National Institutes of Health, AR53579, Osteogenesis: Potenciação com Peptídeos Tropic óssea National Institutes of Health, AR056422, efeito anabólico de Peptídeos Osteogênica National Institutes of Health, T32 AR050960, Reparo de Tecidos musculosqueléticas e Regeneração DOD, PC051219 Nucleolin: A Novel Mediador do câncer de próstata e de Medula Óssea de Adesão Celular Endotelial Departamento de Defesa, PC061508, Prostate Cancer Metástase Célula-Bone Marrow adesão Mediadores

<ol>
	<li>Diduch, D. R., Coe, M. R., Joyner, C., Owen, M. E., Balian, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+cell+lines+from+bone+marrow+that+differ+in+terms+of+collagen+synthesis,+osteogenic+characteristics,+and+matrix+mineralization.">Two cell lines from bone marrow that differ in terms of collagen synthesis, osteogenic characteristics, and matrix mineralization.</a> J. Bone Joint Surg. Am. 75, 92-105 (1993).</li><li>Stoddart, M. J., Furlong, P. I., Simpson, A. E., Davies, C. M., Richards, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viability+in+ex+vivo+cultured+cancellous.">Viability in ex vivo cultured cancellous.</a> Eur. Cells. Mater. 13, 69-70 (2007).</li><li>Lehr, J. E., Pienta, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferential+adhesion+of+prostate+cancer+cells+to+a+human+bone+marrow+endothelial+cell+line.">Preferential adhesion of prostate cancer cells to a human bone marrow endothelial cell line.</a> J. Natl. Cancer Inst. 90, 118-123 (1998).</li><li>Schuster, N., G&#246;tz, C., Faust, M., Schneider, E., Prowald, A., Jungbluth, A., Montenarh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wild-type+p53+inhibits+protein+kinase+CK2+activity.">Wild-type p53 inhibits protein kinase CK2 activity.</a> J. Cell Biochem. 81, 172-183 (2001).</li><li>Cwirla, S. E., Peters, E. A., Barrett, R. W., Dower, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peptides+on+phage:+a+vast+library+of+peptides+for+identifying+ligands.">Peptides on phage: a vast library of peptides for identifying ligands.</a> Proc. Natl. Acad. Sci. U. S. A. 87, 6378-6382 (1990).</li><li>Doorbar, J., Winter, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+peptide+antagonist+to+the+thrombin+receptor+using+phage+display.">Isolation of a peptide antagonist to the thrombin receptor using phage display.</a> J. Mol. Biol. 244, 361-369 (1994).</li><li>Ellerby, H. M., Arap, W., Ellerby, L. M., Kain, R., Andrusiak, R., Rio, G. D., Krajewski, S., Lombardo, C. R., Rao, R., Ruoslahti, E., Bredesen, D. E., Pasqualini, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anti-cancer+activity+of+targeted+pro-apoptotic+peptides.">Anti-cancer activity of targeted pro-apoptotic peptides.</a> Nat. Med. 5, 1032-1038 (1999).</li><li>Goodson, R. J., Doyle, M. V., Kaufman, S. E., Rosenberg, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-affinity+urokinase+receptor+antagonists+identified+with+bacteriophage+peptide+display.">High-affinity urokinase receptor antagonists identified with bacteriophage peptide display.</a> Proc. Natl. Acad. Sci. U. S. A. 91, 7129-7133 (1994).</li><li>Pasqualini, R., Koivunen, E., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+peptide+isolated+from+phage+display+libraries+is+a+structural+and+functional+mimic+of+an+RGD-binding+site+on+integrins.">A peptide isolated from phage display libraries is a structural and functional mimic of an RGD-binding site on integrins.</a> J. Cell Biol. 130, 1189-1196 (1995).</li><li>Pasqualini, R., Koivunen, E., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alpha+v+integrins+as+receptors+for+tumor+targeting+by+circulating+ligands.">Alpha v integrins as receptors for tumor targeting by circulating ligands.</a> Nat. Biotechnol. 15, 542-546 (1997).</li><li>Pasqualini, R., Koivunen, E., Kain, R., Lahdenranta, J., Sakamoto, M., Stryhn, A., Ashmun, R. A., Shapiro, L. H., Arap, W., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aminopeptidase+N+is+a+receptor+for+tumor-homing+peptides+and+a+target+for+inhibiting+angiogenesis.">Aminopeptidase N is a receptor for tumor-homing peptides and a target for inhibiting angiogenesis.</a> Cancer Res. 60, 722-727 (2000).</li><li>Rajotte, D., Arap, W., Hagedorn, M., Koivunen, E., Pasqualini, R., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+heterogeneity+of+the+vascular+endothelium+revealed+by+in+vivo+phage+display.">Molecular heterogeneity of the vascular endothelium revealed by in vivo phage display.</a> J. Clin. Invest. 102, 430-437 (1998).</li><li>Rajotte, D., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane+dipeptidase+is+the+receptor+for+a+lung-targeting+peptide+identified+by+in+vivo+phage+display.">Membrane dipeptidase is the receptor for a lung-targeting peptide identified by in vivo phage display.</a> J. Biol. Chem. 274, 11593-11598 (1999).</li><li>Wang, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+high-affinity+peptide+antagonists+of+14-3-3+proteins+by+phage+display.">Isolation of high-affinity peptide antagonists of 14-3-3 proteins by phage display.</a> Biochemistry. 38, 12499-12504 (1999).</li><li>Sugahara, K. N., Teesalu, T., Karmali, P. P., Kotamraju, V. R., Agemy, L., Greenwald, D. R., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coadministration+of+a+tumor-penetrating+peptide+enhances+the+efficacy+of+cancer+drugs.">Coadministration of a tumor-penetrating peptide enhances the efficacy of cancer drugs.</a> Science. 328, 1031-1035 (2010).</li><li>Sikes, R. A., Cooper, C. R., Beck, G. L., Pruitt, F., Brown, M. L., Balian, G., Meadows, G., Kluwer, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+Stromal+Cells+as+Therapeutics+Targets+in+Osseous+Metastasis.">Bone Stromal Cells as Therapeutics Targets in Osseous Metastasis.</a> Cancer Growth and Progression. "Integration/Interaction of Oncologic Growth". , 369-386 (2005).</li><li>Santos, J. L., Pandita, D., Rodrigues, J., P&#234;go, A. P., Granja, P. L., Tom&#225;s, H., Balian, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Receptor-Mediated+Gene+Delivery+in+Mesenchymal+Stem+Cells+using+PAMAM+Dendrimers+conjugated+with+Osteotropic+Peptides.">Receptor-Mediated Gene Delivery in Mesenchymal Stem Cells using PAMAM Dendrimers conjugated with Osteotropic Peptides.</a> Molecular Pharmaceutics. , (2010).</li></ol>

A produção deste vídeo foi patrocinado pela New England Biolabs, Inc, que produz alguns dos reagentes utilizados neste artigo.

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peptides from phage display library modulate gene expression in mesenchymal cells and potentiate osteogenesis in unicortical bone defects

Dois novos peptídeos sintéticos acelerar a formação óssea e podem ser entregues utilizando uma matriz de colágeno. O objetivo deste estudo foi investigar os efeitos sobre a reparação óssea em um modelo de defeito unicorticais. Tratamento de células mesenquimais produziu um aumento na atividade da fosfatase alcalina, mostrou formação de nódulos pelas células, e aumentou a expressão de genes para Runx2, osterix, sialoproteína óssea e osteocalcina. A esponja de colágeno embebida com a reparação promovida peptídeo de defeitos ósseos, enquanto o controle foi menos eficaz. Os resultados deste estudo demonstraram que as células mesenquimais tratados com peptídeo in vitro para diferenciar a osteogênese, e, que os peptídeos entregues in vivo utilizando uma esponja de colágeno promover a reparação de defeitos unicorticais.

Watch this Scientific Journal Video about Peptides from Phage Display Library Modulate Gene Expression in Mesenchymal Cells and Potentiate Osteogenesis in Unicortical Bone Defects at JoVE.com

Peptides from Phage Display Library Modulate Gene Expression in Mesenchymal Cells and Potentiate Osteogenesis in Unicortical Bone Defects

Uma biblioteca de mostrar fago foi utilizado para identificar seqüências de peptídeos que o osso alvo. O objetivo foi investigar o efeito destes peptídeos sobre a diferenciação de células mesenquimais e determinar seus efeitos sobre a regeneração óssea.

Peptídeos de Phage Biblioteca Mostrar modular a expressão de genes em células mesenquimais e potenciar a osteogênese em defeitos ósseos unicorticais

Two novel synthetic peptides accelerate bone formation and can be delivered using a collagen matrix. The aim of this study was to investigate the effects ...

peptides-from-phage-display-library-modulate-gene-expression

Research

JoVE Journal

Biology

17.9K visualizações.  University of Virginia. Uma biblioteca de mostrar fago foi utilizado para identificar seqüências de peptídeos que o osso alvo. O objetivo foi investigar o efeito destes peptídeos sobre a diferenciação de células mesenquimais e determinar seus efeitos sobre a regeneração óssea.

Vídeo: Peptides from Phage Display Library Modulate Gene Expression in Mesenchymal Cells and Potentiate Osteogenesis in Unicortical Bone Defects

Culture of myeloid dendritic cells from bone marrow precursors

Myeloid dendritic cells (DCs) are frequently used to study the interactions between innate and adaptive immune mechanisms and the early response to infection. Because these are the most potent antigen presenting cells, DCs are being increasingly used as a vaccine vector to study the induction of antigen-specific immune responses. In this video, we demonstrate the procedure for harvesting tibias and femurs from a donor mouse, processing the bone marrow and differentiating DCs in vitro. The properties of DCs change following stimulation: immature dendritic cells are potent phagocytes, whereas mature DCs are capable of antigen presentation and interaction with CD4+ and CD8+ T cells. This change in functional activity corresponds with the upregulation of cell surface markers and cytokine production. Many agents can be used to mature DCs, including cytokines and toll-like receptor ligands. In this video, we demonstrate flow cytometric comparisons of expression of two co-stimulatory molecules, CD86 and CD40, and the cytokine, IL-12, following overnight stimulation with CpG or mock treatment. After differentiation, DCs can be further manipulated for use as a vaccine vector or to generate antigen-specific immune responses by in vitro pulsing using peptides or proteins, or transduced using recombinant viral vectors. 

This video demonstrates the procedure for differentiating myeloid dendritic cells from mouse bone marrow. Isolation of mouse tibia and femur, and processing of bone marrow are demonstrated. Pictures demonstrating cell morphology before and after differentiation, and figures depicting cell phenotype and IL-12 production following maturation using CpG are shown.

Cultura de células dendríticas mielóides a partir de precursores da medula óssea

Myeloid dendritic cells (DCs) are frequently used to study the interactions between innate and adaptive immune mechanisms and the early response to ...

Biologia

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

Elaboração de culturas de células primárias hematopoéticas de medula óssea de camundongos para Eletroporação

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Usando o Sistema de Eletroporação Gene Pulser MXcell para transfectar pilhas com Alta Eficiência

Implantation of Ferumoxides Labeled Human Mesenchymal Stem Cells in Cartilage Defects

The field of tissue engineering integrates the principles of engineering, cell biology and medicine towards the regeneration of specific cells and functional tissue. Matrix associated stem cell implants (MASI) aim to regenerate cartilage defects due to arthritic or traumatic joint injuries. Adult mesenchymal stem cells (MSCs) have the ability to differentiate into cells of the chondrogenic lineage and have shown promising results for cell-based articular cartilage repair technologies. Autologous MSCs can be isolated from a variety of tissues, can be expanded in cell cultures without losing their differentiation potential, and have demonstrated chondrogenic differentiation in vitro and in vivo1, 2.
In order to provide local retention and viability of transplanted MSCs in cartilage defects, a scaffold is needed, which also supports subsequent differentiation and proliferation. The architecture of the scaffold guides tissue formation and permits the extracellular matrix, produced by the stem cells, to expand. Previous investigations have shown that a 2% agarose scaffold may support the development of stable hyaline cartilage and does not induce immune responses3.
Long term retention of transplanted stem cells in MASI is critical for cartilage regeneration. Labeling of MSCs with iron oxide nanoparticles allows for long-term in vivo tracking with non-invasive MR imaging techniques4.
This presentation will demonstrate techniques for labeling MSCs with iron oxide nanoparticles, the generation of cell-agarose constructs and implantation of these constructs into cartilage defects. The labeled constructs can be tracked non-invasively with MR-Imaging.

Goal of the presentation is to demonstrate a highly reproducible method to generate matrix associated stem cell implants in cartilage defects, which can be visualized with MR imaging. Stem cells are labeled with FDA-approved Ferumoxides, mixed with agarose, implanted into cartilage defects and imaged with a 7T MR scanner.

Implantação de Ferumoxides identificadas células-tronco mesenquimais em defeitos da cartilagem

The field of tissue engineering integrates the principles of engineering, cell biology and medicine towards the regeneration of specific cells and ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

Usando um contador de células automatizadas para simplificar Estudos da Expressão Gênica: Knockdown siRNA de Expressão IL-4 Gene Dependente em células NAMALWA

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

Na reconstituição in vitro da atividade T. Telomerase castaneum

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway that polypeptide chain follows during co-translational folding to achieve its functional form is still an enigma. In order to understand this process and to determine the exact conformation of the co-translational folding intermediates, it is essential to develop techniques that allow the isolation of RNCs carrying nascent chains of predetermined sizes to allow their further structural analysis.
SecM (secretion monitor) is a 170 amino acid E. coli protein that regulates expression of the downstream SecA (secretion driving) ATPase in the secM-secA operon6. Nakatogawa and Ito originally found that a 17 amino acid long sequence (150-FSTPVWISQAQGIRAGP-166) in the C-terminal region of the SecM protein is sufficient and necessary to cause stalling of SecM elongation at Gly165, thereby producing peptidyl-glycyl-tRNA stably bound to the ribosomal P-site7-9. More importantly, it was found that this 17 amino acid long sequence can be fused to the C-terminus of virtually any full-length and/or truncated protein thus allowing the production of RNCs carrying nascent chains of predetermined sizes7. Thus, when fused or inserted into the target protein, SecM stalling sequence produces arrest of the polypeptide chain elongation and generates stable RNCs both in vivo in E. coli cells and in vitro in a cell-free system. Sucrose gradient centrifugation is further utilized to isolate RNCs.
The isolated RNCs can be used to analyze structural and functional features of the co-translational folding intermediates. Recently, this technique has been successfully used to gain insights into the structure of several ribosome bound nascent chains10,11. Here we describe the isolation of bovine Gamma-B Crystallin RNCs fused to SecM and generated in an in vitro translation system.

We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.

Usando Seqüência de Detenção SECM como uma ferramenta para isolar Ribossomos Polipeptídeos encadernados

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

A Protocol for Phage Display and Affinity Selection Using Recombinant Protein Baits

Using recombinant phage as a scaffold to present various protein portions encoded by a directionally cloned cDNA library to immobilized bait molecules is an efficient means to discover interactions. The technique has largely been used to discover protein-protein interactions but the bait molecule to be challenged need not be restricted to proteins. The protocol presented here has been optimized to allow a modest number of baits to be screened in replicates to maximize the identification of independent clones presenting the same protein. This permits greater confidence that interacting proteins identified are legitimate interactors of the bait molecule. Monitoring the phage titer after each affinity selection round provides information on how the affinity selection is progressing as well as on the efficacy of negative controls. One means of titering the phage, and how and what to prepare in advance to allow this process to progress as efficiently as possible, is presented. Attributes of amplicons retrieved following isolation of independent plaque are highlighted that can be used to ascertain how well the affinity selection has progressed. Trouble shooting techniques to minimize false positives or to bypass persistently recovered phage are explained. Means of reducing viral contamination flare up are discussed.

Phage display is a powerful technique to capture proteins or protein moieties that interact with an immobilized molecule of interest. Once a decision of the type of phage cDNA library to create and screen has been made, the protocol described here permits efficient affinity selection leading to identification of interactors.

Um protocolo para exibição Fago e Affinity Seleção Usando Iscas proteína recombinante

Using  recombinant phage as a scaffold to present various protein portions encoded by  a directionally cloned cDNA library to immobilized bait molecules ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

Screening siRNA identificar Ubiquitin e ubiquitina-como reguladores do sistema de caminhos biológicos em células de mamíferos cultivadas

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are a frequent problem affecting human health. Therefore, understanding the mechanisms that regulate metabolism is a crucial scientific task. Many disease causing genes in humans have a fly homologue, making Drosophila a good model to study signaling pathways involved in the development of different disorders. Additionally, the tractability of Drosophila simplifies genetic screens to aid in identifying novel therapeutic targets that may regulate metabolism. In order to perform such a screen a simple and fast method to identify changes in the metabolic state of flies is necessary. In general, carbon dioxide production is a good indicator of substrate oxidation and energy expenditure providing information about metabolic state. In this protocol we introduce a simple method to measure CO2 output from flies. This technique can potentially aid in the identification of genetic perturbations affecting metabolic rate.

Measurement of Metabolic Rate in Drosophila using Respirometry

Metabolic disorders are among one of the most common diseases in humans. The genetically tractable model organism D. melanogaster can be used to identify novel genes that regulate metabolism. This paper describes a relatively simple method which allows studying the metabolic rate in flies by measuring their CO2 production.