Identification of osteoglycin as a component of the vascular matrix. Differential expression by vascular smooth muscle cells during neointima formation and in atherosclerotic plaques

Characterization of vestibular schwannoma tissues using liquid chromatography-tandem mass spectrometry analysis of specific peptide fragments separated by in-sample tryptic protein digestion followed by mathematical analysis

Vestibular schwannoma is the most common benign neoplasm of the cerebellopontine angle. Its first symptoms include hearing loss, tinnitus, and vestibular symptoms, followed by cerebellar and brainstem symptoms, along with palsy of the adjacent cranial nerves. However, the clinical picture has unpredictable dynamics and currently, there are no reliable predictors of tumor behavior. Hence, it is desirable to have a fast routine method for analysis of vestibular schwannoma tissues at the molecular level. The major objective of this study was to verify whether a technique using in-sample specific protein digestion with trypsin would have the potential to provide a proteomic characterization of these pathological tissues. The achieved results showed that the use of this approach with subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of released peptides allowed a fast identification of a considerable number of proteins in two differential parts of vestibular schwannoma tissue as well as in tissues of control healthy samples. Furthermore, mathematical analysis of MS data was able to discriminate between pathological vestibular schwannoma tissues and healthy tissues. Thus, in-sample protein digestion combined with LC-MS/MS separation and identification of released specific peptides followed by mathematical analysis appears to have the potential for routine characterization of vestibular schwannomas at the molecular level. Data are available via ProteomeXchange with identifier PXD045261.

Exploring the role of osteoglycin in type 2 diabetes: implications for insulin resistance and vascular pathophysiology

Osteoglycin, a fundamental proteoglycan within the vascular extracellular matrix, is expressed in vascular smooth muscle cells (VSMCs). Type 2 diabetes (T2D) is associated with cardiovascular disease (CVD) but the role of osteoglycin in the development of CVD is controversial to date. Therefore, our aims are to determine and compare the level of osteoglycin in T2D patients with/without CVD versus control subjects both at serum and vascular tissue and to analyze in vitro role of osteoglycin in VSMCs under calcified conditions. For this, serum osteoglycin levels were determined by enzyme-linked immunosorbent assay (ELISA) in 117 controls and 129 patients with T2D (46 with CVD and 83 without CVD), revealing a significant increase in patients with T2D compared with controls. Osteoglycin level was not an estimator of CVD but correlated with markers of insulin resistance (triglycerides and triglycerides/high-density lipoprotein cholesterol index) in patients with T2D. At the vascular level, osteoglycin expression was assessed by RT-qPCR and immunohistochemistry, and no significant differences were observed between calcified arteries from patients with T2D and noncalcified arteries from controls. In vitro experiments using VSMCs (mock and overexpressing osteoglycin) under calcifying conditions were performed to analyze the osteoglycin function. The overexpression of osteoglycin in VMSCs under calcifying conditions revealed an increase of cell proliferation without effect on apoptosis and an upregulation of the expression of autotaxin (ATX) involved in inflammatory processes. In conclusion, osteoglycin could play a role in glycemic homeostasis, being a potential biomarker of insulin resistance in patients with T2D. Furthermore, osteoglycin could indirectly participate in the development of atherosclerosis through its regulatory effect on ATX and by proliferating VSMCs.NEW & NOTEWORTHY This study uncovers an increase of serum osteoglycin levels in patients with type 2 diabetes, which does not appear to be associated with the development of atherosclerosis, but rather with insulin resistance in this population. Overexpression of osteoglycin increased proliferation and upregulated the expression of autotaxin in vascular smooth muscle cells within calcified environments. Osteoglycin could be a biomarker of insulin resistance for type 2 diabetes and could be indirectly involved in the development of atherosclerosis.

Apical Papilla Regulates Dental Follicle Fate via the OGN-Hh Pathway

Root apical complex, including Hertwig's epithelial root sheath, apical papilla, and dental follicle (DF), is the germinal center of root development, wherein the DF constantly develops into periodontal tissue. However, whether DF development is regulated by the adjacent apical papilla remains largely unknown. In this study, we employed a transwell coculture system and found that stem cells from the apical papilla (SCAPs) inhibit the differentiation and maintain the stemness of dental follicle stem cells (DFSCs). Meanwhile, partial SCAP differentiation markers were upregulated after DFSC coculture. High-throughput RNA sequencing revealed that the Hedgehog (Hh) pathway was significantly downregulated in DFSCs cocultured with SCAPs. Upregulation or downregulation of the Hh pathway can respectively activate or inhibit the multidirectional differentiation of DFSCs. Osteoglycin (OGN) (previously known as mimecan) is highly expressed in the dental papilla, similarly to Hh pathway factors. By secreting OGN, SCAP regulated the stemness and multidirectional differentiation of DFSCs via the OGN-Hh pathway. Finally, Ogn^-/- mice were established using the CRISPR/Cas9 system. We found that the root length growth rate was accelerated during root development from PN0 to PN30 in Ogn^-/- mice. Moreover, the hard tissues (including dentin and cementum) of the root in Ogn^-/- mice were thicker than those in wild-type mice. These phenotypes were likely due to Hh pathway activation and the increased cell proliferation and differentiation in both the apical papilla and DF. The current work elucidates the molecular regulation of early periodontal tissue development, providing a theoretical basis for future research on tooth root biology and periodontal tissue regeneration.

Human theca arises from ovarian stroma and is comprised of three discrete subtypes

Theca cells serve multiple essential functions during the growth and maturation of ovarian follicles, providing structural, metabolic, and steroidogenic support. While the function of theca during folliculogenesis is well established, their cellular origins and the differentiation hierarchy that generates distinct theca sub-types, remain unknown. Here, we performed single cell multi-omics analysis of primary cell populations purified from human antral stage follicles (1-3 mm) to define the differentiation trajectory of theca/stroma cells. We then corroborated the temporal emergence and growth kinetics of defined theca/stroma subpopulations using human ovarian tissue samples and xenografts of cryopreserved/thawed ovarian cortex, respectively. We identified three lineage specific derivatives termed structural, androgenic, and perifollicular theca cells, as well as their putative lineage-negative progenitor. These findings provide a framework for understanding the differentiation process that occurs in each primordial follicle and identifies specific cellular/molecular phenotypes that may be relevant to either diagnosis or treatment of ovarian pathologies.

Osteoglycin: An ECM Factor Regulating Fibrosis and Tumorigenesis

The extracellular matrix (ECM) is made up of noncellular components that have special properties for influencing cell behavior and tissue structure. Small leucine-rich proteoglycans (SLRPs) are nonfibrillar ECM components that serve as structural scaffolds and signaling molecules. osteoglycin (OGN), a class III SLRP, is a ubiquitous ECM component that not only helps to organize the extracellular matrix but also regulates a number of important biological processes. As a glycosylated protein in the ECM, OGN was originally considered to be involved in fiber assembly and was reported to have a connection with fibrosis. In addition to these functions, OGN is found in a variety of cancer tissues and is implicated in cellular processes linked to tumorigenesis, including cell proliferation, invasion, metastasis, and epithelial-mesenchymal transition (EMT). In this review, we summarize the structure and functions of OGN as well as its biological and clinical importance in the context of fibrotic illness and tumorigenesis. This review aims to improve our understanding of OGN and provide some new strategies for the treatment of fibrosis and cancer.

Osteoglycin as a Potential Biomarker of Mild Kidney Function Impairment in Type 2 Diabetes Patients

Osteoglycin (OGN) could be a biomarker of mild kidney function impairment in type 2 diabetes (T2D). Our study aimed to determine the association between serum OGN and impaired kidney function risk in T2D patients and to analyze its potential role as an estimator of kidney disturbances in this population. This cross-sectional study included 147 T2D patients (65 ± 8 years, 58.5% males), and 75 healthy controls (63 ± 10 years, 36% males). Circulating OGN levels were determined by ELISA. Linear regression modeling was performed to determine the variables influencing circulating OGN, and an ROC curve was plotted to assess the usefulness of OGN as an estimator of diabetic kidney disease risk. Circulating OGN was significantly increased in T2D patients compared to controls (18.41 (14.45–23.27) ng/mL vs. 8.74 (7.03–12.35) ng/mL; p < 0.001). We found a progressive increase in serum OGN according to the severity of kidney impairment in T2D patients (normal kidney function: 16.14 (12.13–20.48) ng/mL; mildly impaired kidney function: 19.15 (15.78–25.90) ng/mL; moderate impaired kidney function: 21.80 (15.06–29.22) ng/mL; p = 0.006). Circulating OGN was an independent estimator of mildly impaired kidney function risk in T2D patients. We suggest that serum OGN could act as an albuminuria-independent biomarker of incipient kidney dysfunction in T2D patients.

Osteoglycin and Bone-a Systematic Review

PURPOSE OF REVIEW

Bone turnover is a regulated process. Osteoglycin is suggested to have an important impact on bone function but may also affect cardiovascular and metabolic functions. This review investigates the action of osteoglycin in bone as well as its potential endocrine effects.

RECENT FINDINGS

Osteoglycin is expressed by several tissues including bone and muscle. Some studies suggest that osteoglycin increases osteoblast differentiation whereas others suggest that osteoglycin decreases osteoblast differentiation. Thus, findings on the influence of osteoglycin in bone are conflicting. A recent study found increased bone mass in osteoglycin deficient mice. Another study reported that osteoglycin is a marker of low bone mineral density and vertebral fractures in women with type 2 diabetes. Furthermore, clinical studies link osteoglycin to insulin resistance and cardiovascular disease. Osteoglycin may be a novel marker of a muscle, pancreatic, and bone axis. However, current evidence is limited and further research investigating osteoglycin in both a pre-clinical and a clinical setting is needed.

Vertebrate SLRP family evolution and the subfunctionalization of osteoglycin gene duplicates in teleost fish

Background

Osteoglycin (OGN, a.k.a. mimecan) belongs to cluster III of the small leucine-rich proteoglycans (SLRP) of the extracellular matrix (ECM). In vertebrates OGN is a characteristic ECM protein of bone. In the present study we explore the evolution of SLRP III and OGN in teleosts that have a skeleton adapted to an aquatic environment.

Results

The SLRP gene family has been conserved since the separation of chondrichthyes and osteichthyes. Few gene duplicates of the SLRP III family exist even in the teleosts that experienced a specific whole genome duplication. One exception is ogn for which duplicate copies were identified in fish genomes. The ogn promoter sequence and in vitro mesenchymal stem cell (MSC) cultures suggest the duplicate ogn genes acquired divergent functions. In gilthead sea bream (Sparus aurata) ogn1 was up-regulated during osteoblast and myocyte differentiation in vitro, while ogn2 was severely down-regulated during bone-derived MSCs differentiation into adipocytes in vitro.

Conclusions

Overall, the phylogenetic analysis indicates that the SLRP III family in vertebrates has been under conservative evolutionary pressure. The retention of the ogn gene duplicates in teleosts was linked with the acquisition of different functions. The acquisition by OGN of functions other than that of a bone ECM protein occurred early in the vertebrate lineage.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1310-2) contains supplementary material, which is available to authorized users.

Serum osteoinductive factor is associated with microalbuminuria and diabetic nephropathy in type 2 diabetes

We investigated the relationship between serum osteoinductive factor (OIF) and diabetic nephropathy (DN), and its potential use as a diagnostic marker for DN.This study included 177 patients with type 2 diabetes mellitus (T2DM) with normoalbuminuria, 42 with DN and microalbuminuria, and 49 with DN and macroalbuminuria, as well as 296 controls. Baseline characteristics, microalbuminuria prevalence, macroalbuminuria prevalence, and diabetic complications were compared between OIF quartiles. Serum OIF was examined by enzyme-linked immunosorbent assay. Other clinical parameters were measured using standard methods. Correlations between OIF and clinical parameters were assessed using Pearson correlation. Predictive value of OIF for DN was assessed using multivariate logistic regression. Receiver operator characteristic (ROC) curves were used to identify the optimal sensitivity for serum OIF.Univariate analysis showed microalbuminuria prevalence negatively correlated with OIF, 4.3% for quartile 1 (Q1) (>367.5 pg/mL), 13.7% for Q2 (320.3-367.5 pg/mL), 17.9% for Q3 (275.0-320.3 pg/mL), and 28.8% for Q4 (<275.0 pg/mL) (Ptrend < .001), as did T2DM complications. ROC analysis showed an OIF of <343.4 pg/mL was predictive of DN (C statistic 0.702). OIF <343.4 pg/mL remained predictive of microalbuminuria (odds ratio = 11.60; 95% confidence interval: 1.25-107.47) after adjusting for confounding factors.Serum OIF is an independent diagnostic marker of DN.

Low Levels of Plasma Osteoglycin in Patients with Complex Coronary Lesions

Aim: Osteoglycin is one of proteoglycans that are biologically active components of vascular extracellular matrix. However, the role of osteoglycin in atherosclerosis remains unclear.

Methods: We investigated plasma osteoglycin levels and the presence, severity, and lesion morphology of coronary artery disease (CAD) in 462 patients undergoing elective coronary angiography.

Results: Of 462 patients, 245 had CAD. Osteoglycin levels were higher in patients with CAD than without CAD (median 29.7 vs. 25.0 ng/mL, P < 0.05). However, osteoglycin levels did not differ among patients with one-vessel, two-vessel, or three-vessel disease (30.8, 30.6, and 29.4 ng/mL, respectively) and did not correlate with the number of stenotic segments. Among 245 CAD patients, 41 had complex coronary lesions, and 70 had total occlusion, of whom 67 had good collateralization. Between 70 patients with occlusion and 175 without occlusion, osteoglycin levels did not differ (30.4 vs. 29.5 ng/mL). Notably, osteoglycin levels were lower in 41 patients with complex lesions than in 204 without such lesions (24.2 vs. 31.6 ng/mL, P < 0.02). In multivariate analysis, osteoglycin levels were an independent factor for complex lesion but not for CAD. Odds ratio for complex lesion was 0.80 (95%CI = 0.67–0.96) for each 10 ng/mL increase in osteoglycin levels (P < 0.02).

Conclusion: Although plasma osteoglycin levels were high in patients with CAD, they did not correlate with the severity of CAD and were not an independent factor for CAD. Notably, osteoglycin levels were low in patients with complex lesions and were a factor for complex lesions, suggesting that osteoglycin plays a role in coronary plaque stabilization.

Osteoglycin (OGN) reverses epithelial to mesenchymal transition and invasiveness in colorectal cancer via EGFR/Akt pathway

Background

Many types of cancers are devoid of the small leucine-rich proteoglycans: osteoglycin (OGN), but its role in tumorigenesis is poorly studied especially in colorectal cancers (CRC). Here we aim to evaluate the relationship between OGN expression patterns and the clinical course of CRC, and the role of OGN in cancer progression.

Methods

The tissue microarray staining was performed and the relevance between OGN expression and oncologic outcomes was performed using Cox regression analysis. The effect of OGN on cell proliferation and tumorigenesis was examined in vitro and in vivo. Immunoprecipitation assay, immunofluorescence analysis and internalization assay were used for mechanistic study.

Results

Patients with high expression of OGN were associated with a profound longer survival in CRC and the high serum OGN level was also indicative of fewer recurrences consistently. In colon cancer cells, OGN increased dimerization of EGFR, then triggered EGFR endocytosis and induced the recruitment of downstream components of the EGFR internalization machinery (Eps15 and epsin1). Above all, OGN reduced Zeb-1 expression via EGFR/Akt leading to inhibition of epithelial-mesenchymal transition. As results, in vitro and in vivo, the OGN expression was demonstrated to reduce cell proliferation, inhibit invasion of colon cancer cells then impede cancer progression.

Conclusions

There is a positive association between OGN level and prolonged survival in CRC. OGN plays a restrictive role in colorectal cancer progression by reduced activation of EGFR/AKT/Zeb-1.

Enhanced serum levels of matrix Gla protein and bone morphogenetic protein in acute coronary syndrome patients

BACKGROUND

Vascular calcification has been found to be associated with increased risk of cardiovascular (CV) morbidity and mortality. Various bone-associated proteins have been suggested to be related with this process. In this study, we aimed to evaluate whether serum levels of bone morphogenic protein-4 (BMP-4) and matrix Gla protein (MGP) differed in patients who were found to have normal epicardial coronary arteries or a culprit lesion in the coronary angiography leading to acute coronary syndrome (ACS).

METHODS

Patients admitted to emergency department with the diagnosis of ACS who underwent primary percutaneous coronary intervention (PCI) between October 2015 and April 2016 were consecutively recruited as the patient group. Age and gender-matched subjects who underwent coronary angiography following non-invasive ischemia assessment made the control group.

RESULTS

A total of 90 subjects (63.00±14.02 years, 70% male) were included in this study. MGP (<0.001) and BMP-4 (<0.001) levels were significantly elevated when compared to subjects with normal coronary arteries. Fasting blood glucose (P=.024), HDL-cholesterol (P=.002), C-reactive protein (CRP) (P=.001) levels, and left ventricular ejection fraction (LVEF) (P=.021) were significantly correlated with serum MGP levels. HDL-cholesterol (P=.001) and CRP (P=.030) levels were also significantly correlated with serum BMP-4 levels. In the model including HDL-cholesterol, CRP, MGP, and BMP-4 levels, only MGP (odds ratio[OR]: 1.018, P=.019) and BMP-4 (OR: 1.313, P=.023) were found to be independently associated with ACS.

CONCLUSION

This study shows that serum BMP-4 and MGP are independently associated with ACS occurrence when adjusted for other CV risk factors. These biomarkers may have a diagnostic potential in ACS patients.

Osteoglycin prevents the development of age-related diastolic dysfunction during pressure overload by reducing cardiac fibrosis and inflammation

The small leucine-rich proteoglycan osteoglycin has been implicated in matrix homeostasis in different organs, including the ischemic heart. However, whether osteoglycin modulates cardiac hypertrophy, fibrosis or inflammation in hypertensive heart disease and during aging remains unknown. Angiotensin-II-induced pressure overload increases cardiac osteoglycin expression, concomitant with the onset of inflammation and extracellular matrix deposition. Interestingly aging led to decreased cardiac levels of osteoglycin, yet absence of osteoglycin did not affect organ structure or cardiac function up to the age of 18months. However, Angiotensin-II infusion in combination with aging resulted in exaggerated cardiac fibrosis and inflammation in the osteoglycin null mice as compared to wild-type mice, resulting in increased diastolic dysfunction as determined by magnetic resonance imaging. In vitro, stimulation of bone marrow derived macrophages from osteoglycin null mice with Angiotensin-II resulted in significantly higher levels of ICAM-1 as well as pro-inflammatory cytokines and chemokines IL-1β and MCP-1 as compared to WT cells. Further, stimulation of human cardiac fibroblasts with osteoglycin reduced cell proliferation and inhibited TGF-β induced collagen gene expression. In mouse cardiac tissue, osteoglycin expression inversely correlated with TGF-β expression and in cardiac biopsies of aortic stenosis patients, osteoglycin expression is significantly higher than in control biopsies. Interestingly, osteoglycin levels were higher in patients with less severe myocardial fibrosis and overall in the aortic stenosis patients osteoglycin levels negatively correlated with collagen content in the myocardium. In conclusion, osteoglycin expression is increased in the heart in response to pressure overload and its absence results in increased cardiac inflammation and fibrosis resulting in increased diastolic dysfunction.

Osteoglycin promotes meningioma development through downregulation of NF2 and activation of mTOR signaling

BACKGROUND

Meningiomas are the most common primary intracranial tumors in adults. While a majority of meningiomas are slow growing neoplasms that may cured by surgical resection, a subset demonstrates more aggressive behavior and insidiously recurs despite surgery and radiation, without effective alternative treatment options. Elucidation of critical mitogenic pathways in meningioma oncogenesis may offer new therapeutic strategies. We performed an integrated genomic and molecular analysis to characterize the expression and function of osteoglycin (OGN) in meningiomas and explored possible therapeutic approaches for OGN-expressing meningiomas.

METHODS

OGN mRNA expression in human meningiomas was assessed by RNA microarray and RNAscope. The impact of OGN on cell proliferation, colony formation, and mitogenic signaling cascades was assessed in a human meningioma cell line (IOMM-Lee) with stable overexpression of OGN. Furthermore, the functional consequences of introducing an AKT inhibitor in OGN-overexpressing meningioma cells were assessed.

RESULTS

OGN mRNA expression was dramatically increased in meningiomas compared to a spectrum of other brain tumors and normal brain. OGN-overexpressing meningioma cells demonstrated an elevated rate of cell proliferation, cell cycle activation, and colony formation as compared with cells transfected with control vector. In addition, NF2 mRNA and protein expression were both attenuated in OGN-overexpressing cells. Conversely, mTOR pathway and AKT activation increased in OGN-overexpressing cells compared to control cells. Lastly, introduction of an AKT inhibitor reduced OGN expression in meningioma cells and resulted in increased cell death and autophagy, suggestive of a reciprocal relationship between OGN and AKT.

CONCLUSION

We identify OGN as a novel oncogene in meningioma proliferation. AKT inhibition reduces OGN protein levels in meningioma cells, with a concomitant increase in cell death, which provides a promising treatment option for meningiomas with OGN overexpression.

The diverse functions of osteoglycin: a deceitful dwarf, or a master regulator of disease?

Small leucine-rich proteoglycans are emerging as important regulatory proteins within the extracellular matrix, where they exert both structural and nonstructural functions and hence are modulators of numerous biological processes, such as inflammation, fibrosis, and cell proliferation. One proteoglycan in particular, osteoglycin (OGN), also known as mimecan, shows great structural and functional diversity in normal physiology and in disease states, therefore making it a very interesting candidate for the development of novel therapeutic strategies. Unfortunately, the literature on OGN is confusing, as it has different names, and different transcript and protein variants have been identified. This review will give a clear overview of the different structures and functions of OGN that have been identified to date, portray its central role in pathophysiology, and highlight the importance of posttranslational processing, such as glycosylation, for the diversity of its functions.-Deckx, S., Heymans, S., Papageorgiou, A.-P. The diverse functions of osteoglycin: a deceitful dwarf, or a master regulator of disease?

Serum Mimecan Is Associated With Arterial Stiffness in Hypertensive Patients

Background

Mimecan plays an important role in endothelial and vascular smooth muscle cell integrity and may be involved the pathology of arterial stiffness. However, the role of mimecan in arterial stiffness in patients with hypertension is not well defined.

Methods and Results

A total of 116 hypertension patients and 54 healthy controls were enrolled in the investigation. Hypertensive patients were divided into 2 groups: the with arterial stiffness group (brachial-ankle pulse wave velocity [baPWV] ≥1400 cm/s; n=83) and the without arterial stiffness group (baPWV <1400 cm/s; n=33). A noninvasive measure of vascular stiffness was performed using pulse wave velocity (PWV) measurement of baPWV. Hypertensive patients had higher baPWV, mimecan, and endothelin 1 (ET-1) than healthy controls. The arterial stiffness group had higher mimecan and endothelin 1 (ET-1) and lower ankle-brachial pressure index (ABI) than those without stiffness. In hypertensive patients, mimecan was inversely correlated with ABI (P<0.05) and positively correlated with baPWV, ET-1, and total cholesterol. On multivariable logistic regression analysis, diastolic blood pressure, mimecan, ET-1, and creatinine were independent predictors of arterial stiffness in hypertensive patients (P<0.05).

Conclusions

Mimecan levels are higher in hypertensive patients than in healthy controls. Increased plasma mimecan levels are independently associated with increased arterial stiffness as assessed by baPWV.

Aortic wall proteomic analysis in spontaneously hypertensive rats with a blood pressure decrease induced by 6-week load-free swimming

Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall in hypertension. The proteomic approach is a powerful technique to analyze a complex mixture of proteins in various settings. Physical activity level was negatively associated with blood pressure. Sixteen 4-week-old male spontaneously hypertensive rats (SHR) and 16 Wistar-Kyoto (WKY) rats were randomly divided into four groups: i) SHR exercise group, ii) SHR rest group, iii) WKY exercise group and iv) WKY rest group. In the SHR and WKY exercise groups, rats were treated with a 6-week load-free swimming protocol (1 h/day, 5 days/week). The blood pressure of the rats was tested by the CODA^TM2 single non-invasive blood pressure measurement appliance. After the 6-week swimming protocol, the total aorta excluding abdominal aorta was extracted. The proteins were separated by two-dimensional gel electrophoresis and identified via LC-mass spectrometry (MS)/MS. After 6-week load-free swimming, blood pressure decreased in the SHRs. Compared with sedentary SHRs, 11 spots on the 2D-gel showed a significant difference in exercised SHRs. Nine of these were chosen for further identification. There were 5 upregulated proteins (long-chain specific acyl-CoA dehydrogenase, heat shock protein β-1, isocitrate dehydrogenase subunit α, actin, α cardiac muscle 1 preprotein and calmodulin isoform 2) and 4 downregulated proteins (adipocyte-type fatty acid-binding protein, tubulin β-2C chain, 78 kDa glucose-regulated protein precursor and mimecan). Proteomics is an effective method to identify the target proteins of exercise intervention for hypertension.

Overexpression of mimecan in human aortic smooth muscle cells inhibits cell proliferation and enhances apoptosis and migration

The pathogenesis of atherosclerosis is multifactorial. The proliferation and migration of vascular smooth muscle cells (VSMCs) are significant in the genesis and development of atherosclerosis plaques, and the degradation of VSMCs plays a crucial role in the process. Mimecan is a member of the Keratan sulfate family of proteoglycans, which are leucine-rich proteoglycans. It has been demonstrated that mimecan is associated with arteriogenesis and atherosclerosis. In the present study, the effect of mimecan on the characteristics of cultured human aortic smooth muscle cells (HASMCs) was investigated. In vitro, human mimecan was stably overexpressed in HASMCs using a lentiviral system. It was observed that the proliferation rate of HASMCs transduced with mimecan was lower compared with that of control cells; overexpression of mimecan induced HASMC apoptosis. To determine the effect of mimecan on HASMC migration, a Transwell cell culture chamber and sterile cloning cylinder assays were used, and it was noted that mimecan enhanced the migration of HASMCs horizontally and vertically. These data indicated that mimecan may be involved in the pathogenesis of atherosclerosis by regulating the proliferation, apoptosis and migration of VSMCs.

Proteomic analysis identifies cytoskeleton-interacting proteins as major downstream targets of altered folate status in the aorta of adult rat

SCOPE

Mild folate deficiency and subsequently elevated plasma level of homocysteine are associated with an increased risk for vascular diseases in adults. Conversely, high intakes of folic acid (FA) may have beneficial effects on vascular function, presumably in part through homocysteine lowering. However, these effects have not yet been translated in terms of prevention or treatment of vascular pathologies. Besides, the complex biologic perturbation induced by variations of the folate supply is still not fully deciphered. We thus carried out a proteomic analysis of the aorta of adult rats after a dietary FA depletion or supplementation.

METHODS AND RESULTS

Nine month-old rats were fed a FA-depleted, FA-supplemented or control diet for 8 weeks. Total proteins from adventitia-free aortas were separated by 2DE and differentially expressed proteins were identified by MS. FA depletion or supplementation resulted in significantly changed abundance of 29 spots (p < 0.05), of which 20 proteins were identified. Bioinformatic analysis revealed that most of these proteins are involved in cytoskeleton-related processes important to cell function/maintenance, assembly/organization, and movement.

CONCLUSION

Our proteomic study supports that expression of proteins essential to vascular structure and, presumably, function is modulated by high intake as well as deprivation of FA.

Proteomic approach to skin regeneration in a marine teleost: modulation by oestradiol-17β

Skin and scale formation and regeneration in teleosts have mainly been described from a morphological perspective, and few studies of the underlying molecular events exist. The present study evaluates (1) the change in the skin proteome during its regeneration in a marine teleost fish (gilthead sea bream, Sparus aurata) and (2) the impact of oestradiol-17β (Ε2) on regeneration and the involvement of oestrogen receptor (ER) isoforms. Thirty-five candidate proteins were differentially expressed (p < 0.05) between intact and regenerated skin proteome 5 days after scale removal, and 27 proteins were differentially expressed after E2 treatment. Agglomerative hierarchical clustering of the skin proteome revealed that the skin treated with E2 clustered most closely to intact skin, while regenerating untreated skin formed an independent cluster. Gene Ontology classification associated the differentially expressed proteins in E2-treated skin with developmental processes and cellular morphogenesis. The proteins modified during skin regeneration suggest a balance exists between immune response and anatomical repair. Overall, the results indicate that, even after 5 days regeneration, the composition of mature skin is not attained, and endocrine factors, in particular E2, can accelerate wound repair acting possibly via ERβs expressed in the skin-scales. Several candidate proteins probably involved in scale development, osteoglycin, lipocalin2 and lamin A and the transcription factors PHD and grainyhead were identified. Future studies of fish skin regeneration will be required to provide further insight into this multistage process, and the present study indicates it will be useful to explore immune adaptations of epithelia permanently exposed to an aqueous environment.

Molecular differences between human thyroid follicular adenoma and carcinoma revealed by analysis of a murine model of thyroid cancer

Mouse models can provide useful information to understand molecular mechanisms of human tumorigenesis. In this study, the conditional thyroid mutagenesis of Pten and Ras genes in the mouse, which induces very aggressive follicular carcinomas (FTCs), has been used to identify genes differentially expressed among human normal thyroid tissue (NT), follicular adenoma (FA), and FTC. Global gene expression of mouse FTC was compared with that of mouse normal thyroids: 911 genes were found deregulated ± 2-fold in FTC samples. Then the expression of 45 deregulated genes in mouse tumors was investigated by quantitative RT-PCR in a first cohort of human NT, FA, and FTC (discovery group). Five genes were found significantly down-regulated in FA and FTC compared with NT. However, 17 genes were found differentially expressed between FA and FTC: 5 and 12 genes were overexpressed and underexpressed in FTC vs FA, respectively. Finally, 7 gene products, selected from results obtained in the discovery group, were investigated in a second cohort of human tumors (validation group) by immunohistochemistry. Four proteins showed significant differences between FA and FTC (peroxisomal proliferator-activated receptor-γ, serum deprivation response protein, osteoglycin, and dipeptidase 1). Altogether our data indicate that the establishment of an enriched panel of molecular biomarkers using data coming from mouse thyroid tumors and validated in human specimens may help to set up a more valid platform to further improve diagnosis and prognosis of thyroid malignancies.

MicroRNA-22 increases senescence and activates cardiac fibroblasts in the aging heart

MicroRNAs (miRs) are small non- coding RNA molecules controlling a plethora of biological processes such as development, cellular survival and senescence. We here determined miRs differentially regulated during cardiac postnatal development and aging. Cardiac function, morphology and miR expression profiles were determined in neonatal, 4 weeks, 6 months and 19 months old normotensive male healthy C57/Bl6N mice. MiR-22 was most prominently upregulated during cardiac aging. Cardiac expression of its bioinformatically predicted target mimecan (osteoglycin, OGN) was gradually decreased with advanced age. Luciferase reporter assays validated mimecan as a bona fide miR-22 target. Both, miR-22 and its target mimecan were co- expressed in cardiac fibroblasts and smooth muscle cells. Functionally, miR-22 overexpression induced cellular senescence and promoted migratory activity of cardiac fibroblasts. Small interference RNA-mediated silencing of mimecan in cardiac fibroblasts mimicked the miR-22-mediated effects. Rescue experiments revealed that the effects of miR-22 on cardiac fibroblasts were only partially mediated by mimecan. In conclusion, miR-22 upregulation in the aging heart contributed at least partly to accelerated cardiac fibroblast senescence and increased migratory activity. Our results suggest an involvement of miR-22 in age-associated cardiac changes, such as cardiac fibrosis.

A combined proteomic and transcriptomic approach shows diverging molecular mechanisms in thoracic aortic aneurysm development in patients with tricuspid- and bicuspid aortic valve

Thoracic aortic aneurysm is a pathological local dilatation of the aorta, potentially leading to aortic rupture or dissection. The disease is a common complication of patients with bicuspid aortic valve, a congenital disorder present in 1-2% of the population. Using two dimensional fluorescence difference gel electrophoresis proteomics followed by mRNA expression, and alternative splicing analysis of the identified proteins, differences in dilated and nondilated aorta tissues between 44 patients with bicuspid and tricuspid valves was examined. The pattern of protein expression was successfully validated with LC-MS/MS. A multivariate analysis of protein expression data revealed diverging protein expression fingerprints in patients with tricuspid compared with the patients with bicuspid aortic valves. From 302 protein spots included in the analysis, 69 and 38 spots were differentially expressed between dilated and nondilated aorta specifically in patients with tricuspid and bicuspid aortic valve, respectively. 92 protein spots were differentially expressed between dilated and nondilated aorta in both phenotypes. Similarly, mRNA expression together with alternative splicing analysis of the identified proteins also showed diverging fingerprints in the two patient groups. Differential splicing was abundant but the expression levels of differentially spliced mRNA transcripts were low compared with the wild type transcript and there was no correlation between splicing and the number of spots. Therefore, the different spots are likely to represent post-translational modifications. The identification of differentially expressed proteins suggests that dilatation in patients with a tricuspid aortic valve involves inflammatory processes whereas aortic aneurysm in patients with BAV may be the consequence of impaired repair capacity. The results imply that aortic aneurysm formation in patients with bicuspid and tricuspid aortic valves involve different biological pathways leading to the same phenotype.

Role of osteoglycin in the linkage between muscle and bone

The interaction between muscle tissues and bone metabolism is incompletely understood. We hypothesized that there might be some humoral factors that are produced in muscle tissues and exhibit bone anabolic activity. We, therefore, performed comparative DNA microarray analysis between mouse myoblastic C2C12 cells transfected with either stable empty vector or ALK2 (R206H), the mutation that constitutively activates the bone morphogenetic protein (BMP) receptor, to search for muscle-derived bone anabolic factors. Twenty-five genes whose expression was decreased to <1/4, were identified; these included osteoglycin (OGN). Stable overexpression of OGN significantly decreased the levels of Runx2 and Osterix mRNA compared with those in cells transfected with vector alone in MC3T3-E1 cells. On the other hand, it significantly enhanced the levels of alkaline phosphatase (ALP), type I collagen (Col1), and osteocalcin (OCN) mRNA as well as β-catenin and mineralization. A reduction in endogenous OGN level showed the opposite effects to those of OGN overexpression in MC3T3-E1 and mouse calvarial osteoblastic cells. Transient OGN overexpression significantly suppressed the levels of Runx2, Osterix, ALP, Col1, and OCN mRNA induced by BMP-2 in C2C12 cells. The conditioned medium from OGN-overexpressed and OGN-suppressed myoblastic cells enhanced and decreased, respectively, the levels of ALP, Col1, and β-catenin in MC3T3-E1 cells. Moreover, OGN increased Smad3/4-responsive transcriptional activity as well as Col1 mRNA levels independently of endogenous TGF-β in these cells. In conclusion, this study suggests that OGN may be a crucial humoral bone anabolic factor that is produced by muscle tissues.

Levels of Circulating MMCN-151, a Degradation Product of Mimecan, Reflect Pathological Extracellular Matrix Remodeling in Apolipoprotein E Knockout Mice

AIM

Arterial extracellular matrix (ECM) remodeling by matrix metalloproteinases (MMPs) is one of the major hallmarks of atherosclerosis. Mimecan, also known as osteoglycin has been implicated in the integrity of the ECM. This study assessed the validity of an enzyme-linked immunosorbent assay (ELISA) developed to measure a specific MMP12-derived fragment of mimecan, MMCN-151, in apolipoprotein-E knockout (ApoE-KO) mice.

METHODS AND RESULTS

A mouse monoclonal antibody raised against MMCN-151 was used to develop a competitive ELISA. The assay was validated using samples from 20 ApoE-KO and 20 wild type [C57 BL/6] male mice fed a normal or high-fat diet (HFD) for up to 20 weeks. The technical reliability of the assay was established with intra-assay variability <2% and inter-assay variability <10%. The lowest limit of quantification of MMCN-151 was 0.5 ng/ml. ApoE-KO mice fed a HFD for 20 weeks had four-fold increased circulating levels of MMCN-151 compared to baseline, whereas MMCN-151 levels in control mice on HFD increased two-fold compared with baseline. After 10 weeks of a HFD, a significant difference in MMCN-151 levels was observed between ApoE-KO and control mice (P = 0.005) and became more significant at 20 weeks (P = 0.002).

CONCLUSIONS

The newly developed assay is a reliable detector of MMCN-151 levels which ultimately may be useful indicators of arterial remodeling in patients affected by atherosclerotic disease.

Mimecan in pituitary corticotroph cells may regulate ACTH secretion and the HPAA

Mimecan is a protein of unknown function that is expressed in the pituitary tissues of mouse and human. In this study, we observed the function of mimecan on the proopiomelanocortin (POMC) gene in the pituitary and the hypothalamo-pituitary-adrenal axis (HPAA). Incubating pituitary corticotroph AtT-20 cells with recombinant mimecan protein stimulated adrenocorticotrophic hormone (ACTH) secretion without significantly up-regulating POMC gene expression. In addition, pituitary corticotroph AtT-20 cell corticotropin-releasing hormone receptor 1 (CRHR1) gene expression was induced by mimecan. Interestingly, long-term mimecan overexpression in corticotroph cells increased CRHR1 mRNA levels while slightly decreasing POMC mRNA expression and ACTH secretion. Using mimecan knockout mice, we found that, although the serum ACTH concentration was not significantly different between wild type and mimecan knockout mice under basal conditions, the serum ACTH level was relatively lower in mimecan knockout mice after treatment with corticotropin-releasing hormone (CRH). Meanwhile, we observed that POMC and CRHR1 gene expression decreased in primary cultured knockout mouse pituitary cells compared with wild type cells. Taken together, these data suggest that mimecan expressed in pituitary corticotroph cells mainly regulates ACTH secretion in the pituitary and coordinates the HPAA.

A proteomic focus on the alterations occurring at the human atherosclerotic coronary intima

Coronary atherosclerosis still represents the major cause of mortality in western societies. Initiation of atherosclerosis occurs within the intima, where major histological and molecular changes are produced during pathogenesis. So far, proteomic analysis of the atherome plaque has been mainly tackled by the analysis of the entire tissue, which may be a challenging approach because of the great complexity of this sample in terms of layers and cell type composition. Based on this, we aimed to study the intimal proteome from the human atherosclerotic coronary artery. For this purpose, we analyzed the intimal layer from human atherosclerotic coronaries, which were isolated by laser microdissection, and compared with those from preatherosclerotic coronary and radial arteries, using a two-dimensional Differential-In-Gel-Electrophoresis (DIGE) approach. Results have pointed out 13 proteins to be altered (seven up-regulated and six down-regulated), which are implicated in the migrative capacity of vascular smooth muscle cells, extracellular matrix composition, coagulation, apoptosis, heat shock response, and intraplaque hemorrhage deposition. Among these, three proteins (annexin 4, myosin regulatory light 2, smooth muscle isoform, and ferritin light chain) constitute novel atherosclerotic coronary intima proteins, because they were not previously identified at this human coronary layer. For this reason, these novel proteins were validated by immunohistochemistry, together with hemoglobin and vimentin, in an independent cohort of arteries.

Secretome Analysis of Skeletal Myogenesis Using SILAC and Shotgun Proteomics

Myogenesis, the formation of skeletal muscle, is a multistep event that commences with myoblast proliferation, followed by cell-cycle arrest, and finally the formation of multinucleated myotubes via fusion of mononucleated myoblasts. Each step is orchestrated by well-documented intracellular factors, such as cytoplasmic signalling molecules and nuclear transcription factors. Regardless, the key step in getting a more comprehensive understanding of the regulation of myogenesis is to explore the extracellular factors that are capable of eliciting the downstream intracellular factors. This could further provide valuable insight into the acute cellular response to extrinsic cues in maintaining normal muscle development. In this paper, we survey the intracellular factors that respond to extracellular cues that are responsible for the cascades of events during myogenesis: myoblast proliferation, cell-cycle arrest of myoblasts, and differentiation of myoblasts into myotubes. This focus on extracellular perspective of muscle development illustrates our mass spectrometry-based proteomic approaches to identify differentially expressed secreted factors during skeletal myogenesis.

Changes in proteomic features induced by insulin on vascular smooth muscle cells from spontaneous hypertensive rats in vitro

Hyperinsulinemia is a risk factor in atherosclerosis formation that it stimulated vascular smooth muscle cells (VSMCs) proliferation and migration. To understand the underlying molecular mechanism involved in the processes of cellular response to insulin, VSMCs from Wistar-Kyoto rat (WKY) and spontaneous hypertensive rat (SHR) were isolated and cultured, and its proteome was comparatively analyzed with normal control by two-dimensional gel electrophoresis (2-DE). Results showed that the proliferation of VSMCs from SHR be more sensitive to insulin stimulation than that VSMCs from WKY. The detectable spots ranged from 537 to 608 on the gels in VSMCs of SHR, and 413 ± 31 spots in VSMCs of WKY. The different expressed protein spots in VSMCs of SHR were then isolated and measured by matrix-assisted desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). A total of 18 spots showed a sharp clear spectrum, and 13 spots matched with the known proteins from database. These proteins were mainly involved in cytoskeleton, glycometabolism, and post-translational processes. Among these proteins, OPN and matrix gla protein were up-regulated expression proteins, while α-SM actin was down-regulated. Furthermore, these preliminarily identified proteins confirmed by RT-PCR and western blotting analysis were coincident with the changes in 2-DE check. In addition, the cytoskeleton changes and migration rate of VSMCs from SHR treated by insulin increased significantly. The results showed that insulin plays a crucial role in activating proliferation and migration of VSMCs, by regulating the phenotype switch of VSMCs.

Glucocorticoid up-regulates mimecan expression in corticotroph cells

Mimecan is a protein of unknown function that is expressed in the pituitary. The aim of this study is to clarify the regulation and intracellular localisation of mimecan gene expression in the pituitary. With immunohistochemistry, we observed that mimecan protein was co-expressed with ACTH in pituitary corticotroph cells. Northern and Western blot analyses revealed that mimecan expression and secretion in corticotroph cells were up-regulated by treating AtT-20 cells with glucocorticoid. Meanwhile, mimecan expression in rat primary culture pituitary cells was also promoted by glucocorticoid. Co-incubation of AtT-20 cells with RU486 and glucocorticoid completely reversed the induction of mimecan gene expression by glucocorticoid. In addition, luciferase reporter assays showed that the -1474/+43 promoter region of mimecan was sufficient for glucocorticoid-responsive mimecan expression. These data collectively suggest that mimecan expressed in pituitary corticotroph cells is increased by glucocorticoid and that the up-regulation may be mediated by the classical GR pathways.

Extracellular matrix molecules: potential targets in pharmacotherapy

The extracellular matrix (ECM) consists of numerous macromolecules classified traditionally into collagens, elastin, and microfibrillar proteins, proteoglycans including hyaluronan, and noncollagenous glycoproteins. In addition to being necessary structural components, ECM molecules exhibit important functional roles in the control of key cellular events such as adhesion, migration, proliferation, differentiation, and survival. Any structural inherited or acquired defect and/or metabolic disturbance in the ECM may cause cellular and tissue alterations that can lead to the development or progression of disease. Consequently, ECM molecules are important targets for pharmacotherapy. Specific agents that prevent the excess accumulation of ECM molecules in the vascular system, liver, kidney, skin, and lung; alternatively, agents that inhibit the degradation of the ECM in degenerative diseases such as osteoarthritis would be clinically beneficial. Unfortunately, until recently, the ECM in drug discovery has been largely ignored. However, several of today's drugs that act on various primary targets affect the ECM as a byproduct of the drugs' actions, and this activity may in part be beneficial to the drugs' disease-modifying properties. In the future, agents and compounds targeting directly the ECM will significantly advance the treatment of various human diseases, even those for which efficient therapies are not yet available.

High expression of osteoglycin decreases gelatinase activity of murine hepatocarcinoma Hca-F cells

AIM: To investigate the possible correlation between osteoglycin expression and gelatinase activity of mouse hepatocarcinoma Hca-F cells.

METHODS: A eukaryotic expression plasmid pIRESpuro3 osteoglycin(+) was constructed and transfected into Hca-F cells to investigate the possible correlation between osteoglycin expression and gelatinase activity of Hca-F cells cultured with extract of lymph node, liver, spleen or in DMEM medium. The activity of gelatinases was examined through zymographic analysis.

RESULTS: High expression of osteoglycin attenuated the gelatinase activity of Hca-F cells cultured with extract of lymph node, and at the same time, decreased the metastatic potential of Hca-F cells to peripheral lymph nodes in vivo.

CONCLUSION: High expression of osteoglycin decreases the gelatinase activity of Hca-F cells cultured with extract of lymph node; regulation of gelatinase activity might be one of mechanisms that osteoglycin contributes to lymphatic metastasis suppression.

Molecular markers of preterm labor in the choriodecidua

Because relevant biochemical changes are known to begin at the choriodecidual interface some weeks before actual clinical onset of labor, we hypothesized that the preterm choriodecidua may display gene and protein expression patterns specific to preterm labor. Transcriptomic (microarray) and proteomic (2-dimensional gel electrophoresis [2DGE]) profiling methodologies were used to compare changes in choriodecidual tissue collected from women who delivered before 35 weeks of gestation following spontaneous preterm labor (n = 12) and gestation-matched nonlaboring controls (n = 7). Additionally, 2DGE was used to compare differences in protein expression during term and preterm labor and to construct a choriodecidual proteome map. Overall, expressed transcripts and proteins indicated active tissue remodeling independent of labor status and an association with inflammatory processes during labor. Spontaneous, infection-induced and abruption-associated preterm deliveries were each defined by distinct transcriptional profiles. Proteins osteoglycin and progesterone receptor component 2 (PGRMC2) were upregulated during term and preterm labor while galectin 1, annexin 3, annexin 5, and protein disulfide isomerase (PDI) were upregulated only during preterm labor, suggesting a probable association with the underlying pathology. Together, these results represent novel data that warrant further investigations to elucidate plausible causal relationships of these molecules with spontaneous preterm delivery.

Evidence for a calcification process in the trabecular meshwork

The human trabecular meshwork (TM) expresses many genes that have been associated with physiological (bone, cartilage, teeth) and pathological (vascular systems, kidney) calcification. In particular, the TM highly expresses the inhibitor of calcification Matrix Gla (MGP) gene, which encodes a vitamin K-dependent protein that requires post-translational activation to inhibit the formation of calcium precipitates. TM cells have high activity of the activating gamma-carboxylase enzyme and produce active MGP. Silencing MGP increases the activity of alkaline phosphatase (ALP), an enzyme of the matrix vesicles and marker of calcification. Overexpressing MGP reduces the ALP activity induced by bone morphogenetic 2 (BMP2), a potent inducer of calcification. In this review we gathered evidence for the existence of a mineralization process in the TM. We selected twenty regulatory calcification genes, reviewed their functions in their original tissues and looked at their relative abundance in the TM by heat maps derived from existing microarrays. Although results are not yet fully conclusive and more experiments are needed, examining TM expression in the light of the calcification literature brings up many similarities. One such parallel is the role of mechanical forces in bone induction and the high levels of mineralization inhibitors found in the constantly mechanically stressed TM. During the next few years, examination of other calcification-related regulatory genes and pathways, as well as morphological examination of knockout animals, would help to elucidate the relevance of a calcification process to TM's overall function.

The proteoglycan osteoglycin/mimecan is correlated with arteriogenesis

Arteriogenesis or collateral growth is able to compensate for the stenosis of major arteries. Using differential display RT-PCR on growing and quiescent collateral arteries in a rabbit femoral artery ligation model, we cloned the rabbit full-length cDNA of osteoglycin/mimecan. Osteoglycin was present in the adventitia of collateral arteries as a glycosylated protein without keratan sulfate side chains, mainly produced by smooth muscle cells (SMCs) and perivascular fibroblasts. Northern blot, Western blot, and immunohistochemistry confirmed a collateral artery-specific downregulation of osteoglycin from 6 h to 3 weeks after the onset of arteriogenesis. Treatment of primary SMCs with the arteriogenic protein fibroblast growth factor-2 (FGF-2) resulted in a similar reduction of osteoglycin expression as observed in vivo. Application of the FGF-2 inhibitor polyanethole sulfonic acid (PAS) blocked the downregulation of osteoglycin and interfered with arteriogenesis. From our study we conclude that downregulation of osteoglycin is a fundamental requirement for proper arteriogenesis.

Label-free quantitative analysis of one-dimensional PAGE LC/MS/MS proteome: application on angiotensin II-stimulated smooth muscle cells secretome

A widely used method for protein identification couples prefractionation of protein samples by one-dimensional (1D) PAGE with LC/MS/MS. We developed a new label-free quantitative algorithm by combining measurements of spectral counting, ion intensity, and peak area on 1D PAGE-based proteomics. This algorithm has several improvements over other label-free quantitative algorithms: (i) Errors in peak detection are reduced because the retention time is based on each LC/MS/MS run and actual precursor m/z. (ii) Detection sensitivity is increased because protein quantification is based on the combination of peptide count, ion intensity, and peak area. (iii) Peak intensity and peak area are calculated in each LC/MS/MS run for all slices from 1D PAGE for every single identified protein and visualized as a Western blot image. The sensitivity and accuracy of this algorithm were demonstrated by using standard curves (17.4 fmol to 8.7 pmol), complex protein mixtures (30 fmol to 1.16 pmol) of known composition, and spiked protein (34.8 fmol to 17.4 pmol) in complex proteins. We studied the feasibility of this approach using the secretome of angiotensin II (Ang II)-stimulated vascular smooth muscle cells (VSMCs). From the VSMC-conditioned medium, 629 proteins were identified including 212 putative secreted proteins. 26 proteins were differently expressed in control and Ang II-stimulated VSMCs, including 18 proteins not previously reported. Proteins related to cell growth (CYR61, protein NOV, and clusterin) were increased, whereas growth arrest-specific 6 (GAS6) and growth/differentiation factor 6 were decreased by Ang II stimulation. Ang II-stimulated changes of plasminogen activator inhibitor-1, GAS6, cathepsin B, and periostin were validated by Western blot. In conclusion, a novel label-free quantitative analysis of 1D PAGE-LC/MS/MS-based proteomics has been successfully applied to the identification of new potential mediators of Ang II action and may provide an alternative to traditional protein staining methods.

Osteoadherin is upregulated by mature osteoblasts and enhances their in vitro differentiation and mineralization

During the process of differentiation, osteoblasts commit through strictly controlled checkpoints under the influence of several growth factors, cytokines, and extracellular matrix (ECM) proteins. The mineralized tissue-specific ECM component osteoadherin (OSAD) belongs to the small leucine-rich repeat protein family of proteoglycans. Proteoglycans modulate cellular behavior either through the attached glycosaminoglycan chains or by direct protein-protein interactions via the core protein sequences. Leucine-rich repeats have been shown to directly interact with cell-surface receptors such as epidermal growth factor receptor, blocking its ability to bind its ligand. In the present study, we investigated the influence of OSAD on the behavior and maturation of MC3T3E1 osteoblasts. OSAD overexpression and repression clones were created by stably transfecting with plasmids coding for either mouse OSAD cDNA or small-hairpin RNA, targeted against mouse OSAD. Overexpression of OSAD resulted in an increase of osteoblast differentiation features, such as increased alkaline phosphatase (ALP) activity and increased in vitro mineralization, as well as reduced proliferation and migration. Bone sialoprotein (BSP) levels were unchanged, while upregulation of osteocalcin (OC) and osteoglycin (OGN) was observed. Conversely, repression of OSAD expression resulted in increased cell proliferation and migration. BSP and OC were unaffected, while OGN was downregulated. ALP activity was reduced, though no change in in vitro mineralization was observed. We conclude that OSAD overexpression enhanced the differentiation and maturation of osteoblasts in vitro.

A proteomic study of the aortic media in human thoracic aortic dissection: implication for oxidative stress

OBJECTIVE

The aortic media lesion is a key pathologic feature in thoracic aortic dissection. To identify key proteins in aortic media lesions that may contribute to its pathogenesis, we performed proteomic studies to find differentially expressed proteins in the media from diseased and normal thoracic aorta.

METHODS

Ascending aortic segments were obtained from patients with thoracic aortic dissection (n = 8) and age-matched normal donors (n = 6). The differentially expressed proteins of their media tissues were analyzed by 2-dimensional electrophoresis and mass spectrometry, and verified by Western blotting. Oxidative stress was measured by functional assays in a larger sample size (15 patients and 10 controls).

RESULTS

Image analysis of the protein profiles from 2-dimensional gels revealed 126 differentially expressed proteins, of which 26 were identified by mass spectrometry. Among them, extracellular superoxide dismutase, an enzyme involved in oxidative stress, was selected for further studies. Western blotting showed that extracellular superoxide dismutase expression was more than 50% lower in patient samples than in controls (P < .001). Superoxide dismutase activity was consistently decreased (P < .001) and lipid peroxidation was increased (P = .019) in patient media homogenates compared with that in controls.

CONCLUSION

Our results indicate that protein expression profiles in the aortic media from thoracic aortic dissection differ significantly from that of controls, which may provide important insights into the disease mechanisms. This study also suggests that increased oxidative stress may play an important role in the disease.

High expression of osteoglycin decreases the metastatic capability of mouse hepatocarcinoma Hca-F cells to lymph nodes

Osteoglycin, one of the matrix molecules, belongs to the small leucine-rich proteoglycan gene family and might play important roles in cell growth and differentiation and in pathological processes such as fibrosis and cancer growth. In this study, a eukaryotic expression plasmid pIRESpuro3 osteoglycin(+) was constructed and transfected into mouse hepatocarcinoma Hca-F cells to evaluate the contribution of osteoglycin to the malignant behavior of Hca-F. It was found that Hca-F cells transfected with pIRESpuro3 osteoglycin(+) showed significantly decreased potential for both migration and invasion. Furthermore, Hca-F cells transfected with osteoglycin showed decreased metastatic potential to peripheral lymph nodes. However, proliferation potential and adhesive capacity of Hca-F cells to different protein substrates were not influenced by osteoglycin transfection. In summary, high expression of osteoglycin decreases the metastatic capability of Hca-F to lymph nodes.