Quantitative competitive RNA PCR for quantitation of virion-associated HIV-1 RNA

Analysis of viral and cellular proteins in HIV-1 reverse transcription complexes by co-immunoprecipitation

Molecular details and temporal organization of the early (preintegration) phase of HIV life cycle remain among the least investigated and most controversial problems in the biology of HIV. To accomplish reverse transcription and intracellular transport of the viral genetic material, HIV forms multi-molecular complexes termed reverse transcription complexes (RTCs). Analysis of the kinetics of reverse transcription and nuclear import of RTCs, as well as assessment of the changes in their protein content in the course of reverse transcription and nuclear translocation is a necessary step in understanding the mechanisms of cytoplasmic maturation and nuclear import of HIV-1 RTCs. Here, we review methods that allow quantitative assessment of the dynamics of the maturation of HIV-1 RTCs and transformations of RTC protein composition associated with nuclear import of the complexes.

Pharmacological modulation of sarcoplasmic reticulum function in smooth muscle

The sarco/endoplasmic reticulum (SR/ER) is the primary storage and release site of intracellular calcium (Ca2+) in many excitable cells. The SR is a tubular network, which in smooth muscle (SM) cells distributes close to cellular periphery (superficial SR) and in deeper aspects of the cell (deep SR). Recent attention has focused on the regulation of cell function by the superficial SR, which can act as a buffer and also as a regulator of membrane channels and transporters. Ca2+ is released from the SR via two types of ionic channels [ryanodine- and inositol 1,4,5-trisphosphate-gated], whereas accumulation from thecytoplasm occurs exclusively by an energy-dependent sarco-endoplasmic reticulum Ca2+-ATPase pump (SERCA). Within the SR, Ca2+ is bound to various storage proteins. Emerging evidence also suggests that the perinuclear portion of the SR may play an important role in nuclear transcription. In this review, we detail the pharmacology of agents that alter the functions of Ca2+ release channels and of SERCA. We describe their use and selectivity and indicate the concentrations used in investigating various SM preparations. Important aspects of cell regulation and excitation-contractile activity coupling in SM have been uncovered through the use of such activators and inhibitors of processes that determine SR function. Likewise, they were instrumental in the recent finding of an interaction of the SR with other cellular organelles such as mitochondria. Thus, an appreciation of the pharmacology and selectivity of agents that interfere with SR function in SM has greatly assisted in unveiling the multifaceted nature of the SR.

Macrophages archive HIV-1 virions for dissemination in trans

Viruses have evolved various strategies in order to persist within the host. To date, most information on mechanisms of HIV-1 persistence has been derived from studies with lymphocytes, but there is little information regarding mechanisms that govern HIV-1 persistence in macrophages. It has previously been demonstrated that virus assembly in macrophages occurs in cytoplasmic vesicles, which exhibit the characteristics of multivesicular bodies or late endosomes. The infectious stability of virions that assemble intracellularly in macrophages has not been evaluated. We demonstrate that virions assembling intracellularly in primary macrophages retain infectivity for extended intervals. Infectious virus was recovered directly from cytoplasmic lysates of macrophages and could be transmitted from macrophages to peripheral blood lymphocytes in trans 6 weeks after ongoing viral replication was blocked. Cell-associated virus decayed significantly from 1 to 2 weeks post infection, but decreased minimally thereafter. The persistence of intracellular virions did not require the viral accessory proteins Vpu or Nef. The stable sequestration of infectious virions within cytoplasmic compartments of macrophages may represent an additional mechanism for viral persistence in HIV-1-infected individuals.

Tumor necrosis factor-alpha differentially regulates the expression of proinflammatory genes in human airway smooth muscle cells by activation of interferon-beta-dependent CD38 pathway

Recent evidence suggests that CD38, an ectoenzyme that converts NAD(+) to cyclic ADP-ribose (cADPr), may play a role in cytokine-induced airway smooth muscle (ASM) cell hyper-responsiveness, a key feature associated with chronic asthma. In the present study, we investigated the major signaling pathways by which tumor necrosis factor-alpha (TNFalpha) induces CD38 expression and its role in regulating gene expression in human ASM cells. Using flow cytometry analyses, TNFalpha enhanced CD38 expression in a manner that was time-(0-24 h), concentration-(0.1-40 ng/ml), and protein synthesis-(cycloheximide blockade) dependent. A selective agonistic antibody against tumor necrosis factor receptor (TNFR) 1 also augmented CD38 expression, whereas anti-TNFR2 antagonistic antibody did not prevent the TNFalpha response. Inhibition of the Janus activated kinase/signal transducer and activator of transcription pathways using the soluble inhibitor 2-(1,1-dimethylethyl)-9-fluoro-3,6-dihydro-7H-benz-[h]imidaz[4,5-f]isoquinolin-7-one (DBI) or with neutralizing antibody against interferon beta (IFNbeta) completely abrogated TNFalpha-induced CD38 expression at both protein and mRNA levels. Combining TNFalpha (0.1 and 1 ng/ml) and IFNbeta (100 IU/ml) at concentrations alone that had little effect on CD38 expression induced a robust synergistic induction of CD38 mRNA and protein levels. 8-Bromo-cADPr, a cADPr antagonist, significantly augmented TNFalpha-induced interleukin-6 secretion, whereas regulated on activation normal T cell expressed and secreted secretion was suppressed. 8-Bromo-cADPr, however, did not affect TNFalpha-induced cell surface expression of intercellular adhesion molecule-1. Our study is the first to demonstrate that IFNbeta-dependent activation of CD38 pathway is a novel component by which TNFalpha differentially regulates the expression of inflammatory genes in ASM cells.

Inhibition of the functions of the nucleocapsid protein of human immunodeficiency virus-1 by an RNA aptamer

The nucleocapsid (NC) protein plays many roles in the life cycle of human immunodeficiency virus type-1 (HIV-1). Previously we selected the NC binding RNA aptamers from diverse forms of RNA libraries. Here we used one of the RNA aptamers to the NC protein, N70-13, and tested its effect on NC protein in vitro and in cells. The high affinity RNA aptamer completely abolished NC binding to the stable transactivation response hairpin and psi RNA stem-loops of HIV-1 RNA. When it was expressed in cells as an intramer it inhibited the packaging of viral genomic RNA and therefore promises to be an effective anti-HIV therapeutic tool.

Modulation of HIV-1 replication by RNA interference

RNA interference (RNAi) is the process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of messenger RNA in animal and plant cells. In mammalian cells, RNAi can be triggered by 21-nucleotide duplexes of small interfering RNA (siRNA). Here we describe inhibition of early and late steps of HIV-1 replication in human cell lines and primary lymphocytes by siRNAs targeted to various regions of the HIV-1 genome. We demonstrate that synthetic siRNA duplexes or plasmid-derived siRNAs inhibit HIV-1 infection by specifically degrading genomic HIV-1 RNA, thereby preventing formation of viral complementary-DNA intermediates. These results demonstrate the utility of RNAi for modulating the HIV replication cycle and provide evidence that genomic HIV-1 RNA, as it exists within a nucleoprotein reverse-transcription complex, is amenable to siRNA-mediated degradation.