| 1. |
- Cane, Gaëlle, et al.
(författare)
-
Protein Diagnostics by Proximity Ligation: Combining Multiple Recognition and DNA Amplification for Improved Protein Analyses
- 2017. - 3
-
Ingår i: Molecular Diagnostics (Third Edition). - 2016 : Academia Press. - 9780128029718 ; , s. 219-231
-
Bokkapitel (refereegranskat)abstract
- Proximity ligation assay (PLA) is a unique method in which single-stranded oligonucleotides are conjugated to affinity binders of proteins, followed by amplification of the signal by DNA polymerization and hybridization of complementary oligonucleotides labeled with fluorogenic or chromogenic readout. Here, a brief overview of the field of protein analysis describes the background and the initial development of the technique for the detection of protein–protein interactions via the proximity probes mentioned. In this context, PLA can constrain the general problem of cross-reactivity in protein detection by affinity binders, by ensuring that only cognate pairs of proximity probes result in a signal. Thereafter, this chapter deals mainly with derivatives methods and their applications, with a particular interest in improved specificity, application to various biological materials, and multiplexing. The method has been applied in situ and in solution, adapted for the detection of posttranslational modifications such as phosphorylation and interactions between proteins and specific DNA sequences, and multiplexed to a certain extent, which illustrates its versatility. A technique free from enzymatic reaction, the hybridization chain reaction, can be considered a cost-effective alternative particularly suitable to molecular diagnostics. Finally, we explore further development toward higher-level multiplexing and sensitivity. At this point it is not clear what level can be achieved by PLA, but the assay is compatible with a wide range of readout, including separate real-time amplification reactions and novel microfluidic read-out platforms.
|
|
| 2. |
- Ebai, Tonge, et al.
(författare)
-
Analytically Sensitive Protein Detection in Microtiter Plates by Proximity Ligation with Rolling Circle Amplification
- 2017
-
Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 63:9, s. 1497-1505
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Detecting proteins at low concentrations in plasma is crucial for early diagnosis. Current techniques in clinical routine, such as sandwich ELISA, provide sensitive protein detection because of a dependence on target recognition by pairs of antibodies, but detection of still lower protein concentrations is often called for. Proximity ligation assay with rolling circle amplification (PLARCA) is a modified proximity ligation assay (PLA) for analytically specific and sensitive protein detection via binding of target proteins by 3 antibodies, and signal amplification via rolling circle amplification (RCA) in microtiter wells, easily adapted to instrumentation in use in hospitals.METHODS: Proteins captured by immobilized antibodies were detected using a pair of oligonucleotide-conjugated antibodies. Upon target recognition, these PLA probes guided oligonucleotide ligation, followed by amplification via RCA of circular DNA strands that formed in the reaction. The RCA products were detected by horseradish peroxidase-labeled oligonucleotides to generate colorimetric reaction products with readout in an absorbance microplate reader.RESULTS: We compared detection of interleukin (IL)-4, IL-6, IL-8, p53, and growth differentiation factor-15 by PLARCA and conventional sandwich ELISA or immuno RCA. PLARCA detected lower concentrations of proteins and exhibited a broader dynamic range compared ELISA and iRCA using the same antibodies. IL-4 and IL-6 were detected in clinical samples at femtomolar concentrations, considerably lower than for ELISA.CONCLUSIONS: PLARCA offers detection of lower protein levels and increased dynamic ranges compared to ELISA. The PLARCA procedure may be adapted to routine instrumentation available in hospitals and research laboratories.
|
|
| 3. |
- Ebai, Tonge
(författare)
-
Development of Enhanced Molecular Diagnostic Tools for Protein Detection and Analysis
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Improved diagnosis, prognosis and disease follow-up is a fundamental procedure and a constant challenge in medicine. Among the different molecular biomarkers, proteins are the essential regulatory component in blood; hence, by developing enhanced specific and sensitive molecular tools will gives great insight into the different processes in disease treatment. In this thesis, we build on the proximity ligation assay to develop and apply new adaptable methods to facilitate protein detection.In paper I, I present a variant of the proximity ligation assay (we call PLARCA) using micro titer plate for detection and quantification of protein using optical density as readout in the fluorometer. PLARCA detected femtomolar levels of these proteins in patient samples, which was considerably below the detection threshold for ELISA.In paper II, we developed and adapted a new method into the in situ PLA methods for detection and identification of extracellular vesicles (EVs) using flow cytometry as readout (a method we call ExoPLA). We identified five target proteins on the surface of the Evs and using three colors, we identified the EV using flow cytometer.In paper III, we aim to improve the efficiency of in situ PLA by creating and developing new designs and versions of the assay we called Unfold probes Through comparison of detection of protein using in situ PLA versus Unfold probes, we observed considerable decrease in non-specific signals, and also a lower detection threshold.In paper IV, we describe the development of a solid phase proximity extension (sp-PEA) assay for protein detection and quantification. We compared detection of IL-8, TNF-alpha, IL-10 and IL-6 using spPEA and PEA; spPEA demonstrations over 2 orders of magnitudes in the lower detection concentrations by decreased in background noise.
|
|
| 4. |
- Ebai, Tonge, et al.
(författare)
-
Parallel protein detection by solid-phase proximity ligation assay with real-time PCR or sequencing
- 2015
-
Ingår i: Current Protocol in Molecular Biology. - : Wiley. - 1934-3647 .- 1934-3639. ; 109:20
-
Tidskriftsartikel (refereegranskat)abstract
- Proximity ligation assays are a group of protein detection techniques in which reagents with affinity for target proteins, typically antibodies, are coupled to short strands of DNA. DNA-modified affinity reagents are combined in assays constructed such that the coordinated binding of individual target molecules or complexes of interacting proteins by two or more of the reagents, followed by DNA ligation and/or polymerization reactions, gives rise to amplifiable DNA reporter strands. Proximity ligation assays have been shown to exhibit excellent sensitivity in single and multiplexed protein assays for individual or interacting proteins, both in solution and in situ. This unit describes procedures for developing solid-phase proximity ligation assays for soluble proteins using either real-time PCR or DNA sequencing as the readout. In addition, critical steps for assay optimization are discussed.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Klaesson, Axel, et al.
(författare)
-
Improved efficiency of in situ protein analysis by proximity ligation using UnFold probes
- 2018
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- We have redesigned probes for in situ proximity ligation assay (PLA), resulting in more efficient localized detection of target proteins. In situ PLA depends on recognition of target proteins by pairs of antibody-oligonucleotide conjugates (PLA probes), which jointly give rise to DNA circles that template localized rolling circle amplification reactions. The requirement for dual recognition of the target proteins improves selectivity by ignoring any cross-reactivity not shared by the antibodies, and it allows detection of protein-protein interactions and post-translational modifications. We herein describe an improved design of the PLA probes -UnFold probes - where all elements required for formation of circular DNA strands are incorporated in the probes. Premature interactions between the UnFold probes are prevented by including an enzymatic "unfolding" step in the detection reactions. This allows DNA circles to form by pairs of reagents only after excess reagents have been removed. We demonstrate the performance of UnFold probes for detection of protein-protein interactions and post-translational modifications in fixed cells and tissues, revealing considerably more efficient signal generation. We also apply the UnFold probes to detect IL-6 in solution phase after capture on solid supports, demonstrating increased sensitivity over both normal sandwich enzyme-linked immunosorbent assays and conventional PLA assays.
|
|
| 9. |
- Löf, Liza, et al.
(författare)
-
Detecting individual extracellular vesicles using a multicolor in situ proximity ligation assay with flow cytometric readout
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Flow cytometry is a powerful method for quantitative and qualitative analysis of individual cells. However, flow cytometric analysis of extracellular vesicles (EVs), and the proteins present on their surfaces has been hampered by the small size of the EVs - in particular for the smallest EVs, which can be as little as 40 nm in diameter, the limited number of antigens present, and their low refractive index. We addressed these limitations for detection and characterization of EV by flow cytometry through the use of multiplex and multicolor in situ proximity ligation assays (in situ PLA), allowing each detected EV to be easily recorded over background noise using a conventional flow cytometer. By targeting sets of proteins on the surface that are specific for distinct classes of EVs, the method allows for selective recognition of populations of EVs in samples containing more than one type of EVs. The method presented herein opens up for analyses of EVs using flow cytometry for their characterization and quantification.
|
|
| 10. |
- Löf, Liza, et al.
(författare)
-
Detection of Extracellular Vesicles Using Proximity Ligation Assay with Flow Cytometry Readout – ExoPLA : In Print
- 2017
-
Ingår i: Current Protocol in Cytometry. - : John Wiley & Sons. - 1934-9297 .- 1934-9300. ; 81:1
-
Forskningsöversikt (refereegranskat)abstract
- Extracellular vesicles (EVs) are continuously released by most cells, and they carry surface markers of their cells of origin. Found in all body fluids, EVs function as conveyers of cellular information, and evidence implicates them as markers of disease. These characteristics make EVs attractive diagnostic targets. However, detection and characterization of EVs is challenging due to their small size. We've established a method, called ExoPLA, that allows individual EVs to be detected and characterized at high specificity and sensitivity. Based on the in situ proximity ligation assay (in situ PLA), proximal oligonucleotide-conjugated antibodies bound to their targets on the surfaces of the EVs allow formation of circular products that can be fluorescently labeled by rolling circle amplification. The intense fluorescent signals produced in this assay allow detection and enumeration of individual EVs by flow cytometry. We describe the procedures for ExoPLA, along with expected results and troubleshooting.
|
|
