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1.
Am J Pathol ; 192(8): 1122-1135, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35659946

RESUMO

Wound healing typically recruits the immune and vascular systems to restore tissue structure and function. However, injuries to the enthesis, a hypocellular and avascular tissue, often result in fibrotic scar formation and loss of mechanical properties, severely affecting musculoskeletal function and life quality. This raises questions about the healing capabilities of the enthesis. Herein, this study established an injury model to the Achilles entheses of neonatal mice to study the effectiveness of early-age enthesis healing. Histology and immunohistochemistry analyses revealed an atypical process that did not involve inflammation or angiogenesis. Instead, healing was mediated by secretion of collagen types I and II by resident cells, which formed a permanent hypocellular and avascular scar. Transmission electron microscopy showed that the cellular response to injury, including endoplasmic reticulum stress, autophagy, and cell death, varied between the tendon and cartilage ends of the enthesis. Single-molecule in situ hybridization, immunostaining, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays verified these differences. Finally, gait analysis showed that these processes effectively restored function of the injured leg. These findings reveal a novel healing mechanism in neonatal entheses, whereby local extracellular matrix secretion by resident cells forms an acellular extracellular matrix deposit without inflammation, allowing gait restoration. These insights into the healing mechanism of a complex transitional tissue may lead to new therapeutic strategies for adult enthesis injuries.


Assuntos
Cicatriz , Cicatrização , Animais , Matriz Extracelular , Inflamação , Camundongos , Tendões , Cicatrização/fisiologia
2.
Development ; 146(4)2019 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-30745426

RESUMO

Sesamoid bones are small auxiliary bones that form near joints and contribute to their stability and function. Thus far, providing a comprehensive developmental model or classification system for this highly diverse group of bones has been challenging. Here, we compare our previously reported mechanisms of patella development in the mouse with those of two anatomically different sesamoids, namely lateral fabella and digit sesamoids. We show that all three types of sesamoid bones originate from Sox9+ /Scx+ progenitors under the regulation of TGFß and independently of mechanical stimuli from muscles. Whereas BMP2 regulates the growth of all examined sesamoids, the differentiation of lateral fabella or digit sesamoids is regulated redundantly by BMP4 and BMP2. Next, we show that whereas patella and digit sesamoids initially form in juxtaposition to long bones, lateral fabella forms independently and at a distance. Finally, our evidence suggests that, unlike the synovial joint that separates patella from femur, digit sesamoids detach from the phalanx by formation of a fibrocartilaginous joint. These findings highlight both common and divergent molecular and mechanical features of sesamoid bone development, which underscores their evolutionary plasticity.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Músculos/embriologia , Fatores de Transcrição SOX9/genética , Ossos Sesamoides/embriologia , Ossos Sesamoides/crescimento & desenvolvimento , Fator de Crescimento Transformador beta/metabolismo , Animais , Evolução Biológica , Proteína Morfogenética Óssea 2/metabolismo , Proteína Morfogenética Óssea 4/metabolismo , Cartilagem/metabolismo , Linhagem da Célula , Feminino , Fêmur/metabolismo , Fibrocartilagem/metabolismo , Heterozigoto , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculos/metabolismo , Patela/embriologia , Patela/crescimento & desenvolvimento , Ossos Sesamoides/citologia , Transdução de Sinais , Estresse Mecânico , Líquido Sinovial/metabolismo
3.
Development ; 146(14)2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31221640

RESUMO

Bone protrusions provide stable anchoring sites for ligaments and tendons and define the unique morphology of each long bone. Despite their importance, the mechanism by which superstructures are patterned is unknown. Here, we identify components of the genetic program that control the patterning of Sox9+/Scx+ superstructure progenitors in mouse and show that this program includes both global and regional regulatory modules. Using light-sheet fluorescence microscopy combined with genetic lineage labeling, we mapped the broad contribution of the Sox9+/Scx+ progenitors to the formation of bone superstructures. Then, by combining literature-based evidence, comparative transcriptomic analysis and genetic mouse models, we identified Gli3 as a global regulator of superstructure patterning, whereas Pbx1, Pbx2, Hoxa11 and Hoxd11 act as proximal and distal regulators, respectively. Moreover, by demonstrating a dose-dependent pattern regulation in Gli3 and Pbx1 compound mutations, we show that the global and regional regulatory modules work in a coordinated manner. Collectively, our results provide strong evidence for genetic regulation of superstructure patterning, which further supports the notion that long bone development is a modular process.This article has an associated 'The people behind the papers' interview.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Osso e Ossos/anatomia & histologia , Osso e Ossos/embriologia , Genes Controladores do Desenvolvimento , Proteínas de Homeodomínio/genética , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Desenvolvimento Ósseo/genética , Osso e Ossos/metabolismo , Embrião de Mamíferos , Feminino , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Genes Controladores do Desenvolvimento/genética , Proteínas de Homeodomínio/metabolismo , Ligamentos/anatomia & histologia , Ligamentos/embriologia , Ligamentos/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Especificidade de Órgãos/genética , Fator de Transcrição 1 de Leucemia de Células Pré-B/genética , Fator de Transcrição 1 de Leucemia de Células Pré-B/metabolismo , Gravidez , Fatores de Transcrição SOX9/genética , Fatores de Transcrição SOX9/metabolismo , Tendões/anatomia & histologia , Tendões/embriologia , Tendões/metabolismo
4.
Development ; 145(24)2018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30504126

RESUMO

Tendon-bone attachment sites, called entheses, are essential for musculoskeletal function. They are formed embryonically by Sox9+ progenitors and continue to develop postnatally, utilizing Gli1 lineage cells. Despite their importance, we lack information on the transition from embryonic to mature enthesis and on the relation between Sox9+ progenitors and the Gli1 lineage. Here, by performing a series of lineage tracing experiments in mice, we identify the onset of Gli1 lineage contribution to different entheses. We show that Gli1 expression is regulated embryonically by SHH signaling, whereas postnatally it is maintained by IHH signaling. During bone elongation, some entheses migrate along the bone shaft, whereas others remain stationary. Interestingly, in stationary entheses Sox9+ cells differentiate into the Gli1 lineage, but in migrating entheses this lineage is replaced by Gli1 lineage. These Gli1+ progenitors are defined embryonically to occupy the different domains of the mature enthesis. Overall, these findings demonstrate a developmental strategy whereby one progenitor population establishes a simple embryonic tissue, whereas another population contributes to its maturation. Moreover, they suggest that different cell populations may be considered for cell-based therapy of enthesis injuries.


Assuntos
Osso e Ossos/fisiologia , Movimento , Células-Tronco/citologia , Tendões/fisiologia , Animais , Animais Recém-Nascidos , Compartimento Celular , Morte Celular , Linhagem da Célula , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário , Feminino , Proteínas Hedgehog/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Modelos Biológicos , Osteoclastos/citologia , Osteoclastos/metabolismo , Fagócitos/citologia , Fagócitos/metabolismo , Fatores de Transcrição SOX9/metabolismo , Células-Tronco/metabolismo , Proteína GLI1 em Dedos de Zinco/metabolismo
5.
J Prosthet Dent ; 125(5): 816.e1-816.e7, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33745683

RESUMO

STATEMENT OF PROBLEM: Whether recommendations for the use of occlusal devices are made uniformly in terms of indications, designs, and wearing time is unclear. Different recommendations may lead to different clinical outcomes. PURPOSE: The purpose of this survey was to assess the professional practice of dental surgeons in France regarding the use of occlusal devices. MATERIAL AND METHODS: A 26-question cross-sectional survey was sent to a panel of French dentists via the County Councils of the Dental Order. The questionnaire concerned the amount of occlusion-related treatment, the use of an anterior deprogramming device, stabilization splint, and anterior repositioning appliance, and the patient follow-up as well as the drawbacks of using an occlusal device as a therapeutic solution. The statistical tests used in the study were the chi-square test and the Yate correction for continuity. RESULTS: A total of 771 responses were received. Invasive options were still reported as being used as a first-line treatment for temporomandibular disorder, although a statistical difference was found between experienced and recently graduated practitioners, with recent graduates preferring noninvasive options as first-line treatment. Also, the results showed that anterior deprogramming devices were not used or that their application, particularly the length of treatment, was unfamiliar to practitioners. The anterior repositioning appliance seems to be used, but only a few practitioners integrate it into their practice. In general, about one-third of dentists appear to have a good knowledge of occlusion-related treatments, in particular, the use of occlusal devices. CONCLUSIONS: The results indicated that only 20% to 30% of practitioners have good knowledge of contemporary occlusion-related practice. There is a need for the standardization of practice and improved education for practitioners in the use of occlusal devices.


Assuntos
Placas Oclusais , Transtornos da Articulação Temporomandibular , Estudos Transversais , França , Humanos , Prática Profissional
6.
Development ; 143(21): 3933-3943, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27621060

RESUMO

Recently, blood vessels have been implicated in the morphogenesis of various organs. The vasculature is also known to be essential for endochondral bone development, yet the underlying mechanism has remained elusive. We show that a unique composition of blood vessels facilitates the role of the endothelium in bone mineralization and morphogenesis. Immunostaining and electron microscopy showed that the endothelium in developing bones lacks basement membrane, which normally isolates the blood vessel from its surroundings. Further analysis revealed the presence of collagen type I on the endothelial wall of these vessels. Because collagen type I is the main component of the osteoid, we hypothesized that the bone vasculature guides the formation of the collagenous template and consequently of the mature bone. Indeed, some of the bone vessels were found to undergo mineralization. Moreover, the vascular pattern at each embryonic stage prefigured the mineral distribution pattern observed one day later. Finally, perturbation of vascular patterning by overexpressing Vegf in osteoblasts resulted in abnormal bone morphology, supporting a role for blood vessels in bone morphogenesis. These data reveal the unique composition of the endothelium in developing bones and indicate that vascular patterning plays a role in determining bone shape by forming a template for deposition of bone matrix.


Assuntos
Vasos Sanguíneos/embriologia , Desenvolvimento Ósseo/fisiologia , Colágeno Tipo I/metabolismo , Endotélio/metabolismo , Morfogênese/fisiologia , Animais , Vasos Sanguíneos/fisiologia , Padronização Corporal/fisiologia , Matriz Óssea/embriologia , Matriz Óssea/metabolismo , Osso e Ossos/embriologia , Osso e Ossos/metabolismo , Calcificação Fisiológica/fisiologia , Embrião de Mamíferos , Endotélio/irrigação sanguínea , Feminino , Camundongos , Camundongos Transgênicos , Osteoblastos/fisiologia , Gravidez
7.
Development ; 142(4): 672-80, 2015 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-25617432

RESUMO

Blood vessels serve as key regulators of organogenesis by providing oxygen, nutrients and molecular signals. During limb development, programmed cell death (PCD) contributes to separation of the digits. Interestingly, prior to the onset of PCD, the autopod vasculature undergoes extensive patterning that results in high interdigital vascularity. Here, we show that in mice, the limb vasculature positively regulates interdigital PCD. In vivo, reduction in interdigital vessel number inhibited PCD, resulting in syndactyly, whereas an increment in vessel number and distribution resulted in elevation and expansion of PCD. Production of reactive oxygen species (ROS), toxic compounds that have been implicated in PCD, also depended on interdigital vascular patterning. Finally, ex vivo incubation of limbs in gradually decreasing oxygen levels led to a correlated reduction in both ROS production and interdigital PCD. The results support a role for oxygen in these processes and provide a mechanistic explanation for the counterintuitive positive role of the vasculature in PCD. In conclusion, we suggest a new role for vascular patterning during limb development in regulating interdigital PCD by ROS production. More broadly, we propose a double safety mechanism that restricts PCD to interdigital areas, as the genetic program of PCD provides the first layer and vascular patterning serves as the second.


Assuntos
Morte Celular/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Extremidades/irrigação sanguínea , Extremidades/embriologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Camundongos , Técnicas de Cultura de Órgãos , Gravidez
9.
Development ; 139(20): 3859-69, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22951644

RESUMO

Coordination between the vascular system and forming organs is essential for proper embryonic development. The vasculature expands by sprouting angiogenesis, during which tip cells form filopodia that incorporate into capillary loops. Although several molecules, such as vascular endothelial growth factor A (Vegfa), are known to induce sprouting, the mechanism that terminates this process to ensure neovessel stability is still unknown. Sphingosine-1-phosphate receptor 1 (S1P(1)) has been shown to mediate interaction between endothelial and mural cells during vascular maturation. In vitro studies have identified S1P(1) as a pro-angiogenic factor. Here, we show that S1P(1) acts as an endothelial cell (EC)-autonomous negative regulator of sprouting angiogenesis during vascular development. Severe aberrations in vessel size and excessive sprouting found in limbs of S1P(1)-null mouse embryos before vessel maturation imply a previously unknown, mural cell-independent role for S1P(1) as an anti-angiogenic factor. A similar phenotype observed when S1P(1) expression was blocked specifically in ECs indicates that the effect of S1P(1) on sprouting is EC-autonomous. Comparable vascular abnormalities in S1p(1) knockdown zebrafish embryos suggest cross-species evolutionary conservation of this mechanism. Finally, genetic interaction between S1P(1) and Vegfa suggests that these factors interplay to regulate vascular development, as Vegfa promotes sprouting whereas S1P(1) inhibits it to prevent excessive sprouting and fusion of neovessels. More broadly, because S1P, the ligand of S1P(1), is blood-borne, our findings suggest a new mode of regulation of angiogenesis, whereby blood flow closes a negative feedback loop that inhibits sprouting angiogenesis once the vascular bed is established and functional.


Assuntos
Células Endoteliais/metabolismo , Neovascularização Fisiológica , Receptores de Lisoesfingolipídeo/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Vasos Sanguíneos/embriologia , Vasos Sanguíneos/crescimento & desenvolvimento , Embrião de Mamíferos/metabolismo , Camundongos , Camundongos Transgênicos , Receptores de Lisoesfingolipídeo/genética , Peixe-Zebra
10.
Elife ; 122023 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-36744866

RESUMO

The proprioceptive system is essential for the control of coordinated movement, posture, and skeletal integrity. The sense of proprioception is produced in the brain using peripheral sensory input from receptors such as the muscle spindle, which detects changes in the length of skeletal muscles. Despite its importance, the molecular composition of the muscle spindle is largely unknown. In this study, we generated comprehensive transcriptomic and proteomic datasets of the entire muscle spindle isolated from the murine deep masseter muscle. We then associated differentially expressed genes with the various tissues composing the spindle using bioinformatic analysis. Immunostaining verified these predictions, thus establishing new markers for the different spindle tissues. Utilizing these markers, we identified the differentiation stages the spindle capsule cells undergo during development. Together, these findings provide comprehensive molecular characterization of the intact spindle as well as new tools to study its development and function in health and disease.


Assuntos
Multiômica , Fusos Musculares , Camundongos , Animais , Fusos Musculares/fisiologia , Proteômica , Músculo Esquelético/fisiologia , Propriocepção/fisiologia
11.
Nat Commun ; 12(1): 5363, 2021 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508093

RESUMO

The activity of epiphyseal growth plates, which drives long bone elongation, depends on extensive changes in chondrocyte size and shape during differentiation. Here, we develop a pipeline called 3D Morphometric Analysis for Phenotypic significance (3D MAPs), which combines light-sheet microscopy, segmentation algorithms and 3D morphometric analysis to characterize morphogenetic cellular behaviors while maintaining the spatial context of the growth plate. Using 3D MAPs, we create a 3D image database of hundreds of thousands of chondrocytes. Analysis reveals broad repertoire of morphological changes, growth strategies and cell organizations during differentiation. Moreover, identifying a reduction in Smad 1/5/9 activity together with multiple abnormalities in cell growth, shape and organization provides an explanation for the shortening of Gdf5 KO tibias. Overall, our findings provide insight into the morphological sequence that chondrocytes undergo during differentiation and highlight the ability of 3D MAPs to uncover cellular mechanisms that may regulate this process.


Assuntos
Condrócitos/fisiologia , Fator 5 de Diferenciação de Crescimento/metabolismo , Lâmina de Crescimento/crescimento & desenvolvimento , Animais , Animais Recém-Nascidos , Diferenciação Celular , Proliferação de Células , Embrião de Mamíferos , Feminino , Fator 5 de Diferenciação de Crescimento/economia , Lâmina de Crescimento/citologia , Lâmina de Crescimento/diagnóstico por imagem , Imageamento Tridimensional , Microscopia Intravital , Camundongos Knockout , Modelos Animais , Tíbia/citologia , Tíbia/efeitos dos fármacos , Tíbia/crescimento & desenvolvimento , Microtomografia por Raio-X
12.
Dev Cell ; 56(8): 1182-1194.e6, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33773101

RESUMO

Pyruvate dehydrogenase kinases (PDK1-4) inhibit the TCA cycle by phosphorylating pyruvate dehydrogenase complex (PDC). Here, we show that PDK family is dispensable for murine embryonic development and that BCKDK serves as a compensatory mechanism by inactivating PDC. First, we knocked out all four Pdk genes one by one. Surprisingly, Pdk total KO embryos developed and were born in expected ratios but died by postnatal day 4 because of hypoglycemia or ketoacidosis. Moreover, PDC was phosphorylated in these embryos, suggesting that another kinase compensates for PDK family. Bioinformatic analysis implicated branched-chain ketoacid dehydrogenase kinase (Bckdk), a key regulator of branched-chain amino acids (BCAAs) catabolism. Indeed, knockout of Bckdk and Pdk family led to the loss of PDC phosphorylation, an increase in PDC activity and pyruvate entry into the TCA cycle, and embryonic lethality. These findings reveal a regulatory crosstalk hardwiring BCAA and glucose catabolic pathways, which feed the TCA cycle.


Assuntos
Ciclo do Ácido Cítrico , Desenvolvimento Embrionário , Proteínas Quinases/metabolismo , Piruvato Desidrogenase Quinase de Transferência de Acetil/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Animais , Animais Recém-Nascidos , Perda do Embrião/enzimologia , Perda do Embrião/patologia , Deleção de Genes , Hipoglicemia/complicações , Hipoglicemia/enzimologia , Hipoglicemia/patologia , Cetose/complicações , Cetose/enzimologia , Cetose/patologia , Camundongos Knockout , Modelos Biológicos , Fosforilação , Ácido Pirúvico/metabolismo
13.
Elife ; 102021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33448926

RESUMO

The mechanical challenge of attaching elastic tendons to stiff bones is solved by the formation of a unique transitional tissue. Here, we show that murine tendon-to-bone attachment cells are bi-fated, activating a mixture of chondrocyte and tenocyte transcriptomes, under regulation of shared regulatory elements and Krüppel-like factors (KLFs) transcription factors. High-throughput bulk and single-cell RNA sequencing of humeral attachment cells revealed expression of hundreds of chondrogenic and tenogenic genes, which was validated by in situ hybridization and single-molecule ISH. ATAC sequencing showed that attachment cells share accessible intergenic chromatin areas with either tenocytes or chondrocytes. Epigenomic analysis revealed enhancer signatures for most of these regions. Transgenic mouse enhancer reporter assays verified the shared activity of some of these enhancers. Finally, integrative chromatin and motif analyses and transcriptomic data implicated KLFs as regulators of attachment cells. Indeed, blocking expression of both Klf2 and Klf4 in developing limb mesenchyme impaired their differentiation.


Assuntos
Condrócitos/metabolismo , Fatores de Transcrição Kruppel-Like/genética , Tenócitos/metabolismo , Transcriptoma , Animais , Osso e Ossos , Feminino , Fator 4 Semelhante a Kruppel/genética , Fator 4 Semelhante a Kruppel/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Camundongos , Sequências Reguladoras de Ácido Nucleico , Tendões
14.
Nat Commun ; 11(1): 3168, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32576830

RESUMO

In humans, mutations in the PIEZO2 gene, which encodes for a mechanosensitive ion channel, were found to result in skeletal abnormalities including scoliosis and hip dysplasia. Here, we show in mice that loss of Piezo2 expression in the proprioceptive system recapitulates several human skeletal abnormalities. While loss of Piezo2 in chondrogenic or osteogenic lineages does not lead to human-like skeletal abnormalities, its loss in proprioceptive neurons leads to spine malalignment and hip dysplasia. To validate the non-autonomous role of proprioception in hip joint morphogenesis, we studied this process in mice mutant for proprioceptive system regulators Runx3 or Egr3. Loss of Runx3 in the peripheral nervous system, but not in skeletal lineages, leads to similar joint abnormalities, as does Egr3 loss of function. These findings expand the range of known regulatory roles of the proprioception system on the skeleton and provide a central component of the underlying molecular mechanism, namely Piezo2.


Assuntos
Canais Iônicos/metabolismo , Anormalidades Musculoesqueléticas/metabolismo , Sistema Musculoesquelético/metabolismo , Neurônios/metabolismo , Propriocepção/fisiologia , Anormalidades Múltiplas , Animais , Remodelação Óssea , Subunidade alfa 3 de Fator de Ligação ao Core/metabolismo , Modelos Animais de Doenças , Proteína 3 de Resposta de Crescimento Precoce/metabolismo , Predisposição Genética para Doença/genética , Luxação do Quadril/genética , Luxação do Quadril/metabolismo , Luxação do Quadril/patologia , Articulação do Quadril/anatomia & histologia , Articulação do Quadril/metabolismo , Articulação do Quadril/patologia , Canais Iônicos/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Anormalidades Musculoesqueléticas/genética , Anormalidades Musculoesqueléticas/patologia , Sistema Musculoesquelético/patologia , Escoliose
15.
Cell Rep ; 20(8): 1775-1783, 2017 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-28834742

RESUMO

Successful fracture repair requires restoration of bone morphology and mechanical integrity. Recent evidence shows that fractured bones of neonatal mice undergo spontaneous realignment, dubbed "natural reduction." Here, we show that natural reduction is regulated by the proprioceptive system and improves with age. Comparison among mice of different ages revealed, surprisingly, that 3-month-old mice exhibited more rapid and effective natural reduction than newborns. Fractured bones of null mutants for transcription factor Runx3, lacking functional proprioceptors, failed to realign properly. Blocking Runx3 expression in the peripheral nervous system, but not in limb mesenchyme, recapitulated the null phenotype, as did inactivation of muscles flanking the fracture site. Egr3 knockout mice, which lack muscle spindles but not Golgi tendon organs, displayed a less severe phenotype, suggesting that both receptor types, as well as muscle contraction, are required for this regulatory mechanism. These findings uncover a physiological role for proprioception in non-autonomous regulation of skeletal integrity.


Assuntos
Osso e Ossos/patologia , Fraturas Ósseas/etiologia , Animais , Fraturas Ósseas/patologia , Humanos , Camundongos , Propriocepção
16.
Dev Cell ; 42(4): 388-399.e3, 2017 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-28829946

RESUMO

Maintaining posture requires tight regulation of the position and orientation of numerous spinal components. Yet, surprisingly little is known about this regulatory mechanism, whose failure may result in spinal deformity as in adolescent idiopathic scoliosis. Here, we use genetic mouse models to demonstrate the involvement of proprioception in regulating spine alignment. Null mutants for Runx3 transcription factor, which lack TrkC neurons connecting between proprioceptive mechanoreceptors and spinal cord, developed peripubertal scoliosis not preceded by vertebral dysplasia or muscle asymmetry. Deletion of Runx3 in the peripheral nervous system or specifically in peripheral sensory neurons, or of enhancer elements driving Runx3 expression in proprioceptive neurons, induced a similar phenotype. Egr3 knockout mice, lacking muscle spindles, but not Golgi tendon organs, displayed a less severe phenotype, suggesting that both receptor types may be required for this regulatory mechanism. These findings uncover a central role for the proprioceptive system in maintaining spinal alignment.


Assuntos
Subunidade alfa 3 de Fator de Ligação ao Core/genética , Proteína 3 de Resposta de Crescimento Precoce/genética , Mecanorreceptores/metabolismo , Propriocepção , Escoliose/genética , Animais , Elementos Facilitadores Genéticos , Mecanorreceptores/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Fenótipo , Medula Espinal/crescimento & desenvolvimento , Medula Espinal/metabolismo , Medula Espinal/fisiologia
17.
Cell Rep ; 15(12): 2577-87, 2016 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-27292641

RESUMO

Synovial joints comprise several tissue types, including articular cartilage, the capsule, and ligaments. All of these compartments are commonly assumed to originate from an early set of Gdf5-expressing progenitors populating the interzone domain. Here, we provide evidence that joints develop through a continuous influx of cells into the interzone, where they contribute differentially to forming joint tissues. Using a knockin Gdf5-CreER(T2) mouse, we show that early labeling of Gdf5-positive interzone cells failed to mark the entire organ. Conversely, multiple Cre activation steps indicated a contribution of these cells to various joint compartments later in development. Spatiotemporal differences between Gdf5 and tdTomato reporter expression support the notion of a continuous recruitment process. Finally, differential contribution of Gdf5-positive cells to various tissues suggests that the spatiotemporal dynamics of Gdf5 expression may instruct lineage divergence. This work supports the influx model of joint development, which may apply to other organogenic processes.


Assuntos
Fator 5 de Diferenciação de Crescimento/metabolismo , Articulações/citologia , Articulações/metabolismo , Animais , Linhagem da Célula , Proliferação de Células , Regulação da Expressão Gênica , Técnicas de Introdução de Genes , Integrases/metabolismo , Camundongos , Modelos Animais , Modelos Biológicos , Morfogênese , Fatores de Transcrição SOX9/metabolismo , Células-Tronco/citologia
18.
Development ; 136(8): 1263-72, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19261698

RESUMO

Limb development constitutes a central model for the study of tissue and organ patterning; yet, the mechanisms that regulate the patterning of limb vasculature have been left understudied. Vascular patterning in the forming limb is tightly regulated in order to ensure sufficient gas exchange and nutrient supply to the developing organ. Once skeletogenesis is initiated, limb vasculature undergoes two seemingly opposing processes: vessel regression from regions that undergo mesenchymal condensation; and vessel morphogenesis. During the latter, vessels that surround the condensations undergo an extensive rearrangement, forming a stereotypical enriched network that is segregated from the skeleton. In this study, we provide evidence for the centrality of the condensing mesenchyme of the forming skeleton in regulating limb vascular patterning. Both Vegf loss- and gain-of-function experiments in limb bud mesenchyme firmly established VEGF as the signal by which the condensing mesenchyme regulates the vasculature. Normal vasculature observed in limbs where VEGF receptors Flt1, Flk1, Nrp1 and Nrp2 were blocked in limb bud mesenchyme suggested that VEGF, which is secreted by the condensing mesenchyme, regulates limb vasculature via a direct long-range mechanism. Finally, we provide evidence for the involvement of SOX9 in the regulation of Vegf expression in the condensing mesenchyme. This study establishes Vegf expression in the condensing mesenchyme as the mechanism by which the skeleton patterns limb vasculature.


Assuntos
Padronização Corporal , Osso e Ossos/irrigação sanguínea , Osso e Ossos/metabolismo , Botões de Extremidades/irrigação sanguínea , Botões de Extremidades/metabolismo , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Osso e Ossos/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Botões de Extremidades/embriologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Transgênicos , Fatores de Transcrição SOX9/genética , Fatores de Transcrição SOX9/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética
19.
Dev Cell ; 16(5): 734-43, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19460349

RESUMO

During embryogenesis, organ development is dependent upon maintaining appropriate progenitor cell commitment. Synovial joints develop from a pool of progenitor cells that differentiate into various cell types constituting the mature joint. The involvement of the musculature in joint formation has long been recognized. However, the mechanism by which the musculature regulates joint formation has remained elusive. In this study, we demonstrate, utilizing various murine models devoid of limb musculature or its contraction, that the contracting musculature is fundamental in maintaining joint progenitors committed to their fate, a requirement for correct joint cavitation and morphogenesis. Furthermore, contraction-dependent activation of beta-catenin, a key modulator of joint formation, provides a molecular mechanism for this regulation. In conclusion, our findings provide the missing link between progenitor cell fate determination and embryonic movement, two processes shown to be essential for correct organogenesis.


Assuntos
Articulações/citologia , Articulações/embriologia , Contração Muscular , Organogênese , Células-Tronco/metabolismo , Animais , Diferenciação Celular , Proliferação de Células , Condrócitos/metabolismo , Extremidades/embriologia , Extremidades/fisiologia , Proteínas de Homeodomínio/genética , Camundongos , Músculo Esquelético/metabolismo , Mutação , Fatores de Regulação Miogênica/genética , beta Catenina/metabolismo
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