Human Immunodeficiency Virus Transactivator Of Transcription Research Articles

Conditional Human Immunodeficiency Virus Transactivator of Transcription Protein Expression Induces Depression-like Effects and Oxidative Stress

BackgroundThe prevalence of major depression in people with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome is substantially higher than in the general population. Mechanisms underlying this comorbidity are poorly understood. HIV transactivator of transcription (Tat) protein, produced and excreted by HIV, could be involved. We determined whether conditional Tat protein expression in mice is sufficient to induce depression-like behaviors and oxidative stress. Further, as oxidative stress is associated with depression, we determined whether decreasing or increasing oxidative stress by administering methylsulfonylmethane (MSM) or diethylmaleate, respectively, altered depression-like behavior. MethodsGT-tg bigenic mice received intraperitoneal saline or doxycycline (25–100 mg/kg/day) to induce Tat expression. G-tg mice, which do not express Tat protein, also received doxycycline. Depression-like behavior was assessed with the tail suspension test and the two-bottle saccharin/water consumption task. Reactive oxygen species and reactive nitrogen species were assessed ex vivo. Medial frontal cortex oxidative stress and temperature were measured in vivo with 9.4T proton magnetic resonance spectroscopy. ResultsTat expression increased tail suspension test immobility time in an exposure-dependent manner and reduced saccharin consumption. MSM decreased immobility time, whereas diethylmaleate increased it in saline-treated GT-tg mice. Tat and MSM behavioral effects persisted for 28 days. Tat and diethylmaleate increased reactive oxygen species and reactive nitrogen species levels, whereas MSM decreased levels. Tat expression increased medial frontal cortex glutathione levels and temperature. ConclusionsTat expression induced rapid and enduring depression-like behaviors and oxidative stress. Increasing oxidative stress increased depression-like behavior, whereas decreasing oxidative stress decreased depression-like behavior. Thus, Tat produced by HIV may contribute to high depression prevalence among people with HIV. Mitigation of oxidative stress could reduce depression severity.

An Evolved RNA Recognition Motif That Suppresses HIV-1 Tat/TAR-Dependent Transcription.

Potent and selective recognition and modulation of disease-relevant RNAs remain a daunting challenge. We previously examined the utility of the U1A N-terminal RNA recognition motif as a scaffold for tailoring new RNA hairpin recognition and showed that as few as one or two mutations can result in moderate affinity (low μM dissociation constant) for the human immunodeficiency virus (HIV) trans-activation response element (TAR) RNA, an RNA hairpin controlling transcription of the human immunodeficiency virus (HIV) genome. Here, we use yeast display and saturation mutagenesis of established RNA-binding regions in U1A to identify new synthetic proteins that potently and selectively bind TAR RNA. Our best candidate has truly altered, not simply broadened, RNA-binding selectivity; it binds TAR with subnanomolar affinity (apparent dissociation constant of ∼0.5 nM) but does not appreciably bind the original U1A RNA target (U1hpII). It specifically recognizes the TAR RNA hairpin in the context of the HIV-1 5'-untranslated region, inhibits the interaction between TAR RNA and an HIV trans-activator of transcription (Tat)-derived peptide, and suppresses Tat/TAR-dependent transcription. Proteins described in this work are among the tightest TAR RNA-binding reagents-small molecule, nucleic acid, or protein-reported to date and thus have potential utility as therapeutics and basic research tools. Moreover, our findings demonstrate how a naturally occurring RNA recognition motif can be dramatically resurfaced through mutation, leading to potent and selective recognition-and modulation-of disease-relevant RNA.

High Priority of Nanocrystalline Diamond as a Biosensing Platform

Here we report the performance of surface functionalized diamond surfaces as biosensing platform for human immunodeficiency virus trans-activator of transcription (HIV-Tat) peptide detection. Comparative investigations were conducted on nanocrystalline diamond (NCD) and polycrystalline diamond (PCD) films. Scanning electron microscopy (SEM) images revealed the morphology differences between NCD and PCD films. X-ray photoelectron spectroscopy (XPS) data showed that functional components and corresponding coverages, demonstrating denser carboxyl acid groups and fluorinated groups on NCD than that PCD films after UV/ozone and fluorine plasma treatment respectively. Contact angle results showed the differences in surface wettability and free energy between functionalized NCD and PCD biosensors. Fluorescence observations confirmed that higher biosensing performance can be obtained on NCD biosensors with high sensitivity selectivity, and stability. The NCD films with denser surface coverages of functionalizations made NCD films much more priority as an effective biosensing candidate than PCD films.

Synthetic peptides containing ITIM-like sequences of IREM-1 (CD300F) differentially regulate MyD88 and TRIF-mediated TLR signalling through activation of SHP and/or PI3K

The immune receptor expressed on myeloid cells 1 (IREM-1/CD300F) has been shown to inhibit various inflammatory processes in myeloid cells, such as macrophages and mast cells. IREM-1 exerts its inhibitory effect through its intracellular immunoreceptor tyrosine-based inhibition motifs (ITIMs). In order to generate immunomodulatory molecules that can regulate the inflammatory activation of macrophages, decapeptides representing each of the five ITIM-like sequences in the cytoplasmic tail of IREM-1 were synthesized in conjugation with human immunodeficiency virus-transactivator of transcription (HIV-TAT(48-57)), which was added to promote internalization of the peptides. Interestingly, all these TAT-ITIM fusion peptides inhibited Toll-like receptor (TLR)-mediated production of proinflammatory molecules, including matrix metalloproteinase (MMP)-9, tumour necrosis factor (TNF)-α, monocyte chemotactic protein-1 (MCP-1) and interleukin (IL)-8. When various TLR ligands were used to stimulate the human macrophage-like cell line human acute monocytic leukaemia cell line (THP)-1, the TAT-ITIM peptides blocked both myeloid differentiation factor 88 (MyD88) and Toll-interleukin 1 receptor (TIR)-domain-containing adapter-inducing interferon-β (TRIF)-mediated TLR signalling pathways. Utilization of specific inhibitors and detection of the active form of signalling adaptors by Western blot analysis further demonstrated that the inhibitory effects of these TAT-ITIM peptides require activation of Src homology 2 (SH2)-containing tyrosine phosphatase (SHP) and/or phosphoinositide 3-kinase (PI3K). These data indicate that these synthetic peptides may be used to regulate immune responses that involve TLR-mediated inflammatory activation of macrophages.