1. Preparazione delle soluzioni e dei materiali Questi passaggi devono essere effettuati diversi giorni di anticipo. <ol><li> Vetrini coprioggetto. Coprioggetto sono stati puliti per immersione per 10 minuti in una soluzione di detersivo Linbro 7X: acqua, mescolata ad un 1: 3 ratio e riscaldato, mescolando, fino a non toccare. Coprioggetto sono stati ampiamente sciacquati con acqua deionizzata, e poi cotto al forno a 450 ° C per 6 ore. Caricamento coprioggetto in rack colorazione ceramica (vedi reagenti) semplificato questo processo. </li><li> Soluzione proteica per stampaggio. Ricostituire fibronectina seguendo le istruzioni del produttore per una soluzione madre di 1 mg / ml di concentrazione. </li></ol> 2. Cast francobolli dal master topologico Questi passaggi possono essere eseguiti diversi giorni di anticipo. Francobolli negozio modello-up in un piatto coperto, come un piatto di coltura di tessuti. <ol><li> Rimuovere la polvere dal master utilizzando un flusso di compressa, aria filtrata o gas inerte. </li><li> Posizionare il, lato master fantasia alto, sul fondo di un piatto di plastica appena superiore a quella del maestro. 60 - o 100 mm piatti coltura tissutale sono adatte per questo scopo. </li><li> In un tubo di polistirene da 50 ml centrifuga, combinare i componenti Sylgard con un rapporto di catalizzatore: elastomero di base di 1: 10 in peso. Mescolare accuratamente con un dispositivo di plastica, come una pipetta monouso. Preparare almeno 0,2 ml di elastomero per centimetro quadrato di area piatto. </li><li> Centrifugare il tubo da 50 ml a 300 g per 5 minuti per rimuovere le bolle d&#39;aria. </li><li> Versare l&#39;elastomero sopra il maestro, poi posto in un essiccatore, sotto vuoto, per 30 minuti. </li><li> Curare l&#39;elastomero in un forno a 65 ° C per almeno 2 ore. Polimerizzazione a temperature più elevate e più a lungo i risultati in tempi più rigido elastomero. Lasciate raffreddare a temperatura ambiente. </li><li> Separare il foglio di francobolli dal master. </li></ol> 3. Stampa microcontact della fibronectina su vetro <ol><li> Tagliare un unico timbro. Francobolli di misura 4 mm x 4 mm a 1 cm x 1 cm in area e 1 - 2 mm di spessore sono più facili per iniziare. Luogo lato modello su un vetrino o un piatto di plastica di piccole dimensioni. </li><li> Posto timbro e un detersivo plasma, e di processo, sotto vuoto, per 30 secondi. Un Harrick scientifico plasma pulito (vedi attrezzature), impostare l&#39;impostazione di massima di uscita renderà la superficie PDMS idrofila. Risultato più volte la rottura del elastomero. </li><li> Diluire la soluzione fibronectina con acqua deionizzata ad una concentrazione stampaggio di 50 mg / ml. </li><li> Mettere una piccola goccia (10 - 50 ml) di stampaggio soluzione sul timbro. Si diffonderà su tutta la superficie idrofila. Aggiungi unica soluzione sufficiente che la caduta di coprire il timbro, ma non travolto i bordi. Lasciate assorbire le proteine ​​di bollo per 5 minuti. </li><li> Utilizzando un Kimwipe ® o su altri tessuti carta pulita, stoppino via la maggior parte della soluzione proteica dal timbro, senza toccare la regione fantasia. </li><li> Asciugare la soluzione rimanente dal timbro sotto un flusso di aria pulita, asciutta, gas inerte, come l&#39;azoto. </li><li> Utilizzando le pinzette, rimuovere il timbro dal vetrino, invertire, e mettere in contatto con il coprioggetto di vetro pulito (la superficie da fantasia). Mettere un peso sopra per promuovere un buon contatto. Il peso specifico che offre la migliore patterning dipende dalla dimensione del timbro e modello; iniziare con un peso di 5 g, e regolare tra stampati. Lascia timbro in contatto con la superficie per 1 minuto. </li><li> Con attenzione smontare la pila, e il timbro separato da coprioggetto. </li><li> Vigorosamente sciacquare il coprioggetto fantasia in PBS, seguita da acqua deionizzata, per rimuovere le proteine ​​che non è assorbito in superficie. Coprioggetto secco sotto corrente di azoto. </li></ol> Rappresentante Risultati Stampa microcontact è un potente processo di patterning molecole su superfici. Questo processo ha la capacità di creare funzioni con dimensioni che vanno da decine di micrometri a centinaia di nanometri, in fig. 1A, il logo a sinistra sono ogni 200 micron di altezza, mentre le macchie verdi illustrato nella fig. 1B sono 1 micron di diametro e distanziati ad intervalli di 4 micron, misurato da centro a centro. Fig. 1B illustra anche una proprietà potente di stampa microcontact, cioè che è e di processo additivo. Vari cicli di stampa microcontact può essere applicato a una singola superficie per creare sistemi multicomponente 3. <img src="/files/ftp_upload/old/1065_2008_11_24_3/Figure_a.jpg" alt="Figura A" /><img src="/files/ftp_upload/old/1065_2008_11_24_4/FIGURE_B.jpg" alt="Figura B" />

<ol>
	<li>Chen, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geometric+control+of+cell+life+and+death.">Geometric control of cell life and death.</a> Science. 276, 1425-1425 (1997).</li><li>Kumar, A., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Features+of+Gold+Having+Micrometer+to+Centimeter+Dimensions+can+be+Formed+Through+a+Combination+of+Stamping+with+an+Elastomeric+Stamp+and+an+Alkanethiol+"Ink"+Followed+by+Chemical+Etching.">Features of Gold Having Micrometer to Centimeter Dimensions can be Formed Through a Combination of Stamping with an Elastomeric Stamp and an Alkanethiol "Ink" Followed by Chemical Etching.</a> Applied Physics Letters. 63, 4-4 (1993).</li><li>St. John, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferential+Glial+Cell+Attachment+to+Microcontact-printed+Surfaces.">Preferential Glial Cell Attachment to Microcontact-printed Surfaces.</a> Journal of Neuroscience Methods. 75, 171-171 (1997).</li><li>Kam, L., Boxer, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+adhesion+to+protein-micropatterned-supported+lipid+bilayer+membranes.">Cell adhesion to protein-micropatterned-supported lipid bilayer membranes.</a> Journal of Biomedical Materials Research. 55, 487-487 (2001).</li><li>Kung, L. A., Kam, L., Hovis, J. S., Boxer, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patterning+Hybrid+Surfaces+of+Proteins+and+Supported+Lipid+Bilayers.">Patterning Hybrid Surfaces of Proteins and Supported Lipid Bilayers.</a> Langmuir. 16, 6773-6773 (2000).</li><li>Shen, K., Thomas, V. K., Dustin, M. L., Kam, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micropatterning+of+costimulatory+ligands+enhances+CD4++T+cell+function.">Micropatterning of costimulatory ligands enhances CD4+ T cell function.</a> Proceedings of the National Academy of Sciences. 105, 7791-7791 (2008).</li><li>Shi, P., Shen, K., Kam, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+presentation+of+L1+and+N-cadherin+in+multicomponent,+microscale+patterns+differentially+direct+neuron+function+in+vitro.">Local presentation of L1 and N-cadherin in multicomponent, microscale patterns differentially direct neuron function in vitro.</a> Developmental Neurobiology. 67, 1765-1765 (2007).</li></ol>

The authors have nothing to disclose.

Il processo di stampa microcontact è concettualmente semplice e molto robusto, essendo stata applicata a patterning una vasta gamma di molecole su una varietà di substrati. Tuttavia, questo processo rimane qualcosa di un&#39;arte. La geometria specifica del modello da creare, le proteine ​​per essere modellata, peso applicato, e di rivestimento / condizioni di stampaggio tutti influiscono sulla qualità di stampaggio. Per esempio, troppo poco peso, applicata a funzioni di grandi dimensioni, si traduce spesso in lacune nel modello di c...

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Plasma Cleaner</td>
<td>&nbsp;</td>
<td>Harrick Scientific Products, Inc.</td>
<td>PDC-32G</td>
<td>&nbsp;</td>
<tr>
<td>Desiccator</td>
<td>&nbsp;</td>
<td>Nalgene</td>
<td>5315-0150</td>
<td>&nbsp;</td>
<tr>
<td>PBS</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>10010-072</td>
<td>&nbsp;</td>
<tr>
<td>Protein labeling kit</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>A30006</td>
<td>&nbsp;</td>
<tr>
<td>Fibronectin </td>
<td>Reagent</td>
<td>Sigma-Aldrich</td>
<td>F2006</td>
<td>&nbsp;</td>
<tr>
<td>Staining rack</td>
<td>Reagent</td>
<td>Thomas Scientific</td>
<td>8542E40</td>
<td>&nbsp;</td>
<tr>
<td>Coverslips</td>
<td>Reagent</td>
<td>Fisher Scientific</td>
<td>12-544-12</td>
<td>&nbsp;</td>
<tr>
<td>Sylgard 184</td>
<td>Reagent</td>
<td>Ellsworth Adhesives</td>
<td>184 Sil Elast Kit</td>
<td>&nbsp;</td>
<tr>
<td>Diffraction Grating</td>
<td>Reagent</td>
<td>Edmund Scientific</td>
<td>3040267</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

microcontact printing of proteins for cell biology

La capacità di proteine ​​modello e altre biomolecole su substrati è importante per catturare la complessità spaziale dell&#39;ambiente extracellulare. Sviluppo della stampa microcontatto dal gruppo Whitesides (<a href="http://gmwgroup.harvard.edu/"&gt; Http://gmwgroup.harvard.edu/</a&gt;) A metà degli anni 1990 rivoluzionato questo campo facendo microelettronica / tecniche di microfabbricazione accessibile ai laboratori focalizzati sulle scienze della vita. Implementazioni iniziali di questo metodo utilizzato polidimetilsilossano (PDMS) francobolli per creare modelli di prodotti chimici sulle superfici funzionalizzate materiale<sup&gt; 1</sup&gt;. Da allora, una serie di approcci innovativi sono stati sviluppati per altre molecole modello, comprese le proteine<sup&gt; 2</sup&gt;. Questo video mostra il processo di base della creazione di timbri PDMS e li utilizza per le proteine ​​modello, in quanto questi passaggi sono difficili da esprimere con precisione a parole. Ci concentriamo su patterning la proteina della matrice extracellulare fibronectina sul coprioggetto di vetro come un esempio specifico di patterning. Una componente importante del processo di stampa microcontact è un maestro topologica, da cui sono espressi i francobolli, le regioni sollevato e abbassato del maestro si specchiano nel timbro e definire il modello finale. Tipicamente, un maestro è costituito da un wafer di silicio ricoperto di photoresist e poi modellata da fotolitografia come è fatto qui. Creazione di master contenente un modello specifico richiede attrezzature specializzate, ed è meglio affrontato in collaborazione con un centro di fabbricazione o struttura. Tuttavia, quasi ogni tipo di superficie con topologia può essere utilizzato come un maestro, come reticoli di diffrazione di plastica (vedi Reagenti per un esempio), e tali maestri fortuita fornire prontamente disponibili, i modelli semplici. Questo protocollo inizia al punto di avere un master in mano.

Watch this Scientific Journal Video about Microcontact Printing of Proteins for Cell Biology at JoVE.com

Microcontact Printing of Proteins for Cell Biology

Stampa microcontact viene utilizzato estensivamente alle proteine ​​modello e altre molecole sulle superfici dei materiali. Dimostriamo i passaggi fondamentali di questo processo, stampaggio modelli di fibronectina su vetro.

Stampa microcontatto di proteine ​​per Cell Biology

The ability to pattern proteins and other biomolecules onto substrates is important for capturing the spatial complexity of the extracellular environment. ...

microcontact-printing-of-proteins-for-cell-biology

Research

JoVE Journal

Biology

20.0K Views.  Columbia University. Stampa microcontact viene utilizzato estensivamente alle proteine ​​modello e altre molecole sulle superfici dei materiali. Dimostriamo i passaggi fondamentali di questo processo, stampaggio modelli di fibronectina su vetro.

Video: Microcontact Printing of Proteins for Cell Biology

A Gradient-generating Microfluidic Device for Cell Biology

 The fabrication and operation of a gradient-generating microfluidic device for studying cellular behavior is described.  A microfluidic platform is an enabling experimental tool, because it can precisely manipulate fluid flows, enable high-throughput experiments, and generate stable soluble concentration gradients.  Compared to conventional gradient generators, poly(dimethylsiloxane) (PDMS)-based  microfluidic devices can generate stable concentration gradients of growth factors with well-defined profiles.  Here, we developed simple gradient-generating microfluidic devices with three separate inlets.  Three microchannels combined into one microchannel to generate concentration gradients.  The stability and shape of growth factor gradients were confirmed by fluorescein isothyiocyanate (FITC)-dextran with a molecular weight similar to epidermal growth factor (EGF).  Using this microfluidic device, we demonstrated that fibroblasts exposed to concentration gradients of EGF migrated toward higher concentrations.  The directional orientation of cell migration and motility of migrating cells were quantitatively assessed by cell tracking analysis.  Thus, this gradient-generating microfluidic device might be useful for studying and analyzing the behavior of migrating cells.

We describe a protocol for the microfabrication of the gradient-generating microfluidic device that can generate spatial and temporal gradients in well-defined microenvironment. In this approach, the gradient-generating microfluidic device can be used to study directed cell migration, embryogenesis, wound healing, and cancer metastasis.

Un gradiente di generazione del dispositivo Microfluidic di Biologia Cellulare

 The fabrication and operation of a gradient-generating microfluidic device for studying cellular behavior is described.  A microfluidic platform is an ...

Ricerca

Biologia

Micro-scale Engineering for Cell Biology

Micro-scala di Ingegneria di biologia cellulare

Selective Labelling of Cell-surface Proteins using CyDye DIGE Fluor Minimal Dyes

Surface  proteins are central to the cell's ability to react to its environment and to interact with neighboring cells. They are known to be inducers of almost all intracellular signaling. Moreover, they play an important role in environmental adaptation and drug treatment, and are often involved in disease pathogenesis and pathology (1). Protein-protein interactions are intrinsic to signaling pathways, and to gain more insight in these complex biological processes, sensitive and reliable methods are needed for studying cell surface proteins. Two-dimensional (2-D) electrophoresis is used extensively for detection of biomarkers and other targets in complex protein samples to study differential changes. Cell surface proteins, partly due to their low abundance (1 2% of cellular proteins), are difficult to detect in a 2-D gel without fractionation or some other type of enrichment. They are also often poorly represented in 2-D gels due to their hydrophobic nature and high molecular weight (2). In this study, we present a new protocol for intact cells using CyDye  DIGE Fluor minimal dyes for specific labeling and detection of this important group of proteins. The results showed specific labeling of a large number of cell surface proteins with minimal labeling of intracellular proteins. This protocol is rapid, simple to use, and all three CyDye DIGE Fluor minimal dyes (Cy 2, Cy 3 and Cy 5) can be used to label cell-surface proteins. These features allow for multiplexing using the 2-D Fluorescence Difference Gel Electrophoresis (2-D DIGE) with Ettan  DIGE technology and analysis of protein expression changes using DeCyder  2-D Differential Analysis Software. The level of cell-surface proteins was followed during serum starvation of CHO cells for various lengths of time (see Table 1). Small changes in abundance were detected with high accuracy, and results are supported by defined statistical methods.

A simple and specific method was demonstrated for fluorescent labeling and enhanced detection of cell surface proteins without a fractionation step. Differential abundance in cell surface proteins was analyzed using two-dimensional (2-D) electrophoresis and Ettan&#x2122; DIGE technology.

Etichettatura selettiva di proteine ​​della superficie cellulare utilizzando CyDye DIGE Coloranti Fluor Minimal

Surface  proteins are central to the cell's ability to react to its environment and to interact with neighboring cells. They are known to be inducers of ...

Assessing Two-dimensional Crystallization Trials of Small Membrane Proteins for Structural Biology Studies by Electron Crystallography

Electron crystallography has evolved as a method that can be used either alternatively or in combination with three-dimensional crystallization and X-ray crystallography to study structure-function questions of membrane proteins, as well as soluble proteins. Screening for two-dimensional (2D) crystals by transmission electron microscopy (EM) is the critical step in finding, optimizing, and selecting samples for high-resolution data collection by cryo-EM. Here we describe the fundamental steps in identifying both large and ordered, as well as small 2D arrays, that can potentially supply critical information for optimization of crystallization conditions.
By working with different magnifications at the EM, data on a range of critical parameters is obtained. Lower magnification supplies valuable data on the morphology and membrane size. At higher magnifications, possible order and 2D crystal dimensions are determined. In this context, it is described how CCD cameras and online-Fourier Transforms are used at higher magnifications to assess proteoliposomes for order and size.
While 2D crystals of membrane proteins are most commonly grown by reconstitution by dialysis, the screening technique is equally applicable for crystals produced with the help of monolayers, native 2D crystals, and ordered arrays of soluble proteins. In addition, the methods described here are applicable to the screening for 2D crystals of even smaller as well as larger membrane proteins, where smaller proteins require the same amount of care in identification as our examples and the lattice of larger proteins might be more easily identifiable at earlier stages of the screening.

Evaluating two-dimensional (2D) crystallization trials for the formation of ordered membrane protein arrays is a highly critical and difficult task in electron crystallography. Here we describe our approach in screening for and identifying 2D crystals of predominantly small membrane proteins in the range of 15 &#x2013; 90kDa.

Valutazione bidimensionale Prove di cristallizzazione delle proteine ​​di membrana per piccoli studi di biologia strutturale di Cristallografia Electron

Electron crystallography has evolved as a method that can be used either alternatively or in combination with three-dimensional crystallization and X-ray ...

Fluorescent Labeling of COS-7 Expressing SNAP-tag Fusion Proteins for Live Cell Imaging

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest in live cells. These systems offer a broad selection of fluorescent substrates optimized for a range of imaging instrumentation. Once cloned and expressed, the tagged protein can be used with a variety of substrates for numerous downstream applications without having to clone again. There are two steps to using this system: cloning and expression of the protein of interest as a SNAP-tag fusion, and labeling of the fusion with the SNAP-tag substrate of choice. The SNAP-tag is a small protein based on human O6-alkylguanine-DNA-alkyltransferase (hAGT), a DNA repair protein. SNAP-tag labels are dyes conjugated to guanine or chloropyrimidine leaving groups via a benzyl linker. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag. CLIP-tag is a modified version of SNAP-tag, engineered to react with benzylcytosine rather than benzylguanine derivatives. When used in conjunction with SNAP-tag, CLIP-tag enables the orthogonal and complementary labeling of two proteins simultaneously in the same cells.

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest in live cells. Once cloned and expressed, the tagged protein can be used with a variety of substrates for numerous downstream applications without having to clone again.

Etichettatura fluorescente di COS-7 Esprimendo SNAP-tag proteine ​​di fusione per l&#39;imaging cellulare dal vivo

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest ...

Pull-down of Calmodulin-binding Proteins

Calcium (Ca2+) is an ion vital in regulating cellular function through a variety of mechanisms. Much of Ca2+ signaling is mediated through the calcium-binding protein known as calmodulin (CaM)1,2. CaM is involved at multiple levels in almost all cellular processes, including apoptosis, metabolism, smooth muscle contraction, synaptic plasticity, nerve growth, inflammation and the immune response. A number of proteins help regulate these pathways through their interaction with CaM. Many of these interactions depend on the conformation of CaM, which is distinctly different when bound to Ca2+ (Ca2+-CaM) as opposed to its Ca2+-free state (ApoCaM)3.
While most target proteins bind Ca2+-CaM, certain proteins only bind to ApoCaM. Some bind CaM through their IQ-domain, including neuromodulin4, neurogranin (Ng)5, and certain myosins6. These proteins have been shown to play important roles in presynaptic function7, postsynaptic function8, and muscle contraction9, respectively. Their ability to bind and release CaM in the absence or presence of Ca2+ is pivotal in their function. In contrast, many proteins only bind Ca2+-CaM and require this binding for their activation. Examples include myosin light chain kinase10, Ca2+/CaM-dependent kinases (CaMKs)11 and phosphatases (e.g. calcineurin)12, and spectrin kinase13, which have a variety of direct and downstream effects14.
The effects of these proteins on cellular function are often dependent on their ability to bind to CaM in a Ca2+-dependent manner. For example, we tested the relevance of Ng-CaM binding in synaptic function and how different mutations affect this binding. We generated a GFP-tagged Ng construct with specific mutations in the IQ-domain that would change the ability of Ng to bind CaM in a Ca2+-dependent manner. The study of these different mutations gave us great insight into important processes involved in synaptic function8,15. However, in such studies, it is essential to demonstrate that the mutated proteins have the expected altered binding to CaM.
Here, we present a method for testing the ability of proteins to bind to CaM in the presence or absence of Ca2+, using CaMKII and Ng as examples. This method is a form of affinity chromatography referred to as a CaM pull-down assay. It uses CaM-Sepharose beads to test proteins that bind to CaM and the influence of Ca2+ on this binding. It is considerably more time efficient and requires less protein relative to column chromatography and other assays. Altogether, this provides a valuable tool to explore Ca2+/CaM signaling and proteins that interact with CaM.

Calmodulin (CaM) pull-down assay is an effective way to investigate the interaction of CaM with various proteins. This method uses CaM-sepharose beads for efficient and specific analysis of CaM-binding proteins. This provides an important tool to explore CaM signaling in cellular function.

Pull-down di Calmodulina proteine ​​leganti

Calcium (Ca2+) is an ion vital in regulating cellular function through a variety of mechanisms. Much of Ca2+ signaling is mediated through the ...

Modified Yeast-Two-Hybrid System to Identify Proteins Interacting with the Growth Factor Progranulin

Progranulin (PGRN), also known as granulin epithelin precursor (GEP), is a 593-amino-acid autocrine growth factor. PGRN is known to play a critical role in a variety of physiologic and disease processes, including early embryogenesis, wound healing 1, inflammation 2, 3, and host defense 4. PGRN also functions as a neurotrophic factor 5, and mutations in the PGRN gene resulting in partial loss of the PGRN protein cause frontotemporal dementia 6, 7. Our recent studies have led to the isolation of PGRN as an important regulator of cartilage development and degradation 8-11. Although PGRN, discovered nearly two decades ago, plays crucial roles in multiple physiological and pathological conditions, efforts to exploit the actions of PGRN and understand the mechanisms involved have been significantly hampered by our inability to identify its binding receptor(s). To address this issue, we developed a modified yeast two-hybrid (MY2H) approach based on the most commonly used GAL4 based 2-hybrid system. Compared with the conventional yeast two-hybrid screen, MY2H dramatically shortens the screen process and reduces the number of false positive clones. In addition, this approach is reproducible and reliable, and we have successfully employed this system in isolating the binding proteins of various baits, including ion channel 12, extracellular matrix protein 10, 13, and growth factor14. In this paper, we describe this MY2H experimental procedure in detail using PGRN as an example that led to the identification of TNFR2 as the first known PGRN-associated receptor 14, 15.

We have modified the conventional yeast two-hybrid screening, an effective genetic tool in identifying protein interaction. This modification markedly shortens the process, reduces the workload, and most importantly, reduces the number of false positives. In addition, this approach is reproducible and reliable.

Modificato lievito-sistema del doppio ibrido per identificare proteine ​​che interagiscono con il fattore di crescita progranulina

Progranulin (PGRN), also known as granulin epithelin precursor (GEP), is a 593-amino-acid autocrine growth factor. PGRN is known to play a critical role ...

Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins

Double-strand breaks (DSBs) are the most deleterious DNA lesions a cell can encounter. If left unrepaired, DSBs harbor great potential to generate mutations and chromosomal aberrations1. To prevent this trauma from catalyzing genomic instability, it is crucial for cells to detect DSBs, activate the DNA damage response (DDR), and repair the DNA. When stimulated, the DDR works to preserve genomic integrity by triggering cell cycle arrest to allow for repair to take place or force the cell to undergo apoptosis. The predominant mechanisms of DSB repair occur through nonhomologous end-joining (NHEJ) and homologous recombination repair (HRR) (reviewed in2). There are many proteins whose activities must be precisely orchestrated for the DDR to function properly. Herein, we describe a method for 2- and 3-dimensional (D) visualization of one of these proteins, 53BP1.
The p53-binding protein 1 (53BP1) localizes to areas of DSBs by binding to modified histones3,4, forming foci within 5-15 minutes5. The histone modifications and recruitment of 53BP1 and other DDR proteins to DSB sites are believed to facilitate the structural rearrangement of chromatin around areas of damage and contribute to DNA repair6. Beyond direct participation in repair, additional roles have been described for 53BP1 in the DDR, such as regulating an intra-S checkpoint, a G2/M checkpoint, and activating downstream DDR proteins7-9. Recently, it was discovered that 53BP1 does not form foci in response to DNA damage induced during mitosis, instead waiting for cells to enter G1 before localizing to the vicinity of DSBs6. DDR proteins such as 53BP1 have been found to associate with mitotic structures (such as kinetochores) during the progression through mitosis10.
In this protocol we describe the use of 2- and 3-D live cell imaging to visualize the formation of 53BP1 foci in response to the DNA damaging agent camptothecin (CPT), as well as 53BP1's behavior during mitosis. Camptothecin is a topoisomerase I inhibitor that primarily causes DSBs during DNA replication. To accomplish this, we used a previously described 53BP1-mCherry fluorescent fusion protein construct consisting of a 53BP1 protein domain able to bind DSBs11. In addition, we used a histone H2B-GFP fluorescent fusion protein construct able to monitor chromatin dynamics throughout the cell cycle but in particular during mitosis12. Live cell imaging in multiple dimensions is an excellent tool to deepen our understanding of the function of DDR proteins in eukaryotic cells.

This protocol describes a method for visualizing a DNA double-strand break signaling protein activated in response to DNA damage as well as its localization during mitosis.

Due-e tridimensionale Live Cell Imaging di proteine ​​danno al DNA di risposta

Double-strand breaks (DSBs) are the most deleterious DNA lesions a cell can encounter. If left unrepaired, DSBs harbor great potential to generate ...

Cell Tracking Using Photoconvertible Proteins During Zebrafish Development

Embryogenesis is a dynamic process that is best studied by using techniques that allow the documentation of developmental changes in vivo. The use of genetically-encoded fluorescent proteins has proven a valuable strategy for elucidating dynamic morphogenetic processes as they occur in the intact organism. During the past decade, the development of photoactivatable and photoconvertible fluorescent proteins has opened the possibility to investigate the fate of discrete subpopulations of tagged proteins1. Unlike photoactivatable proteins, photoconvertible fluorescent proteins (PCFPs) are readily tracked and imaged in their native emission state prior to photoconversion, making it easier to identify and select regions by optical inspection. PCFPs, such as Kaede2, KikGR3, Dendra4 and EosFP5, can be shifted from green to red upon exposure to UV or blue light due to a His-Tyr-Gly tripeptide sequence which forms a green chromophore that can be photoconverted to a red one by a light-catalyzed &beta;-elimination and subsequent extension of a &pi;-conjugated system3. PCFPs and their monomeric variants are useful tools for tracking cells6-10 and studying protein dynamics11-14, respectively. During recent years, PCFPs have been expressed in different animal model, such as zebrafish6, chicken7,8 and mouse9,10 for cell fate tracking. Here we report a protocol for cell-specific photoconversion of PCFPs in the living zebrafish embryo and further tracking of photoconverted proteins at later developmental stages. This methodology allows studying, in a tissue-specific manner, cell biological events underlying morphogenesis in the zebrafish animal model.

Here, we present a method for the photoactivated switch of photoconvertible fluorescent proteins (PCFPs) in the living zebrafish embryo and further tracking of photoconverted protein at specific time points during development. This methodology allows monitoring of cell biological events underlying different developmental processes in a live vertebrate organism.

Cella di rilevamento utilizzando proteine ​​Photoconvertible durante lo sviluppo Zebrafish

Embryogenesis is a dynamic process that is best studied by using techniques that allow the documentation of developmental changes in vivo. The use of ...

The Use of Chemostats in Microbial Systems Biology

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated including macromolecular synthesis, metabolism and ultimately, commitment to the cell division cycle. The chemostat, a method of experimentally controlling cell growth rate, provides a powerful means of systematically studying how growth rate impacts cellular processes - including gene expression and metabolism - and the regulatory networks that control the rate of cell growth. When maintained for hundreds of generations chemostats can be used to study adaptive evolution of microbes in environmental conditions that limit cell growth. We describe the principle of chemostat cultures, demonstrate their operation and provide examples of their various applications. Following a period of disuse after their introduction in the middle of the twentieth century, the convergence of genome-scale methodologies with a renewed interest in the regulation of cell growth and the molecular basis of adaptive evolution is stimulating a renaissance in the use of chemostats in biological research.

Cell growth rate is a regulated process and a primary determinant of cell physiology. Continuous culturing using chemostats enables extrinsic control of cell growth rate by nutrient limitation facilitating the study of molecular networks that control cell growth and how those networks evolve to optimize cell growth.

L&#39;uso di chemostati in Biologia microbica Sistemi

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated ...

Stampa microcontatto di proteine ​​per Cell Biology

Stampa microcontatto di proteine per Cell Biology