Search

In the Drosophila wing, the Nedd4 ubiquitin ligases (E3s), dNedd4 and Su(dx), are important negative regulators of Notch signaling; they ubiquitinate Notch, promoting its endocytosis and turnover. Here, we show that Drosophila Nedd4 family interacting protein (dNdfip) interacts with the Drosophila Nedd4-like E3s. dNdfip expression dramatically enhances dNedd4 and Su(dx)-mediated wing phenotypes and further disrupts Notch signaling. dNdfip colocalizes with Notch in wing imaginal discs and with the late endosomal marker Rab7 in cultured cells. In addition, dNdfip expression in the wing leads to ectopic Notch signaling. Supporting this, expression of dNdfip suppressed Notch+/− wing phenotype and knockdown of dNdfip enhanced the Notch+/− wing phenotype. The increase in Notch activity by dNdfip is ligand independent as dNdfip expression also suppressed deltex RNAi and Serrate+/− wing phenotypes. The opposing effects of dNdfip expression on Notch signaling and its late endosomal localization support a model whereby dNdfip promotes localization of Notch to the limiting membrane of late endosomes allowing for activation, similar to the model previously shown with ectopic Deltex expression. When dNedd4 or Su(dx) are also present, dNdfip promotes their activity in Notch ubiquitination and internalization to the lysosomal lumen for degradation. [ABSTRACT FROM AUTHOR]

Presents an abstract of the article "The Prospective Identification of Patients at Risk of Developing Secondary Disease During a Triple FISH Assay Prior to High Dose Therapy," by Lisa Cunningham, N. Foot, A. Dixon-Mclver, M. Cross, C. Evans, T. A. Lister, and D. Lillington.

Glucagon signaling is essential for maintaining normoglycemia in mammals. The arrestin fold superfamily of proteins controls the trafficking, turnover, and signaling of transmembrane receptors as well as other intracellular signaling functions. Further investigation is needed to understand the in vivo functions of the arrestin domain-containing 4 (ARRDC4) protein family member and whether it is involved in mammalian glucose metabolism. Here, we show that mice with a global deletion of the ARRDC4 protein have impaired glucagon responses and gluconeogenesis at a systemic and molecular level. Mice lacking ARRDC4 exhibited lower glucose levels after fasting and could not suppress gluconeogenesis at the refed state. We also show that ARRDC4 coimmunoprecipitates with the glucagon receptor, and ARRDC4 expression is suppressed by insulin. These results define ARRDC4 as a critical regulator of glucagon signaling and glucose homeostasis and reveal a novel intersection of insulin and glucagon pathways in the liver., Competing Interests: Conflict of interest R. T. L. is a cofounder, scientific advisory board member, and private equity holder of Elevian, Inc. R. T. L. is a member of the scientific advisory board of Revidia Therapeutics, Inc, and the laboratory receives research support from BlueRock Therapeutics. J. K. K. is a scientific advisor of Elevian, Inc. All other authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Relapse remains the most common cause of treatment failure for patients with acute myeloid leukemia (AML) who undergo allogeneic stem cell transplantation (alloSCT), and carries a grave prognosis. Multiple studies have identified the presence of measurable residual disease (MRD) assessed by flow cytometry before alloSCT as a strong predictor of relapse, but it is not clear how these findings apply to patients who test positive in molecular MRD assays, which have far greater sensitivity. We analyzed pretransplant blood and bone marrow samples by reverse-transcription polymerase chain reaction in 107 patients with NPM1-mutant AML enrolled in the UK National Cancer Research Institute AML17 study. After a median follow-up of 4.9 years, patients with negative, low (<200 copies per 105ABL in the peripheral blood and <1000 copies in the bone marrow aspirate), and high levels of MRD had an estimated 2-year overall survival (2y-OS) of 83%, 63%, and 13%, respectively (P < .0001). Focusing on patients with low-level MRD before alloSCT, those with FLT3 internal tandem duplications(ITDs) had significantly poorer outcome (hazard ratio [HR], 6.14; P = .01). Combining these variables was highly prognostic, dividing patients into 2 groups with 2y-OS of 17% and 82% (HR, 13.2; P < .0001). T-depletion was associated with significantly reduced survival both in the entire cohort (2y-OS, 56% vs 96%; HR, 3.24; P = .0005) and in MRD-positive patients (2y-OS, 34% vs 100%; HR, 3.78; P = .003), but there was no significant effect of either conditioning regimen or donor source on outcome. Registered at ISRCTN (http://www.isrctn.com/ISRCTN55675535)., (© 2020 by The American Society of Hematology.)

Newly synthesized transmembrane proteins undergo a series of steps to ensure that only the required amount of correctly folded protein is localized to the membrane. The regulation of protein quality and its abundance at the membrane are often controlled by ubiquitination, a multistep enzymatic process that results in the attachment of ubiquitin, or chains of ubiquitin to the target protein. Protein ubiquitination acts as a signal for sorting, trafficking, and the removal of membrane proteins via endocytosis, a process through which multiple ubiquitin ligases are known to specifically regulate the functions of a number of ion channels, transporters, and signaling receptors. Endocytic removal of these proteins through ubiquitin-dependent endocytosis provides a way to rapidly downregulate the physiological outcomes, and defects in such controls are directly linked to human pathologies. Recent evidence suggests that ubiquitination is also involved in the shedding of membranes and associated proteins as extracellular vesicles, thereby not only controlling the cell surface levels of some membrane proteins, but also their potential transport to neighboring cells. In this review, we summarize the mechanisms and functions of ubiquitination of membrane proteins and provide specific examples of ubiquitin-dependent regulation of membrane proteins., (Copyright © 2017 the American Physiological Society.)

Context: Individuals with a history of anterior cruciate ligament reconstruction (ACLR) are at greater risk of reinjury and developing early-onset osteoarthritis due to persistent abnormal joint loading. Real-time clinical assessment tools may help identify patients experiencing abnormal movement patterns after ACLR., Objective: To compare performance on the Landing Error Scoring System (LESS) between participants with ACLR and uninjured control participants and to determine the relationship between LESS score and knee-extension strength in these participants., Design: Controlled laboratory study., Setting: Research laboratory., Patients or Other Participants: Forty-six recreationally active participants, consisting of 22 with ACLR (12 men, 10 women; age = 22.5 ± 5.0 years, height = 172.8 ± 7.2 cm, mass = 74.2 ± 15.6 kg, body mass index = 24.6 ± 4.0) and 24 healthy control participants (12 men, 12 women; age = 21.7 ± 3.6 years, height = 168.0 ± 8.8 cm, mass = 69.2 ± 13.6 kg, body mass index = 24.3 ± 3.2) were enrolled., Main Outcome Measure(s): Bilateral normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg) and LESS scores were measured during a single testing session. We compared LESS scores between groups using a Mann-Whitney U test and the relationships between LESS scores and normalized knee-extension MVIC torque using Spearman ρ bivariate correlations., Results: The ACLR participants had a greater number of LESS errors (6.0 ± 3.6) than healthy control participants (2.8 ± 2.2; t44 = -3.73, P = .002). In ACLR participants, lower normalized knee-extension MVIC torque in the injured limb (ρ = -0.455, P = .03) was associated with a greater number of landing errors., Conclusions: Participants with ACLR displayed more errors while landing. The occurrence of landing errors was negatively correlated with knee-extension strength, suggesting that weaker participants had more landing errors. Persistent quadriceps weakness commonly associated with ACLR may be related to a reduced quality of lower extremity movement during dynamic tasks.

The ability to remove unwanted proteins is an important cellular feature. Classically, this involves the enzymatic addition of ubiquitin moieties followed by degradation in the proteasome. Nedd4 proteins are ubiquitin ligases important not only for protein degradation, but also for protein trafficking. Nedd4 proteins can bind to target proteins either by themselves or through adaptor protein Ndfip1 (Nedd4 family-interacting protein 1). An alternative mechanism for protein removal and trafficking is provided by exosomes, which are small vesicles (50-90-nm diameter) originating from late endosomes and multivesicular bodies (MVBs). Exosomes provide a rapid means of shedding obsolete proteins and also for cell to cell communication. In the present work, we show that Ndfip1 is detectable in exosomes secreted from transfected cells and also from primary neurons. Compared with control, Ndfip1 increases exosome secretion from transfected cells. Furthermore, while Nedd4, Nedd4-2, and Itch are normally absent from exosomes, expression of Ndfip1 results in recruitment of all three Nedd4 proteins into exosomes. Together, these results suggest that Ndfip1 is important for protein trafficking via exosomes, and provides a mechanism for cargoing passenger proteins such as Nedd4 family proteins. Given the positive roles of Ndfip1/Nedd4 in improving neuronal survival during brain injury, it is possible that exosome secretion provides a novel route for rapid sequestration and removal of proteins during stress.

Background and Objectives: The acquisition of additional cytogenetic changes (clonal evolution, CE) during treatment of chronic myeloid leukemia (CML) with imatinib mesylate is currently regarded as an index of increasing resistance to imatinib. Therefore, to investigate whether CE as an isolated event increases the risk of disease progression during imatinib treatment, we compared the outcome of patients with CML in chronic phase (CML-CP) who developed CE whilst in complete hematologic remission with the outcome of comparable patients in complete hematologic remission who showed no evidence of CE., Design and Methods: We serially studied cytogenetic findings in 102 patients receiving the Abl-tyrosine kinase inhibitor, imatinib mesylate, as sole agent to treat CML-CP who had no evidence of CE before initiation of imatinib treatment., Results: CE was identified during treatment with imatinib in 15 patients, 10 of whom were in complete hematologic remission. In most cases these changes occurred exclusively in the Ph+ population but in three patients additional changes occurred in a co-existing Ph-negative population. Patients with de novo CE in the absence of any other sign of disease progression had a significantly higher incidence of progression by 18 months than did non-CE patients (progression-free survival 34.3% (CI 10.5-69.8%) vs. 94.1% (CI 80.6-98.4%), p<0.0001)., Interpretation and Conclusions: Based on this relatively small series of patients, we conclude that acquisition of clonal evolution increases the risk of subsequent disease progression also in CML patients in complete hematologic remission on imatinib.

1. Lymphocytes were usually the first cells to migrate out into the plasmic clot from explanted pieces of lymph nodes. 2. Their paths of migration were irregular but in general they proceeded away from the explant. 3. The lymphocytes migrated at rates varying from 0.03 to 0.0013 mm. per minute. The rate of any one varied from minute to minute, and they often came to rest for varying lengths of time. 4. The migrating lymphocytes were very much elongated, with the nucleus always near the anterior end. The elongated tail contained the endoplasm with a few granular mitochondria and usually a few granules which took up neutral red. 5. The lymphocytes in cultures made from normal and pathological lymph nodes in auto and homoplasma showed no differences.

If the spleen be removed from rabbits and tubercle bacilli be injected intravenously, it is found that the lesions produced differ materially from those observed in control animals; the lungs present the most marked contrast, the liver also shows a definite difference in the distribution of the tubercles, and the kidney lesions also differ in the two instances. In discussing these facts we must answer, if possible, the four questions formulated above. It appears that the pulmonary lesions in Group S are small and discrete because of some inhibitory factor that prevents the diffusion of the products of dead tubercle bacilli. The organisms, far from being killed, are more numerous and better preserved in this group, but their destructive action is localized. This seems to be connected with the presence of polymorphonuclear leucocytes, for these cells are more numerous in the lesions and more plentiful in the lumina of the pulmonary capillaries of Group S than they are in the controls. The conclusion to be drawn from this covers the answer to the second question. It is not the tubercle bacillus itself that produces the destructive changes, but the toxins liberated by the breaking down of its substance. The well known experiments of Hodenpyl and Armand-Delille, already referred to in this series of papers, show this to be true; dead tubercle bacilli, or even extracts of these organisms, will produce typical tubercles. Removing the spleen stimulates the production of polymorphonuclear leucocytes, as shown by Johnstone (1922). These cells may prevent the diffusion of split products from the bacilli by removing or neutralizing them. The third question, as to why the liver is more affected after splenectomy than in normal controls, is more readily answered. Probably the spleen acts as a catch-basin for the bacteria; once removed it can no longer withhold them from the portal circulation and the liver receives a larger number than it would were this bacterial filter still operative. On the other hand, there may be an increase in the phagocytic activity of the endothelium of the sinusoids which might take up more bacteria under these changed conditions. Several investigators have claimed, recently, that there is an increased activity of the liver endothelium following splenectomy, their experiments being directed chiefly toward determining the fate of the erythrocytes. Pearce (1918) in reporting the effects of experimental splenectomy in dogs, states that there are definite compensatory changes in the lymph nodes, in the form of an increased proliferation of endothelial phagocytes, and that the stellate cells of the liver sinusoids often show a similar compensatory increase in number. In both cases the cells are, apparently, formed in situ rather than transported to the organs. He says: 'Such findings suggest the development of a compensatory function on the part of the lymph-nodes and possibly the liver,' and suggests that, in times of stress 'the stellate cells of the liver thus assume, in part at least, the function of destroying red blood-corpuscles by phagocytosis.' Incidentally, he presents an excellent discussion of the history and subject of splenectomy. Motohashi (1922) reports a great increase in the hemophagic power of the hepatic endothelium and an increase in the number of endothelial elements, after some 45 days following splenectomy in rabbits. Nishikawa and Takagi (1922) have observed similar phenomena with white rats, the Kupffer cells taking up erythrocytes in large numbers in splenectomized animals, whereas controls never show similar propensities on the part of these cells. It may be that different substances cause different reactions on the part of the hepatic endothelium. Contributory Experiment.-A side experiment was performed with five rabbits, two splenectomized and three controls, into which uniform doses of pneumococci were injected intravenously. They all died of septicemia after a few days. The results of this experiment strengthen the foregoing conclusions materially. It was found that there were many polymorphonuclear amphophils in the pulmonary capillaries of the splenectomized animals and that there were numerous focal necroses in the livers. The controls showed much fewer polymorphonuclear cells in the lungs and no focal necroses in the livers, while the spleens were actively congested and inflamed. Otherwise the experiment was not of sufficient importance to warrant a separate report. The question as to why the endothelium of the pulmonary capillaries shows no stimulation similar to that observed in the carbon experiment, but rather less activity than that of the controls, must be answered hypothetically for the present. With the carbon, comparatively huge amounts of foreign matter were injected repeatedly; here but one injection of a much smaller amount of suspended tubercle bacilli was administered. The resulting stimulus to the pulmonary endothelium would, therefore, differ materially in the two instances. In one there would be succeeding waves of stimulation following each injection of irritating foreign substance. In the other an entirely different sort of stimulus would result; the bacteria would be withdrawn from the circulation within an hour or two, judging by past experience, and would then multiply, to be cast off into the circulation in driblets, as the lesions containing them broke down. At least it can be said that there is a good theoretical reason for the difference in the endothelial reaction in the lungs of the two groups of animals.

1. The injection of a colloidal suspension, or sol, of carbon into the veins of a living animal, as recommended by McJunkin, furnishes an apparently reliable means of tracing the so called epithelioid cell of the pulmonary tubercle from its origin in the vascular endothelium to the lesion. 2. Experimental tubercles are formed in the lung, as in the liver, primarily by cells originating in the capillary endothelium. These cells are probably present in small numbers in the normal lung, lying free both in the alveolar wall and the air vesicles. In response to infection they proliferate in the capillary walls in the vicinity of the invading organisms, migrate in steadily increasing numbers, and, arriving at the site of the infection, further multiply and to some extent fuse to form the syncytia known as giant cells. 3. The epithelial cell takes no active part in the process; its proliferation tends to repair denuded surfaces and is regenerative rather than combative or phagocytic in nature. This cell is free from carbon and stains only diffusely with carmine, in contradistinction to the endothelial cell which readily takes up both pigments in granular form. 4. The cells of endothelial origin not only phagocytose tubercle bacilli, but carry them into the tissues, for example into lymph nodes, by way of the lymphatics, or into other lung lobules by way of the air passages, in which they are readily demonstrable.

1. The development of the polymorphonuclear leucocyte from a mesenchymal, lymphoid type of cell is possible in adult life and in vitro in chicken bone marrow. 2. These cells can rapidly proliferate by means of amitotic division of an unripe form very similar to, but smaller than themselves. 3. All the cells of chicken bone marrow can undergo a transformation to a type of cell resembling, although not proved to be identical with the cells of connective tissue.