| 1. |
- Cane, Gaëlle, et al.
(författare)
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Protein Diagnostics by Proximity Ligation: Combining Multiple Recognition and DNA Amplification for Improved Protein Analyses
- 2017. - 3
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Ingår i: Molecular Diagnostics (Third Edition). - 2016 : Academia Press. - 9780128029718 ; , s. 219-231
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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.
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| 2. |
- Clausson, Carl-Magnus, 1985-, et al.
(författare)
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Compaction of rolling circle amplification products increases signal integrity and signal–to–noise ratio
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5, s. 12317:1-10
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Tidskriftsartikel (refereegranskat)abstract
- Rolling circle amplification (RCA) for generation of distinct fluorescent signals in situ relies upon the self-collapsing properties of single-stranded DNA in commonly used RCA-based methods. By introducing a cross-hybridizing DNA oligonucleotide during rolling circle amplification, we demonstrate that the fluorophore-labeled RCA products (RCPs) become smaller. The reduced size of RCPs increases the local concentration of fluorophores and as a result, the signal intensity increases together with the signal-to-noise ratio. Furthermore, we have found that RCPs sometimes tend to disintegrate and may be recorded as several RCPs, a trait that is prevented with our cross-hybridizing DNA oligonucleotide. These effects generated by compaction of RCPs improve accuracy of visual as well as automated in situ analysis for RCA based methods, such as proximity ligation assays (PLA) and padlock probes.
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| 3. |
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| 4. |
- Jeibmann, Astrid, et al.
(författare)
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Identification of genes involved in the biology of atypical teratoid/rhabdoid tumours using Drosophila melanogaster
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 4005-
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Tidskriftsartikel (refereegranskat)abstract
- Atypical teratoid/rhabdoid tumours (AT/RT) are malignant brain tumours. Unlike most other human brain tumours, AT/RT are characterized by inactivation of one single gene, SMARCB1. SMARCB1 is a member of the evolutionarily conserved SWI/SNF chromatin remodelling complex, which has an important role in the control of cell differentiation and proliferation. Little is known, however, about the pathways involved in the oncogenic effects of SMARCB1 inactivation, which might also represent targets for treatment. Here we report a comprehensive genetic screen in the fruit fly that revealed several genes not yet associated with loss of snr1, the Drosophila homologue of SMARCB1. We confirm the functional role of identified genes (including merlin, kibra and expanded, known to regulate hippo signalling pathway activity) in human rhabdoid tumour cell lines and AT/RT tumour samples. These results demonstrate that fly models can be employed for the identification of clinically relevant pathways in human cancer.
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| 5. |
- Klaesson, Axel, et al.
(författare)
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Improved efficiency of in situ protein analysis by proximity ligation using UnFold probes
- 2018
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
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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.
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| 6. |
- Koechling, Michaela, et al.
(författare)
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hTERT promoter methylation in pituitary adenomas
- 2016
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Ingår i: BRAIN TUMOR PATHOLOGY. - : Springer Science and Business Media LLC. - 1433-7398 .- 1861-387X. ; 33:1, s. 27-34
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Tidskriftsartikel (refereegranskat)abstract
- Telomerase reverse transcriptase (TERT) expression is a hallmark in tumorigenesis and upregulated due to mutations and methylation of the human (h)TERT promoter. As mutations are rare but methylation is common in pituitary adenomas (PA), we determined promoter methylation and its clinical impact in 85 primary and 15 recurrent PA by methylation-specific PCR. 40 females (47 %) and 45 males (53 %) with a median age of 53 years harboring micro-, macro-, and giant adenomas in 12, 82, and 6 % were included (prolactinomas, corticotroph, somatotroph, gonadotroph, thyreotroph, plurihormonal, and null cell adenomas in 11, 18, 10, 29, 1, 10, and 21 %, respectively). In primary diagnosed tumors, methylation rate was 27 % and higher in males than in females (40 vs. 13 %, p = 0.001) after uni- and multivariate analyses. Methylation differed among PA subtypes (0-42 %, p = n.s.) and was not significantly correlated with tumor size, cavernous sinus invasion, or serum hormone levels. Ki67 labeling index and recurrence (N = 16, 19 %) were independent of methylation. In recurrent tumors, methylation was similar to primary PA (N = 5/15, 33 %) and remained unchanged along follow-up. Thus, while being commonly observed in PA, hTERT promoter methylation is stable along follow-up and independent of most clinical variables, PA subtype, proliferation, and without prognostic value.
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| 7. |
- Koos, Björn, et al.
(författare)
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Analysis of protein interactions in situ by proximity ligation assays
- 2014
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Ingår i: High-Dimensional Single Cell Analysis. - Berlin, Heidelberg : Springer. ; , s. 111-26
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Bokkapitel (refereegranskat)abstract
- The fate of the cell is governed by interactions among proteins, nucleic acids, and other biomolecules. It is vital to look at these interactions in a cellular environment if we want to increase our understanding of cellular processes. Herein we will describe how the in situ proximity ligation assay (in situ PLA) can be used to visualize protein interactions in fixed cells and tissues. In situ PLA is a novel technique that uses DNA, together with DNA modifying processes such as ligation, cleavage, and polymerization, as tools to create surrogate markers for protein interactions of interest. Different in situ PLA designs make it possible not only to detect protein-protein interactions but also post-translational modifications and interactions of proteins with nucleic acids. Flexibility in DNA probe design and the multitude of different DNA modifying enzymes provide the basis for modifications of the method to make it suitable to use in many applications. Furthermore, examples of how in situ PLA can be combined with other methods for a comprehensive view of the cellular activity status are discussed.
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| 8. |
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| 9. |
- Koos, Björn, et al.
(författare)
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Next-Generation Pathology : Surveillance of Tumor Microecology
- 2015
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 427:11, s. 2013-2022
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Forskningsöversikt (refereegranskat)abstract
- A tumor is a heterogeneous population of cells that provides an environment in which every cell resides in a microenvironmental niche. Microscopic evaluation of tissue sections, based on histology and immunohistochemistry, has been a cornerstone in pathology for decades. However, the dawn of novel technologies to investigate genetic aberrations is currently adopted in routine molecular pathology. We herein describe our view on how recent developments in molecular technologies, focusing on proximity ligation assay and padlock probes, can be applied to merge the two branches of pathology, allowing molecular profiling under histologic observation. We also discuss how the use of image analysis will be pivotal to obtain information at a cellular level and to interpret holistic images of tissue sections. By understanding the cellular communications in the microecology of tumors, we will be at a better position to predict disease progression and response to therapy.
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| 10. |
- Koos, Björn, et al.
(författare)
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Platelet-derived growth factor receptor expression and activation in choroid plexus tumors
- 2009
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Ingår i: American Journal of Pathology. - : Elsevier BV. - 0002-9440 .- 1525-2191. ; 175:4, s. 1631-1637
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Tidskriftsartikel (refereegranskat)abstract
- Choroid plexus tumors are intraventricular neoplasms predominantly affecting young children. In contrast to choroid plexus papillomas, choroid plexus carcinomas progress frequently, necessitating the development of adjuvant treatment concepts. Platelet derived growth factor (PDGF) signaling has been shown to support growth in a variety of tumors. The finding of PDGF receptor expression in choroid plexus tumors prompted us to elucidate PDGF receptor activation state using a novel method, in situ proximity ligation assay, on formalin-fixed, paraffin-embedded, archival samples of 19 choroid plexus tumors. As assessed by in situ proximity ligation assay, the proportion of phosphorylated PDGF receptor alpha was low in choroid plexus papillomas and choroid plexus carcinomas, whereas phosphorylated PDGF receptor beta was found to be significantly higher in choroid plexus carcinomas. In the immortalized choroid plexus epithelial cell line Z310 expressing PDGF receptor beta, PDGF-BB exhibited a time- and dose-dependent proliferative response, which was significantly attenuated by imatinib (gleevec). In conclusion, our findings suggest that PDGF receptor beta is functionally involved in the biology of choroid plexus tumors and may represent a molecular target for therapy. In addition, this study demonstrates the feasibility and usefulness of in situ proximity ligation assay for monitoring receptor tyrosine kinase activation in formalin-fixed, paraffin-embedded, archival tissues.
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