Studies carried out till date to elucidate the pathways involved in HIV-1-induced T-cell depletion has revealed that apoptosis underlie the etiology, however, a clear molecular understanding of HIV-1-induced apoptosis has remained elusive. Although evidences pointing towards the importance of mitochondrial energy generating system in apoptosis exist but it's exact role remains to be clearly understood. Here, we describe for the first time specific downregulation of a complex I subunit NDUFA6 with simultaneous impairment of mitochondrial complex I activity in HIV infection. We also show that NDUFA6 gene silencing induces apoptosis and its overexpression reduces apoptosis in HIV-infected cells. Finally, sensitivity to complex I inhibitor Rotenone is reduced in HIV-1-infected T cells indicating an important role for it in the death process. Our data provide a novel molecular basis as to how the virus might interfere with host cell energy generating system during apoptotic cell death.

A recent transcriptome analysis of graded patient glioma samples led to identification of AEBP1 as one of the genes upregulated in majority of the primary GBM as against secondary GBM. Aebp1 is a transcriptional repressor that is involved in adipogenesis. It binds to AE-1 element present in the proximal promoter of aP2 gene that codes for fatty acid binding protein (FABP4). A comprehensive study was undertaken to elucidate the role of AEBP1 overexpression in glioblastoma. We employed complementary gene silencing approach to identify the genes that are perturbed in a glioma cell line (U87MG). A total of 734 genes were differentially regulated under these conditions (≥ 1.5-fold, P ≤ 0.05) belonging to different GO categories such as transcription regulation, cell growth, proliferation, differentiation, and apoptosis of which perturbation of 114 genes of these pathways were validated by quantitative real time PCR (qRT-PCR). This approach was subsequently combined with ChIP-chip technique using an Agilent human promoter tiling array to identify genomic binding loci of Aebp1 protein. A subset of these genes identified for Aebp1 occupancy was also validated by ChIP-PCR. Bioinformatics analysis of the promoters identified by ChIP-chip technique revealed a consensus motif GAAAT present in 66% of the identified genes. This consensus motif was experimentally validated by functional promoter assay using luciferase as the reporter gene. Both cellular proliferation and survival were affected in AEBP1-silenced U87MG and U138MG cell lines and a significant percentage of these cells were directed towards apoptosis.

The human immunode¢ciency virus (HIV-1) Nef protein is now regarded as a regulatory protein responsible not only for establishment of infection and increased pathogenesis but also for enhancement of viral replication. However, the mechanism of Nef-induced activation of viral replication remains to be clearly understood. Using transient transfection assay, co-immunoprecipitation and pull-down analysis, we demonstrate in this report that the HIV-1 Nef protein physically interacts with Tat, the principal transactivating protein of HIV-1. Our observations with single cycle replication experiments further indicate that this interaction results not only in enhancement of Tat-induced HIV-1 long terminal repeat-mediated gene expression but also in virus production. ß

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Glioblastoma (GBM; grade IV astrocytoma) is a very aggressive form of brain cancer with a poor survival and few qualified predictive markers. This study integrates experimentally validated genes that showed specific upregulation in GBM along with their protein-protein interaction information. A system level analysis was used to construct GBM-specific network. Computation of topological parameters of networks showed scale-free pattern and hierarchical organization. From the large network involving 1,447 proteins, we synthesized subnetworks and annotated them with highly enriched biological processes. A careful dissection of the functional modules, important nodes, and their connections identified two novel intermediary molecules CSK21 and protein phosphatase 1 α (PP1A) connecting the two subnetworks CDC2-PTEN-TOP2A-CAV1-P53 and CDC2-CAV1-RB-P53-PTEN, respectively. Real-time quantitative reverse transcription-PCR analysis revealed CSK21 to be moderately upregulated and PP1A to be overexpressed by 20-fold in GBM tumor samples. Immunohistochemical staining revealed nuclear expression of PP1A only in GBM samples. Thus, CSK21 and PP1A, whose functions are intimately associated with cell cycle regulation, might play key role in gliomagenesis.