-
Investigative Ophthalmology & Visual... Dec 2022Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein abundantly expressed in basement membranes and capsules surrounding a variety of...
PURPOSE
Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein abundantly expressed in basement membranes and capsules surrounding a variety of organs and tissues. It mediates extracellular matrix organization and has been implicated in cell contraction. Here, we evaluated the expression of SPARC in the murine lacrimal gland at adulthood and during inflammation.
METHODS
Lacrimal glands of young mice (4-6 weeks old) and adult mice (32-40 weeks old) were used for extraction of DNA, RNA, and protein. The presence of SPARC was assessed by quantitative PCR, ELISA, and immunofluorescence microscopy. 5-Methylcytosine and DNA methylation were evaluated using ELISA and bisulfite genomic sequencing, respectively. The effects of cytokines and inflammation in Sparc expression were evaluated in vitro and in the non-obese diabetic (NOD) mouse model of Sjögren's syndrome.
RESULTS
The mRNA and protein levels of SPARC were downregulated in lacrimal glands of mature adult mice presenting age-related histological alterations such as increased deposition of lipofuscin and lipids. Epigenetic analyses indicated that glands in adult mice contain higher levels of global DNA methylation and show increased hypermethylation of specific CpG sites within the Sparc gene promoter. Analysis of smooth muscle actin (SMA)-green fluorescent protein (GFP) transgenic mice revealed that SPARC localizes primarily to myoepithelial cells within the gland. Treatment of myoepithelial cells with IL-1β or TNF-α and the development of inflammation in the NOD mice led to decreased transcription of Sparc.
CONCLUSIONS
SPARC is a novel matricellular glycoprotein expressed by myoepithelial cells in the lacrimal gland. Loss of SPARC during adulthood and chronic inflammation might have detrimental consequences on myoepithelial cell contraction and the secretion of tear fluid.
Topics: Animals; Mice; Lacrimal Apparatus; Mice, Inbred NOD; Microscopy, Fluorescence; Osteonectin; Inflammation; Age Factors
PubMed: 36479944
DOI: 10.1167/iovs.63.13.8 -
BioMed Research International 2022Secreted protein, acidic and rich in cysteine (SPARC, also known as osteonectin), is a small molecule glycoprotein associated with cell secretions. The purpose of our... (Meta-Analysis)
Meta-Analysis Review
Secreted protein, acidic and rich in cysteine (SPARC, also known as osteonectin), is a small molecule glycoprotein associated with cell secretions. The purpose of our research is to clarify the clinicopathological and prognostic significance of SPARC expression in breast cancer. In this study, we performed a meta-analysis and bioinformatics analysis using the PubMed, Web of Science, Wanfang Data, and CNKI databases. The meta-analysis showed that SPARC expression was elevated in breast cancer tissue, compared with normal tissue, while SPARC expression in tumor stromal cells was higher than that of tumor cells. The expression of SPARC was positively correlated with histological grade and TNM staging. The Kaplan-Meier plotter showed that low SPARC expression was negatively correlated with the overall, postprogression, and distant metastasis survival rates of patients. According to Oncomine database, SPARC expression was upregulated in breast cancer than normal tissues. In TCGA database, univariate analysis showed that lymph node metastasis, distant metastasis, and TNM staging were negatively correlated with patient prognosis in breast cancers. Cox multivariate analysis showed that age, lymph node metastasis, distant metastasis, and TNM staging were important factors affecting the survival time of breast cancer patients. SPARC expression can be employed as a good indicator of prognosis of breast cancer patients, which will provide new methods and ideas of preventive treatment.
Topics: Breast Neoplasms; Computational Biology; Disease Progression; Female; Humans; Osteonectin; Prognosis
PubMed: 35211625
DOI: 10.1155/2022/8600419 -
Blood Mar 1990Our laboratory has previously shown that osteonectin, an abundant noncollagenous bone protein, is contained in and secreted from human platelets. In this study, the...
Our laboratory has previously shown that osteonectin, an abundant noncollagenous bone protein, is contained in and secreted from human platelets. In this study, the distribution of osteonectin both in the supernatant and on the platelet surface after activation was measured by fluid-phase and solid-phase radioimmunoassay, respectively. Total cellular osteonectin was determined by RIA of guanidinium chloride extracted platelets and ranged from 0.65 to 2.2 micrograms/10(8) platelets or 135,000 to 457,000 molecules/platelet. Platelets treated with varying concentrations of collagen and thrombin released osteonectin in a dose-dependent fashion. Approximately 61% of the total platelet osteonectin was secreted at saturating concentrations of collagen and thrombin. A small fraction of platelet osteonectin is expressed on the surface of platelets in an activation-specific manner as evidenced by the specific and saturable binding of [125I]-anti-osteonectin monoclonal antibody, IIIA3A8, to thrombin-activated platelets. Based on a non-linear least squares regression analysis of the antibody binding, 2,200 IIIA3A8 molecules, or 0.8% of the total platelet osteonectin, is expressed on the platelet surface on activation. Platelet osteonectin was purified from the supernatant of thrombin-activated platelets by immunoaffinity chromatography. Western blotting of proteins secreted by washed, thrombin-stimulated platelets with IIIA3A8 indicated that the osteonectin molecule released from the platelet is a single chain polypeptide. Comparison of immunopurified platelet osteonectin with isolated bovine bone osteonectin and isolated human bone osteonectin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that platelet osteonectin has a greater apparent molecular weight than bone osteonectin. The NH2-terminal sequence of immunopurified platelet osteonectin was obtained by automated Edman degradation and is identical to the sequence of human bone osteonectin derived from the cDNA of SaOS-2 cells. Collectively, these data suggest that platelet osteonectin is structurally distinct from bone osteonectin in a region of the molecule at a distance from the NH2-terminus.
Topics: Amino Acid Sequence; Antibodies, Monoclonal; Antigens, Surface; Blood Platelets; Collagen; Humans; Molecular Sequence Data; Molecular Weight; Osteonectin; Platelet Activation; Radioimmunoassay; Thrombin
PubMed: 2306517
DOI: No ID Found -
Cell Communication and Signaling : CCS May 2023Ovarian hyperstimulation syndrome (OHSS) is a serious complication during in vitro fertilization (IVF) treatment. The upregulation of ovarian transforming growth...
TGF-β1 upregulates secreted protein acidic and rich in cysteine expression in human granulosa-lutein cells: a potential mechanism for the pathogenesis of ovarian hyperstimulation syndrome.
BACKGROUND
Ovarian hyperstimulation syndrome (OHSS) is a serious complication during in vitro fertilization (IVF) treatment. The upregulation of ovarian transforming growth factor-beta 1 (TGF-β1) is involved in the development of OHSS. The secreted protein acidic and rich in cysteine (SPARC) is a secreted multifunctional matricellular glycoprotein. Although the regulatory effects of TGF-β1 on SPARC expression have been reported, whether TGF-β1 regulates SPARC expression in the human ovary remains unknown. In addition, the role of SPARC in the pathogenesis of OHSS is unclear.
METHODS
A steroidogenic human ovarian granulosa-like tumor cell line, KGN, and primary culture of human granulosa-lutein (hGL) cells obtained from patients undergoing IVF treatment were used as experimental models. OHSS was induced in rats, and ovaries were collected. Follicular fluid samples were collected from 39 OHSS and 35 non-OHSS patients during oocyte retrieval. The underlying molecular mechanisms mediating the effect of TGF-β1 on SPARC expression were explored by a series of in vitro experiments.
RESULTS
TGF-β1 upregulated SPARC expression in both KGN and hGL cells. The stimulatory effect of TGF-β1 on SPARC expression was mediated by SMAD3 but not SMAD2. The transcription factors, Snail and Slug, were induced in response to the TGF-β1 treatment. However, only Slug was required for the TGF-β1-induced SPARC expression. Conversely, we found that the knockdown of SPARC decreased Slug expression. Our results also revealed that SPARC was upregulated in the OHSS rat ovaries and in the follicular fluid of OHSS patients. Knockdown of SPARC attenuated the TGF-β1-stimulated expression of vascular endothelial growth factor (VEGF) and aromatase, two markers of OHSS. Moreover, the knockdown of SPARC reduced TGF-β1 signaling by downregulating SMAD4 expression.
CONCLUSIONS
By illustrating the potential physiological and pathological roles of TGF-β1 in the regulation of SPARC in hGL cells, our results may serve to improve current strategies used to treat clinical infertility and OHSS. Video Abstract.
Topics: Female; Humans; Animals; Rats; Ovarian Hyperstimulation Syndrome; Cysteine; Osteonectin; Transforming Growth Factor beta1; Luteal Cells; Vascular Endothelial Growth Factor A
PubMed: 37158892
DOI: 10.1186/s12964-023-01123-2 -
Journal of Cellular Biochemistry Sep 2009The matricellular protein osteonectin, secreted protein acidic and rich in cysteine (SPARC, BM-40), is the most abundant non-collagenous matrix protein in bone....
The matricellular protein osteonectin, secreted protein acidic and rich in cysteine (SPARC, BM-40), is the most abundant non-collagenous matrix protein in bone. Matricellular proteins play a fundamental role in the skeleton as regulators of bone remodeling. In the skeleton, osteonectin is essential for the maintenance of bone mass and for balancing bone formation and resorption in response to parathyroid hormone (PTH). It promotes osteoblast differentiation and cell survival. Mechanisms regulating the expression of osteonectin in the skeleton and in other tissues remain poorly understood. We found that the proximal region of the mouse osteonectin 3' untranslated region (UTR) contains a well-conserved, dominant regulatory motif that interacts with microRNAs (miRs)-29a and -29c. Transfection of osteoblastic cells with miR-29a inhibitors increased osteonectin protein levels, whereas transfection of miR-29a precursor RNA decreased osteonectin. miR-29a and -29c were increased during osteoblastic differentiation in vitro. The up-regulation of these miRNAs correlated with decreased osteonectin protein during the matrix maturation and mineralization phases of late differentiation. In contrast, osteonectin transcript levels remained relatively constant during this process, implying repression of translation. Treatment of osteoblasts with LiCl induced miR-29a and -29c expression and decreased osteonectin synthesis. When cells were treated with Dickkopf-1 (Dkk-1), miR-29a and -29c expression was repressed. These data suggest that canonical Wnt signaling, which is increased during osteoblastic differentiation, induces expression of miR-29. Osteonectin and miR-29 are co-expressed in extra-skeletal tissues, and the post-transcriptional mechanisms regulating osteonectin in osteoblasts are likely to be active in other cell systems.
Topics: Animals; Base Sequence; Cell Differentiation; Mice; Mice, Inbred C57BL; MicroRNAs; Molecular Sequence Data; Osteoblasts; Osteonectin; Signal Transduction; Wnt Proteins
PubMed: 19565563
DOI: 10.1002/jcb.22243 -
Blood Dec 1992Osteonectin is an adhesive, cell, and extracellular matrix-binding glycoprotein found primarily in the matrix of bone and in blood platelets in vivo. Osteonectins... (Comparative Study)
Comparative Study
Osteonectin is an adhesive, cell, and extracellular matrix-binding glycoprotein found primarily in the matrix of bone and in blood platelets in vivo. Osteonectins isolated from these two sources differ with respect to the complexity of their constituent N-linked oligosaccharide. In this study, osteonectin synthesized by bone-forming cells (osteoblasts) and platelet-producing cells (megakaryocytes) in vitro was analyzed to determine if the proteins produced were analogous in terms of glycosylation to those isolated from bone and platelets, respectively. Immunoblot analyses of osteonectin produced by the osteoblast-like cell lines, SaOS-2 and MG-63, indicated that secreted and intracellular forms of the molecule are structurally distinct. Endoglycosidase treatment and immunoblotting of osteonectin secreted from SaOS-2 and MG-63 cells, under serum-deprived conditions, suggested that the molecule possessed a complex type oligosaccharide unlike the high-mannose moiety found on bone matrix-derived osteonectin. Biosynthetic labeling of SaOS-2 cells and human megakaryocytes indicated that both cell types synthesize osteonectin de novo. Electrophoretic and glycosidase sensitivity analyses of [35S]-osteonectin isolated from lysates of metabolically labeled SaOS-2 cells and megakaryocytes indicated that these two cell types synthesize osteonectin molecules that are identical in oligosaccharide structure to the isolated bone and platelet proteins. These data suggest that the intracellular form of the osteonectin molecule is glycosylated differently in SaOS-2 cells and megakaryocytes but that the extracellular form which is secreted from platelets in vivo and osteoblasts in vitro is characterized by the presence of a complex type N-linked oligosaccharide.
Topics: Adult; Blood Platelets; Bone Marrow; Bone Marrow Cells; Carbohydrate Sequence; Cell Line; Cells, Cultured; Electrophoresis, Polyacrylamide Gel; Endothelium, Vascular; Glycoside Hydrolases; Humans; Megakaryocytes; Molecular Sequence Data; Molecular Weight; Osteoblasts; Osteonectin; Osteosarcoma; Umbilical Veins
PubMed: 1467517
DOI: No ID Found -
Investigative Ophthalmology & Visual... Aug 2000Osteonectin/SPARC is a secreted protein that has been implicated in ocular disease. Deletion of osteonectin/SPARC causes age-onset cataract in mice and the cataractous...
PURPOSE
Osteonectin/SPARC is a secreted protein that has been implicated in ocular disease. Deletion of osteonectin/SPARC causes age-onset cataract in mice and the cataractous human lens has increased expression of osteonectin/SPARC. In this study, the expression and localization of osteonectin/SPARC in the monkey retina were determined as was secretion by cultured human retinal pigment epithelial (RPE) cells.
METHODS
Adult Rhesus monkey eyes (Macaca mulatta) were dissected, and 5-mm macula and peripheral retina punches were obtained. Supernatants were collected from cultured human RPE cells. Subcellular fractionation of whole monkey retina was also performed. Osteonectin/SPARC expression and/or secretion was monitored by Northern and Western blot analyses, and localization was determined by immunocytochemistry.
RESULTS
Outside of the retina osteonectin/SPARC mRNA is broadly expressed in many human tissues. Northern blot analysis shows that in the retina osteonectin/SPARC is expressed almost exclusively by the macular RPE/choroid. Western blot analysis revealed osteonectin/SPARC in both the macula and the peripheral neural retina but only in trace amounts in the RPE/choroid. In subcellular fractions of the whole retina, osteonectin/SPARC was detected, mainly in the soluble fraction but also in the membrane and nuclear fractions. Immunohistochemical analysis localized osteonectin/SPARC specifically to the outer plexiform layer. Western blot analysis of conditioned medium from human RPE cells cultured on porous substrates indicated that osteonectin/SPARC is secreted in large amounts from both the apical and basal sides of the RPE.
CONCLUSIONS
Collectively these data provide evidence that osteonectin/SPARC is synthesized in the macular RPE, secreted, and subsequently transported to the outer plexiform layer. The expression pattern of osteonectin/SPARC in the subcellular retinal fractions is consistent with a soluble protein that is transported and internalized.
Topics: Animals; Biological Transport; Blotting, Northern; Blotting, Western; Cells, Cultured; DNA Primers; Electrophoresis, Polyacrylamide Gel; Eye Proteins; Immunoenzyme Techniques; Macaca mulatta; Osteonectin; Pigment Epithelium of Eye; RNA, Messenger; Retina; Subcellular Fractions
PubMed: 10937551
DOI: No ID Found -
The International Journal of... Mar 2012The SPARC family of proteins represents a diverse group of proteins that modulate cell interaction with the extracellular milieu. The eight members of the SPARC protein... (Review)
Review
The SPARC family of proteins represents a diverse group of proteins that modulate cell interaction with the extracellular milieu. The eight members of the SPARC protein family are modular in nature. Each shares a follistatin-like domain and an extracellular calcium binding E-F hand motif. In addition, each family member is secreted into the extracellular space. Some of the shared activities of this family include, regulation of extracellular matrix assembly and deposition, counter-adhesion, effects on extracellular protease activity, and modulation of growth factor/cytokine signaling pathways. Recently, several SPARC family members have been implicated in human disease pathogenesis. This review discusses recent advances in the understanding of the functional roles of the SPARC family of proteins in development and disease.
Topics: Animals; Cell Adhesion; Cytokines; EF Hand Motifs; Extracellular Matrix Proteins; Follistatin; Humans; Intercellular Signaling Peptides and Proteins; Neoplasms; Neovascularization, Pathologic; Osteonectin; Protein Folding; Protein Multimerization
PubMed: 22249026
DOI: 10.1016/j.biocel.2011.12.021 -
The American Journal of Pathology Sep 1997Osteonectin/SPARC is a glycoprotein involved in the regulation of cell shape, adhesion, migration, and proliferation. It also has complex effects on extracellular matrix...
Osteonectin/SPARC is a glycoprotein involved in the regulation of cell shape, adhesion, migration, and proliferation. It also has complex effects on extracellular matrix synthesis and turnover. We found that osteonectin mRNA was very abundant in a human liver myofibroblast library. Using Northern and Western blot, immunoprecipitation, and radioimmunoassay, we found that cultured liver myofibroblasts actively secreted osteonectin. Myofibroblasts are very rare in normal liver but proliferate during liver fibrosis where they synthesize extracellular matrix components. Thus, we studied the distribution of osteonectin in normal and fibrotic human liver using in situ hybridization. Osteonectin mRNA expression was weak in normal liver but very high in fibrotic liver within fibrous septae and scattered sinusoidal cells. Serial sectioning and double staining experiments with an antibody to smooth muscle alpha-actin showed that osteonectin transcripts were mostly co-localized with myofibroblasts. In conclusion, osteonectin is highly expressed in human liver myofibroblasts in culture as well as in human liver fibrosis in vivo. The many biological properties of osteonectin make it a candidate effector of human liver fibrogenesis.
Topics: Actins; Blotting, Northern; Cells, Cultured; Humans; Immunoblotting; Immunohistochemistry; In Situ Hybridization; Liver; Liver Cirrhosis; Osteonectin; RNA, Messenger
PubMed: 9284812
DOI: No ID Found -
Biomolecules Jan 2023Intracranial hypertension (ICP) and visual impairment intracranial pressure (VIIP) are some of the consequences of long-term space missions. Here we examined the...
Intracranial hypertension (ICP) and visual impairment intracranial pressure (VIIP) are some of the consequences of long-term space missions. Here we examined the behavior of oligodendrocyte progenitors (OLPs) after space flight using time-lapse microscopy. We show that most OLPs divided more than ground control (GC) counterparts did. Nonetheless, a subpopulation of OLPs flown to space presented a significant increase in autophagic cell death. Examination of the proteomic profile of the secretome of space flown OLPs (SPC-OLPs) revealed that the stress protein heat shock protein-90 beta "HSP-90β" was the 5 most enriched (6.8 times) and the secreted protein acidic and rich in cysteine "SPARC" was the 7 most enriched (5.2 times), with respect to ground control cells. SPARC induces endoplasmic reticulum stress, which leads to autophagy. Given the roles and importance of these two proteins in mammalian cells' metabolism, their upregulation may hold the key to modulating cell proliferation and autophagy, in order to mitigate ICP and VIIP during and after space missions.
Topics: Animals; Osteonectin; Oligodendrocyte Precursor Cells; Proteomics; Space Flight; Autophagy; Cell Proliferation; Mammals
PubMed: 36830573
DOI: 10.3390/biom13020201