Glutathione deficit impairs myelin maturation: relevance for white matter integrity in schizophrenia patients

Schizophrenia pathophysiology implies both abnormal redox control and dysconnectivity of the prefrontal cortex, partly related to oligodendrocyte and myelin impairments. As oligodendrocytes are highly vulnerable to altered redox state, we investigated the interplay between glutathione and myelin. In control subjects, multimodal brain imaging revealed a positive association between medial prefrontal glutathione levels and both white matter integrity and resting-state functional connectivity along the cingulum bundle. In early psychosis patients, only white matter integrity was correlated with glutathione levels. On the other side, in the prefrontal cortex of peripubertal mice with genetically impaired glutathione synthesis, mature oligodendrocyte numbers, as well as myelin markers, were decreased. At the molecular levels, under glutathione-deficit conditions induced by short hairpin RNA targeting the key glutathione synthesis enzyme, oligodendrocyte progenitors showed a decreased proliferation mediated by an upregulation of Fyn kinase activity, reversed by either the antioxidant N-acetylcysteine or Fyn kinase inhibitors. In addition, oligodendrocyte maturation was impaired. Interestingly, the regulation of Fyn mRNA and protein expression was also impaired in fibroblasts of patients deficient in glutathione synthesis. Thus, glutathione and redox regulation have a critical role in myelination processes and white matter maturation in the prefrontal cortex of rodent and human, a mechanism potentially disrupted in schizophrenia

Genetic Diversity of EBV-Encoded LMP1 in the Swiss HIV Cohort Study and Implication for NF-Κb Activation

Epstein-Barr virus (EBV) is associated with several types of cancers including Hodgkin's lymphoma (HL) and nasopharyngeal carcinoma (NPC). EBV-encoded latent membrane protein 1 (LMP1), a multifunctional oncoprotein, is a powerful activator of the transcription factor NF-κB, a property that is essential for EBV-transformed lymphoblastoid cell survival. Previous studies reported LMP1 sequence variations and induction of higher NF-κB activation levels compared to the prototype B95-8 LMP1 by some variants. Here we used biopsies of EBV-associated cancers and blood of individuals included in the Swiss HIV Cohort Study (SHCS) to analyze LMP1 genetic diversity and impact of sequence variations on LMP1-mediated NF-κB activation potential. We found that a number of variants mediate higher NF-κB activation levels when compared to B95-8 LMP1 and mapped three single polymorphisms responsible for this phenotype: F106Y, I124V and F144I. F106Y was present in all LMP1 isolated in this study and its effect was variant dependent, suggesting that it was modulated by other polymorphisms. The two polymorphisms I124V and F144I were present in distinct phylogenetic groups and were linked with other specific polymorphisms nearby, I152L and D150A/L151I, respectively. The two sets of polymorphisms, I124V/I152L and F144I/D150A/L151I, which were markers of increased NF-κB activation in vitro, were not associated with EBV-associated HL in the SHCS. Taken together these results highlighted the importance of single polymorphisms for the modulation of LMP1 signaling activity and demonstrated that several groups of LMP1 variants, through distinct mutational paths, mediated enhanced NF-κB activation levels compared to B95-8 LMP1

Silencing of both β-TrCP1 and HOS (β-TrCP2) Is Required To Suppress Human Immunodeficiency Virus Type 1 Vpu-Mediated CD4 Down-Modulation

The human immunodeficiency virus type 1 (HIV-1) Vpu protein interacts with CD4 within the endoplasmic reticula of infected cells and targets CD4 for degradation through interaction with β-TrCP1. Mammals possess a homologue of β-TrCP1, HOS, which is also named β-TrCP2. We show by coimmunoprecipitation experiments that β-TrCP2 binds Vpu and is able to induce CD4 down-modulation as efficiently as β-TrCP1. In two different cell lines, HeLa CD4(+) and Jurkat, Vpu-mediated CD4 down-modulation could not be reversed through the individual silencing of endogenous β-TrCP1 or β-TrCP2 but instead required the two genes to be silenced simultaneously

Mutation screening of the glutamate cysteine ligase modifier (GCLM) gene in patients with schizophrenia

Experimental evidences show that glutathione and its rate-limiting synthesizing enzyme, the glutamate-cysteine ligase (GCL), are involved in the pathogenesis of schizophrenia. Furthermore, genetic association has been previously reported between two single nucleotide polymorphisms lying in noncoding regions of glutamate cysteine ligase modifier (GCLM) gene, which specifies for the modifier subunit of GCL and schizophrenia.; We wanted to investigate the presence of GCLM true functional mutations, likely in linkage disequilibrium with the previously identified single nucleotide polymorphism alleles, in the same set of cases that allowed the detection of the original association signal.; We screened all the coding regions of GCLM and their intronic flanking vicinities in 353 patients with schizophrenia by direct DNA sequencing.; Ten sequence variations were identified, five of which were not previously described. None of these DNA changes was within the GCLM coding sequence and in-silico analysis failed to indicate functional impairment induced by these variations. Furthermore, screening of normal controls and downstream statistical analyses revealed no significant relationship of any of these DNA variants with schizophrenia.; It is unlikely that functional mutations in the GCLM gene could play a major role in genetic predisposition to schizophrenia and further studies will be required to assess its etiological function in the disease

Protection from HIV-1 Infection of Primary Cd4 T Cells by Ccr5 Silencing is Effective for the Full Spectrum of Ccr5 Expression

Stable gene silencing by RNA interference (RNAi) can be achieved by expression of small hairpin RNAs (shRNAs) from RNA polymerase III promoters. We have tested lentiviral vectors expressing shRNAs targetting CCR5 in primary CD4 T cells from donors representing various CCR5 and CCR2 genetic backgrounds covering the full spectrum of CCR5 expression levels and permissiveness for HIV-1 infection. A linear decrease in CCR5 expression resulted in a logarithmic decrease in cellular infection, giving up to three logs protection from HIV-1 infection in vitro. Protection was maintained at very high multiplicity of infection. This and other recent reports on RNAi should open a debate about the use of RNAi gene therapy for HIV infection. </jats:p