Monoclonal Nonspecific Suppressor Factor Research Articles

Investigating the regulatory mechanism of glucose metabolism by ubiquitin-like protein MNSFβ.

Monoclonal nonspecific suppressor factor β (MNSFβ), a ubiquitously expressed member of the ubiquitin-like protein family, is associated with diverse cell regulatory functions. It has been implicated in glycolysis regulation and cell proliferation enhancement in the macrophage-like cell line Raw264.7. This study aims to show that HIF-1α regulates MNSFβ-mediated metabolic reprogramming. In Raw264.7 cells, MNSFβ siRNA increased the oxygen consumption rate and reactive oxygen species (ROS) production but decreased ATP levels. Cells with MNSFβ knockdown showed a markedly increased ATP reduction rate upon the addition of oligomycin, a mitochondrial ATP synthase inhibitor. In addition, MNSFβ siRNA decreased the expression levels of mRNA and protein of HIF-1α-a regulator of glucose metabolism. Evaluation of the effect of MNSFβ on glucose metabolism in murine peritoneal macrophages revealed no changes in lactate production, glucose consumption, or ROS production. MNSFβ affects both glycolysis and mitochondrial metabolism, suggesting HIF-1α involvement in the MNSFβ-regulated glucose metabolism in Raw264.7 cells.

Ubiquitin-like protein MNSFβ regulates glycolysis and promotes cell proliferation with HSC70 assistance

Monoclonal non-specific suppressor factor β (MNSFβ) is a universally expressed ubiquitin-like protein that has multiple biological functions. MNSFβ modifies its target molecules through covalent conjugation. Most recently, we identified a molecular chaperone, HSC70, that facilitates the stabilization of aggregable MNSFβ. In the current study, we determined the role of HSC70 in stabilizing unstable MNSFβ. HSC70 promoted the correct folding of MNSFβ both in vitro and in vivo. We also examined the regulatory function of MNSFβ in cell proliferation and glycolysis. MNSFβ siRNA and HSC70 siRNA treatment attenuated lactate release from Raw264.7 macrophage-like cells. MNSFβ siRNA inhibited glucose uptake in Raw264.7 cells. We found that glucose transporter 1 (GLUT1) is an important membrane protein involved in the regulatory function of MNSFβ during glycolysis. MNSFβ siRNA inhibited the increased GLUT1 expression in LPS-stimulated cells, suggesting that MNSFβ controls the inflammatory response through GLUT1 regulation. We identified several important molecules, including lactate dehydrogenase A, which are regulated by MNSFβ and involved in glucose metabolism. Here we firstly report that MNSFβ regulates glycolysis and promotes cell proliferation.

Quercetin and HSC70 coregulate the anti-inflammatory action of the ubiquitin-like protein MNSFβ.

Quercetin is a flavonol that modifies many cellular processes. Monoclonal nonspecific suppressor factor β is a member of the ubiquitin-like family of proteins that are involved in various biological processes. It has been demonstrated that quercetin regulates the effect of MNSFβ on tumor necrosis factor-α secretion in lipopolysaccharide (LPS)-stimulated macrophages. This study found that quercetin and the heat shock protein HSC70 coregulate the action of MNSFβ. Quercetin dose-dependently suppressed the LPS/interferon γ-induced nitric oxide production without cytotoxicity in the macrophage-like cell line Raw264.7. SiRNA knockdown experiments showed that quercetin inhibited the MNSFβ and HSC70 siRNA-mediated enhancement of TNFα and the production of RANTES, a member of C-C chemokine superfamily, in LPS-stimulated Raw264.7 cells. Western blot analysis showed that quercetin and HSC70 regulated ERK1/2 activation and LPS-stimulated IκBα degradation by affecting the complex formation of MNSFβ and the proapoptotic protein Bcl-G. Moreover, MNSFβ is implicated in TLR4/MyD88 signaling but not in TLR3 signaling. HSC70 is an important chaperone that facilitates the stabilization of MNSFβ. Quercetin may negatively control the function of MNSFβ by regulating the action of the molecular chaperone HSC70. MNSFβ mediates TLR4/Myd88 signaling but not TLR3 signaling.

MNSFβ regulates placental development by conjugating IGF2BP2 to enhance trophoblast cell invasiveness.

ObjectivesSuccess in pregnancy in mammals predominantly depends on a well‐developed placenta. The differentiation of invasive trophoblasts is a fundamental process of placentation, the abnormalities of which are tightly associated with pregnancy disorders including preeclampsia (PE). Monoclonal nonspecific suppressor factor beta (MNSFβ) is an immunosuppressive factor. Its conventional knockout in mice induced embryonic lethality, whereas the underlying mechanism of MNSFβ in regulating placentation and pregnancy maintenance remains to be elucidated.MethodsTrophoblast‐specific knockout of MNSFβ was generated using Cyp19‐Cre mice. In situ hybridization (ISH), haematoxylin and eosin (HE), immunohistochemistry (IHC) and immunofluorescence (IF) were performed to examine the distribution of MNSFβ and insulin‐like growth factor 2 mRNA‐binding protein 2 (IGF2BP2) at the foeto‐maternal interface. The interaction and expression of MNSFβ, IGF2BP2 and invasion‐related molecules were detected by immunoprecipitation (IP), immunoblotting and quantitative real‐time polymerase chain reaction (qRT‐PCR). The cell invasion ability was measured by the Transwell insert assay.ResultsWe found that deficiency of MNSFβ in trophoblasts led to embryonic growth retardation by mid‐gestation and subsequent foetal loss, primarily shown as apparently limited trophoblast invasion. In vitro experiments in human trophoblasts demonstrated that the conjugation of MNSFβ with IGF2BP2 and thus the stabilization of IGF2BP2 essentially mediated the invasion‐promoting effect of MNSFβ. In the placentas from MNSFβ‐deficient mice and severe preeclamptic (PE) patients, downregulation of MNSFβ was evidently associated with the repressed IGF2BP2 expression.ConclusionsThe findings reveal the crucial role of MNSFβ in governing the trophoblast invasion and therefore foetal development, and add novel hints to reveal the placental pathology of PE.

MNSFβ Promotes the Proliferation and Migration of Human Extravillous Trophoblast Cells and the Villus Expression Level of MNSFβ Is Decreased in Recurrent Miscarriage Patients

Aims: The invasion of extravillous trophoblast (EVT) cells into maternal decidua is essential for the establishment and maintenance of pregnancy. Derangement of EVT cell invasion might cause pregnancy complications including recurrent miscarriage (RM). We previously reported that deficiency of monoclonal nonspecific suppressor factor beta (MNSFβ) led to the early pregnancy failure in mice and the decidual MNSFβ expression level in RM patients was significantly decreased, but the underlying molecular mechanism of the role that MNSFβ played at the maternal-fetal interface remains unclear. Thus, in the present study, we determined effects of downregulated MNSFβ expression on human EVT cell activities. Methods: The MNSFβ expression in first-trimester human decidual and placental villus tissues was detected, respectively, by immunofluorescence or immunohistochemical analyses. The MNSFβ expression level in the immortalized first-trimester human EVT cell line HTR8/SVneo was downregulated by transfecting the small interfering RNA against MNSFβ and upregulated by transfecting the recombinant pDsRed-MNSFβ plasmids. The proliferation, migration, invasion, and apoptosis activities of HTR8/SVneo cells were, respectively, determined by cytometry assay, scratch test, transwell assay, and FITC/PI staining. The expression levels of P53, RhoA, Bcl-2, Bax, and MMP-9 in HTR8/SVneo cells, as well as the expression levels of MNSFβ and RhoA in placental villi of RM patients and physically normal pregnant women (NP), were examined by Western blot analysis. Results: MNSFβ protein signals were observed in first-trimester human villus and extravillous trophoblast cells. The downregulated MNSFβ expression significantly attenuated the proliferation, migration, and invasion abilities of HTR8/SVneo cells, accompanied with the obviously decreased expression levels of P53, RhoA, Bcl-2, Bax, and MMP-9, whereas the upregulated MNSFβ expression in HTR8/SVneo cells represented the inverse effects. Furthermore, expression levels of MNSFβ and RhoA in first-trimester human placental villus tissues of RM patients were significantly decreased compared to that of NP women. Conclusion: These data suggested that MNSFβ promotes proliferation and migration of human EVT cells, probably via the P53 signaling pathway, and the deficiency of MNSFβ in placental villi might lead to early pregnancy loss by reducing proliferation and invasion activities of EVTs.

Porcine ubiquitin-like protein MNSFβ promotes cell apoptosis and covalently binds to BCL-G to enhance staurosporine-induced apoptosis.

BackgroundMonoclonal non-specific suppressor factor β (MNSFβ) is a ubiquitously expressed member of the ubiquitin-like family. It functions as a regulator of cell apoptosis and a potential tumor suppressor, playing a vital role in the processes of immune cell function and apoptosis.MethodsThe present study constructed GFP-pMNSFβ swine umbilical vein endothelial cell (SUVEC) lines and investigated the function of porcine MNSFβ (pMNSFβ) in apoptosis, as well as its interactions with pBCL-G. Results revealed that stably expressed pMNSFβ protein in SUVEC lines significantly enhanced staurosporine (STS)-induced apoptosis. pMNSFβ proteins interacted with pBCL-G proteins and the expression of these interacting proteins synergized to further enhance STS-induced apoptosis.ResultsGFP-pMNSFβ stably expressed SUVEC lines through transient transfection and neomycin screening methods. Over 90% of the SUVEC cultures expressed GFP signals, and 41.5 kDa GFP-pMNSFβ proteins were detected with western blotting methods. Annexin V-PE/PI staining and flow cytometry analyses showed that overexpression of pMNSFβ proteins significantly elevated STS-induced apoptosis rates. Co-immunoprecipitation methods revealed an interaction between pMNSFβ and pBCL-G proteins. BCL-G is a proapoptotic member of the BCL-2 family that has been shown to be misexpressed in human systemic lupus erythematosus, as well as mammary and prostate cancers. Here, we demonstrated that the co-expression and potential conjugation of pMNSFβ and pBCL-G proteins synergistically enhanced STS-induced apoptosis.ConclusionsThe present study was the first to characterize the function of MNSFβ in porcine cells, and to clarify the function of MNSFβ in apoptosis. These results reveal that pMNSFβ is a potential molecular model for future investigations of diseases related to human MNSFβ dysfunction.

Heat shock protein 60 negatively regulates the biological functions of ubiquitin-like protein MNSFβ in macrophages.

Monoclonal nonspecific suppressor factor β (MNSFβ) is a ubiquitously expressed ubiquitin-like protein known to be involved in various biological functions. Previous studies have demonstrated that MNSFβ covalently modify its target proteins including Bcl-G, a proapoptotic protein. In this study, we purified a 65kDa MNSFβ adduct from mouse liver lysates by sequential chromatography on DEAE and glutathione S-transferase (GST)-fusioned MNSFβ immobilized on glutathione-Sepharose beads in the presence of ATP. MALDI-TOF mass spectrometry fingerprinting revealed that this MNSFβ adduct consists of an 8.5kDa MNSFβ and heat shock protein 60 (HSP60), a mitochondrial protein involved in protein folding. Fingerprinting analysis of the MNSFβ adduct demonstrates that MNSFβ conjugates to HSP60 with a linkage between the C-terminal Gly74 and Lys481. HSP60 siRNA neutralized the inhibition of apoptosis by MNSFβ siRNA in LPS/IFNγ-stimulated Raw264.7, a murine macrophage cell line. HSP60 siRNA also down-regulated the enhancement of TNFα production by MNSFβ siRNA in LPS-stimulated Raw264.7 cells. Here, we firstly report that MNSFβ activity is negatively regulated by molecular chaperone.

Deficiency of monoclonal non-specific suppressor factor beta (MNSFB) promotes pregnancy loss in mice.

Maternal immune tolerance to the semi-allogenic fetus is required for successful pregnancy in mammals. Monoclonal nonspecific suppressor factor beta (MNSFB) is an immunosuppressive factor present in uterine epithelial and stromal cells, as well as in macrophages and T cells. Although the functional neutralization of MNSFB using specific antibodies against it lead to failed embryo implantation in mice, the exact role of MNSFB at the fetal-maternal interface remains unclear. The present study generated conditional heterozygous Mnsfb-deficient (Mnsfb(+/) (-) ) mice using the LoxP/Cre system. Western-blot analyses showed that uterine MNSFB protein in Mnsfb(+/-) mice was remarkably down-regulated compared to that in the wild-type (Mnsfb(+/+) ) mice. The litter size of female Mnsfb(+/-) mice was significantly reduced, which corresponded to developmental failure of embryos beyond Day 11 of pregnancy. The expression level of MNSFB protein was also lower in the failing compared to the normal embryos. An aberrant interaction between the embryos of Day-4 pregnant wild-type mice and endometrial stromal cells of female Mnsfb(+/-) mice was observed in vitro. The uterine Day-5 abundance of P53, BAX, and BCL-G in pregnant Mnsfb(+/-) mice was significantly decreased compared to that of wild-type mice, whereas the expression of P27 and tumor necrosis factor alpha (TNFA) was elevated. By comparison, the levels of MNSFB and BAX proteins in human decidual tissues obtained from recurrent spontaneous miscarriage patients were significantly reduced compared to those obtained from legal medial abortion, highlighting the involvement of MNSFB in the pathogenesis of recurrent spontaneous miscarriage. Together, these results demonstrated that a deficiency in MNSFb is associated with pregnancy loss, probably through reduced P53 and/or increased TNFA production at the fetal-maternal interface.

Deficiency of monoclonal nonspecific suppressor factor beta (MNSF[beta]) gene leaded to the early loss of pregancy in mice

Deficiency of monoclonal nonspecific suppressor factor beta (MNSF[beta]) gene leaded to the early loss of pregancy in mice

Ubiquitin-like protein MNSFβ negatively regulates T Cell function and survival

Monoclonal non-specific suppressor factor β (MNSFβ) is a ubiquitously expressed member of the ubiquitin-like family that is involved in various biological functions. Previous studies have demonstrated that MNSFβ covalently binds to intracellular pro-apoptotic protein Bcl-G and regulates apoptosis in macrophages. In this study, we demonstrate that MNSFβ negatively regulates T cell function. In murine T-helper type 2 clone, D10.G4.1 (D10) cells transfected with MNSFβ cDNA, CD3/CD28-induced ERK1/2 phosphorylation leading to IL-4 production was significantly inhibited. The formation of MNSFβ-Bcl-G complex was induced by the CD3/CD28 stimulation. Co-transfection with MNSFβ and Bcl-G greatly enhanced CD3/CD28-induced apoptosis in D10 cells. Similarly, co-over-expression of MNSFβ and Bcl-G caused a marked enhancement of apoptosis in purified splenic T cells. Interestingly, this MNSFβ adduct was also induced in T cells derived from DO11.10 mice stimulated with antigen. Collectively, CD3/CD28-inducible MNSFβ-Bcl-G complex may be involved in the regulation of T cell function and survival.

Cloning, eukaryotic expression and spatial expression patterns of porcine MNSFβ

MNSFbeta (Monoclonal nonspecific suppressor factor beta) is a natural immunosuppressive factor which has been reported to be involved in various biological processes, such as immune responses, cell division, stress response, cell apoptosis, and nuclear transport. However, study on porcine MNSFbeta has been rarely reported. In this study, the full-length sequence of porcine MNSFbeta (GenBank accession number: KF77642500) was predicted in silicon and its cDNA sequence was obtained through RT-PCR from porcine spleen. The nucleic acid and protein sequences were analyzed. Then, the gene was subcloned into pEGFP-C1 to construct a recombinant plasmid pEGFP-MNSFbeta which was transfected into swine umbilical vein endothelial cells (SUVECs) using Lipofectamine 2000. The expression of GFP was detected by fluorescence microscopy, Western blot, and laser confocal fluorescence microscopy. The spatial expression patterns of porcine MNSFbeta were detected by real-time qPCR. Results showed that the full length of porcine MNSFbeta was 402 bp encoding 133 amino acids with only one exon. Bioinformatics analysis showed that porcine MNSFbeta protein was a stable protein consisting of a ubiquitin-like domain fused to the ribosomal protein S30 with no signal peptide. The analyses of homology and phylogenetic tree of porcine MNSFbeta and its homologs in other 18 species showed that the identities of MNSFbeta protein sequence were higher than 91% among different species and the evolutionary distance was less than 0.05. It indicates that MNSFbeta is highly conserved in the process of evolution. Fluorescence signal showed that the fusion protein GFP-MNSFbeta was successfully expressed in SUVECs which was then confirmed by Western blot. Laser confocal fluorescence microscopy showed that MNSFbeta was expressed in both nucleus and cytoplasm. Analysis of spatial expression patterns showed that procine MNSFbeta was widely expressed in immune tissues, but not in lung, suggesting that MNSFbeta may play an important role in immune response.

Ubiquitin‐like protein MNSFβ covalently binds to Bcl–G and enhances lipopolysaccharide/interferon γ‐induced apoptosis in macrophages

Monoclonal non-specific suppressor factor β (MNSFβ) is a ubiquitously expressed member of the ubiquitin-like family that is involved in various biological functions. Previous studies have demonstrated that MNSFβ covalently binds to intracellular pro-apoptotic protein Bcl-G and regulates the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) cascade in the mouse macrophage cell line Raw264.7. In this study, we demonstrate that MNSFβ promotes lipopolysaccharide (LPS)/interferon γ (IFNγ)-induced apoptosis of Raw264.7 macrophages. In Raw264.7 cells treated with MNSFβ small interfering RNA (siRNA), LPS/IFNγ- or NO donor S-nitrosoglutathione-induced apoptosis was inhibited. siRNA-mediated knockdown of MNSFβ did not affect inducible nitric-oxide synthase (iNOS) expression in LPS/IFNγ-stimulated Raw264.7 cells. Conversely, co-transfection with MNSFβ and Bcl-G greatly enhanced LPS/IFNγ- induced apoptosis in Raw264.7 cells, accompanied by increased expression of p53 and decreased Cox-2 activity. Unlike co-transfection with wild-type MNSFβ, co-transfection of a mutant MNSFβ (G74A) and Bcl-G did not result in enhancement of LPS/IFNγ-induced apoptosis. Co-over-expression of MNSFβ and Bcl-G reduced S-nitrosoglutathione-induced ERK1/2 phosphorylation. Furthermore, electrophoretic mobility shift assay experiments revealed that MNSFβ down-regulates the ERK/activator protein 1 (AP-1) signaling cascade which leads to Cox-2 activation. We also observed that MNSFβ-Bcl-G promotes LPS/IFNγ-induced apoptosis of mouse peritoneal macrophages, together with a decrease in Cox-2 expression. Taken together, our data indicate an apoptosis-enhancing effect of MNSFβ-Bcl-G is due in part to down-regulation of Cox-2 activation in macrophages.

Ubiquitin-like protein MNSFβ regulates TLR-2-mediated signal transduction

Post-translational modification by monoclonal nonspecific suppressor factor β (MNSFβ) has been involved in the regulation of a variety of cellular processes. Previous studies have demonstrated that MNSFβ covalently binds to the intracellular pro-apoptotic protein Bcl-G and regulates TLR-4-mediated signal transduction. Recently, we found that MNSFβ also covalently conjugates to endophilin II, a member of the endophilin A family, and inhibits the signal pathway upstream of IKK activation, but not downstream of TLR-2 signaling. In this study, we further examined the mechanism of action of MNSFβ in TLR-2-mediated signal transduction in macrophage-like cell line Raw264.7 cells. Although MNSFβ siRNA enhanced Pam(3)CDK(4) (TLR-2-specific ligand)-stimulated TNFα production, Bcl-G siRNA did not affect. MNSFβ cDNA inhibited the Pam(3)CDK(4)-stimulated TNFα production. High-molecular weight (130 kDa) MNSFβ-adduct was induced in Pam(3)CDK(4)-stimulated Raw264.7 cells. This MNSFβ-adduct was not induced by LPS, indicative of the specificity of TLR-2-mediated signal transduction. Similar observations were seen in BALB/c peritoneal macrophages. Interestingly, 40-kDa MNSFβ-adduct was tyrosine phosphorylated by Pam(3)CDK(4) stimulation. Collectively, novel MNSFβ-adducts may regulate TLR-2 signaling pathway in macrophages.

Immunosuppressive Factor MNSFβRegulates Cytokine Secretion by Mouse Lymphocytes and Is Involved in Interactions between the Mouse Embryo and Endometrial CellsIn Vitro

Immune tolerance at the fetomaternal interface must be established during the processes of implantation and pregnancy. Monoclonal nonspecific suppressor factor beta (MNSFβ) is a secreted protein that possesses antigen-nonspecific immune-suppressive function. It was previously reported that intrauterine immunoneutralization of MNSFβsignificantly inhibited embryo implantation in mice. In the present study, MNSFβprotein expression was up- or downregulated by overexpression or RNA interference, respectively, in HCC-94 cells and the culture supernatants used to determine effects of MNSFβon the secretion of IL-4 and TNFαfrom mouse lymphocytes as detected by ELISA. A coculture model of mouse embryos and endometrial stromal cells was also utilized to determine the effects of a specific anti-MNSFβantibody on hatching and growth of embryosin vitro. The results show that MNSFβinduced secretion of IL-4 and inhibited secretion of TNFαfrom mouse lymphocytes. Following immunoneutralization of MNSFβprotein in the HCC-94 supernatant, the stimulatory effect of MNSFβon IL-4 secretion from mouse lymphocytes was reduced, while the inhibitory effect on secretion of TNFαwas abrogated. Expression of MNSFβwas detected in both embryonic and endometrial stromal cells, and its immunoneutralization inhibited the hatching and spreading of embryos in anin vitrococulture model. These results indicated that MNSFβmay play critical roles during the peri-implantation process by regulating cytokine secretion of lymphocytes and by mediating the crosstalk between embryonic cells and endometrial stromal cells.

Ubiquitin-like protein MNSFβ/endophilin II complex regulates Dectin-1-mediated phagocytosis and inflammatory responses in macrophages

Post-translational modification by monoclonal nonspecific suppressor factor β (MNSFβ) has been implicated in the regulation of a variety of cellular events. Previous studies have demonstrated that MNSFβ covalently binds to the intracellular pro-apoptotic protein Bcl-G in a macrophage cell line, Raw264.7, suggesting involvement of this ubiquitin-like protein in apoptosis. Most recently, we found that MNSFβ covalently conjugates to endophilin II, a member of the endophilin A family, and inhibits phagocytosis by macrophages. In this study, we further examined the mechanism of action of MNSFβ/endophilin II complex in the phagocytosis of zymosan. MNSFβ/endophilin II I mediated inhibition of phagocytosis in Raw264.7 cells was neutralized by anti-Decti-1, β-glucan receptor, mAb, indicating that MNSFβ/endophilin II is a mediator of Dectin-1 signaling in regulating phagocytosis. The β-glucan-dependent TNFα response to zymosan was significantly increased by the treatment with endophilin II siRNA and/or MNSFβ siRNA. Conversely, cotransfection of endophilin II and MNSFβ cDNAs inhibited the enhancement of zymosan-induced TNFα production. Interestingly, endophilin II siRNA did not affect Pam3CSK4 (TLR2 specific ligand)-induced TNFα production. Endophilin II and/or MNSFβ siRNA enhanced zymosan-induced IκBα degradation. Together, these results demonstrate that MNSFβ/endophilin II inhibits the signal pathway upstream of IKK activation, but not downstream of TLR2 signaling.

The ubiquitin‐like protein monoclonal nonspecific suppressor factor β conjugates to endophilin II and regulates phagocytosis

Monoclonal nonspecific suppressor factor beta (MNSFbeta) is a ubiquitously expressed member of the ubiquitin-like family that has been implicated in various biological functions. Previous studies have demonstrated that MNSFbeta covalently binds to the intracellular proapoptotic protein Bcl-G in cells of the macrophage cell line Raw264.7, suggesting involvement of this ubiquitin-like protein in apoptosis. In this study, we purified a 62 kDa MNSFbeta adduct from murine liver lysates by sequential chromatography on DEAE and anti-MNSFbeta IgG-conjugated Sepharose. MALDI-TOF MS fingerprinting revealed that this MNSFbeta adduct consists of an 8.5 kDa MNSFbeta and endophilin II, a member of the endophilin A family. MNSFbeta may conjugate to endophilin II with a linkage between the C-terminal Gly74 and Lys294. We confirmed this result by immunoprecipitation/western blot studies. Endophilin II was ubiquitously expressed in various tissues, although a truncated form was observed in liver. The 62 kDa MNSFbeta-endophilin II was specifically expressed in liver and macrophages. Small interfering RNA-mediated knockdown of endophilin II and/or MNSFbeta promoted phagocytosis of zymosan in Raw264.7 cells. Conversely, cotransfection of endophilin II and MNSFbeta cDNAs inhibited the phagocytosis of zymosan. Such inhibition was not observed in cells expressing a mutant of endophilin II in which Lys294 was replaced by arginine. These results suggest that the post-translational modification of endophilin II by MNSFbeta might be implicated in phagocytosis by macrophages.

Quercetin Regulates the Inhibitory Effect of Monoclonal Non-Specific Suppressor Factor β on Tumor Necrosis Factor-α Production in LPS-Stimulated Macrophages

Monoclonal non-specific suppressor factor beta (MNSFbeta) is a member of the ubiquitin-like family that has been implicated in various biological functions. Previous studies have demonstrated that MNSFbeta regulates the ERK1/2-MAPK cascade in the macrophage cell line Raw 264.7. In this study, we found evidence that the flavonol quercetin regulates the effect of MNSFbeta on TNFalpha production in LPS-stimulated Raw264.7 cells. Quercetin inhibited MNSFbeta siRNA-mediated enhancement of both TNFalpha production and ERK1/2 phosphorylation in LPS-stimulated Raw264.7 cells. Quercetin decreased the expression of 33.5-kDa MNSFbeta adduct, which is important to the regulation of ERK1/2 activity, in unstimulated Raw264.7 cells. The various flavonoids tested, including other flavonols, did not affect the formation of this adduct. Collectively, MNSFbeta and quercetin might share a common pathway in regulating the ERK1/2 pathway in macrophages. This is the first report describing the involvement of flavonoids in the action of ubiquitin-like proteins.

Immunoneutralization of endometrial monoclonal nonspecific suppressor factor beta (MNSFβ) inhibits mouse embryo implantation in vivo

Successful embryo implantation and pregnancy in mammals depends on the establishment of immune tolerance between the maternal immune system and fetal cells. Monoclonal nonspecific suppressor factor beta (MNSFbeta), a cytokine produced by suppressor T cells in various tissues, possesses an antigen-nonspecific immune-suppressive function, and may be involved in the regulation of the uterine immune response during embryo implantation. In this study, anti-MNSFbeta IgG administered directly into the uterine lumen, significantly inhibited mouse embryo implantation in a dose-dependent manner in vivo, and this effect was reversed by co-administration of recombinant MNSFbeta. The effects of anti-MNSFbeta IgG on the gene pattern profiles in mouse uterine tissues were examined by cDNA microarray and several changes were confirmed by real-time PCR. Anti-MNSFbeta IgG caused up-regulation (> or = 2-fold) of 71 known genes and 17 unknown genes, and decreased expression (> or = 2-fold) of 74 known genes and 43 unknown genes, including several genes previously associated with embryo implantation or fetal development. Most of the known genes are involved in immune regulation, cell cycle/proliferation, cell differentiation/apoptosis, and lipid/glucose metabolism. These results demonstrate that MNSFbeta plays critical roles during the early pregnancy via multiple pathways.

The Ubiquitin-like Protein MNSFβ Regulates ERK-MAPK Cascade

MNSFbeta is a ubiquitously expressed member of the ubiquitin-like family that has been implicated in various biological functions. Previous studies have demonstrated that MNSFbeta covalently binds to intracellular proapoptotic protein Bcl-G in mitogen-activated murine T cells. In this study, we further investigated the intracellular mechanism of action of MNSFbeta in macrophage cell line, Raw 264.7 cells. We present evidence that MNSFbeta.Bcl-G complex associates with ERKs in non-stimulated Raw 264.7. We found that MNSFbeta.Bcl-G directly bound to ERKs and inhibited ERK activation by MEK1. In Raw 264.7 cells treated with MNSFbeta small interfering RNA (siRNA) lipopolysaccharide (LPS)-induced ERK1/2 activation was enhanced and LPS-induced JNK and p38 activation was unaffected. SiRNA-mediated knockdown of MNSFbeta increased tumor necrosis factor alpha (TNFalpha) expression at mRNA and protein levels in LPS-stimulated Raw 264.7 cells. Finally, we found that transfection with MNSFbeta expression construct resulted in a significant inhibition of LPS-induced ERK activation and TNFalpha production. Co-transfection experiments with MNSFbeta and Bcl-G greatly enhanced this inhibition. Collectively, these findings indicate that MNSFbeta might be implicated in the macrophage response to LPS.

Identification of novel endometrial targets for contraception

Successful embryo implantation is a critical step in establishing pregnancy and requires appropriate preparation of the endometrium to provide a transient state of “uterine receptivity.” The most essential of the molecular events determining receptivity may therefore provide potential targets for postcoital contraception. Using the mouse as a model, we identified molecules specifically regulated in the endometrium at very early implantation: these were monoclonal nonspecific suppressor factor beta (MNSFβ), splicing factor SC35, a novel protease of the HtrA family, termed HtrA3, calcium-binding protein (CaBP)-d9k (calbindin d9k) and proprotein convertase 6 (PC6). All of these molecules were also expressed in human endometrium, with the exception of CaBP-d9k, which was represented by the functionally similar CaBP-d28k. Appropriate spatial and temporal expressions of mRNA and protein were demonstrated for all five candidate molecules in mouse and primate (human and rhesus monkey) endometrium during the menstrual cycle and early pregnancy. Functional studies in mice established that blocking production of the CaBPs and PC6 within the endometrium completely prevented implantation and thus provided proof of principle that these molecules are potential contraceptive targets.