Biotechnology and Bioinformatics - Publications

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    A study of the Topoisomerase II activity in HIV-1 replication using the ferrocene derivatives as probes
    ( 2006-06-15) Kondapi, Anand K. ; Satyanarayana, Nathamu ; Saikrishna, A. D.
    Human Topoisomerase II is present in two isoforms, 170 KDa α and 180 KDa β. Both the isoforms play a crucial role in maintenance of topological changes during DNA replication and recombination. It has been shown that Topoisomerase II activity is required for HIV-1 replication and the enzyme is phosphorylated during early time points of HIV-1 replication. In the present study, we have studied the molecular action of Topoisomerase II inhibitors, azalactone ferrocene (AzaFecp), Thiomorpholide amido methyl ferrocene (ThioFecp), and Ruthenium benzene amino pyridine (Ru(ben)Apy) on cell proliferation and also on various events of HIV-1 replication cycle. The Topoisomerase II β over-expressing neuroblastoma cell line shows a higher sensitivity to these compounds compared to the Sup-T1 cell line. All the three Topoisomerase II inhibitors show significant anti-HIV activity at nanomolar concentrations against an Indian isolate of HIV-193IN101 in Sup-T1 cell line. An analysis of action of these compounds on proviral DNA synthesis at 5 h of post-infection shows that they inhibit proviral DNA synthesis as well as the formation of pre-integration complexes completely. Further analysis, using polymerase chain reaction and western blot, showed that both the Topoisomerase II α and β isoforms are present in the pre-integration complexes, suggesting their significant role in HIV-1 replication. © 2006 Elsevier Inc. All rights reserved.
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    New anticancer bastadin alkaloids from the sponge Dendrilla cactos
    ( 2006-07-01) Reddy, A. Vijender ; Ravinder, K. ; Narasimhulu, M. ; Sridevi, A. ; Satyanarayana, N. ; Kondapi, Anand K. ; Venkateswarlu, Y.
    Two new bastadin alkaloids, bastadins-22 (1) and 23 (2), together with six known bastadins, bastadins-6 (3), -12 (4) (formerly basatadin-9), -14 (5), -15 (6), -16 (7), -19 (8), and a common steroid cholesterol were isolated from the sponge Dendrilla cactos. The structures of the isolates were established by the study of extensive spectroscopic analysis (1D and 2D NMR and MS data). Anticancer activity of the isolates has been carried out against Sup-T1 cancer cells (T cell lymphoma). © 2006 Elsevier Ltd. All rights reserved.
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    A conserved molecular action of native and recombinant Epap-1 in inhibition of HIV-1 gp120 mediated viral entry
    ( 2006-12-01) Roda Rani, K. P. ; Pelluru, Dheeraj ; Kondapi, Anand K.
    The early expression of Epap-1 (early pregnancy associated protein), a 90 kDa anti-HIV-1 active glycoprotein, in the first trimester placental tissue suggests that it is one of the innate immune factors/proteins protecting the fetus from HIV infections. In the present investigation, we have cloned and expressed Epap-1 in bacterial and baculovirus expression systems. The recombinant Epap-1 as well as native Epap-1 shows a conserved molecular mode of action. These proteins exhibit significant antiviral activity and inhibit the cell fusion reaction between gp120 expressing HeLa (HL2/3) cells and T cell line (SupT1). Further, the rhodamine labeled Epap-1 specifically bound to gp120 expressed on the surface of HL2/3 cells during fusion reaction thereby inhibiting viral entry. Analysis of the interacting gp120 epitopes revealed that Epap-1 binds specifically to epitopes of gp120, recognizing constant-5 (C5) region and the variable-3 (V3) epitope of gp120 expressed on HL2/3 cells; It exhibits specific interaction with C5 region of cell-free virus in four HIV-1 isolates suggesting that the molecular interaction of Epap-1 is specific and is highly conserved in binding to gp120 leading to inhibition of viral entry. Epap-1 can thus be a very efficient natural protection mechanism against cell-free and cell-associated viral infections during early pregnancy. © 2006 Elsevier Inc. All rights reserved.
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    Regulation of topoisomerase II α and β in HIV-1 infected and uninfected neuroblastoma and astrocytoma cells: Involvement of distinct nordihydroguaretic acid sensitive inflammatory pathways
    ( 2007-05-01) Mandraju, Raj Kumar ; Kondapi, Anand K.
    The activity of Topoisomerase II α and β isoforms is tightly regulated during different phases of cell cycle. In the present study, the action of anti-inflammatory agents, nordihydroguaretic acid (NDGA) is analyzed in HIV-1 infected CXCR4+, CCR5+ and CD4- SK-N-SH neuroblastoma, CXCR4+, CCR5+ and CD4- 1321N1 astrocytoma and CXCR4+, CCR5+/- and CD4- GO-G-CCM glioblastoma cell lines. In SK-N-SH and 1321N1 the expression of Topoisomerase II α is concomitant with that of LOX-5 and is highly sensitive to NDGA, while the Topoisomerase II β is expressed along with TNFα and exhibits low sensitivity to NDGA, suggesting distinct pathways of regulation for the two isoforms. HIV-1 infection in these cells enhanced the expression of Topo II α and β. Further, the regulation of Topo II β and TNFα in infected and uninfected SK cells is distinctly different. HIV-1 gp120 derived peptides could block HIV-1 mediated inflammation and Topoisomerase II α and β expression, suggesting the viral mediated response. A combination of NDGA, gp-120 derived peptides and AZT has completely blocked the viral replication, suggesting the enhancement of potency of AZT under the suppression of inflammatory response. In contrast, the expression of Topo II α and β was stimulated by NDGA in GO-G-CCM cells showing distinct regulatory pathway in these cells that was resistant to HIV-1 infection. This suggests the requirement of inflammatory response for productive viral infection. In summary, an induction of co-receptor mediated inflammatory response can distinctly enhance regulated expression of the cellular Topo II α and β and promote productive infection in neurons and astrocytes. © 2007 Elsevier Inc. All rights reserved.
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    Distinct roles of Topoisomerase II isoforms: DNA damage accelerating α, double strand break repair promoting β
    ( 2008-02-01) Mandraju, Raj Kumar ; Kannapiran, P. ; Kondapi, Anand K.
    Topoisomerase II α (TopoIIα) and Topoisomerase II β (TopoIIβ) isoforms are different gene products having conserved catalytic activities. The α isoform is present in proliferating cell, while β isoform is predominantly present in non-proliferating cells namely neurons suggesting its role in non-replicating functions of DNA. The functions of TopoIIα and TopoIIβ isoforms are analyzed in peroxide-mediated DNA damage and double strand breaks (DSBs) repair in neuroblastoma and astrocytoma cells. The results show a strong correlation of TopoIIα level with the progression of DNA damage, while the TopoIIβ expression is correlated with the DNA DSBs repair activity of cells in Ku70, Werner's helicase and pol-β dependent pathways. The functional roles of TopoIIα and TopoIIβ are assessed using siRNA mediated TopoIIα and TopoIIβ knockdown in cells. The results show that TopoIIα-TopoIIβ+ cells are resistant to peroxide-mediated DNA damage, while TopoIIα+TopoIIβ- cells are 2-fold more sensitive to peroxide and TopoIIβ deficiency lead to cellular apoptosis. These results are correlated with cell survival from peroxide-mediated insult. The result of this study that TopoIIα accelerates peroxide-mediated DNA damage, while TopoIIβ promotes DNA DSBs repair activity should provide new directions toward understanding of normalytic ageing processes in human brain. © 2007 Elsevier Inc. All rights reserved.