Nucleocytoplasmic shuttling of endocytic proteins.

Many cellular processes rely on the ordered assembly of macromolecular structures. Here, we uncover an unexpected link between two such processes, endocytosis and transcription. Many endocytic proteins, including eps15, epsin1, the clathrin assembly lymphoid myeloid leukemia (CALM), and alpha-adaptin, accumulate in the nucleus when nuclear export is inhibited. Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis. In the nucleus, eps15 and CALM acted as positive modulators of transcription in a GAL4-based transactivation assay, thus raising the intriguing possibility that some endocytic proteins play a direct or indirect role in transcriptional regulation.

Dynamic palmitoylation of lymphoma proprotein convertase prolongs its half-life, but is not essential for trans-Golgi network localization.

Proprotein convertases are responsible for the endoproteolytic activation of proproteins in the secretory pathway. The most recently discovered member of this family, lymphoma proprotein convertase (LPC), is a type-I transmembrane protein. Previously, we have demonstrated that its cytoplasmic tail is palmitoylated. In this study, we have identified the two most proximal cysteine residues in the cytoplasmic tail as palmitoylation sites. Substitution of either cysteine residue by alanine interfered with palmitoylation of the other. Palmitoylation of LPC was found to be sensitive to the protein palmitoyltransferase inhibitor tunicamycin but not cerulenin. It was also insensitive to the drugs brefeldin A, monensin and cycloheximide, indicating that the modification occurs in a late exocytic or endocytic compartment. Turnover of palmitoylated LPC is significantly faster (t(1/2) approximately 50 min) than that of the LPC polypeptide backbone (t(1/2) approximately 3 h), suggesting that palmitoylation is reversible. Abrogation of palmitoylation reduced the half-life of the LPC protein, but did not affect steady-state localization of LPC in the trans-Golgi network. Finally, LPC could not be detected in detergent-resistant membrane rafts. Taken together, these results suggest that dynamic palmitoylation of LPC is important for stability, but does not function as a dominant trafficking signal.

Binding of BiP to the processing enzyme lymphoma proprotein convertase prevents aggregation, but slows down maturation.

Lymphoma proprotein convertase (LPC) is a subtilisin-like serine protease of the mammalian proprotein convertase family. It is synthesized as an inactive precursor protein, and propeptide cleavage occurs via intramolecular cleavage in the endoplasmic reticulum. In contrast to other convertases like furin and proprotein convertase-1, propeptide cleavage occurs slowly. Also, both a glycosylated and an unglycosylated precursor are detected. Here we demonstrate that the unglycosylated precursor form of LPC is localized in the cytosol due to the absence of a signal peptide. Using a reducible cross-linker, we found that glycosylated pro-LPC is associated with the molecular chaperone BiP. In addition, we show that pro-LPC is prone to aggregation and forms large complexes linked via interchain disulfide bonds. BiP is associated mainly with non-aggregated pro-LPC and pro-LPC dimers and trimers, suggesting that BiP prevents aggregation. Overexpression of wild-type BiP or a dominant-negative BiP ATPase mutant resulted in reduced processing of pro-LPC. Taken together, these results suggest that binding of BiP to pro-LPC prevents aggregation, but results in slower maturation.

Lovastatin induces p21WAF1/Cip1 in human vascular smooth muscle cells: influence on protein phosphorylation, cell cycle, induction of apoptosis, and growth inhibition.

Morbidity, mortality and the incidence of myocardial revascularisation procedures can be reduced by simvastatin, an inhibitor of the HMG-CoA reductase (EC 1.1.1.34). It was hypothesised that inhibition of isoprenylation of signalling proteins by HMG-CoA reductase inhibitors (vastatins), especially of the p21ras proteins could be causative for suppression of vascular smooth muscle cell (SMC) proliferation. The primary pharmacological mechanism of vastatins on human vascular SMC still remains unexplained. To analyse the influence of vastatins, SMC grown in presence of endothelial cell growth supplement (ECGS) were exposed to different concentrations of lovastatin. At 10 microM concentration, inhibition of SMC proliferation was associated with induction of apoptosis in a large fraction of cells as at the 1 microM level apoptosis was induced only in a minority of SMC. Protein phosphorylation on tyrosine, serine and threonine residues demonstrated no differences to untreated controls. Lovastatin induced arrest of cells in G0/G1 phase of the cell cycle and DNA synthesis was reduced. Western blot analysis demonstrated a significant induction of p21WAF1/Cip1 protein expression. This led to strong inhibition of cyclin dependent kinases (cdks) resulting in a cell cycle arrest. Our study provides evidence for a pharmacological explanation for the inhibition of ECGS-driven proliferation of human SMC by lovastatin.

The vasopressin precursor is not processed in the hypothalamus of Wolfram syndrome patients with diabetes insipidus: evidence for the involvement of PC2 and 7B2.

Wolfram syndrome (WS) is characterized by optic atrophy, insulin-dependent diabetes mellitus, vasopressin (VP)-sensitive diabetes insipidus, and neurosensory hearing loss. Here we report a disturbance in VP precursor processing in the supraoptic and paraventricular nuclei of WS patients. In these patients with diabetes insipidus we could hardly detect any cellular immunoreactivity for processed VP in the supraoptic and paraventricular nuclei. On the other hand, in the paraventricular nucleus a considerable number of cells immunoreactive for the VP precursor were present. In addition, the proprotein convertase PC2 and the molecular chaperone 7B2 were absent. As expression of PC2 and 7B2 was detected in the nearby nucleus basalis of Meynert of one WS patient and in the anterior lobe of the other WS patient, the absence of the two proteins in the paraventricular nucleus was not due to mutations in their genes. These results indicate that in WS patients with diabetes insipidus, not only does VP neuron loss occur in the supraoptic nucleus, but there is also a defect in VP precursor processing.

Furin and proprotein convertase 7 (PC7)/lymphoma PC endogenously expressed in rat liver can be resolved into distinct post-Golgi compartments.

The intracellular compartmentalization in rat liver of the membrane-associated convertases furin and proprotein convertase 7 (PC7)/lymphoma PC (LPC) was investigated by analytical subcellular fractionation. In control animals, both enzymes were found to localize in fractions depleted of endoplasmic reticulum, cis-Golgi and lysosomal markers, but to co-distribute with the Golgi marker galactosyltransferase and the trans-Golgi network (TGN) marker TGN38. After overloading Golgi-derived vesicles with very-low-density lipoproteins (VLDL) by feeding rats with ethanol, the distribution of PC7/LPC was shifted markedly towards lower densities, in contrast with those of furin and the TGN marker. This provides support for the TGN localization of endogenously expressed furin and indicates that, at steady state, a considerable proportion of PC7/LPC may be associated with vesicles derived from the TGN.

The molecular basis of antithrombin deficiency in Belgian and Dutch families.

The molecular basis of hereditary antithrombin (AT) deficiency has been investigated in ten Belgian and three Dutch unrelated kindreds. Eleven of these families had a quantitative or type I AT deficiency, with a history of major venous thromboembolic events in different affected members. In the other two families a qualitative or type II AT deficiency was occasionally diagnosed. DNA studies of the AT gene were performed, using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis, followed by direct sequencing of the seven exons and intron-exon junction regions. Six novel point mutations were identified: four missense, one nonsense mutation and a single nucleotide deletion near the reactive site, causing a frameshift with premature translation termination. In two kindreds the underlying genetic defect was caused by a whole gene deletion, known as a rare cause of AT deficiency. In these cases, Southern blot and polymorphism analysis of different parts of the AT gene proved useful for diagnosis. In another kindred a partial gene deletion spanning 698 basepairs could precisely be determined to a part of intron 3B and exon 4. In two type I and in both type II AT deficient families a previously reported mutation was identified. In all cases, the affected individuals were heterozygous for the genetic defect.

Relation of urokinase-type plasminogen activator expression to presence and severity of atherosclerotic lesions in human coronary arteries.

Urokinase-type plasminogen activator (UPA) has been implicated in a broad spectrum of pathological processes - e.g. cell adhesion, migration and proliferation and matrix remodeling - that are considered important features of atherogenesis and plaque disruption. In this study, we have analyzed the content and expression of UPA in human coronary arteries and its relation to the presence and severity of atherosclerotic lesions. Segments of coronary arteries obtained from human heart explants (n = 15) were classified by the presence and types of atherosclerotic lesions. UPA was quantitatively determined in protein extracts of the intimal and medial layers. In situ hybridization and immunohistochemical analyses were performed on serial sections of representative tissue specimens. UPA was detected in the extracts as pro-UPA, UPA complexed to plasminogen activator inhibitor-1, or as otherwise inactive UPA antigen, but not in the active two-chain form. Both functional and total UPA were increased several-fold in extracts of advanced lesions, while the ratios of functional over total UPA showed the opposite trend suggesting enhanced UPA inactivation and turnover. UPA expression in early atherosclerotic lesions was particularly prominent in areas of proliferating SMCs in the abluminal part of the neointima, whereas in advanced lesions UPA was widely expressed in macrophage-rich areas adjacent to the rims and shoulder regions of the necrotic cores. The results strongly suggest a causal involvement of UPA in coronary atherogenesis and its clinical outcome.

Quality of life in adult patients with acute myeloid leukemia receiving intensive and prolonged chemotherapy -- a longitudinal study.

Intensification of treatment for acute myeloid leukemia (AML) in adult patients resulted in a substantial improvement in long-term prognosis. Therefore, the assessment of quality of life (QL) of patients undergoing treatment is of growing interest. This study was designed to evaluate QL in patients with AML treated according to the protocol of the German AML-Cooperative Group (Münster, Germany). The EORTC QLQ-C 30 questionnaire was used to analyze QL throughout therapy, evaluating defined specific parameters at 12 different time-points. Sixty-one patients were recruited within the first 30 months of the study. Those 28 patients who have completed the course of inpatient treatment (n=28) are evaluated for changes in the conceptually distinct QL domains: Physical Functioning (P<0.001), Role Functioning (P=0.001), Emotional Functioning (P < 0.001) and Social Functioning (P=0.007) improve significantly from beginning of chemotherapy to the end of inpatient treatment. Individual assessment of Global Health Status and Subjective QL improves significantly over the same time (P< 0.001). At the end of inpatient treatment patients suffer significantly less from fatigue, nausea/emesis, loss of appetite and sleep disturbance (P < 0.001). Although most patients with AML eventually relapse, the evaluation of QL in patients undergoing treatment shows that subjective benefit outweighs the adverse effects of antileukemic therapy.

Attenuation of the polypeptide 7B2, prohormone convertase PC2, and vasopressin in the hypothalamus of some Prader-Willi patients: indications for a processing defect.

7B2 is a neuroendocrine chaperone interacting with the prohormone convertase PC2 in the regulated secretory pathway. Its gene is located near the Prader-Willi syndrome (PWS) region on chromosome 15. In a previous study we were able to show 7B2 immunoreactivity in the supraoptic nucleus (SON) or the paraventricular nucleus (PVN) in only three of five PWS patients. Here we report that in contrast with five other PWS patients, the neurons in the hypothalamic SON and PVN of the two 7B2-immunonegative PWS patients also failed to show any reaction using two antibodies directed against processed vasopressin (VP). On the other hand, even these two cases reacted normally with five antibodies that recognize different parts of the VP precursor. This finding pointed to a processing defect. Indeed, the same patients had no PC2 immunoreactivity in the SON or PVN, whereas PC1 immunoreactivity was only slightly diminished. In conclusion, in the VP neurons of two PWS patients, greatly reduced amounts of 7B2 and PC2 are present, resulting in diminished VP precursor processing.

Biosynthesis, distinct post-translational modifications, and functional characterization of lymphoma proprotein convertase.

Proprotein convertases are responsible for the endoproteolytic processing of prohormones, neuropeptide precursors, and other proproteins within the constitutive and regulated secretory pathways. Cleavage occurs carboxyl-terminally of basic amino acid motifs, such as RX(K/R)R, RXXR, and (R/K)R. As already available for the other known mammalian members of this enzyme family, we here define structural and functional features of human lymphoma proprotein convertase (LPC). Analysis of expression of recombinant LPC in stably transfected Chinese hamster ovary cells reveals biosynthesis of a 92-kDa nonglycosylated precursor (proLPC) and a 102-kDa endoglycosidase H-sensitive glycosylated form of proLPC. Only the latter is further processed and after propeptide removal converted into a complexly N-glycosylated mature form of LPC of about 92 kDa. Co-expression experiments of truncated LPC with an active site mutant of LPC (LPCS265A) indicate that prodomain removal of LPC occurs via an autoproteolytic, intramolecular mechanism, as was demonstrated before for some of the other members of this enzyme family. Prodomain removal is shown to be required for LPC to exit the endoplasmic reticulum. As far as subcellular localization is concerned, immunocytochemical, ultrastructural, and biochemical analyses show that LPC is concentrated in the trans-Golgi network, associated with membranes, and not secreted. Carboxyl-terminal domains are critically involved in this cellular retention, because removal of both the hydrophobic region and the cytoplasmic tail of LPC results in secretion. Of interest are the observations that LPC is not phosphorylated like furin but is palmitoylated in its cytoplasmic tail. Finally, substrate specificity of LPC is similar to that of furin but not identical. Whereas for furin a basic substrate residue at position P-2 is dispensable, it is essential for LPC. For optimal LPC substrate processing activity, an arginine at position P-6 is preferred over an arginine at P-4.

Coagulation factor VII and the risk of coronary heart disease in healthy men.

Numerous investigations have demonstrated the role of thrombus formation in the pathogenesis of coronary heart disease (CHD). A tendency to thrombosis may also be indicated by elevated levels of coagulation factor VII clotting activity (FVIIc). Significant associations of FVIIc with increased coronary risk, however, have been found only in the Northwick Park Heart Study. Here we present the results of the 8-year follow-up of FVIIc measurements in 2780 healthy men of the Prospective Cardiovascular Münster study. In the study population (age at entry, 49.3 +/- 6.1 years, mean +/- SD), 130 CHD events occurred during follow-up. FVIIc was significantly higher in subjects with coronary events than in those without (112.4 +/- 20.1% vs 108.7 +/- 21.4%, P = .023). Compared with individuals without coronary events, FVIIc was not significantly higher in men with nonfatal events (111.7 +/- 20.4%; P = .196, n = 93), but there was a tendency toward higher FVIIc activity in subjects with fatal events (114.6 +/- 19.5%; P = .076, n = 37). In the multiple logistic regression analysis, we did not find FVIIc to be an independent risk factor for CHD, and the significance of FVIIc disappeared after total cholesterol, LDL-cholesterol, and triglycerides were taken into account. The increase in the number of CHD events through higher levels of FVIIc was more pronounced in the presence of additional cardiovascular risk factors: smoking; myocardial infarction events in family; angina pectoris; high levels of fibrinogen, total cholesterol, LDL cholesterol, and triglycerides; and a low level of HDL cholesterol. We conclude that FVIIc is a risk factor for CHD, especially in the presence of additional risk factors, and must be taken into account when assessing cardiovascular risk in men.

Efficacy and kinetics of bone marrow processing and enrichment of haematopoietic progenitor cells (HPC) by a large-volume apheresis procedure.

We investigated the efficacy of bone marrow (BM) processing by an automated large-volume apheresis procedure (6 x original BM volume) in 10 paediatric and adult patients undergoing BM harvesting before myeloablative therapy. Volume-dependent kinetics during apheresis were analyzed by sequential collection of processed cells into a six-fold collection bag system with consecutive analysis of the single bags. BM processing resulted in an 83.3% (+/- 21) recovery of mononuclear cells (MNC), a 97.9% (+/- 1.1) reduction of erythrocytes (RBC) and a 87.7% (+/- 2.9) volume reduction. To determine volume-dependent kinetics of haematopoietic progenitor cell (HPC) enrichment during apheresis, leukocytes (WBC), mononuclear cells (MNC), CD34 cells and colony-forming cells (CFU-GM) were serially quantitated in subsequent collection bags. Large-volume BM processing significantly enhanced absolute yields of CD34+ cells (mean: 4.01 (+/- 2.81) x 10(6)/kg bw) and CFU-GM (mean: 1.92 (+/- 1.47) x 10(4)/kg bw) compared with the standard procedure (3 x BM volume) by 26.9% (+/- 10.9) and 27.2% (+/- 11.6), respectively. We concluded that large-volume apheresis for BM processing is an efficient technique significantly improving the yields of haematopoietic progenitor cells (HPC) without any relevant changes in the purity of the final product. Moreover, sequential collection and analysis of HPC represents a good model to investigate the volume-dependent kinetics and efficacy of BM processing.

[Quality of life and coping with illness in patients with acute myeloid leukemia]. / Lebensqualität und Krankheitsverarbeitung bei Patienten mit akuter myeloischer Leukämie.

Advances in chemotherapy significantly prolong survival of patients with acute myeloid leukemia (AML) and may cure a significant percentage of patients. Therefore, the assessment of quality of life (QL) of patients undergoing chemotherapy is of growing interest. This study was designed to evaluate QL in patients with AML treated according to the protocol of the German AML-Cooperative Group (Münster, FRG). Based on conceptual, methodological and practical criteria, the EORTC-QLQ C 30 questionnaire was used. In addition, patients' coping strategies were assessed by the FQCI. Patients' individual perception of their disease and therapy was evaluated by a semi-structured interview. Currently, 61 patients are enrolled in the protocol. For those patients having completed the course of inpatient treatment, individual assessment of Global Health Status and Subjective QL improves significantly. The content analysis of the interviews shows to what extent aspects of the inpatient setting influence patients' QL. Although only a minority of patients with AML remain in continuous complete remission, the evaluation of QL in patients undergoing treatment shows that subjective benefit outweighs the effects of antileukemic therapy.

Identification of a transferable sorting domain for the regulated pathway in the prohormone convertase PC2.

The mammalian subtilisin-like endoproteases furin and PC2 catalyze similar reactions but in different parts of the cell: furin in the trans-Golgi network and PC2 in dense-core granules. To map targeting domains within PC2, chimeras were constructed of the pro-, catalytic, and middle domains of furin with the carboxyl-terminal domain of PC2 (F-S-P) or of the pro- and catalytic domains of furin with the middle and carboxyl-terminal domains of PC2 (F-N-P). Their behavior in stable transfected AtT-20 cells was compared to a furin mutant truncated after the middle domain (F-S), wild-type furin, and with wild-type PC2. F-S-P, F-N-P, and F-S were catalytically active and underwent post-translational proteolysis and N-glycosylation with similar kinetics to wild-type furin. The truncated furin mutant was not stored intracellularly, whereas both chimeras, like PC2, showed intracellular retention and regulated release. Immunofluorescence and immuno-electron microscopy showed the presence of the chimeras and PC2 in dense-cored secretory granules together with proopiomelanocortin immunoreactivity. PC2 was sorted more efficiently than F-S-P, and the inclusion of the middle domain (F-N-P) further enhanced intracellular retention. It is concluded that sorting of PC2 into the regulated pathway depends on its carboxyl terminus. The middle domain may provide additional sorting determinants or a conformational framework for expression of the sorting signal.

[Successful multimodal therapy of a locally advanced non-small-cell bronchial cancer]. / Erfolgreiche multimodale Behandlung eines lokal weit fortgeschrittenen nicht-kleinzelligen Bronchialkarzinoms.

HISTORY AND CLINICAL FINDINGS: A chest radiogram, performed on a 60-year-old man with unproductive cough for 3 months, showed a space-occupying lesion in the right upper lobe, and breath sounds were diminished in this area. He had been a heavy smoker. His general condition and nutritional state were good. INVESTIGATIONS: Computed tomography, skeletal scintigraphy, bronchoscopy with biopsy and mediastinoscopy established the diagnosis of a locally advanced non-small-cell bronchial carcinoma (stage IIIB or T2N3M0). TREATMENT AND COURSE: Combined adjuvant treatment was begun in the hope of improving the median survival time of 8 months predicted for this tumour stage. After two cycles of a combined chemotherapy scheme (ifosfamide, carboplatin, etoposide) he received hyperfractionated-accelerated radiotherapy (total dose 45 Gy; 1.5 Gy twice daily) together with carboplatin and vindesine. This was followed by a right upper lobectomy with lymphadenectomy. Full remission was confirmed in both the resected specimen and the lymph nodes. The patients remains free of tumour 30 months after the diagnosis. CONCLUSION: Neoadjuvant treatment can significantly improve the prognosis of non-small-cell bronchial carcinoma in stage III. Such patients should therefore be treated according to the appropriate study protocol, if possible.