The functional repertoire of prokaryote cellulosomes includes the serpin superfamily of serine proteinase inhibitors

Many of the Firmicutes bacteria responsible for plant polysaccharide degradation in Nature produce a multiprotein complex called a cellulosome, which co-ordinates glycoside hydrolase assembly, bacterial adhesion to substrate and polysaccharide hydrolysis. Cellulosomal proteins possess a dockerin module, which mediates their attachment to the scaffoldin protein via its interaction with cohesin modules, and only glycoside hydrolases and other carbohydrate active enzymes were known to reside within the cellulosome. We show here with Clostridium thermocellum ATCC 27405 that members of the serpin superfamily of serine proteinase inhibitors, which are best recognized for their conformational flexibility and co-ordination of key regulatory functions in multicellular eukaryotes, also reside within the cellulosome. These studies are the first to expand the cellulosome paradigm of protein complex assembly beyond glycoside hydrolase and carbohydrate active enzymes, and to include a newly identified functionality in the Firmicutes.

Protease inhibitors in bacteria: an emerging concept for the regulation of bacterial protein complexes?

Serine protease inhibitors (serpins), the antagonists of serine proteases, were unknown in the bacterial kingdom until recently. Kang et al. in this issue of Molecular Microbiology report the cloning and functional analysis of the three serpin genes from the thermophilic anaerobic bacterium Clostridium thermocellum. Two of the serpins contain a dockerin module for location in the extracellular hydrolytic multienzyme complex, the cellulosome. The susceptibility of cellulosome to proteolytic degradation and the presence of a serine protease in the same complex provoke speculation that protease inhibitor/protease pairs could play hitherto unrecognized roles in protein stability and regulation in bacteria.

Maspin expression is characteristic for cisplatin-sensitive ovarian cancer cells and for ovarian cancer cases of longer survival rates

High cytoplasmic expression of maspin was described in ovarian cancers of shorter survival rates. Until now, no relationship has been described between expression of maspin and sensitivity to cisplatin in ovarian cancers. This study aimed at examining the relationship between expression of maspin, detected by immunohistochemistry and clinical response to cisplatin in ovarian cancer cases as well as the in vitro sensitivity to cisplatin of 11 ovarian cancer cell lines. The analyzes were performed on 73 samples of ovarian cancer and on A2780P, A2780RCIS, CAOV-3, EFO 21, EFO 27, ES-2, Mdah 2774, OAW 42, OVCAR-3, PA-1, and SKOV-3 ovarian cancer cells. Cytoplasmic maspin expression in studied cells significantly correlated with cisplatin sensitivity. A significantly shorter overall survival and progression-free survival was associated with lower cytoplasmic maspin expression at first-look laparotomies and nuclear maspin expression and secondary cytoreductions. Higher nuclear maspin at first-look laparotomies expression was specific for cases of complete response. In the study, the elevated expression of maspin was shown to be typical for cisplatin-sensitive ovarian cancers.

Targeting maspin in endothelial cells to induce cell apoptosis

The diseases of cancer remain as some of the leading causes of death in the industrialised world, although there are a multitude of technologies being used in the field of medical oncology to combat these diseases and scientific research continues to make discoveries to improve patient outcomes. Some of this research has focused on the maspin gene and protein. Maspin is predicted to be a unique serpin with tumour suppressor activity. Recent studies have explored the use of maspin as a therapeutic agent against cancer. In one study, maspin was found to inhibit cancer growth and metastasis in a breast cancer mouse model through a maspin DNA-liposome therapy. A separate study showed the ability of maspin to induce apoptosis in tumour-specific endothelial cells. Taken together, these studies demonstrate the potential use of maspin as a viable anticancer therapeutic agent.

Detection of PEDF in Subretinal Fluid of Retinal Detachment: Possible Role in the Prevention of Subretinal Neovascularization

PEDF (pigment-epithelium-derived factor) is a member of the serpin family of protease inhibitors. It is considered to be an important regulator of human eye disease and is known to inhibit angiogenesis. We have therefore investigated the presence of PEDF in the subretinal fluid of patients with retinal detachment.

METHODS

Eighteen samples from SRF were collected from patients during retinal detachment surgery. Specific ELISA analysis was performed with specific IgG against human PEDF.

RESULTS

PEDF was detected in the subretinal fluid of all cases. The mean concentration of PEDF was 33.9 ng/ml (SD 23.7 ng/ml; range 5.3-74.7 ng/ml). The majority of samples had however a concentration of more than 22 ng PEDF/ml fluid.

CONCLUSION

PEDF appears to be a constant component of the fluid accumulating in the subretinal space after retinal detachment. The known effects of PEDF, however, suggest that it may be involved in physiological processes of wound healing in the subretinal space.

Progressive increase of SCCA-IgM immune complexes in cirrhotic patients is associated with development of hepatocellular carcinoma

About 3-4% of cirrhotic patients develop primary liver cancer every year. Specific serologic markers have not yet been identified for screening of high risk patients. The serpin squamous cell carcinoma antigen (SCCA) is overexpressed in liver cancer and circulating SCCA-IgM complexes have been described in patients with hepatocellular carcinoma (HCC). The aim of the present study was to assess the behavior of SCCA-IgM in relation to HCC development in patients with cirrhosis. A retrospective, longitudinal study was conducted in a cohort of prospectively followed cirrhotic patients. Two groups with similar clinical profile at presentation were studied : group A included 16 patients who developed HCC during a median follow up of 4 years; group B included 17 patients who did not develop HCC during the same time interval. Circulating SCCA-IgM immune complexes were determined using a recently standardized ELISA assay. At presentation similar levels of SCCA-IgM complexes [mean +/- SD: 267.40 +/- 382.25 U/ml vs. 249.10 +/- 446.90 U/ml, p = 0.9006] and of alpha-fetoprotein [AFP; 24.11 +/- 59.04 IU/ml vs. 10.91 +/- 23.34 IU/ml, p = 0.3995] were detected in group A and in group B. The increase over time (phi) of SCCA-IgM, assessed within at least one year before clinical diagnosis of HCC, was remarkably higher in group A than in group B (mean +/- SD = 280.05 +/- 606.71 (U/ml)/year vs. -37.92 +/- 95.94 (U/ml)/year, p = 0.0408), while AFP increase was not significantly different (11.89 +/- 23.27 (IU/ml)/year vs. 3.67 +/- 11.46 (IU/ml)/year, p = 0.2179). Receiver operating characteristic (ROC) curves were plotted for the rate of change in the levels of both markers and the diagnostic accuracy measured as AUROC was higher for SCCA-IgM phi (0.821) than for AFP phi (0.654). In conclusion, the progressive increase of SCCA-IgM over time was associated with liver tumor development, suggesting that monitoring the behavior of SCCA-IgM might become useful to identify cirrhotic patients at higher risk of HCC development.

A rat model of human FENIB (familial encephalopathy with neuroserpin inclusion bodies)

FENIB (familial encephalopathy with neuroserpin inclusion bodies) is caused by intracellular accumulation/polymerization of mutant neuroserpins in the endoplasmic reticulum (ER). Transgenic rats overexpressing megsin (Tg meg), a newly identified serine protease inhibitor (serpin), demonstrated intraneuronal periodic-acid Schiff (PAS)-positive inclusions distributed throughout deeper layers of cerebral cortex, CA1 of the hippocampus, and substantia nigra. Hippocampal extracts from Tg meg rats showed increased expression of ER stress proteins, and activation of caspases-12 and -3, associated with decreased neuronal density. Enhanced ER stress was also observed in dopaminergic neurons in the substantia nigra, in parallel with decreased neuronal viability and motor coordination. In each case, PAS-positive inclusions were also positive for megsin. These data suggest that overexpression of megsin results in ER stress, eventuating in the formation of PAS-positive inclusions. Tg meg rats provide a novel model of FENIB, where accumulation of serpins in the ER induces selective dysfunction/loss of specific neuronal populations.

Regulation of serine protease inhibitor-E2 and plasminogen activator expression and secretion by follicle stimulating hormone and growth factors in non-luteinizing bovine granulosa cells in vitro

During ovarian follicle growth, there is expansion of the basal lamina and changes in the follicular extracellular matrix (ECM) that are mediated in part by proteolytic enzyme cascades regulated by tissue-type plasminogen activator (tPA) and urokinase plasminogen activator (uPA). One PA inhibitor, serine protease inhibitor-E2 (SERPINE2) is expressed in granulosa but not theca cells, and expression changes with follicle development. In this study, we hypothesized that PA and SERPINE2 expression/secretion by granulosa cells are regulated by FSH and growth factors. SERPINE2 mRNA and protein levels, tPA gene expression and uPA secretion were stimulated by FSH. Insulin-like growth factor-I stimulated SERPINE2 secretion and uPA activity, and decreased secreted tPA activity and gene expression. Bone morphogenetic protein-7 increased SERPINE2 secretion and expression and tPA secretion. In contrast, fibroblast growth factor-2 inhibited tPA secretion and SERPINE2 secretion and expression. Epidermal growth factor inhibited SERPINE2 secretion and expression, but increased secreted tPA activity. Estradiol and SERPINE2 secretion were highly positively correlated, but estradiol did not alter SERPINE2 expression. These data demonstrate that SERPINE2 expression and protein secretion are regulated by FSH and growth factors in non-luteinizing bovine granulosa cells. As estradiol is a known marker of follicle health, and SERPINE2 is an anti-apoptotic factor, we propose that SERPINE2 is involved in the regulation of atresia in bovine follicles.

Correlation of serpin–protease expression by comparative analysis of real-time PCR profiling data

Imbalanced protease activity has long been recognized in the progression of disease states such as cancer and inflammation. Serpins, the largest family of endogenous protease inhibitors, target a wide variety of serine and cysteine proteases and play a role in a number of physiological and pathological states. The expression profiles of 20 serpins and 105 serine and cysteine proteases were determined across a panel of normal and diseased human tissues. In general, expression of serpins was highly restricted in both normal and diseased tissues, suggesting defined physiological roles for these protease inhibitors. A high correlation in expression for a particular serpin-protease pair in healthy tissues was often predictive of a biological interaction. The most striking finding was the dramatic change observed in the regulation of expression between proteases and their cognate inhibitors in diseased tissues. The loss of regulated serpin-protease matched expression may underlie the imbalanced protease activity observed in pathological states.

Intracellular retention of hepatic serpins caused by severe hyperlipidemia

BACKGROUND

High levels of circulating lipids contribute to both the development of non-alcoholic liver steatosis (NALS) and peripheral arterial disease, leading to increased thrombotic risk. However, the effects of hyperlipidemia on hepatic proteins have barely been studied. Antithrombin is a hepatic serpin with anticoagulant and anti-inflammatory roles. The conformational flexibility of antithrombin renders it susceptible to both, genetic and posttranslational modifications. Thus, mutations and environmental factors have been shown to alter this molecule.

METHODS

We used a chick model to assess the effects of hyperlipidemic diets (HD) on this conformationally sensitive molecule. We determined antithrombin activity in plasma and evaluated the histological and immunohistological features of livers from these animals.

RESULTS

A HD for 6 months led to a significant intrahepatic retention and aggregation of antithrombin, which correlated with hepatic steatosis, as revealed by immunohistological analysis. Accordingly, a decrease in circulating antithrombin activity (48.71 +/- 6.35%) was observed. Other hepatic proteins, including heparin cofactor II, another anticoagulant serpin, also accumulated intracellularly. Atorvastatin and reversion to a normal diet after 3 months partially protected livers from these deleterious effects.

CONCLUSIONS

Our results support that hyperlipidemia-induced NALS causes a significant intracellular aggregation of hemostatic serpins in liver, which determines a decrease in their circulating levels.

Pigment epithelium-derived factor downregulates vascular endothelial growth factor (VEGF) expression and inhibits VEGF-VEGF receptor 2 binding in diabetic retinopathy

It has been shown that the balance between vascular endothelial growth factor (VEGF), a major angiogenic stimulator, and pigment epithelium-derived factor (PEDF), a potent angiogenic inhibitor, is critical for the regulation of vascular permeability and angiogenesis. However, the regulation of the balance is largely unclear. The present study demonstrated that there is a reciprocal interaction between VEGF and PEDF in the retina. PEDF significantly decreased VEGF expression in both retinal capillary endothelial cells (RCEC) and Müller cells. This PEDF effect was confirmed in the retina of rats with oxygen-induced retinopathy. Silencing of the PEDF gene by siRNA in Müller cells resulted in a significant upregulation of VEGF expression at both the RNA and protein levels, suggesting that PEDF is an endogenous negative regulator of VEGF. The further study of the mechanism showed that PEDF inhibited hypoxia-induced increases in VEGF promoter activity, HIF-1 nuclear translocation and mitogen activated protein kinase phosphorylation. These results suggest that PEDF inhibits VEGF expression at the transcriptional level. In addition, PEDF effectively inhibited VEGF binding to RCEC. Moreover, in vitro receptor-binding assay demonstrated that PEDF competed with VEGF for binding to VEGF receptor 2, which may represent a new mechanism for PEDF activity. On the other hand, VEGF significantly downregulated PEDF expression in RCEC, but not in retinal Müller cells, suggesting a VEGF receptor-mediated process. These results suggest that the reciprocal regulation between VEGF and PEDF may play a role in angiogenic control. The decrease in PEDF levels in the retina is at least partially responsible for the increase in VEGF expression and subsequent vascular leakage and neovascularization in diabetes.

Progesterone Regulation of Preimplantation Conceptus Growth and Galectin 15 (LGALS15) in the Ovine Uterus1

Peri-implantation conceptus (embryo/fetus and associated extraembryonic membranes) growth and development are primarily regulated by secretions from the uterus. This study investigated the effects of progesterone on preimplantation conceptus development and endometrial galectin 15 (LGALS15). Ewes received daily injections of either corn oil (CO) vehicle or 25 mg progesterone (P4) from 36 h postmating to hysterectomy. Treatment with P4 increased blastocyst diameter by 220% on Day 9 and advanced time of elongation of blastocysts to a filamentous conceptus on Day 12. Effects of P4 treatment on blastocyst development were blocked by administration of RU486, a progesterone receptor antagonist. Consistent with early elongation of blastocysts, interferon tau (IFNT) protein was about 50-fold greater in uterine flushes from Day 12 in ewes receiving P4 compared with those receiving CO. Expression of cathepsin L (CTSL) and radical S-adenosyl methionine domain containing 2 (RSAD2), both IFNT-stimulated genes, was increased in endometria of Day 12 P4-treated ewes. LGALS15 mRNA, expressed only in the endometrial luminal epithelium and superficial glands, was detected between Days 9 and 12 and was more abundant in ewes receiving P4 than in those receiving CO on both Days 9 and 12. RU486 treatment ablated P4 induction of LGALS15 mRNA in the endometrial epithelia. LGALS15 protein in uterine flushings was not different on Day 9 but tended to be greater in P4-treated ewes than in those receiving CO on Day 12. The advanced development of blastocysts in P4-treated ewes is hypothesized to involve early induction of specific genes in the endometrial epithelia, such as LGALS15, and undoubtedly components of uterine histotroph.

Age- and cell cycle-dependent changes in EPC-1/PEDF promoter activity in human diploid fibroblast-like (HDF) cells

The changes in gene expression during senescence are very interesting. Early population doubling cDNA-1 (EPC-1, also known as pigment epithelial derived factor, PEDF) is one of the genes whose expression decreases dramatically during cellular aging. We examined whether or not EPC-1/PEDF promoter activity was affected by the cellular ageing using human diploid lung fibroblast cells in culture. Here we showed the promoter/enhancer region of EPC-1/PEDF existed at more than 1760 bp upstream from the transcriptional initiation site of the gene, and was regulated by both aging and cell cycle. These findings suggest that the expression of the EPC-1/PEDF gene is, at least in part, regulated transcriptionally in the cells. The analysis of the promoter region of the EPC-1/PEDF gene in this paper suggests the age- and cell cycle-dependent expression of specific transcriptional factor(s).

Inhibitory plant serpins with a sequence of three glutamine residues in the reactive center

Serpins appear to be ubiquitous in eukaryotes, except fungi, and are also present in some bacteria, archaea and viruses. Inhibitory serpins with a glutamine as the reactive-center P1 residue have been identified exclusively in a few plant species. Unique serpins with a reactive center sequence of three Gln residues at P3-P1 or P2-P1' were isolated from barley and wheat grain, respectively. Barley BSZ3 was an irreversible inhibitor of chymotrypsin, with a second-order association rate constant for complex formation k(a)' of the order of 10(4) M(-1) s(-1); however, only a minor fraction of the serpin molecules reacted with chymotrypsin, with the majority insensitive to cleavage in the reactive center loop. Wheat WSZ3 was cleaved specifically at P8 Thr and was not an inhibitor of chymotrypsin. These reactive-center loops may have evolved conformations that are optimal as inhibitory baits for proeinases that specifically degrade storage prolamins containing Gln-rich repetitive sequences, most likely for digestive proteinases of insect pests or fungal pathogens that infect cereals. An assembled full-length amino acid sequence of a serpin expressed in cotton boll fiber (GaZ1) included conserved regions essential for serpin-proteinase interaction, suggesting inhibitory capacity at a putative reactive center P2-P2' with a sequence of four Gln residues.

The regulation of exosome secretion: a novel function of the p53 protein

The p53 protein responds to stress signals by regulating the transcription of a variety of genes. Some of these genes encode secreted proteins that may be involved in the communication between adjacent cells. In this study, a proteomics approach was employed to identify proteins secreted by cells in a p53-dependent manner after DNA damage. In addition to the known transcriptional targets of p53, a set of proteins encoded by genes that are not transcriptional targets of p53 were found to increase in the culture medium after p53 activation. These proteins exit the cell via small, secreted vesicles called exosomes and exosome production by cells was found to be regulated by the p53 response. A p53-regulated gene product, TSAP6, was shown to enhance exosome production in cells undergoing a p53 response to stress. Thus, the p53 pathway regulates the production of exosomes into the medium and these vesicles can communicate with adjacent cells and even cells of the immune system.

Expression of VEGF and PEDF in choroidal neovascular membranes following verteporfin photodynamic therapy

PURPOSE

To examine the impact of photodynamic therapy (PDT) on pigment epithelium derived factor (PEDF) expression in human choroidal neovascularization (CNV) membranes with regard to vascular endothelial growth factor (VEGF) expression.

DESIGN

Interventional case series.

METHODS

Retrospective review of interventional case series of 42 patients (42 eyes) who underwent removal of CNV. CNV was secondary to age-related macular degeneration (AMD) in all cases. Fifteen patients were treated with PDT, 3 to 246 days before surgery. CNV were stained for CD34, CD105, cytokeratin 18, VEGF, and PEDF. Twenty-seven CNV without previous treatment were used as control.

RESULTS

Specimens without pretreatment disclosed varying degrees of vascularization, VEGF, and PEDF expression by different cells. Specimens treated by PDT, three days previously showed mostly occluded vessels lined with damaged endothelial cells (EC). In contrast, specimens excised at later time points after PDT were highly vascularized with healthy EC. This chronology was associated with an impressive VEGF immunoreactivity increased considerably in retinal pigment epithelial cells as well as significantly reduced PEDF expression in EC and stroma.

CONCLUSIONS

PDT induces a selective vascular damage in CNV. The effectiveness of PDT, however, seems to be jeopardized by a rebound effect initiated by an enhanced VEGF and reduced PEDF expression in CNV.

Characterisation of a new C1 inhibitor mutant in a patient with hepatocellular carcinoma

A patient developed the first case of hepatocarcinoma associated with hereditary angioedema within the context of a 13-year long prophylactic danazol exposure. We sought to identify the molecular defect and to test the relative contribution to the development of hepatocarcinoma of intracellular accumulation of abnormal C1 inhibitor (C1-INH) protein. The de novo mutation c.878_881delTCTA was identified, leading to a premature stop codon. Monocyte C1-INH secretions of the patient and of her affected daughter were, respectively, 26 and 18% compared to controls. Mutant transcripts compatible with the 4bp deletion were detectable as a faint RT-PCR product both in interferon-stimulated monocytes and in liver tissue, whereas total C1-INH mRNA was found nearly half the amount recovered from normal subjects. In order to study the consequences at the protein level of the low expression of the mutant allele, we analysed the intracellular fate of mutant products. COS-7 cells were transiently transfected with a C1-INH expression minigene encoding the mutant protein. In pulse-chase experiments, a faint 75,000-M(r) band was detected only within 10min. Both the c.878_881delTCTA mutant transcript and the intracellular abnormal C1-INH protein are unstable. Our data therefore rule out the hypothesis of an accumulation of the mutant protein at levels relevant for the pathology and strengthen the link between the development of hepatocarcinoma and danazol exposure.

Overexpression of hepatitis B virus-binding protein, squamous cell carcinoma antigen 1, extends retention of hepatitis B virus in mouse liver

How receptors mediate the entry of hepatitis B virus (HBV) into the target liver cells is poorly understood. Recently, human squamous cell carcinoma antigen 1 (SCCA1) has been found to mediate binding and internalization of HBV to liver-derived cell lines in vitro. In this report, we investigate if SCCA1 is able to function as an HBV receptor and mediate HBV entry into mouse liver. SCCA1 transgene under the control of Rous sarcoma virus promoter was constructed in a minicircle DNA vector that was delivered to NOD/SCID mouse liver using the hydrodynamic technique. Subsequently, HBV-positive human serum was injected intravenously. We demonstrated that approximately 30% of the mouse liver cells expressed a high level of recombined SCCA1 protein for at least 37 d. The HBV surface antigen was found to persist in mouse liver for up to 17 d. Furthermore, HBV genome also persisted in mouse liver, as determined by polymerase chain reaction, for up to 17 d, and in mouse circulation for 7 d. These results suggest that SCAA1 might serve as an HBV receptor or co-receptor and play an important role in mediating HBV entry into hepatocytes, although its role in human HBV infection remains to be determined.

X-ray crystal structure of MENT: evidence for functional loop-sheet polymers in chromatin condensation

Most serpins are associated with protease inhibition, and their ability to form loop-sheet polymers is linked to conformational disease and the human serpinopathies. Here we describe the structural and functional dissection of how a unique serpin, the non-histone architectural protein, MENT (Myeloid and Erythroid Nuclear Termination stage-specific protein), participates in DNA and chromatin condensation. Our data suggest that MENT contains at least two distinct DNA-binding sites, consistent with its simultaneous binding to the two closely juxtaposed linker DNA segments on a nucleosome. Remarkably, our studies suggest that the reactive centre loop, a region of the MENT molecule essential for chromatin bridging in vivo and in vitro, is able to mediate formation of a loop-sheet oligomer. These data provide mechanistic insight into chromatin compaction by a non-histone architectural protein and suggest how the structural plasticity of serpins has adapted to mediate physiological, rather than pathogenic, loop-sheet linkages.

Maspin retards cell detachment via a novel interaction with the urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor system

It is well documented that tumor suppressive maspin inhibits tumor cell invasion and extracellular matrix remodeling. Maspin is a cytosolic, cell surface-associated, and secreted protein in the serine protease inhibitor superfamily. Although several molecules have been identified as candidate intracellular maspin targets, the extracellular maspin target(s) remains elusive. Although maspin does not directly inhibit urokinase-type plasminogen activator (uPA) activity, we have shown evidence that maspin may block the pericellular proteolysis mediated by cell surface-associated uPA. In the current study, maspin significantly inhibited the Ca2+ reduction-induced detachment of DU145 cells. This maspin effect was associated with increased and sustained levels of mature focal adhesion contacts (FAC). We noted that maspin (a) colocalized with uPA and uPA receptor (uPAR), (b) enhanced the interaction between uPAR and low-density lipoprotein receptor related protein, and (c) induced rapid internalization of uPA and uPAR. The maspin effects on surface-associated uPA and uPAR required the interaction between uPA and uPAR. Further biochemical and biophysical analyses revealed that maspin specifically bound to pro-uPA with a deduced K(d) of 270 nmol/L and inhibited the plasmin-mediated pro-uPA cleavage. Interestingly, substitution of maspin p1' site Arg340 in the reactive site loop (RSL) with alanine not only abolished the binding to pro-uPA but also diminished the maspin effects on pro-uPA cleavage and cell detachment. These data show an important role of maspin RSL in regulating the uPA/uPAR-dependent cell detachment. Together, our data led to a new hypothesis that maspin may stabilize mature FACs by quenching localized uPA/uPAR complex before uPA activation.

Simultaneous evaluation of maspin and CXCR4 in patients with breast cancer

AIM

To study simultaneously the actions of maspin and CXCR4, which share several similar pathways in cancer, including apoptosis and angiogenesis.

METHODS

Our material consisted of 151 invasive breast carcinomas arranged in a tissue microarray setting. Maspin and CXCR4 expression was evaluated by immunohistochemistry. Microvessel density was assessed by CD34 immunodetection and apoptosis by the Tdt-mediated dUTP nick end labelling assay.

RESULTS

Maspin expression was related to CXCR4 expression, apoptosis, patient age and the Nottingham prognostic index. The expression of both maspin and CXCR4 progressively increased in high-grade tumours. In patients with lymph node negative breast cancer, maspin overexpression was associated with increased risk of death. High CXCR4 expression was associated with prolonged survival of patients with high maspin expression.

CONCLUSIONS

Our results show that maspin overexpression could prove to be a potentially useful marker, especially for the clinically important group of patients with lymph node negative breast cancer. The expression of CXCR4 is of less significance in our study, but may be informative for specific patient subsets or in a longer time frame.

Molecular collaborations between serpins and trefoil factor promote endodermal cell growth and gastrointestinal differentiation in budding tunicates

We present evidence supporting novel collaborations between the serine protease inhibitor (serpin) and the trefoil factor during the budding stage of the tunicate Polyandrocarpa misakiensis. Using a maltose-binding protein/P-serpin fusion protein, two polypeptides of 40 kDa and 45 kDa were pulled down from Polyandrocarpa homogenates. Based on their partial amino acid sequence data, a single cDNA (928 bp) was cloned. It encodes a polypeptide that has five tandem repeats of a trefoil consensus motif. Thus, we termed the cDNA P-trefoil. Both P-trefoil and P-serpin were expressed exclusively by coelomic cells during budding. P-Trefoil was expressed mainly by coelomic cells throughout the asexual life cycle of Polyandrocarpa, while P-Serpin was localized particularly in coelomic cells and in the extracellular matrix in developing buds. The native P-Trefoil protein showed aminopeptidase activity. It induced cell growth in cultured Polyandrocarpa cells at a concentration of 8 microg/mL. P-Serpin reinforced this activity of P-Trefoil. Further, a mixture of P-Trefoil and P-Serpin exhibited the in vitro induction of a gut-specific alkaline phosphatase. These results show for the first time that a serpin can interact with a trefoil factor to play a role in the cellular growth and differentiation of the gastric epithelium.

Sugar and alcohol molecules provide a therapeutic strategy for the serpinopathies that cause dementia and cirrhosis

Mutations in neuroserpin and alpha1-antitrypsin cause these proteins to form ordered polymers that are retained within the endoplasmic reticulum of neurones and hepatocytes, respectively. The resulting inclusions underlie the dementia familial encephalopathy with neuroserpin inclusion bodies (FENIB) and Z alpha1-antitrypsin-associated cirrhosis. Polymers form by a sequential linkage between the reactive centre loop of one molecule and beta-sheet A of another, and strategies that block polymer formation are likely to be successful in treating the associated disease. We show here that glycerol, the sugar alcohol erythritol, the disaccharide trehalose and its breakdown product glucose reduce the rate of polymerization of wild-type neuroserpin and the Ser49Pro mutant that causes dementia. They also attenuate the polymerization of the Z variant of alpha1-antitrypsin. The effect on polymerization was apparent even when these agents had been removed from the buffer. None of these agents had any detectable effect on the structure or inhibitory activity of neuroserpin or alpha1-antitrypsin. These data demonstrate that sugar and alcohol molecules can reduce the polymerization of serpin mutants that cause disease, possibly by binding to and stabilizing beta-sheet A.

Salutary effect of pigment epithelium-derived factor in diabetic nephropathy: evidence for antifibrogenic activities

Diabetic nephropathy is a major complication of diabetes and a leading cause of end-stage renal diseases in the U.S. Pigment epithelium-derived factor (PEDF) is a potent angiogenic inhibitor that has been extensively studied in diabetic retinopathy. Recently, we reported that PEDF is expressed at high levels in normal kidneys and that PEDF levels are decreased in kidneys of streptozotocin (STZ)-induced diabetic rats. In the present study, we injected STZ-diabetic rats with an adenovirus expressing PEDF (Ad-PEDF) to evaluate its effects in diabetes. The results showed that increased expression of PEDF in the kidney in response to Ad-PEDF delivery significantly alleviated microalbuminuria in early stages of diabetes. Administration of Ad-PEDF was found to prevent the overexpression of two major fibrogenic factors, transforming growth factor-beta (TGF-beta)1 and connective tissue growth factor (CTGF), and to significantly reduce the production of an extracellular matrix (ECM) protein in the diabetic kidney. Moreover, PEDF upregulated metalloproteinase-2 expression in diabetic kidney, which is responsible for ECM degradation. In cultured human mesangial cells, PEDF significantly inhibited the overexpression of TGF-beta1 and fibronectin induced by angiotensin II. PEDF also blocked the fibronectin production induced by TGF-beta1 through inhibition of Smad3 activation. These findings suggest that PEDF functions as an endogenous anti-TGF-beta and antifibrogenic factor in the kidney. A therapeutic potential of PEDF in diabetic nephropathy is supported by its downregulation in diabetes; its prevention of the overexpression of TGF-beta, CTGF, and ECM proteins in diabetic kidney; and its amelioration of proteinuria in diabetic rats following Ad-PEDF injection.