NBEAL2 deficiency in humans leads to low CTLA-4 expression in activated conventional T cells.

Loss of NBEAL2 function leads to grey platelet syndrome (GPS), a bleeding disorder characterized by macro-thrombocytopenia and α-granule-deficient platelets. A proportion of patients with GPS develop autoimmunity through an unknown mechanism, which might be related to the proteins NBEAL2 interacts with, specifically in immune cells. Here we show a comprehensive interactome of NBEAL2 in primary T cells, based on mass spectrometry identification of altogether 74 protein association partners. These include LRBA, a member of the same BEACH domain family as NBEAL2, recessive mutations of which cause autoimmunity and lymphocytic infiltration through defective CTLA-4 trafficking. Investigating the potential association between NBEAL2 and CTLA-4 signalling suggested by the mass spectrometry results, we confirm by co-immunoprecipitation that CTLA-4 and NBEAL2 interact with each other. Interestingly, NBEAL2 deficiency leads to low CTLA-4 expression in patient-derived effector T cells, while their regulatory T cells appear unaffected. Knocking-down NBEAL2 in healthy primary T cells recapitulates the low CTLA-4 expression observed in the T cells of GPS patients. Our results thus show that NBEAL2 is involved in the regulation of CTLA-4 expression in conventional T cells and provide a rationale for considering CTLA-4-immunoglobulin therapy in patients with GPS and autoimmune disease.

Fanconi anemia proteins counteract the implementation of the oncogene-induced senescence program.

Fanconi Anemia (FA), due to the loss-of-function of the proteins that constitute the FANC pathway involved in DNA replication and genetic stability maintainance, is a rare genetic disease featuring bone marrow failure, developmental abnormalities and cancer predisposition. Similar clinical stigmas have also been associated with alterations in the senescence program, which is activated in physiological or stress situations, including the unscheduled, chronic, activation of an oncogene (oncogene induced senescence, OIS). Here, we wanted to determine the crosstalk, if any, between the FANC pathway and the OIS process. OIS was analyzed in two known cellular models, IMR90-hTERT/ER:RASG12V and WI38-hTERT/ER:GFP:RAF1, harboring 4-hydroxytamoxifen-inducible oncogenes. We observed that oncogene activation induces a transitory increase of both FANCA and FANCD2 as well as FANCD2 monoubiquitination, readout of FANC pathway activation, followed by their degradation. FANCD2 depletion, which leads to a pre-senescent phenotype, anticipates OIS progression. Coherently, FANCD2 overexpression or inhibition of its proteosomal-dependent degradation slightly delays OIS progression. The pro-senescence protease cathepsin L, which activation is anticipated during OIS in FANCD2-depleted cells, also participates to FANCD2 degradation. Our results demonstrate that oncogene activation is first associated with FANCD2 induction and activation, which may support initial cell proliferation, followed by its degradation/downregulation when OIS proceeds.

New piperazine multi-effect drugs prevent neurofibrillary degeneration and amyloid deposition, and preserve memory in animal models of Alzheimer's disease.

Alzheimer's Disease is a devastating dementing disease involving amyloid deposits, neurofibrillary tangles, progressive and irreversible cognitive impairment. Today, only symptomatic drugs are available and therapeutic treatments, possibly acting at a multiscale level, are thus urgently needed. To that purpose, we designed multi-effects compounds by synthesizing drug candidates derived by substituting a novel N,N'-disubstituted piperazine anti-amyloid scaffold and adding acetylcholinesterase inhibition property. Two compounds were synthesized and evaluated. The most promising hybrid molecule reduces both the amyloid pathology and the Tau pathology as well as the memory impairments in a preclinical model of Alzheimer's disease. In vitro also, the compound reduces the phosphorylation of Tau and inhibits the release of Aß peptides while preserving the processing of other metabolites of the amyloid precursor protein. We synthetized and tested the first drug capable of ameliorating both the amyloid and Tau pathology in animal models of AD as well as preventing the major brain lesions and associated memory impairments. This work paves the way for future compound medicines against both Alzheimer's-related brain lesions development and the associated cognitive impairments.

Contribution of the Endosomal-Lysosomal and Proteasomal Systems in Amyloid-ß Precursor Protein Derived Fragments Processing.

Aß peptides, the major components of Alzheimer's disease (AD) amyloid deposits, are released following sequential cleavages by secretases of its precursor named the amyloid precursor protein (APP). In addition to secretases, degradation pathways, in particular the endosomal/lysosomal and proteasomal systems have been reported to contribute to APP processing. However, the respective role of each of these pathways toward APP metabolism remains to be established. To address this, we used HEK 293 cells and primary neurons expressing full-length wild type APP or the ß-secretase-derived C99 fragment (ß-CTF) in which degradation pathways were selectively blocked using pharmacological drugs. APP metabolites, including carboxy-terminal fragments (CTFs), soluble APP (sAPP) and Aß peptides were studied. In this report, we show that APP-CTFs produced from endogenous or overexpressed full-length APP are mainly processed by γ-secretase and the endosomal/lysosomal pathway, while in sharp contrast, overexpressed C99 is mainly degraded by the proteasome and to a lesser extent by γ-secretase.

A phenotypic approach to the discovery of compounds that promote non-amyloidogenic processing of the amyloid precursor protein: Toward a new profile of indirect ß-secretase inhibitors.

Dysregulation of the Amyloid Precursor Protein (APP) processing leading to toxic species of amyloid ß peptides (Aß) is central to Alzheimer's disease (AD) etiology. Aß peptides are produced by sequential cleavage of APP by ß-secretase (BACE-1) and γ-secretase. Lysosomotropic agent, chloroquine (CQ), has been reported to inhibit Aß peptide production. However, this effect is accompanied by an inhibition of lysosome-mediated degradation pathways. Following on from the promising activity of two series of APP metabolism modulators derived from CQ, we sought to develop new series of compounds that would retain the inhibitory effects on Aß production without altering lysosome functions. Herein, we applied a ligand-based pharmacophore modeling approach coupled with de novo design that led to the discovery of a series of biaryl compounds. Structure-activity relationship studies revealed that minor modifications like replacing a piperidine moiety of compound 30 by a cyclohexyl (compound 31) allowed for the identification of compounds with the desired profile. Further studies have demonstrated that compounds 30 and 31 act through an indirect mechanism to inhibit ß-secretase activity. This work shows that it is possible to dissociate the inhibitory effect on Aß peptide secretion of CQ-derived compounds from the lysosome-mediated degradation effect, providing a new profile of indirect ß-secretase inhibitors.

Migration of photoinitiators from cardboard into dry food: evaluation of Tenax® as a food simulant.

Photoinitiators are widely used to cure ink on packaging materials used in food applications such as cardboards for the packaging of dry foods. Conventional migration testing for long-term storage at ambient temperature with Tenax(®) was applied to paperboard for the following photoinitiators: benzophenone (BP), 4,4'-bis(diethylamino)benzophenone (DEAB), 2-chloro-9H-thioxanthen-9-one (CTX), 1-chloro-4-propoxy-9H-thioxanthen-9-one (CPTX), 4-(dimethylamino)benzophenone (DMBP), 2-ethylanthraquinone (EA), 2-ethylhexyl-4-dimethylaminobenzoate (EDB), ethyl-4-dimethylaminobenzoate (EDMAB), 4-hydroxybenzophenone (4-HBP), 2-hydroxy-4-methoxybenzophenone (HMBP), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HMMP), 2-isopropyl-9H-thioxanthen-9-one (ITX), 4-methylbenzophenone (MBP) and Michler's ketone (MK). Test conditions (10 days at 60°C) were according to Regulation (EU) No. 10/2011 and showed different migration patterns for the different photoinitiators. The results were compared with the migration in cereals after a storage of 6 months at room temperature. The simulation with Tenax at 60°C overestimated actual migration in cereals up to a maximum of 92%. In addition, the effect of a lower contact temperature and the impact of the Tenax pore size were investigated. Analogous simulation performed with rice instead of Tenax resulted in insufficiently low migration rates, showing Tenax is a much stronger adsorbent than rice and cereals.