Activation of the signal transducer and activator of transcription 1 signaling pathway in thymocytes from HIV-1-infected human thymus

A critical role for Rictor in T lymphopoiesis

Apart from a critical role for Notch and pre-TCR, the signaling pathway required for T lymphopoiesis is largely unknown. Given the potential link between Notch and mammalian target of rapamycin (mTOR) signaling in cancer cells, we used mice with conditional deletion of either Raptor or Rictor genes to determine potential contribution of the mTOR complex I and II in T lymphopoiesis. Our data demonstrated that targeted mutation of Rictor in the thymocytes drastically reduced the thymic cellularity, primarily by reducing proliferation of the immature thymocytes. Rictor deficiency caused a partial block of thymocyte development at the double-negative 3 stage. The effect of Rictor deficiency is selective for the T cell lineage, as the development of B cells, erythrocytes, and myeloid cells is largely unaffected. Analysis of bone marrow chimera generated from a mixture of wild-type and Rictor-deficient hematopoietic stem cells demonstrated that the function of Rictor is cell intrinsic. These data revealed a critical function of mTOR complex 2 in T lymphopoiesis.

Disability grant for people living with HIV/AIDS in the Eastern Cape of South Africa

A cross-sectional explorative descriptive qualitative/quantitative study was conducted in the Eastern Cape of South Africa. The qualitative component involved 38 HIV/AIDS stakeholders who were interviewed telephonically using a semi-structured interview schedule. The quantitative component comprised 607 People Living With HIV/AIDS (PLWHA) who were interviewed using a structured questionnaire. The majority of PLWHA were female, never married, unemployed, aged between 26 to 45 years, Black African, and had more than grade 7 education. All stakeholders supported the disability grant (DG) because it improved the lifestyle of PLWHA. The CD4 count was cited as the main criterion for putting PLWHA on the DG. The conditions and characteristics of the DG were not clearly explained to PLWHA. The DG application process was viewed to be too long. Access to service points was perceived as a challenge for some PLWHA. The DG was used to meet basic household and health care needs. Not being on a DG was associated with lower CD4 counts, often without enough food, and less often without needed medicines in the past 12 months. Having the DG stopped was associated with often not having enough medicines that were needed in the past 12 months. We conclude that the DG is a lifeline for most HIV/AIDS-affected families. We recommend that DG should not use CD4 cell counts as criterion for DG eligibility; the conditions and characteristics of the DG should be fully explained to recipients; the DG application process should be completed within one day; PLWHA who no longer qualify for the DG yet do not have adequate financial means to meet basic necessities should be put on a nutritional support program; and access to the location of the grants by the poor and vulnerable should be improved.

Lentivirus infection causes neuroinflammation and neuronal injury in dorsal root ganglia: pathogenic effects of STAT-1 and inducible nitric oxide synthase

Distal sensory polyneuropathy (DSP) is currently the most common neurological complication of HIV infection in the developed world and is characterized by sensory neuronal injury accompanied by inflammation, which is clinically manifested as disabling pain and gait instability. We previously showed that feline immunodeficiency virus (FIV) infection of cats caused DSP together with immunosuppression in cats, similar to that observed in HIV-infected humans. In this study, we investigated the pathogenic mechanisms underlying the development of FIV-induced DSP using feline dorsal root ganglia (DRG) cultures, consisting of neurons, Schwann cells, and macrophages. FIV-infected cultures exhibited viral Ags (p24 and envelope) in macrophages accompanied by neuronal injury, indicated by neurite retraction, neuronal loss and decreased soma size, compared with mock-infected (control) cultures. FIV infection up-regulated inducible NO synthase (iNOS), STAT-1, and TNF-alpha mRNA levels in DRG cultures. Increased STAT-1 and iNOS mRNA levels were also observed in DRGs from FIV-infected animals relative to mock-infected controls. Similarly, immunolabeling studies of DRGs from FIV-infected animals showed that macrophages were the principal sources of STAT-1 and iNOS protein production. The iNOS inhibitor aminoguanidine reduced nitrotyrosine and protein carbonyl levels, together with preventing neuronal injury in FIV-infected DRG cultures. The present studies indicate that FIV infection of DRGs directly contributes to axonal and neuronal injury through a mechanism involving macrophage immune activation, which is mediated by STAT-1 and iNOS activation.

Expression-based monitoring of transcription factor activity: the TELiS database

MOTIVATION

In microarray studies it is often of interest to identify upstream transcription control pathways mediating observed changes in gene expression. The Transcription Element Listening System (TELiS) combines sequence-based analysis of gene regulatory regions with statistical prevalence analyses to identify transcription-factor binding motifs (TFBMs) that are over-represented among the promoters of up- or down-regulated genes. Efficiency is maximized by decomposing the problem into two steps: (1) a priori compilation of prevalence matrices specifying the number of putative binding sites for a variety of transcription factors in promoters from all genes assayed by a given microarray, and (2) real-time statistical analysis of pre-compiled prevalence matrices to identify TFBMs that are over- or under-represented in promoters of differentially expressed genes. The interlocking JAVA applications namely, PromoterScan and PromoterStats carry out these tasks, and together constitute the TELiS database for reverse inference of transcription factor activity.

RESULTS

In two validation studies, TELiS accurately detected in vivo activation of NF-kappaB and the Type I interferon system by HIV-1 infection and pharmacologic activation of the glucocorticoid receptor in peripheral blood mononuclear cells. The population-based statistical inference underlying TELiS out-performed conventional statistical tests in analytic sensitivity, with parametric studies demonstrating accurate identification of transcription factor activity from as few as 20 differentially expressed genes. TELiS thus provides a simple, rapid and sensitive tool for identifying transcription control pathways mediating observed gene expression dynamics.