Regulation of cargo transfer between ESCRT-0 and ESCRT-I complexes by flotillin-1 during endosomal sorting of ubiquitinated cargo

Ubiquitin-dependent sorting of membrane proteins in endosomes directs them to lysosomal degradation. In the case of receptors such as the epidermal growth factor receptor (EGFR), lysosomal degradation is important for the regulation of downstream signalling. Ubiquitinated proteins are recognised in endosomes by the endosomal sorting complexes required for transport (ESCRT) complexes, which sequentially interact with the ubiquitinated cargo. Although the role of each ESCRT complex in sorting is well established, it is not clear how the cargo is passed on from one ESCRT to the next. We here show that flotillin-1 is required for EGFR degradation, and that it interacts with the subunits of ESCRT-0 and -I complexes (hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) and Tsg101). Flotillin-1 is required for cargo recognition and sorting by ESCRT-0/Hrs and for its interaction with Tsg101. In addition, flotillin-1 is also required for the sorting of human immunodeficiency virus 1 Gag polyprotein, which mimics ESCRT-0 complex during viral assembly. We propose that flotillin-1 functions in cargo transfer between ESCRT-0 and -I complexes

Autologous transplantation in multiple myeloma: a GITMO retrospective analysis on 290 patients. Gruppo Italiano Trapianti di Midollo Osseo.

BACKGROUND AND OBJECTIVE: Autologous transplantation is a better treatment for multiple myeloma (MM) than chemotherapy, but uncertainty remains about patient selection, optimal timing of autograft, conditioning regimen, need for a second autograft, and role of maintenance. To provide partial answers to these questions we assessed the results of autologous transplantation in a large cohort of patients whose data were reported to the GITMO registry. DESIGN AND METHODS: We retrospectively analyzed data from 290 patients with MM (M = 150; F = 140; median age 52 years, range 19-70; stage I = 34, stage II = 75, stage III = 167) reported to the GITMO. At the time of autograft, 20% were in CR, 66% in PR, while the remaining had non-responsive or progressive disease. Median time between diagnosis and transplant was 16 months (1-90). Seventy-two patients (26%) had been planned to receive a double autograft, but this was actually done in only 35 (12%). The conditioning was chemotherapy in 90%. Peripheral blood was the only source of stem cells in 94%, and purging was applied in 10% of cases. For statistical analysis of data, differences between patient subsets were analyzed using the chi-square test, while the Kaplan-Meier method was used to estimate event-free survival (EFS) and survival (OS) probabilities. The Cox model was used for multivariate analysis. RESULTS: Following the autograft, 116 patients (40%) were in CR, 144 (50%) in PR, 24 (8%) did not respond or progressed and 6 (2%) died before response evaluation. Transplant-related mortality occurred in 3%. At a median follow-up of 23 months, 223 (77%) patients are alive, 71 (24%) of them in CR, and 67 (23%) patients have died at a median time of 20 months (0-70). OS and EFS at 6 years are 47% and 28%, respectively, but the EFS curve shows no plateau. In multivariate analysis, age, beta2-microglobulin level and status at transplant emerged as significant prognostic factors for both OS and EFS, while time from diagnosis to transplant showed borderline significance. INTERPRETATION AND CONCLUSIONS: Based on the prognostic factors identified in multivariate analysis, we were able to assess the weight of a single prognostic factor or their combinations on transplant outcome. We also calculated the probability of OS and EFS by the number of factors at the time of autograft. Autologous transplantation is a safe and effective procedure, not only in sensitive patients, but also in resistant cases, provided they are <55 years of age and have low beta2-microglobulin. It should be applied early after the diagnosis of multiple myeloma, following the delivery of brief primary chemotherapy

Reggies/flotillins regulate E-cadherin-mediated cell contact formation by affecting EGFR trafficking.

The reggie/flotillin proteins are implicated in membrane trafficking and, together with the cellular prion protein (PrP), in the recruitment of E-cadherin to cell contact sites. Here, we demonstrate that reggies, as well as PrP down-regulation, in epithelial A431 cells cause overlapping processes and abnormal formation of adherens junctions (AJs). This defect in cell adhesion results from reggie effects on Src tyrosine kinases and epidermal growth factor receptor (EGFR): loss of reggies reduces Src activation and EGFR phosphorylation at residues targeted by Src and c-cbl and leads to increased surface exposure of EGFR by blocking its internalization. The prolonged EGFR signaling at the plasma membrane enhances cell motility and macropinocytosis, by which junction-associated E-cadherin is internalized and recycled back to AJs. Accordingly, blockage of EGFR signaling or macropinocytosis in reggie-deficient cells restores normal AJ formation. Thus, by promoting EGFR internalization, reggies restrict the EGFR signaling involved in E-cadherin macropinocytosis and recycling and regulate AJ formation and dynamics and thereby cell adhesion

Consumption of clotting factors in severe haemophilia patients undergoing prophylaxis and on-demand treatment in Italy.

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