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Isolation and mass spectrometry analysis of urinary extraexosomal proteins.

ABSTRACT: The aim of the present study was to develop a LC-MS/MS-based proteomic analysis method of urinary exosomal proteins that has the potential to discover disease biomarkers. In short, urinary exosomes from healthy subjects were isolated by immunocapture on magnetic beads, detected by immunofluorescence and TEM, trypsin digested directly on the beads for an accelerated time with no addition of detergents before performing an LC-MS analysis of the trypsinate. To our knowledge, this is the first proteomic analysis of proteins displayed on the outer surface of exosomes. The outer exosome proteome may contain proteins that are of higher biomarker value compared to soluble cargo protein as the proteins projecting into the extracellular milieu might be more directly involved in physiological functions of exosomes. The proteomic analysis identified 49 proteins that were considered significant; the majority is involved in carbohydrate and lipid metabolism or in immune responses. Thirty of the proteins are linked to diseases. The developed proteomic method exploiting urinary exosomes might be of great value in search for diagnostic or prognostic biomarkers of especially metabolic and immune-related diseases.

SUBMITTER: Hildonen S

PROVIDER: S-EPMC5090863 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Isolation and mass spectrometry analysis of urinary extraexosomal proteins.

Hildonen Siri S Skarpen Ellen E Halvorsen Trine Grønhaug TG Reubsaet Léon L

Scientific reports 20161102

The aim of the present study was to develop a LC-MS/MS-based proteomic analysis method of urinary exosomal proteins that has the potential to discover disease biomarkers. In short, urinary exosomes from healthy subjects were isolated by immunocapture on magnetic beads, detected by immunofluorescence and TEM, trypsin digested directly on the beads for an accelerated time with no addition of detergents before performing an LC-MS analysis of the trypsinate. To our knowledge, this is the first prote ...[more]

PMID: 27805059

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Project description:Poxviruses replicate within the cytoplasm and encode proteins for DNA and mRNA synthesis. To investigate poxvirus replication and transcription from a new perspective, we incorporated 5-ethynyl-2'-deoxyuridine (EdU) into nascent DNA in cells infected with vaccinia virus (VACV). The EdU-labeled DNA was conjugated to fluor- or biotin-azide and visualized by confocal, superresolution, and transmission electron microscopy. Nuclear labeling decreased dramatically after infection, accompanied by intense labeling of cytoplasmic foci. The nascent DNA colocalized with the VACV single-stranded DNA binding protein I3 in multiple puncta throughout the interior of factories, which were surrounded by endoplasmic reticulum. Complexes containing EdU-biotin-labeled DNA cross-linked to proteins were captured on streptavidin beads. After elution and proteolysis, the peptides were analyzed by mass spectrometry to identify proteins associated with nascent DNA. The known viral replication proteins, a telomere binding protein, and a protein kinase were associated with nascent DNA, as were the DNA-dependent RNA polymerase and intermediate- and late-stage transcription initiation and elongation factors, plus the capping and methylating enzymes. These results suggested that the replicating pool of DNA is transcribed and that few if any additional viral proteins directly engaged in replication and transcription remain to be discovered. Among the host proteins identified by mass spectrometry, topoisomerases II? and II? and PCNA were noteworthy. The association of the topoisomerases with nascent DNA was dependent on expression of the viral DNA ligase, in accord with previous proteomic studies. Further investigations are needed to determine possible roles for PCNA and other host proteins detected.IMPORTANCE Poxviruses, unlike many well-characterized animal DNA viruses, replicate entirely within the cytoplasm of animal cells, raising questions regarding the relative roles of viral and host proteins. We adapted newly developed procedures for click chemistry and iPOND (Isolation of proteins on nascent DNA) to investigate vaccinia virus (VACV), the prototype poxvirus. Nuclear DNA synthesis ceased almost immediately following VACV infection, followed swiftly by the synthesis of viral DNA within discrete cytoplasmic foci. All viral proteins known from genetic and proteomic studies to be required for poxvirus DNA replication were identified in the complexes containing nascent DNA. The additional detection of the viral DNA-dependent RNA polymerase and intermediate and late transcription factors provided evidence for a temporal coupling of replication and transcription. Further studies are needed to assess the potential roles of host proteins, including topoisomerases II? and II? and PCNA, which were found associated with nascent DNA.

Dataset Information

Isolation and mass spectrometry analysis of urinary extraexosomal proteins.

Publications

Isolation and mass spectrometry analysis of urinary extraexosomal proteins.

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