The Urine Proteome Profile Is Different in Neuromyelitis Optica Compared to Multiple Sclerosis: A Clinical Proteome Study.

OBJECTIVES: Inflammatory demyelinating diseases of the CNS comprise a broad spectrum of diseases like neuromyelitis optica (NMO), NMO spectrum disorders (NMO-SD) and multiple sclerosis (MS). Despite clear classification criteria, differentiation can be difficult. We hypothesized that the urine proteome may differentiate NMO from MS. METHODS: The proteins in urine samples from anti-aquaporin 4 (AQP4) seropositive NMO/NMO-SD patients (n = 32), patients with MS (n = 46) and healthy subjects (HS, n = 31) were examined by quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) after trypsin digestion and iTRAQ labelling. Immunoglobulins (Ig) in the urine were validated by nephelometry in an independent cohort (n = 9-10 pr. groups). RESULTS: The analysis identified a total of 1112 different proteins of which 333 were shared by all 109 subjects. Cluster analysis revealed differences in the urine proteome of NMO/NMO-SD compared to HS and MS. Principal component analysis also suggested that the NMO/NMO-SD proteome profile was useful for classification. Multivariate regression analysis revealed a 3-protein profile for the NMO/NMO-SD versus HS discrimination, a 6-protein profile for NMO/NMO-SD versus MS discrimination and an 11-protein profile for MS versus HS discrimination. All protein panels yielded highly significant ROC curves (AUC in all cases >0.85, p≤0.0002). Nephelometry confirmed the presence of increased Ig-light chains in the urine of patients with NMO/NMO-SD. CONCLUSION: The urine proteome profile of patients with NMO/NMO-SD is different from MS and HS. This may reflect differences in the pathogenesis of NMO/NMO-SD versus MS and suggests that urine may be a potential source of biomarkers differentiating NMO/NMO-SD from MS.

Quantitative Proteome Analysis Reveals Increased Content of Basement Membrane Proteins in Arteries From Patients With Type 2 Diabetes Mellitus and Lower Levels Among Metformin Users.

BACKGROUND: The increased risk of cardiovascular diseases in type 2 diabetes mellitus has been extensively documented, but the origins of the association remain largely unknown. We sought to determine changes in protein expressions in arterial tissue from patients with type 2 diabetes mellitus and moreover hypothesized that metformin intake influences the protein composition. METHODS AND RESULTS: We analyzed nonatherosclerotic repair arteries gathered at coronary bypass operations from 30 patients with type 2 diabetes mellitus and from 30 age- and sex-matched nondiabetic individuals. Quantitative proteome analysis was performed by isobaric tag for relative and absolute quantitation-labeling and liquid chromatography-mass spectrometry, tandem mass spectrometry analysis on individual arterial samples. The amounts of the basement membrane components, α1-type IV collagen and α2-type IV collagen, γ1-laminin and ß2-laminin, were significantly increased in patients with diabetes mellitus. Moreover, the expressions of basement membrane components and other vascular proteins were significantly lower among metformin users when compared with nonusers. Patients treated with or without metformin had similar levels of hemoglobin A1c, cholesterol, and blood pressure. In addition, quantitative histomorphometry showed increased area fractions of collagen-stainable material in tunica intima and media among patients with diabetes mellitus. CONCLUSIONS: The distinct accumulation of arterial basement membrane proteins in type 2 diabetes mellitus discloses a similarity between the diabetic macroangiopathy and microangiopathy and suggests a molecular explanation behind the alterations in vascular remodeling, biomechanical properties, and aneurysm formation described in diabetes mellitus. The lower amounts of basement membrane components in metformin-treated individuals are compatible with the hypothesis of direct beneficial drug effects on the matrix composition in the vasculature.

Plasma proteome profiling of atherosclerotic disease manifestations reveals elevated levels of the cytoskeletal protein vinculin.

Atherosclerosis is a chronic disease of the arterial wall that is recognized as the leading cause of mortality and morbidity worldwide. There is an eminent need for better biomarkers that can aid in patient care before the onset of the first cardiovascular event. We used quantitative proteomics to identify proteins with altered concentrations in plasma samples from four groups: 1) Individuals without cardiovascular symptoms and without the presence of coronary calcium, 2) individuals without cardiovascular symptoms, but with high amounts of coronary calcium, 3) individuals operated because of atherosclerotic diseases, and 4) individuals with an acute coronary syndrome. Immunoassays and SRM-MS were used for single patient verification of candidate proteins. Proteins involved in cardiovascular diseases i.e. serum amyloid protein A (SAA), C-reactive protein (CRP), and apolipoprotein(a) [apo(a)] displayed an increased expression profile from groups 1 to 4. The top-most elevated protein, vinculin (Vcl) displayed a similar profile. Immunoassays confirmed the expression profile of apo(a) and CRP. A 5-plex SRM-MS assay for Vcl, SAA, CRP, apo(a) and thrombospondin-4 (TSP-4) was developed for multiplex verification in all 120 individual samples. The 5-plex SRM assay confirmed a statistically significant up-regulation of Vcl in the acute coronary syndrome group. BIOLOGICAL SIGNIFICANCE: The aim of this study was to identify new candidate plasma markers of atherosclerosis manifestations, which may develop into screening-, diagnostic- or monitoring biomarkers for risk stratification of cardiovascular disease (CVD). At present no studies have elucidated the proteomic changes that occur along with several stages and manifestations of atherosclerotic disease. By using 4-plex iTRAQ, we identified and quantified proteins with altered concentrations in pooled plasma samples from 120 individuals from four middle-aged groups. Proteins involved in cardiovascular diseases i.e. serum amyloid protein A (SAA), C-reactive protein (CRP), and apolipoprotein(a) [apo(a)] displayed an increased expression profile along with increased manifestations of CVD. A novel candidate marker was identified as vinculin (Vcl), a multi-protein linker that connects cell-matrix adhesions and cell-cell adhesions to the actin-based cytoskeleton. Immuno- and SRM-assays were used for single patient validation of candidate proteins. While further studies needs to address the role of Vcl in the development of atherosclerosis, the combined data provided in this report offers a catalog of the proteomic changes that occurs in plasma over several stages and manifestations of atherosclerotic disease.

Temporal profiling and pulsed SILAC labeling identify novel secreted proteins during ex vivo osteoblast differentiation of human stromal stem cells.

It is well established that bone forming cells (osteoblasts) secrete proteins with autocrine, paracrine, and endocrine function. However, the identity and functional role for the majority of these secreted and differentially expressed proteins during the osteoblast (OB) differentiation process, is not fully established. To address these questions, we quantified the temporal dynamics of the human stromal (mesenchymal, skeletal) stem cell (hMSC) secretome during ex vivo OB differentiation using stable isotope labeling by amino acids in cell culture (SILAC). In addition, we employed pulsed SILAC labeling to distinguish genuine secreted proteins from intracellular contaminants. We identified 466 potentially secreted proteins that were quantified at 5 time-points during 14-days ex vivo OB differentiation including 41 proteins known to be involved in OB functions. Among these, 315 proteins exhibited more than 2-fold up or down-regulation. The pulsed SILAC method revealed a strong correlation between the fraction of isotope labeling and the subset of proteins known to be secreted and involved in OB differentiation. We verified SILAC data using qRT-PCR analysis of 9 identified potential novel regulators of OB differentiation. Furthermore, we studied the biological effects of one of these proteins, the hormone stanniocalcin 2 (STC2) and demonstrated its autocrine effects in enhancing osteoblastic differentiation of hMSC. In conclusion, combining complete and pulsed SILAC labeling facilitated the identification of novel factors produced by hMSC with potential role in OB differentiation. Our study demonstrates that the secretome of osteoblastic cells is more complex than previously reported and supports the emerging evidence that osteoblastic cells secrete proteins with endocrine functions and regulate cellular processes beyond bone formation.

Decellularized matrix from tumorigenic human mesenchymal stem cells promotes neovascularization with galectin-1 dependent endothelial interaction.

BACKGROUND: Acquisition of a blood supply is fundamental for extensive tumor growth. We recently described vascular heterogeneity in tumours derived from cell clones of a human mesenchymal stem cell (hMSC) strain (hMSC-TERT20) immortalized by retroviral vector mediated human telomerase (hTERT) gene expression. Histological analysis showed that cells of the most vascularized tumorigenic clone, -BD11 had a pericyte-like alpha smooth muscle actin (ASMA+) and CD146+ positive phenotype. Upon serum withdrawal in culture, -BD11 cells formed cord-like structures mimicking capillary morphogenesis. In contrast, cells of the poorly tumorigenic clone, -BC8 did not stain for ASMA, tumours were less vascularized and serum withdrawal in culture led to cell death. By exploring the heterogeneity in hMSC-TERT20 clones we aimed to understand molecular mechanisms by which mesenchymal stem cells may promote neovascularization. METHODOLOGY/PRINCIPAL FINDINGS: Quantitative qRT-PCR analysis revealed similar mRNA levels for genes encoding the angiogenic cytokines VEGF and Angiopoietin-1 in both clones. However, clone-BD11 produced a denser extracellular matrix that supported stable ex vivo capillary morphogenesis of human endothelial cells and promoted in vivo neovascularization. Proteomic characterization of the -BD11 decellularized matrix identified 50 extracellular angiogenic proteins, including galectin-1. siRNA knock down of galectin-1 expression abrogated the ex vivo interaction between decellularized -BD11 matrix and endothelial cells. More stable shRNA knock down of galectin-1 expression did not prevent -BD11 tumorigenesis, but greatly reduced endothelial migration into -BD11 cell xenografts. CONCLUSIONS: Decellularized hMSC matrix had significant angiogenic potential with at least 50 angiogenic cell surface and extracellular proteins, implicated in attracting endothelial cells, their adhesion and activation to form tubular structures. hMSC -BD11 surface galectin-1 expression was required to bring about matrix-endothelial interactions and for xenografted hMSC -BD11 cells to optimally recruit host vasculature.

Phosphorylation of the regulatory beta-subunit of protein kinase CK2 by checkpoint kinase Chk1: identification of the in vitro CK2beta phosphorylation site.

The regulatory beta-subunit of protein kinase CK2 mediates the formation of the CK2 tetrameric form and it has functions independent of CK2 catalytic subunit through interaction with several intracellular proteins. Recently, we have shown that CK2beta associates with the human checkpoint kinase Chk1. In this study, we show that Chk1 specifically phosphorylates in vitro the regulatory beta-subunit of CK2. Chymotryptic peptides and mutational analyses have revealed that CK2beta is phosphorylated at Thr213. Formation of a stable complex between CK2beta and Chk1 is not affected by the modification of Thr213 but it does require the presence of an active Chk1 kinase.