Extracellular 20S proteasome secreted via microvesicles can degrade poorly folded proteins and inhibit Galectin-3 agglutination activity.

Proteasomes are major non-lysosomal proteolytic complexes localized in the cytoplasm and in the nucleus of eukaryotic cells. Strikingly, high levels of extracellular proteasome have also been evidenced in the plasma (p-proteasome) of patients with specific diseases. Here, we examined the process by which proteasomes are secreted, as well as their structural and functional features once in the extracellular space. We demonstrate that assembled 20S core particles are secreted by cells within microvesicles budding from the plasma membrane. Part of the extracellular proteasome pool is also free of membranes in the supernatant of cultured cells, and likely originates from microvesicles leakage. We further demonstrate that this free proteasome released by cells (cc-proteasome for cell culture proteasome) possesses latent proteolytic activity and can degrade various extracellular proteins. Both standard (no immune-subunits) and intermediate (containing some immune-subunits) forms of 20S are observed. Moreover, we show that galectin-3, which displays a highly disordered N-terminal region, is efficiently cleaved by purified cc-proteasome, without SDS activation, likely after its binding to PSMA3 (α7) subunit through its intrinsically disordered region. As a consequence, galectin-3 is unable to induce red blood cells agglutination when preincubated with cc-proteasome. These results highlight potential novel physio- and pathologic functions for the extracellular proteasome.

Melanotransferrin is efficiently sorted on the surface of exosomes secreted by melanoma cells.

Cutaneous melanoma is the most lethal type of skin cancer. Early detection is crucial to improve the outcome of melanoma patients. The identification of noninvasive prognostic biomarkers for the follow-up of melanoma patients is still in demand for clinical use. We show here that exosomal melanotransferrin fulfills the biomarker characteristics required to meet this demand. Melanotransferrin is typically overexpressed in melanoma cells compared to other cell types - including cancer cells - and is efficiently sorted and secreted with nanovesicles, or so-called exosomes, due to its membrane-anchoring by a glycosylphosphatidylinositol. Melanotransferrin is exposed on the surface of exosomes and is accessible for antibody recognition. An ELISA was set up to quantify melanotransferrin after immobilization of nanovesicles through the exosomal constituent tetraspanins CD63. Melanotransferrin was detected using a low number of exosomes purified from melanoma cell line cultures, and melanotransferrin detection was abolished by phosphatidylinositol-specific phospholipase C treatment. This exosomal melanotransferrin ELISA was able to discriminate an equal number of assayed exosomes purified from two different melanoma cell lines (A-375 vs. SK-MEL-28). Moreover, plasma samples from patients with melanoma and noncancer disease were assayed using this ELISA and elevated levels of exosomal melanotransferrin were seen in the plasma of patients with melanoma. We propose that exosomal melanotransferrin should be assessed as a potential melanoma biomarker.

Proteasome 19S RP and translation preinitiation complexes are secreted within exosomes upon serum starvation.

The aim of our study was to investigate the impact of macroautophagy on exosome secretion. Exosomes are small membrane vesicles released in the extracellular space upon fusion of multivesicular endosomes with the plasma membrane. They were initially discovered as a way to remodel the reticulocyte plasma membrane before entering the blood circulation (Current Opinion in Hematology 2010, 17:177-183) and are now essentially studied as mediators of intercellular communication. Using iTRAQ proteomics, we compared the protein composition of purified exosomes secreted by cells impaired or not for macroautophagy by Atg5 depletion, during serum starvation conditions or complete medium culture. We show that the absence of serum modifies exosomal content, especially inducing secretion of two cytoplasmic protein complexes, namely proteasomal 19S regulatory particle (RP) and components of noncanonical translation preinitiation complex (PIC). This process is enhanced when autophagy is impaired by Atg5 depletion. Moreover, we show that the proteasome 20S core particle (CP) is released in the extracellular space. However, in striking contrast to what seen for its 19S RP regulator, release is independent of the exosomal vesicles, Atg5 expression and cell culture conditions. Exosome secretion can thus be considered as a cell process that participates in and reflects cell homeostasis, and care must be taken when studying potential extracellular function of exosomes due to the possible copurification of proteasome 20S CP.

The proteasome maturation protein POMP increases proteasome assembly and activity in psoriatic lesional skin.

BACKGROUND: The ubiquitin proteasome pathway is involved in the pathogenesis of psoriasis and proteasome subunits are increased in lesional psoriatic skin. Recent works have highlighted that proteasome levels can be regulated through modulation of proteasome assembly notably by the proteasome maturation protein POMP. OBJECTIVES: To investigate whether proteasome assembly and POMP expression are modified in psoriatic skin. METHODS: Proteasome assembly as well as expression of proteasome regulators were assessed in non-lesional and lesional psoriatic skin using native gel electrophoresis and western blots respectively. The protein and mRNA expression levels of POMP were compared by western blots, immunohistochemistry and quantitative polymerase chain reaction. The role of POMP in keratinocyte proliferation and differentiation was assessed by silencing POMP gene expression by RNA interference in human immortalized keratinocyte HaCaT cells. RESULTS: Both 20S and 26S proteasomes (and their respective proteolytic activities) as well as the main proteasome regulators are increased in lesional psoriatic skin. POMP binds to 20S precursor complexes and is overexpressed in lesional epidermal psoriatic skin, supporting that POMP-mediated proteasome assembly is increased in psoriatic skin. POMP silencing inhibited HaCaT cell proliferation and induced apoptosis through the inhibition of the proteasome assembly. Moreover POMP partial depletion decreased the expression of the differentiation markers keratin 10 and involucrin during the [Ca2+]-induced HaCaT cells differentiation. CONCLUSION: Altogether these results establish a potential role for POMP and proteasome assembly in psoriasis pathogenesis.

Evolutionary conservation of early mesoderm specification by mechanotransduction in Bilateria.

The modulation of developmental biochemical pathways by mechanical cues is an emerging feature of animal development, but its evolutionary origins have not been explored. Here we show that a common mechanosensitive pathway involving ß-catenin specifies early mesodermal identity at gastrulation in zebrafish and Drosophila. Mechanical strains developed by zebrafish epiboly and Drosophila mesoderm invagination trigger the phosphorylation of ß-catenin-tyrosine-667. This leads to the release of ß-catenin into the cytoplasm and nucleus, where it triggers and maintains, respectively, the expression of zebrafish brachyury orthologue notail and of Drosophila Twist, both crucial transcription factors for early mesoderm identity. The role of the ß-catenin mechanosensitive pathway in mesoderm identity has been conserved over the large evolutionary distance separating zebrafish and Drosophila. This suggests mesoderm mechanical induction dating back to at least the last bilaterian common ancestor more than 570 million years ago, the period during which mesoderm is thought to have emerged.

Clinical use of p-proteasome in discriminating metastatic melanoma patients: comparative study with LDH, MIA and S100B protein.

Plasmatic proteasome (p-proteasome) has recently been described as a new marker for metastatic melanoma. The objective of this study was to compare the diagnostic and prognostic values of p-proteasome with three other melanoma serological markers: S100B protein, melanoma inhibitory activity protein (MIA) and lactate dehydrogenase (LDH) in the plasma of 121 stage I-IV melanoma patients. Laboratory analyses were performed by standardized ELISA (p-proteasome, MIA), immunoluminometric assay (S100B) and colorimetry (LDH). We found that all markers were relevant for discriminating metastatic from nonmetastatic patients but p-proteasome displayed the highest diagnostic accuracy. P-proteasome and S100B were the most sensitive (58.1%) and p-proteasome and MIA the most specific (98.7 and 100%) in detecting metastatic disease. P-proteasome and S100B had the highest area under receiver operating characteristics curve, 0.811 (95% CI: 0.725-0.897) and 0.822 (95% CI: 0.738-0.906), respectively. These two markers were the best in detecting patients with lymph node metastases. S100B, MIA and LDH diagnostic accuracy was increased when these markers were combined with p-proteasome. As shown with univariate analysis, shorter progression-free and overall survival rates were significantly associated with elevated plasma levels of each markers. The multivariate Cox regression analysis identified p-proteasome as the only independent predictor of a poorer progression-free survival (p = 0.030). In conclusion, this comparative study established that p-proteasome quantification in combination with other melanoma biomarkers is an attractive approach for the biological follow-up of melanoma patients.

Nested high-resolution melting curve analysis a highly sensitive, reliable, and simple method for detection of JAK2 exon 12 mutations--clinical relevance in the monitoring of polycythemia.

JAK2 exon 12 mutations are found in myeloproliferative disorders characterized by erythrocytosis. Lying in a 33-bp region and conserving the open reading frame, they often present a low allelic burden (<10%), which excludes screening with techniques such as allele-specific PCR or different sequencing protocols. High-resolution melting (HRM), a fast in-tube method, seems the most accurate routine technique for that. We describe a reliable and powerful nested HRM technique, independent of DNA preparation and with technical sensitivity of 100% (95% CI, 93% to 100%) and specificity of 96.7% (95% CI, 89.7% to 96.7%). Screening a cohort of 10 idiopathic erythrocytosis, 28 polycythemia vera, and 7 secondary erythrocytosis cases allowed the detection of 15 mutants, including 9 different mutations, of which 3 were unreported, all in the polycythemia vera group, and presented a characteristic profile: pure erythrocytosis associated with low serum erythropoietin. Threshold detection level ranged from 1% to 3% allelic burden, depending on the mutation. All of the HRM positive signals were found mutated by sequencing. Six of them (40%), however, required cloning before sequencing, because of low allelic burden. Classic techniques such as genomic sequencing may therefore miss patients with mutations. Given its sensitivity, HRM (and nested HRM) can be used in routine diagnosis and seems to be the most efficient of current techniques for detection of JAK2 exon 12 mutations.

Diagnostic value and prognostic significance of plasmatic proteasome level in patients with melanoma.

Plasmatic proteasome (p-proteasome) also called circulating proteasome has recently been described as a tumor marker. We investigated the diagnostic and prognostic accuracies of p-proteasome levels in a melanoma population classified according to the American Joint Committee on Cancer staging system. Using an ELISA test, we measured p-proteasome levels in 90 patients and 40 controls between March 2003 and March 2008. The subunit composition of p-proteasomes was determined in metastatic melanoma by proteomic analysis. The mean p-proteasome levels were correlated with stages (P < 0.0001; r(S) = 0.664). They were significantly higher in patients with stage IV and stage III with lymph node metastasis (9187 ± 1294 and 5091 ± 454 ng/ml, respectively) compared to controls (2535 ± 187 ng/ml; P < 0.001), to stage I/II (2864 ± 166 ng/ml; P < 0.001) and to stage III after curative lymphadenectomy (2859 ± 271 ng/ml; P < 0.001). The diagnostic accuracy of p-proteasome was evaluated by receiver operating characteristic analysis. With a cut-off of 4300 ng/ml, diagnostic specificity and sensitivity of p-proteasome for regional or visceral metastases were respectively 96.3% and 72.2%. In univariate analysis, high p-proteasome levels (>4300 ng/ml) were significantly correlated with an increased risk of progression [hazard ratio (HR) = 7.34; 95% CI 3.54-15.21, P < 0.0001] and a risk of death (HR = 5.92; 95% CI 2.84-12.33, P < 0.0001). In multivariate analysis, high p-proteasome levels were correlated with a poorer clinical outcome in the subgroup analysis limited to patients with disease stages I, II and III. Proteomic analysis confirmed the presence of all proteasome and immunoproteasome subunits. Taken together, these results indicate that p-proteasomes are a new marker for metastatic dissemination in patients with melanoma.

Association of familial pernicious anaemia and hereditary haemochromatosis.

We report the case of a 54-year-old patient presenting with a typical pernicious anaemia. His mother was diagnosed with unquestionable pernicious anaemia 5 years previously. Serum ferritin was strongly increased (1,160 microg/l, normal range 29-380), with a transferrin saturation of 95%. We found a homozygous C282Y mutation of the HFE gene in our patient, his mother being heterozygous. The son of our patient was compound C282Y/H63D heterozygous without detectable pernicious anaemia. This seems to be the first report of an association between familial pernicious anaemia and hereditary haemochromatosis. The simultaneous occurrence of the 2 diseases in the same patient helps to delineate the relative contribution of each of them to iron metabolism and erythropoiesis: iron overload was only moderately increased and responded rapidly to phlebotomies, whereas haemochromatosis did not modify the cytologic presentation of pernicious anaemia.

Long-lasting bioresorbable poly(lactic acid) (PLA94) mesh: a new approach for soft tissue reinforcement based on an experimental pilot study.

The purpose of this study was to evaluate host response and soft-tissue regeneration after poly(lactic acid) (PLA) mesh implantation in a rat model, in comparison with light-weight polypropylene (PPL) and poly(glycolic acid) (PGA) meshes. Full-thickness abdominal wall defects were created in 45 Wistar rats and reconstructed with 15 PLA(94), 15 PPL and 15 PGA meshes. Animals were killed on days 7, 30 and 90 to evaluate the presence of adhesions and changes in tensile strength of the implants. Histopathology and immunohistochemistry were performed to evaluate the collagen deposition and the inflammatory response. Statistics were done using unpaired Student's t-test, Mann-Whitney rank sum test, Student-Newman-Keuls test and Bonferroni (Dunn) t-test. The inflammatory response induced by the PLA mesh implantation was significantly milder than after PPL mesh. In PLA, vascularity and collagen organization was significantly higher than in PPL and PGA at 30 and 90 days, and collagen composition score was significantly higher than in PPL at 7 and 30 days. In PLA, shrinkage was significantly lower than in PPL and PGA at 7 and 30 days. Elongation at break and tensile strength were comparable between PLA and PPL over the 90-day period. The PLA mesh induces a milder inflammatory response, more orderly collagen deposition than PPL, and preserved comparable tensile strength after 90 days.

Long-term alpha interferon treatment is effective on anaemia and significantly reduces iron overload in congenital dyserythropoiesis type I.

Interferon has been shown to be an effective treatment of congenital dyserythropoiesis type I (CDA-I), but the optimal dose and the feasibility of this treatment remains to be determined. Here, in a 9-yr follow-up of a single patient, we show that interferon remains active during such a long period. The optimal dose of conventional alpha interferon could be evaluated at 2 million units twice a week. Pegylated interferon could be used as well at a dose of 30 microg/wk. During interferon treatment, serum and erythrocyte ferritin levels decreased progressively, and remained inversely correlated with haemoglobin levels. On repeated liver biopsies, iron overload could be normalized. Low dose interferon is a long-term treatment of CDA-I, and allows a significant decrease in iron overload, that could be interesting even in patients who are only moderately anaemic.

Influence of age, castration, and testosterone on T cell subsets in healthy and leukemia grafted mice.

The distribution of T cell subsets in pubertal (2 months) and post-pubertal (10 months) mice showed a significant decrease in the percentage of CD4+ splenocytes and peripheral blood lymphocytes (PBL) with age, unlike the percentage of CD8+ cells in PBL, which remained unchanged. The change in the distribution of T cell subsets in the spleen and blood occurred in 2 months old castrated mice, as in 10 months old animals. P388 tumor grew better in post-pubertal and in castrated mice than in young mice. The intact mice survived longer than the castrated ones. The relative number of CD4+, CD8+ and CD2+ splenocytes was lower in transplanted intact mice than that in controls. The CD8+ and CD2+ subsets in the blood of 2 months transplanted mice were higher than those in controls, whereas in PBL, in 10 months old and castrated mice, the T lymphocyte subsets remain unchanged. Depo-testosterone (DT) injection strongly reduced weight and tumor growth in all the intact and castrated animals. A significant correlation is observed between the tumor weight and testosterone level in the plasma of the 2 months old DT treated mice. Moreover, DT injection induced a significant increase in the percentage of blood CD8+ cells in all the batches. These data indicate that physiologically, androgens affect the age-related distribution of lymphocyte T subsets and suggest that they slow down tumor growth, besides causing a direct effect, through an immunological process.

[Vaginal delivery in a patient with an artificial urinary sphincter and augmentation enterocystoplasty]. / Accouchement par voie basse chez une patiente porteuse d'un sphincter artificiel urinaire et d'une entérocystoplastie d'agrandissement.

Few cases of management of pregnancy in patients with an artificial sphincter (AS) have been reported in the literature, but this situation is very likely to become increasingly frequent with the more frequent use of AS in children. The authors report the case of a pregnancy in a 36-year-old woman with lumbosacral spina bifida, treated by artificial urinary sphincter and augmentation enterocystoplasty. The pregnancy and vaginal delivery did not raise any particular problems. Vaginal delivery is possible provided several precautions are observed: pelvimetry, MRI at the 8th month of pregnancy and close collaboration between urologists and obstetricians near term. Emergency caesarean section should be avoided due to the risk of lesions caused by elements of the AS and the surgical difficulties related to the presence of the augmentation enterocystoplasty.

Development and evaluation of a sandwich ELISA for quantification of the 20S proteasome in human plasma.

Because quantification of the 20S proteasome by functional activity measurements is difficult and inaccurate, we have developed an indirect sandwich enzyme-linked immunosorbent assays (ELISA) for quantification of the 20S proteasome in human plasma. This sandwich ELISA uses a combination of a monoclonal antibody (mcp 20) recognizing the C2-beta subunit of human 20S proteasome (Mr approximately 30,000) and a polyclonal rabbit anti-20S antibody which labels different subunits of the complex. The detection limit of the assay was established as 10 ng/ml (n=10, mean of zero standard+2 S.D.) and the recovery rate ranged from 96% to 104%. The within-run and between-run coefficients of variation (CV) ranges were 2.8-3.3 and 3.0-3.4, respectively. Using serial dilutions of plasma to which various amounts of purified 20S proteasome were added, a linear dose-response was observed between 102 and 2050 ng/ml with a slope of 1.004 and a coefficient of determination r(2) of 0.99. In a preliminary experiment performed on a limited number of patients, the present assay was used to quantify the 20S proteasome in plasma from healthy subjects (n=11) and from a limited number of patients with various diseases (two patients with each of the following diagnoses: acute myeloid leukaemia, chronic myeloproliferative syndromes, Hodgkin's disease and solid tumors). The average concentration of 20S proteasome in plasma from normal subjects was found to be 2319+/-237 ng/ml (n=11). With reference to this normal range, the plasma proteasome concentration was found to be increased in most of these pathological state and as high as 1200% when solid tumors had been detected. For patients with Hodgkin's disease, the changes were more variable whereas in patients with chronic lymphocytic leukaemia, the proteasome concentration was raised during the acute phase of disease and decreased during therapy. We suggest that this robust, accurate and highly reproducible assay could be used to quantify proteasome in human plasma and investigate its value as a biological marker for various malignant and nonmalignant diseases.