The Dually Acylated NH2-terminal Domain of Gi1α Is Sufficient to Target a Green Fluorescent Protein Reporter to Caveolin-enriched Plasma Membrane Domains: PALMITOYLATION OF CAVEOLIN-1 IS REQUIRED FOR THE RECOGNITION OF DUALLY ACYLATED G-PROTEIN α SUBUNITS IN VIVO

Here we investigate the molecular mechanisms that govern the targeting of G-protein α subunits to the plasma membrane. For this purpose, we used Gi1α as a model dually acylated G-protein. We fused full-length Gi1α or its extreme NH2-terminal domain (residues 1–32 or 1–122) to green fluorescent protein (GFP) and analyzed the subcellular localization of these fusion proteins. We show that the first 32 amino acids of Gi1α are sufficient to target GFP to caveolin-enriched domains of the plasma membrane in vivo, as demonstrated by co-fractionation and co-immunoprecipitation with caveolin-1. Interestingly, when dual acylation of this 32-amino acid domain was blocked by specific point mutations (G2A or C3S), the resulting GFP fusion proteins were localized to the cytoplasm and excluded from caveolin-rich regions. The myristoylated but nonpalmitoylated (C3S) chimera only partially partitioned into caveolin-containing fractions. However, both nonacylated GFP fusions (G2A and C3S) no longer co-immunoprecipitated with caveolin-1. Taken together, these results indicate that lipid modification of the NH2-terminal of Gi1α is essential for targeting to its correct destination and interaction with caveolin-1. Also, a caveolin-1 mutant lacking all three palmitoylation sites (C133S, C143S, and C156S) was unable to co-immunoprecipitate these dually acylated GFP-G-protein fusions. Thus, dual acylation of the NH2-terminal domain of Gi1α and palmitoylation of caveolin-1 are both required to stabilize and perhaps regulate this reciprocal interaction at the plasma membrane in vivo. Our results provide the first demonstration of a functional role for caveolin-1 palmitoylation in its interaction with signaling molecules

Antiadhesive Role of Apical Decay-accelerating Factor (CD55) in Human Neutrophil Transmigration across Mucosal Epithelia

Neutrophil migration across mucosal epithelium during inflammatory episodes involves the precise orchestration of a number a cell surface molecules and signaling pathways. After successful migration to the apical epithelial surface, apically localized epithelial proteins may serve to retain PMN at the lumenal surface. At present, identification of apical epithelial ligands and their PMN counter-receptors remain elusive. Therefore, to define the existence of apical epithelial cell surface proteins involved in PMN–epithelial interactions, we screened a panel of antibodies directed against epithelial plasma membranes. This strategy identified one antibody (OE-1) that both localized to the apical cell membrane and significantly inhibited PMN transmigration across epithelial monolayers. Microsequence analysis revealed that OE-1 recognized human decay-accelerating factor (DAF, CD55). DAF is a highly glycosylated, 70–80-kD, glycosyl-phosphatidyinositol–linked protein that functions predominantly as an inhibitor of autologous complement lysis. DAF suppression experiments using antisense oligonucleotides or RNA interference revealed that DAF may function as an antiadhesive molecule promoting the release of PMN from the lumenal surface after transmigration. Similarly, peptides corresponding to the antigen recognition domain of OE-1 resulted in accumulation of PMN on the apical epithelial surface. The elucidation of DAF as an apical epithelial ligand for PMN provides a target for novel anti-inflammatory therapies directed at quelling unwanted inflammatory episodes

Job Scheduling Using successive Linear Programming Approximations of a Sparse Model

EuroPar 2012In this paper we tackle the well-known problem of scheduling a collection of parallel jobs on a set of processors either in a cluster or in a multiprocessor computer. For the makespan objective, i.e., the completion time of the last job, this problem has been shown to be NP-Hard and several heuristics have already been proposed to minimize the execution time. We introduce a novel approach based on successive linear programming (LP) approximations of a sparse model. The idea is to relax an integer linear program and use lp norm-based operators to force the solver to find almost-integer solutions that can be assimilated to an integer solution. We consider the case where jobs are either rigid or moldable. A rigid parallel job is performed with a predefined number of processors while a moldable job can define the number of processors that it is using just before it starts its execution. We compare the scheduling approach with the classic Largest Task First list based algorithm and we show that our approach provides good results for small instances of the problem. The contributions of this paper are both the integration of mathematical methods in the scheduling world and the design of a promising approach which gives good results for scheduling problems with less than a hundred processors

Synchronization and variability imbalance underlie cognitive impairment in primary-progressive multiple sclerosis.

We aimed to investigate functional connectivity and variability across multiple frequency bands in brain networks underlying cognitive deficits in primary-progressive multiple sclerosis (PP-MS) and to explore how they are affected by the presence of cortical lesions (CLs). We analyzed functional connectivity and variability (measured as the standard deviation of BOLD signal amplitude) in resting state networks (RSNs) associated with cognitive deficits in different frequency bands in 25 PP-MS patients (12 M, mean age 50.9 ± 10.5 years) and 20 healthy subjects (9 M, mean age 51.0 ± 9.8 years). We confirmed the presence of a widespread cognitive deterioration in PP-MS patients, with main involvement of visuo-spatial and executive domains. Cognitively impaired patients showed increased variability, reduced synchronicity between networks involved in the control of cognitive macro-domains and hyper-synchronicity limited to the connections between networks functionally more segregated. CL volume was higher in patients with cognitive impairment and was correlated with functional connectivity and variability. We demonstrate, for the first time, that a functional reorganization characterized by hypo-synchronicity of functionally-related/hyper-synchronicity of functionally-segregated large scale networks and an abnormal pattern of neural activity underlie cognitive dysfunction in PP-MS, and that CLs possibly play a role in variability and functional connectivity abnormalities

Coenzyme Q10 and the exclusive club of diseases that show a limited response to treatment

Introduction: Coenzyme Q10 (CoQ10) is a ubiquitous organic molecule with a significant role in the mitochondrial electron transport chain (ETC). As a result of its role in such an important biological process, CoQ10 deficiency has been implicated in the pathogenesis of numerous diseases such as Parkinson’s disease (PD) and multiple sclerosis (MS). This has led to multiple attempts to use CoQ10 supplementation as a treatment or pre-treatment with varying degrees of success. Areas covered: The present review will identify evidence of mitochondrial dysfunction in MS, PD and mitochondrial ETC disorders. In addition, the inability of Co10 supplementation to elicit significant clinical outcome in these disorders and possible flaws in these studies will be discussed. The databases utilized for this review were the Web of science and PubMed, with inclusive dates (1957–2021). Expert opinion: A lack of improved neurological outcome in these disorders post treatment with CoQ10 may be attributable to the limited ability of CoQ10 to cross the blood–brain barrier. Thus, CoQ10 alternatives should also be considered. Other factors including time of disease diagnosis, dosage, administration, and duration of CoQ10 therapy may have a significant influence on the efficacy of this treatment

A randomized, placebo-controlled phase 2 trial of laquinimod in primary progressive multiple sclerosis

OBJECTIVE: To evaluate efficacy, safety, and tolerability of laquinimod in patients with primary progressive multiple sclerosis (PPMS). METHODS: In the randomized, double-blind, placebo-controlled, phase 2 study ARPEGGIO (A Randomized Placebo-controlled trial Evaluating laquinimod in PPMS, Gauging Gradations In MRI and clinical Outcomes), eligible PPMS patients were randomized 1:1:1 to receive once-daily oral laquinimod 0.6 mg or 1.5 mg or matching placebo. Percentage brain volume change (PBVC; primary endpoint) from baseline to week 48 was assessed by MRI. Secondary and exploratory endpoints included clinical and MRI measures. Efficacy endpoints were evaluated using a predefined, hierarchical statistical testing procedure. Safety was monitored throughout the study. The laquinimod 1.5 mg dose arm was discontinued on January 1, 2016 due to findings of cardiovascular events. RESULTS: 374 patients were randomized to laquinimod 0.6 mg (n = 139) or 1.5 mg (n = 95) or placebo (n = 140). ARPEGGIO did not meet the primary endpoint of significant treatment effect with laquinimod 0.6 mg versus placebo on PBVC from baseline to week 48 (adjusted mean difference = 0.016%, p = 0.903). Laquinimod 0.6 mg reduced the number of new T2 brain lesions at week 48 (risk ratio = 0.4; 95% confidence interval, 0.26-0.69; p = 0.001). Incidence of adverse events was higher among patients treated with laquinimod 0.6 mg (83%) versus laquinimod 1.5 mg (66%) and placebo (78%). CONCLUSIONS: Laquinimod 0.6 mg did not demonstrate a statistically significant effect on brain volume loss in PPMS at week 48

Recent Progress In The Diagnosis And Treatment Of Multiple Sclerosis

Magnetic resonance imaging (MRI) now provides valuable diagnostic and prognostic information for the management of multiple sclerosis (MS) but the diagnosis still largely rests on the clinical features of central nervous system (CNS) lesions disseminated in time and place. Recent histological and MRI studies indicate that extensive axonal damage can occur in MS, even early in the disease course, and is likely to be an important cause of accumulating disability. Several immunomodulating agents have now been shown to have beneficial effects in MS. High dose intravenous or high dose oral methylprednisolone therapy accelerates recovery from attacks of relapsing-remitting MS, but at present there is no convincing evidence that standard dose (intermediate dose) oral corticosteroid therapy is beneficial for such attacks. Interferon beta, copolymer 1 (glatiramer acetate) and i.v. immunoglobulin therapy each significantly reduce the frequency of attacks of relapsing-remitting MS. Interferon beta also inhibits the progression of disability in relapsing-remitting MS and secondary progressive MS, but its effect on primary progressive MS is unknown. Oral low dose methotrexate therapy slows the progression of disability in secondary progressive MS and possibly in primary progressive MS, but it is likely that the currently used dosage (7.5 mg weekly) is suboptimal. Further research is needed to determine the optimal doses and combinations of the above therapies in MS and to develop better therapies, particularly for primary progressive MS

Increased circulating T cell reactivity to GM3 and GQ1b gangliosides in primary progressive multiple sclerosis

We have previously shown that patients with primary progressive multiple sclerosis (MS) have significantly elevated plasma levels of antibody to GM3 ganglioside compared to patients with relapsing-remitting MS, healthy subjects and patients with other neurological diseases. Anti-GM3 antibody levels were elevated also in patients with secondary progressive MS but to a lesser extent than in primary progressive MS. As gangliosides are particularly enriched in the axonal membrane, these findings suggested that antiganglioside immune responses might contribute to the axonal damage in progressive forms of MS. The present study was performed to determine whether peripheral blood T cell responses to GM3 are also increased in progressive MS. Blood was collected from 98 untreated patients with MS (40 with relapsing-remitting, 27 with secondary progressive and 31 with primary progressive MS), 50 healthy subjects and 24 patients with other disorders of the CNS, and reactivity to GM1, GM3, GD1a, GD1b, GD3, GT1b, GQ1b and sulphatide was assessed by 6-day T cell proliferation assays. Increased T cell reactivity to GM3 and GQ1b occurred significantly more often in patients with primary progressive MS than in healthy subjects and patients with other CNS diseases. These findings suggest that ganglioside-specific T cells may contribute to the axonal damage in primary progressive MS. (C) 2002 Elsevier Science Ltd. All rights reserved