other during development to form a functional ganglion. Gap junctions are intercellular channels that allow for the passage of small solutes between connected cells and could serve as one potential mechanism by which neural crest and placode cells communicate to create the trigeminal ganglia. To this end, we have generated a comprehensive spatiotemporal expression profile for the gap junction protein Connexin 43, a highly expressed member of the Connexin protein family during development. Our results reveal that Connexin 43 is expressed in the neural folds during neural fold fusion and in premigratory neural crest cells prior to the epithelial-to-mesenchymal transition (EMT), during EMT, and in migratory neural crest cells. During trigeminal gangliogenesis, Connexin 43 is expressed in cranial neural crest cells and the mesenchyme but is strikingly absent in the placode-derived neurons. These data underscore the complexity of bringing two distinct cell populations together to form a new tissue during development and suggest that Connexin 43 may play a key role within neural crest cells during EMT, migration, and trigeminal gangliogenesis.


Subject(s)
Chickens/metabolism , Connexin 43/metabolism , Embryonic Development , Gene Expression Regulation, Developmental , Neural Crest/metabolism , Spatio-Temporal Analysis , Animals , Cell Differentiation , Cells, Cultured , Chick Embryo , Chickens/genetics , Connexin 43/genetics , Neural Crest/cytology
17.
Genesis ; 55(6)2017 06.
Article in English | MEDLINE | ID: mdl-28253541

ABSTRACT

Our increasing comprehension of neural crest cell development has reciprocally advanced our understanding of cadherin expression, regulation, and function. As a transient population of multipotent stem cells that significantly contribute to the vertebrate body plan, neural crest cells undergo a variety of transformative processes and exhibit many cellular behaviors, including epithelial-to-mesenchymal transition (EMT), motility, collective cell migration, and differentiation. Multiple studies have elucidated regulatory and mechanistic details of specific cadherins during neural crest cell development in a highly contextual manner. Collectively, these results reveal that gradual changes within neural crest cells are accompanied by often times subtle, yet important, alterations in cadherin expression and function. The primary focus of this review is to coalesce recent data on cadherins in neural crest cells, from their specification to their emergence as motile cells soon after EMT, and to highlight the complexities of cadherin expression beyond our current perceptions, including the hypothesis that the neural crest EMT is a transition involving a predominantly singular cadherin switch. Further advancements in genetic approaches and molecular techniques will provide greater opportunities to integrate data from various model systems in order to distinguish unique or overlapping functions of cadherins expressed at any point throughout the ontogeny of the neural crest.


Subject(s)
Cadherins/genetics , Gene Expression Regulation, Developmental , Neural Crest/metabolism , Animals , Cadherins/metabolism , Humans , Neural Crest/embryology , Protein Processing, Post-Translational , Transcriptional Activation
18.
Dev Biol ; 425(1): 85-99, 2017 05 01.
Article in English | MEDLINE | ID: mdl-28315296

ABSTRACT

Cranial sensory ganglia are components of the peripheral nervous system that possess a significant somatosensory role and include neurons within the trigeminal and epibranchial nerve bundles. Although it is well established that these ganglia arise from interactions between neural crest and neurogenic placode cells, the molecular basis of ganglia assembly is still poorly understood. Members of the Annexin protein superfamily play key roles in sensory nervous system development throughout metazoans. Annexin A6 is expressed in chick trigeminal and epibranchial placode cell-derived neuroblasts and neurons, but its function in cranial ganglia formation has not been elucidated. To this end, we interrogated the role of Annexin A6 using gene perturbation studies in the chick embryo. Our data reveal that placode cell-derived neuroblasts with reduced Annexin A6 levels ingress and migrate normally to the ganglionic anlage, where neural crest cell corridors correctly form around them. Strikingly, while Annexin A6-depleted placode cell-derived neurons still express mature neuronal markers, they fail to form two long processes, which are considered morphological features of mature neurons, and no longer innervate their designated targets due to the absence of this bipolar morphology. Moreover, overexpression of Annexin A6 causes some placode cell-derived neurons to form extra protrusions alongside these bipolar processes. These data demonstrate that the molecular program associated with neuronal maturation is distinct from that orchestrating changes in neuronal morphology, and, importantly, reveal Annexin A6 to be a key membrane scaffolding protein during sensory neuron membrane biogenesis. Collectively, our results provide novel insight into mechanisms underscoring morphological changes within placode cell-derived neurons that are essential for cranial gangliogenesis.


Subject(s)
Annexin A6/metabolism , Avian Proteins/metabolism , Cell Membrane/metabolism , Ganglia, Sensory/metabolism , Sensory Receptor Cells/metabolism , Skull/innervation , Alternative Splicing , Animals , Annexin A6/genetics , Avian Proteins/genetics , Base Sequence , Chick Embryo , Chickens , Ganglia, Sensory/cytology , Ganglia, Sensory/embryology , Gene Expression Regulation, Developmental , Gene Knockdown Techniques , Immunoblotting , Microscopy, Confocal , Neural Stem Cells/cytology , Neural Stem Cells/metabolism , Sensory Receptor Cells/cytology , Sequence Homology, Nucleic Acid
19.
J Cell Biol ; 215(5): 735-747, 2016 Dec 05.
Article in English | MEDLINE | ID: mdl-27856599

ABSTRACT

During epithelial-to-mesenchymal transitions (EMTs), cells disassemble cadherin-based junctions to segregate from the epithelia. Chick premigratory cranial neural crest cells reduce Cadherin-6B (Cad6B) levels through several mechanisms, including proteolysis, to permit their EMT and migration. Serial processing of Cad6B by a disintegrin and metalloproteinase (ADAM) proteins and γ-secretase generates intracellular C-terminal fragments (CTF2s) that could acquire additional functions. Here we report that Cad6B CTF2 possesses a novel pro-EMT role by up-regulating EMT effector genes in vivo. After proteolysis, CTF2 remains associated with ß-catenin, which stabilizes and redistributes both proteins to the cytosol and nucleus, leading to up-regulation of ß-catenin, CyclinD1, Snail2, and Snail2 promoter-based GFP expression in vivo. A CTF2 ß-catenin-binding mutant, however, fails to alter gene expression, indicating that CTF2 modulates ß-catenin-responsive EMT effector genes. Notably, CTF2 association with the endogenous Snail2 promoter in the neural crest is ß-catenin dependent. Collectively, our data reveal how Cad6B proteolysis orchestrates multiple pro-EMT regulatory inputs, including CTF2-mediated up-regulation of the Cad6B repressor Snail2, to ensure proper cranial neural crest EMT.


Subject(s)
Avian Proteins/metabolism , Cadherins/metabolism , Epithelial-Mesenchymal Transition/genetics , Gene Expression Regulation, Developmental , Neural Crest/cytology , Proteolysis , Transcription, Genetic , Amino Acid Sequence , Animals , Avian Proteins/chemistry , Cadherins/chemistry , Cell Line , Cell Nucleus/metabolism , Chickens , Chromatin/metabolism , Cytosol/metabolism , Models, Biological , Protein Binding , Protein Stability , Snail Family Transcription Factors/metabolism , Up-Regulation , beta Catenin/metabolism
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