| 1. |
- Conze, Tim, et al.
(författare)
-
Analysis of Genes, Transcripts, and Proteins via DNA Ligation
- 2009. - 2
-
Ingår i: Annual review of analytical chemistry. - : Annual Reviews. - 1936-1327 .- 1936-1335. ; 2, s. 215-239
-
Forskningsöversikt (refereegranskat)abstract
- Analytical reactions in which short DNA strands are used in combination with DNA ligases have proven useful for measuring, decoding, and locating most classes of macromolecules. Given the need to accumulate large amounts of precise molecular information from biological systems in research and in diagnostics, ligation reactions will continue to offer valuable strategies for advanced analytical reactions. Here, we provide a basis for further development of methods by reviewing the history of analytical ligation reactions, discussing the properties of ligation reactions that render them suitable for engineering novel assays, describing a wide range of successful ligase-based assays, and briefly considering future directions.
|
|
| 2. |
- Conze, Tim, 1977-
(författare)
-
Ligation-mediated Molecular Analysis of Influenza Subtypes, Splicing and Protein Glycosylation
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Binder-based assays are employed throughout the life sciences. Powerful signal amplification techniques have enabled detection of very rare molecule species diluted in simple buffers. Unspecific binding of primary binders leads to increased background in more complex samples. By requiring two recognition events, ligation-based molecular analyses provide highly specific detection of biomolecules in complex samples. We developed a highly multiplexed padlock-ligation assay targeting signature sequences in the hemagglutinin and neuraminidase genes. From a panel of 77 avian influenza isolates of all major serotypes, 97% were genotyped correctly in accordance with previous classifications by classical diagnostic methods (Paper I). Alternative splicing is an important mechanism expanding the proteome. Current analysis techniques fail to provide sequences of complete transcripts beyond the read length of sequencing instruments. We devised and implemented a strategy to compress the sequence information contained in the splicing pattern of a transcript into the presence or absence of sequence-blocks. We demonstrate that this assay yields information about the splicing patterns in thousands of transcripts from cellular cDNA (Paper II). Expression changes of mucin proteins and glycosylation structures are frequently observed from the early stages of cancer development. Expression of mucin 2 and sialyl-Tn are common features of intestinal metaplasia and gastric cancer, and are known to co-locate. Here we have developed an in situ proximity ligation assay (PLA) directed against mucin 2 and sialyl-Tn. Our study on intestinal metaplasia and gastric cancer tissue sections identified mucin 2 as a major carrier of sialyl-Tn in these conditions, and demonstrated how conveniently glycosylation of proteins can be studied by in situ PLA (Paper III). This thesis shows how the dual recognition requirement of ligation-based assays can be employed to detect target molecules with high specificity, to analyze several sequence features of nucleic acids or to study the proximity of two antigens in situ.
|
|
| 3. |
- Conze, Tim, 1977-, et al.
(författare)
-
MUC2 mucin is a major carrier of the cancer-associated sialyl-Tn antigen in intestinal metaplasia and gastric carcinomas
- 2010
-
Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 20:2, s. 199-206
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in mucin protein expression and in glycosylation are common features in pre-neoplastic lesions and cancer and are therefore used as cancer-associated markers. De novo expression of intestinal mucin MUC2 and cancer-associated sialyl-Tn antigen are frequently observed in intestinal metaplasia (IM) and gastric cancer. However, despite that these antigens often co-localize, MUC2 has not been demonstrated to be a carrier of sialyl-Tn. By using the in situ proximity ligation assay (in situ PLA), we herein could show that MUC2 is a major carrier of the sialyl-Tn antigen in all IM cases and in most gastric carcinoma cases. The requirement by in situ PLA for the presence of both antigens in close proximity increases the selectivity compared to measurement of co-localization, as determined by immunohistochemistry. Identification of the mucin which is the carrier of a carbohydrate structure offers unique advantages for future development of more accurate diagnostic and prognostic markers.
|
|
| 4. |
- Conze, Tim, 1977-, et al.
(författare)
-
Single molecule analysis of combinatorial splicing
- 2010
-
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 38:16, s. e163-
-
Tidskriftsartikel (refereegranskat)abstract
- Alternative splicing forms diverse mRNA isoform populations from a single ancestral pre-mRNA and thereby enhances complexity of transcript structure and of gene function. We describe a method called spliceotyping, which translates combinatorial mRNA splicing patterns into a library of binary strings of nucleic acid tags, encoding the exon composition of transcripts. The transcript abundance is registered by counts of individual molecules and individual exon inclusion patterns are represented as strings of binary data. The technique is illustrated by analyzing the splicing patterns of the adenovirus early 1A gene and the beta actin reference transcript. The method permits different genes to be analyzed in parallel and will be valuable for elucidating the complex effects of combinatorial splicing.
|
|
| 5. |
- Gavrilovic, Milan, et al.
(författare)
-
Automated Classification of Multicolored Rolling Circle Products in Dual-Channel Wide-Field Fluorescence Microscopy
- 2011
-
Ingår i: Cytometry Part A. - : Wiley. - 1552-4922. ; 79A:7, s. 518-527
-
Tidskriftsartikel (refereegranskat)abstract
- Specific single-molecule detection opens new possibilities in genomics and proteomics, and automated image analysis is needed for accurate quantification. This work presents image analysis methods for the detection and classification of single molecules and single-molecule interactions detected using padlock probes or proximity ligation. We use simple, widespread, and cost-efficient wide-field microscopy and increase detection multiplexity by labeling detection events with combinations of fluorescence dyes. The mathematical model presented herein can classify the resulting point-like signals in dual-channel images by spectral angles without discriminating between low and high intensity. We evaluate the methods on experiments with known signal classes and compare to classical classification algorithms based on intensity thresholding. We also demonstrate how the methods can be used as tools to evaluate biochemical protocols by measuring detection probe quality and accuracy. Finally, the method is used to evaluate single-molecule detection events in situ.
|
|
| 6. |
- Gyarmati, Péter, et al.
(författare)
-
Simultaneous genotyping of all hemagglutinin and neuraminidase subtypes of avian influenza viruses by use of padlock probes
- 2008
-
Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 46:5, s. 1747-1751
-
Tidskriftsartikel (refereegranskat)abstract
- A subtyping assay for both the hemagglutinin (HA) and neuraminidase (NA) surface antigens of the avian influenza virus (AIV) has been developed. The method uses padlock probe chemistry combined with a microarray output for detection. The outstanding feature of this assay is its capability to designate both the HA and the NA of an AIV sample from a single reaction mixture. A panel of 77 influenza virus strains was tested representing the entire assortment of the two antigens. One hundred percent (77/77) of the samples tested were identified as AIV, and 97% (75/77) were subtyped correctly in accordance with previous examinations performed by classical diagnostic methods. Testing of heterologous pathogens verified the specificity of the assay. This assay is a convenient and practical tool for the study of AIVs, providing important HA and NA data more rapidly than conventional methods.
|
|
| 7. |
- Pinto, Rita, et al.
(författare)
-
Identification of new cancer biomarkers based on aberrant mucin glycoforms by in situ proximity ligation
- 2012
-
Ingår i: Journal of Cellular and Molecular Medicine. - : Wiley. - 1582-1838 .- 1582-4934. ; 16:7, s. 1474-1484
-
Tidskriftsartikel (refereegranskat)abstract
- Mucin glycoproteins are major secreted or membrane-bound molecules that, in cancer, show modifications in both the mucin proteins expression and in the O-glycosylation profile, generating some of the most relevant tumour markers in clinical use for decades. Thus far, the identification of these biomarkers has been based on the detection of either the protein or the O-glycan modifications. We therefore aimed to identify the combined mucin and O-glycan features, i.e. specific glycoforms, in an attempt to increase specificity of these cancer biomarkers. Using in situ proximity ligation assays (PLA) based on existing monoclonal antibodies directed to MUC1, MUC2, MUC5AC and MUC6 mucins and to cancer-associated carbohydrate antigens Tn, Sialyl-Tn (STn), T, Sialyl-Lea (SLea) and Sialyl-Lex (SLex) we screened a series of 28 mucinous adenocarcinomas from different locations (stomach, ampulla of Vater, colon, lung, breast and ovary) to detect specific mucin glycoforms. We detected Tn/STn/SLea/SLex-MUC1 and STn/SLea/SLex-MUC2 glycoforms in ≥50% of the cases, with a variable distribution among organs. Some new glycoforms – T/SLea-MUC2, STn/T/SLea/SLex-MUC5AC and STn/T/SLea/SLex-MUC6 – were identified for the first time in the present study in a variable percentage of cases from different organs. In conclusion, application of the PLA technique allowed sensitive detection of specific aberrant mucin glycoforms in cancer, increasing specificity to the use of antibodies either to the mucin protein backbone or the O-glycan haptens alone.
|
|
| 8. |
- Tavoosidana, Gholamreza, et al.
(författare)
-
Multiple recognition assay reveals prostasomes as promising plasma biomarkers for prostate cancer
- 2011
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:21, s. 8809-8814
-
Tidskriftsartikel (refereegranskat)abstract
- Prostasomes are microvesicles (mean diameter, 150 nm) that are produced and secreted by normal and malignant prostate acinar cells. It has been hypothesized that invasive growth of malignant prostate cells may cause these microvesicles, normally released into seminal fluid, to appear in interstitial space and therewith into peripheral circulation. The suitability of prostasomes as blood biomarkers in patients with prostate cancer was tested by using an expanded variant of the proximity ligation assay (PLA). We developed an extremely sensitive and specific assay (4PLA) for detection of complex target structures such as microvesicles in which the target is first captured via an immobilized antibody and subsequently detected by using four other antibodies with attached DNA strands. The requirement for coincident binding by five antibodies to generate an amplifiable reporter results in both increased specificity and sensitivity. The assay successfully detected significantly elevated levels of prostasomes in blood samples from patients with prostate cancer before radical prostatectomy, compared with controls and men with benign biopsy results. The medians for prostasome levels in blood plasma of patients with prostate cancer were 2.5 to sevenfold higher compared with control samples in two independent studies, and the assay also distinguished patients with high and medium prostatectomy Gleason scores (8/9 and 7, respectively) from those with low score (<= 6), thus reflecting disease aggressiveness. This approach that enables detection of prostasomes in peripheral blood may be useful for early diagnosis and assessment of prognosis in organ-confined prostate cancer.
|
|
| 9. |
- Wang, Xiaolu, et al.
(författare)
-
A protein interaction node at the neurotransmitter release site : domains of Aczonin/Piccolo, Bassoon, CAST, and rim converge on the N-terminal domain of Munc13-1
- 2009
-
Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 29:40, s. 12584-12596
-
Tidskriftsartikel (refereegranskat)abstract
- Multidomain scaffolding proteins organize the molecular machinery of neurotransmitter vesicle dynamics during synaptogenesis and synaptic activity. We find that domains of five active zone proteins converge on an interaction node that centers on the N-terminal region of Munc13-1 and includes the zinc-finger domain of Rim1, the C-terminal region of Bassoon, a segment of CAST1/ELKS2, and the third coiled-coil domain (CC3) of either Aczonin/Piccolo or Bassoon. This multidomain complex may constitute a center for the physical and functional integration of the protein machinery at the active zone. An additional connection between Aczonin and Bassoon is mediated by the second coiled-coil domain of Aczonin. Recombinant Aczonin-CC3, expressed in cultured neurons as a green fluorescent protein fusion protein, is targeted to synapses and suppresses vesicle turnover, suggesting involvements in synaptic assembly as well as activity. Our findings show that Aczonin, Bassoon, CAST1, Munc13, and Rim are closely and multiply interconnected, they indicate that Aczonin-CC3 can actively participate in neurotransmitter vesicle dynamics, and they highlight the N-terminal region of Munc13-1 as a hub of protein interactions by adding three new binding partners to its mechanistic potential in the control of synaptic vesicle priming.
|
|
| 10. |
- Weibrecht, Irene, et al.
(författare)
-
Proximity ligation assays : a recent addition to the proteomics toolbox
- 2010
-
Ingår i: Expert Reviews of Proteomics. - 1478-9450. ; 7:3, s. 401-409
-
Forskningsöversikt (refereegranskat)abstract
- An essential skill for every researcher is to learn how to select and apply the most appropriate methods for the questions they are trying to answer. With the extensive variety of methods available, it is increasingly important to scrutinize the advantages and disadvantages of these techniques prior to making a decision on which to use. In this article, we describe an approach to evaluate methods by reducing them into subcomponents. This is exemplified by a brief description of some commonly used proteomics methods. The same approach can also be used in method development by rearranging subcomponents in order to create new methods, as demonstrated with the development of proximity ligation assays (PLAs). PLA is a method as designed in our laboratory for detection of proteins, protein-protein interactions and post-translational modifications. Fundamentally, protein-recognition events are converted into detectable DNA molecules. The technique uses protein DNA conjugates as binders for the targets of interest. Binding of two or more conjugates to the target results in assembly of an assay-specific DNA molecule. Subsequent amplification of the DNA molecule generates a signal that can be detected using PCR, for detection of minute amounts of proteins in serum, or standard fluorescence microscopy for detection of protein protein interactions in tissue sections. Lastly, we apply the approach of recombining subcomponents to develop a few novel hypothetical methods hoping this might stimulate the readers to utilize this approach themselves.
|
|
