Name: Autor em destaque: Compreendendo a rede de microtúbulos nas junções neuromusculares de Drosophila
Uploaded: 2023-10-20T14:00:00
Description: Watch this Scientific Journal Video about Understanding Microtubule Network in Drosophila Neuromuscular Junctions at JoVE.com

Agradecemos ao Dr. Ying Xiong pelas discussões e comentários sobre o manuscrito. Este trabalho é apoiado por uma bolsa da National Science Foundation of China (NSFC) para C. M. (31500839).

1. Dissecção de larvas
OBS: A solução dissecante salina hemolinf-símile (HL3.1)18 e a solução fixadora paraformaldeído (PFA) a 4%19,20 são utilizadas à temperatura ambiente, pois os microtúbulos se despolimerizam quando a temperatura é muito baixa.
<ol><li>Escolha uma larva errante de3º ínstar com pinças longas e rombas. Lave-o com HL3.1 e coloque-o na placa de dissec...

Visualização de redes de microtúbulos em junções neuromusculares e células musculares de Drosophila

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Aqui é descrito um protocolo para a dissecção e imunomarcação de larvas de Drosophila , junções neuromusculares e células musculares. Há vários pontos essenciais a serem considerados. Em primeiro lugar, evitar a lesão dos músculos observados é crucial durante o processo de dissecção. Pode valer a pena fixar o filé antes de retirar os órgãos internos para evitar o contato direto entre a pinça e os músculos. Para evitar danos musculares ou separação da epiderme larval, é importante garantir ...

Os microtúbulos (MTs), como um dos componentes estruturais do citoesqueleto, desempenham um papel importante em diversos processos biológicos, incluindo divisão celular, crescimento e motilidade celular, transporte intracelular e manutenção da forma celular. A dinâmica e a função dos microtúbulos são moduladas por interações com outras proteínas, como MAP1, MAP2, Tau, Katanin e Kinesin 1,2,3,4,5.
Nos neurônios, os microtúbulos são essenciais para o desenvolvimento e manutenção de axônios e dendritos. Anormalidades nos microtúbulos levam à disfunção e até mesmo à morte dos neurônios. Por exemplo, no cérebro de pacientes com Alzheimer, a hiperfosforilação da proteína Tau reduz a estabilidade da rede de microtúbulos, causando irregularidades neurológicas6. Assim, o exame das redes de microtúbulos contribuirá para a compreensão do neurodesenvolvimento e da patogênese das doenças neurológicas.
A junção neuromuscular (JNM) é a sinapse periférica formada entre um axônio terminal do neurônio motor e uma fibra muscular, que é um excelente e poderoso sistema modelo para o estudo da estrutura e funçõessinápticas7. Futsch é uma proteína de Drosophila homóloga à proteína de ligação a microtúbulos MAP1B encontrada em mamíferos8. É expressa apenas em neurônios e desempenha um papel no desenvolvimento dos botões sinápticos do NMJ 8,9. No tipo selvagem, feixes filamentosos que correm ao longo do centro dos processos NMJ são visualizados por imunomarcação com anti-Futsch. Ao atingir o final do NMJ, esse feixe tem a capacidade de formar uma alça constituída por microtúbulos ou de perder sua estrutura filamentosa, resultando em uma aparência difusa e puntiforme10. Alças de microtúbulos estão associadas a cones de crescimento pausados, o que sugere que a matriz de microtúbulos é estável11. Portanto, podemos determinar indiretamente o desenvolvimento de microtúbulos estáveis no NMJ pela coloração de Futsch. O grande tamanho das células musculares na larva de Drosophila permite uma visualização clara da rede de microtúbulos. Os fatores que afetam a estabilidade da rede de microtúbulos podem ser encontrados através da análise da densidade e forma dos microtúbulos. Simultaneamente, o estado da rede de microtúbulos das células musculares pode ser verificado de forma cruzada com o resultado do NMJ para obter conclusões mais abrangentes.
Muitos protocolos têm sido empregados para investigar a rede e a dinâmica dos microtúbulos. No entanto, essas pesquisas têm frequentemente se concentrado em estudos in vitro 12,13,14,15,16. Alternativamente, alguns experimentos in vivo têm empregado microscopia eletrônica para detectar o citoesqueleto17. De acordo com a ligação específica de anticorpos fluorescentemente marcados ou corantes químicos a proteínas ou DNA, os métodos aqui apresentados permitem a detecção de redes de microtúbulos em NMJ em nível de neurônios individuais in vivo, com resultados corroborados por observações em células musculares. Este protocolo é simples, estável e repetível quando combinado com as poderosas ferramentas genéticas disponíveis em Drosophila melanogaster, permitindo uma gama diversificada de exames fenotípicos e rastreios genéticos para o papel de proteínas reguladoras da rede de microtúbulos no sistema nervoso in vivo.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alexa Fluor Plus 405 phalloidin</td>
			<td>invitrogen</td>
			<td>A30104</td>
			<td>dilute 1:200</td>
		</tr>
		<tr>
			<td>Enhanced Antifade Mounting Medium</td>
			<td>Beyotime</td>
			<td>P0128M</td>
			<td></td>
		</tr>
		<tr>
			<td>FV10-ASW confocal microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-Mouse antibody, Alexa Fluor 488 conjugated</td>
			<td>Thermo Fisher</td>
			<td>A-11001</td>
			<td>dilute 1:1,000</td>
		</tr>
		<tr>
			<td>Laser confocal microscope LSM 710</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Scissors</td>
			<td>66vision</td>
			<td>54138B</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse anti-Futsch antibody</td>
			<td>Developmental Studies Hybridoma Bank&#160;&#160;</td>
			<td>22C10</td>
			<td>dilute 1:50</td>
		</tr>
		<tr>
			<td>Mouse anti-&#945;-tubulin antibody</td>
			<td>Sigma</td>
			<td>T5168</td>
			<td>dilute 1:1,000</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Wako</td>
			<td>168-20955</td>
			<td>Final concentration: 4% in PB Buffer</td>
		</tr>
		<tr>
			<td>Stainless Steel Minutien Pins</td>
			<td>Entomoravia</td>
			<td></td>
			<td>0.1mm Diam</td>
		</tr>
		<tr>
			<td>Stereomicroscope SMZ161</td>
			<td>Motic</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>stereoscopic fluorescence microscope BX41</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Texas Red-conjugated goat anti-HRP</td>
			<td>Jackson ImmunoResearch</td>
			<td></td>
			<td>dilute 1:100</td>
		</tr>
		<tr>
			<td>TO-PRO(R) 3 iodide</td>
			<td>Invitrogen</td>
			<td>T3605</td>
			<td>dilute 1:1,000</td>
		</tr>
		<tr>
			<td>Transfer decoloring shaker TS-8</td>
			<td>Kylin-Bell lab instruments</td>
			<td>E0018</td>
			<td></td>
		</tr>
		<tr>
			<td>TritonX-100</td>
			<td>BioFroxx</td>
			<td>1139</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezers&#160;</td>
			<td>dumont</td>
			<td>500342</td>
			<td></td>
		</tr>
	</tbody>
</table>

using drosophila larval neuromuscular junction and muscle cells to visualize microtubule network

A rede de microtúbulos é um componente essencial do sistema nervoso. Mutações em muitas proteínas reguladoras dos microtúbulos estão associadas a distúrbios do neurodesenvolvimento e doenças neurológicas, tais como proteína Tau associada a microtúbulos a doenças neurodegenerativas, proteína cortadora de microtúbulos Spastin e Katanin 60 causam paraplegia espástica hereditária e anormalidades do neurodesenvolvimento, respectivamente. A detecção de redes de microtúbulos em neurônios é vantajosa para elucidar a patogênese de distúrbios neurológicos. No entanto, o pequeno tamanho dos neurônios e o arranjo denso dos feixes axonais de microtúbulos tornam a visualização das redes de microtúbulos um desafio. Neste estudo, descrevemos um método para dissecção da junção neuromuscular larval e células musculares, bem como imunomarcação de α-tubulina e proteína associada a microtúbulos Futsch para visualização de redes de microtúbulos em Drosophila melanogaster. A junção neuromuscular permite observar microtúbulos pré e pós-sinápticos, e o grande tamanho das células musculares na larva de Drosophila permite uma clara visualização da rede de microtúbulos. Aqui, ao mutar e superexpressar Katanin 60 em Drosophila melanogaster, e então examinar as redes de microtúbulos na junção neuromuscular e células musculares, revelamos com precisão o papel regulatório de Katanin 60 no neurodesenvolvimento. Portanto, combinado com as poderosas ferramentas genéticas de Drosophila melanogaster, este protocolo facilita muito a triagem genética e a análise da dinâmica de microtúbulos para o papel das proteínas reguladoras da rede de microtúbulos no sistema nervoso.

Microtubules (MTs), as one of the structural components of the cytoskeleton, play an important role in diverse biological processes, including cell division, cell growth and motility, intracellular transport, and the maintenance of cell shape. Microtubule dynamics and function are modulated by interactions with other proteins, such as MAP1, MAP2, Tau, Katanin, and Kinesin1,2,3,4,5.
In neurons, microtubules are essential for the development and maintenance of axons and dendrites. Abnormalities in microtubules lead to dysfunction and even the death of neurons. For instance, in the brain of Alzheimer&#39;s patients, Tau protein hyperphosphorylation reduces the stability of the microtubule network, causing neurological irregularities6. Thus, examining microtubule networks will contribute to a comprehension of neurodevelopment and the pathogenesis of neurological diseases.
The neuromuscular junction (NMJ) is the peripheral synapse formed between a motor neuron axon terminal and a muscle fiber, which is an excellent and powerful model system for studying synaptic structure and functions7. Futsch is a protein in Drosophila that is homologous to the microtubule-binding protein MAP1B found in mammals8. It is expressed only in neurons and plays a role in the development of the NMJ&#39;s synaptic buttons8,9. In wild-type, filamentous bundles that run along the center of NMJ processes are visualized by immunostaining with anti-Futsch. When reaching NMJ&#39;s end, this bundle has the ability to either form a loop consisting of microtubules or to lose its filamentous structure, resulting in a diffuse and punctate appearance10. Microtubule loops are associated with paused growth cones, which suggests the microtubule array is stable11. Therefore, we can indirectly determine the stable microtubule development in NMJ by Futsch staining. The large size of muscle cells in Drosophila larva allows for clear visualization of the microtubule network. The factors affecting the stability of the microtubule network can be found by analyzing the density and shape of microtubules. Simultaneously, the microtubule network status of muscle cells can be cross-verified with the result of NMJ to obtain more comprehensive conclusions.
Many protocols have been employed for investigating the network and dynamics of microtubules. However, these researches have often focused on in vitro studies12,13,14,15,16. Alternatively, some in vivo experiments have employed electron microscopy to detect the cytoskeleton17. According to the specific binding of fluorescently labeled antibodies or chemical dyes to proteins or DNA, the methods presented here allow the detection of microtubule networks in NMJ at the level of individual neurons in vivo, with results corroborated by observations in muscle cells. This protocol is simple, stable, and repeatable when combined with the powerful genetic tools available in Drosophila melanogaster, enabling a diverse range of phenotypic examinations and genetic screenings for the role of microtubule network regulatory proteins in the nervous system in vivo.

Autor em destaque: Compreendendo a rede de microtúbulos nas junções neuromusculares de Drosophila 

Usando a junção neuromuscular de larvas de Drosophila e células musculares para visualizar a rede de microtúbulos

Currently, microtubule dynamics are observed indirectly through microtubule-binding proteins such as EB1. Since alphabeta tubulin heterodimers are abundant in the cytoplasm, fold directly, neighboring tubulin heterodimers are lacking the dynamics of microtubule networks in vivo. Our protocol visualizes microtubules in neuromuscular synapses and muscle cells.When combined with the powerful genetic tools available in Drosophila melanogaster, enabling a diverse range of phenotypic examinations and the genetic screening for the role of microtubule network regulatory proteins in the nervous system in vivo. Our research focuses on the relationship between the cytoskeleton and the neurodevelopment, as well as its implications for neurological diseases. We hope to discover the mechanism of neurodevelopment and the parthenogenesis for neurological diseases by highlighting the effect of cytoskeletal regulatory proteins on neurons.

Demonstramos um procedimento passo a passo para visualizar a rede de microtúbulos nas junções neuromusculares (NMJs) e nas células musculares. Após a dissecção de acordo com o diagrama esquemático (Figura 1A-E), a imunomarcação é realizada e, posteriormente, as imagens são observadas e coletadas em microscópio confocal a laser ou microscópio de fluorescência estereoscópica (Figura 1F,G).
<p class="jove_conten...

Watch this Scientific Journal Video about Understanding Microtubule Network in Drosophila Neuromuscular Junctions at JoVE.com

Aqui, apresentamos um protocolo detalhado para visualizar as redes de microtúbulos nas junções neuromusculares e células musculares. Combinado com as poderosas ferramentas genéticas de Drosophila melanogaster, este protocolo facilita muito a triagem genética e a análise da dinâmica de microtúbulos para o papel das proteínas reguladoras da rede de microtúbulos no sistema nervoso.

The microtubule network is an essential component of the nervous system. Mutations in many microtubules regulatory proteins are associated with ...

Atualmente, a dinâmica dos microtúbulos é observada indiretamente através de proteínas ligadoras de microtúbulos, como a EB1. Como os heterodímeros da alfabética tubulina são abundantes no citoplasma, dobram-se diretamente, os heterodímeros tubulínicos vizinhos não possuem a dinâmica das redes de microtúbulos in vivo. Nosso protocolo visualiza microtúbulos em sinapses neuromusculares e células musculares.Quando combinado com as poderosas ferramentas genéticas disponíveis em Drosophila melanogaster, possibilitando uma gama diversificada de exames fenotípicos e a triagem genética para o papel das proteínas reguladoras da rede de microtúbulos no sistema nervoso in vivo. Nossa pesquisa enfoca a relação entre o citoesqueleto e o neurodesenvolvimento, bem como suas implicações para doenças neurológicas. Esperamos descobrir o mecanismo do neurodesenvolvimento e a partenogênese para doenças neurológicas, destacando o efeito das proteínas reguladoras do citoesqueleto sobre os neurônios.

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Research

JoVE Journal

Neuroscience

Using Drosophila Larval Neuromuscular Junction and Muscle Cells to Visualize Microtubule Network

The microtubule network is an essential component of the nervous system. Mutations in many microtubules regulatory proteins are associated with neurodevelopmental disorders and neurological diseases, such as microtubule-associated protein Tau to neurodegenerative diseases, microtubule severing protein Spastin and Katanin 60 cause hereditary spastic paraplegia and neurodevelopmental abnormalities, respectively. Detection of microtubule networks in neurons is advantageous for elucidating the pathogenesis of neurological disorders. However, the small size of neurons and the dense arrangement of axonal microtubule bundles make visualizing the microtubule networks challenging. In this study, we describe a method for dissection of the larval neuromuscular junction and muscle cells, as well as immunostaining of &#945;-tubulin and microtubule-associated protein Futsch to visualize microtubule networks in Drosophila melanogaster. The neuromuscular junction permits us to observe both pre-and post-synaptic microtubules, and the large size of muscle cells in Drosophila larva allows for clear visualization of the microtubule network. Here, by mutating and overexpressing Katanin 60 in Drosophila melanogaster,&#160;and then examining the microtubule networks in the neuromuscular junction and muscle cells, we&#160;accurately reveal the regulatory role of Katanin 60 in neurodevelopment. Therefore, combined with the powerful genetic tools of Drosophila&#160;melanogaster, this protocol greatly facilitates genetic screening and microtubule dynamics analysis for the role of microtubule network regulatory proteins in the nervous system.

Here, we present a detailed protocol to visualize the microtubule networks in neuromuscular junctions and muscle cells. Combined with the powerful genetic tools of Drosophila melanogaster, this protocol greatly facilitates genetic screening and microtubule-dynamics analysis for the role of microtubule network regulatory proteins in the nervous system.

Neurociência

Drosophila Larval Dissection and Fixation for Microtubule Visualization

Begin by picking out a wandering Drosophila third instar larva using long blunt forceps. Wash the larva with hemolymph-like saline, then dry it with a wipe. Next, position the larva dorsally or ventrally on a dissection dish under the stereo microscope.Depending on the tissue to be observed, opt for dorsal or ventral dissection. Pin the larva's mouth hooks and tail to maintain extended positioning. Next, add a drop of the hemolymph-like saline to prevent the larva from drying.Using dissection scissors, make a small transverse incision close to the posterior end without severing it completely. Proceed to cut along the ventral midline, moving toward the anterior end. Now insert four insect pins each into the corners of the larva.Make necessary adjustments to the insect pins to maximize the stretching of the larva. Use forceps to gently remove the internal organs while avoiding harm to the muscles. To fix the larva, immerse the carcasses in 100 L of 4%paraformaldehyde, while still affixed to the dissecting dish.After this, dismount the pins. Then transfer the sample into a 2 mL microcentrifuge tube filled with 0.2%PBST. Place the tube on a shaker for 10 minutes at 15 RPM.

Drosófila Dissecção e fixação larval para visualização de microtúbulos

Immunohistochemistry of Drosophila Larva for Microtubule Visualization

Remove the PBST and immerse the paraformaldehyde-fixed drosophila larval carcasses in a blocking agent for 40 minutes at room temperature. Replace the blocking agent with 200 microliters of the primary antibody diluted with 0.2%PBST. Leave the larvae to incubate at four degrees Celsius overnight.The next day, wash the larvae with 0.2%PBST for 10 minutes. Next, remove the PBST from the tube and add 200 microliters of diluted secondary antibody. Incubate it at ambient temperature for 1.5 hours in the dark.Introduce a nuclear dye such as TO-PRO R 3 iodide into the incubating tube for 30 minutes while staining the microtubules in the dark. Finally, rinse off the secondary antibody and the nuclear dye with 0.2%PBST for 10 minutes.

Imunohistoquímica de larvas de Drosophila para visualização de microtúbulos

Mounting and Image Acquisition of Drosophila Larval Microtubules

Begin by placing the antibody labeled drosophila larval carcasses in 0.2%PBST on a glass slide. Adjusted under the stereo microscope, ensuring that the inner surface of the larval carcass is facing up. Absorb the excess PBST solution using a wipe.Then delicately add a drop of Anti-Fade mounting medium. Next place a cover slip on the slide covering the dissected larvae slowly and gently, avoiding bubble formation. Secure the cover slip in place by applying fingernail polish around its edges.Store the slide in a dark location to minimize fluorescent attenuation. For image acquisition, use the laser scanning confocal microscope with the 63x Oil immersion objective. Then adjust the wavelength and laser power to fit the requirements of the experiment best.To identify the neuromuscular junctions and capture images of muscle four in segment A three, select a 488 nanometer laser to activate alpha tubulin or Futsch, and 546 nanometers to activate the HRP imaging track. Modify the parameters to achieve a frame size of 1, 024 by 1, 024 pixels, a digital zoom of 1.0, and an imaging interval of 0.8 micrometers. To visualize microtubules in the muscle, capture images of muscle two in the segments A three to A five as it has fewer tracheal branches.Choose a 488 nanometer laser for activating alpha tubulin and a 633 nanometer laser for activating the T3605 imaging track. Adjust the imaging parameters to a frame size of 1, 024 by 1, 024 pixels, a digital zoom of 2.0, and an imaging interval of 0.4 micrometers. Both pre-and post-synaptic microtubule organizations of the neuromuscular junction were labeled with anti-alpha tubulin.Futsch staining reflected the abundance of stable microtubules in the pre-synaptic neurons. Decreased signal intensity of anti-Futsch was observed when microtubules severing protein Katanin 60 was overexpressed in the presynaptic neurons. The staining intensity of the axon trunk was stronger than that of the branches.Katanin 60 mutations resulted in increased microtubule loops. Overexpression of Katanin 60 caused short microtubule fragments within the terminal buttons. Alpha tubulin staining demonstrated a clear network of microtubules around the nucleus.Muscle cells had a significantly increased perinuclear microtubular intensity and exhibited stronger bundles in the Katanin 60 mutant. Overexpression resulted in fragmentation of the microtubule fibers.