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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Viral entry through the blood-brain barrier (BBB) has not been fully defined and identification of coreceptors that can facilitate this phenomenon is crucial in understanding disease progression. Using a RNAse protection assay to examine chemokine receptor families simultaneously, we analyzed the total RNA of in vitro BBB cultures treated with purified preparations of HIV gp120, gp41, TAT proteins and TNF-alpha. HIV tat protein affected CCRI and CCR3 mRNA expression whereas the other viral by-products had no effect. Interestingly, TNF-alpha was able to induce CCR1, CCR3 as well as CXCR1, CXCR2, CXCR4 receptors and Burkitt's lymphoma receptor BLR2. These results suggest that HIV-induced molecules can manipulate the surface receptor expression of the BBB to allow for their preferential entry into brain.
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PMID:Chemokine receptor mRNA expression at the in vitro blood-brain barrier during HIV infection. 1009 32

Human immunodeficiency virus-1 (HIV-1)-Tat, the transactivating gene product of HIV-1, has been shown to interact with different cell types, inducing gene expression, altering their growth and migratory behavior. In this study we examined whether Tat might affect functions of acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphoma (NHL), relevant to the in vivo dissemination. Our results show that Tat significantly augmented the motility of the two AIDS-related Burkitt's lymphoma cell lines (AS283 and PA682PB) and AIDS-primary effusion lymphoma cell line (HBL-6-AIDS-PEL). Mutations in RGD or basic domain of Tat (KGE-MBP and LxI-MBP, respectively) sharply reduced migration compared with wild type, suggesting that both domains are required for migration. In contrast, a Tat protein mutation outside the active domains (NH(2)-TAT-GST) did not reduce lymphoma cell migration. The treatment of lymphoma cells with Tat did not influence their adhesion to matrix proteins or to human vascular endothelial cells, but endothelial cells treated with Tat became more adhesive to lymphoma cells. Flow cytometric analysis showed that treatment of endothelial cells with Tat induced the cell surface expression of the adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and E-selectin and increased the expression of intercellular adhesion molecule-1 (ICAM-1). Only antibodies against VCAM-1 on endothelial cells or against the VLA-4 integrin expressed on AS283 cells inhibited the increment of adhesion, indicating the relevance of this pathway in the adhesion of lymphoma cells to vascular endothelium. In our work, we show for the first time that Tat can enhance the migration of lymphoma cells and their adhesion to endothelial cells, two processes that may contribute to the malignant behavior of NHL in patients with AIDS.
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PMID:Human immunodeficiency virus-1 (HIV-1)-Tat protein promotes migration of acquired immunodeficiency syndrome-related lymphoma cells and enhances their adhesion to endothelial cells. 1047

A change of mitochondrial membrane permeability is essential for apoptosis, leading to translocation of apoptogenic cytochrome c and apoptosis-inducing factor into the cytoplasm. We recently showed that the Bcl-2 family of proteins regulate cytochrome c release and the mitochondrial membrane potential (Deltapsi) by directly modulating the activity of the voltage-dependent anion channel (VDAC) through binding. Here we investigated the biochemical role of the conserved N-terminal homology domain (BH4) of Bcl-x(L), which has been shown to be essential for inhibition of apoptosis, with respect to the regulation of mitochondrial membrane permeability and found that BH4 was required for Bcl-x(L) to prevent cytochrome c release and Deltapsi loss. A study using VDAC liposomes revealed that Bcl-x(L), but not Bcl-x(L) lacking the BH4 domain, inhibited VDAC activity. Furthermore, BH4 oligopeptides of Bcl-2 and Bcl-x(L), but not mutant peptides, were able to inhibit both VDAC activity on liposomes even in the presence of Bax and apoptotic Deltapsi loss in isolated mitochondria. It was also shown that the BH4 domain, fused to the protein transduction domain of HIV TAT protein (TAT-BH4), efficiently prevented apoptotic cell death. These results indicate that the BH4 of Bcl-2/Bcl-x(L) is essential and sufficient for inhibiting VDAC activity, which in turn prevents apoptotic mitochondrial changes, and for preventing apoptotic cell death. Finally, the data suggest that the TAT-BH4 peptide is potentially useful as a therapeutic agent for diseases caused by accelerated apoptosis.
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PMID:BH4 domain of antiapoptotic Bcl-2 family members closes voltage-dependent anion channel and inhibits apoptotic mitochondrial changes and cell death. 1073 88

Protein transduction domains (PTDs), such as the third helix of the Drosophila Antennapedia homeobox gene (Antp) and the HIV TAT PTD, possess a characteristic positive charge on the basis of their enrichment for arginine and lysine residues. To determine whether cationic peptides are able to function as protein transduction domains, 12-mer peptide sequences from an M13 phage library were selected for synthesis on the basis of their varying cationic charge content. In addition, polylysine and polyarginine peptides were synthesized in order to assess the effect of charge contribution in protein transduction. Coupling of the biotinylated peptides to avidin-beta-galactosidase facilitated transduction in a wide variety of cell lines and primary cells, including islet beta-cells, synovial cells, polarized airway epithelial cells, dendritic cells, myoblasts, and tumor cells. Two of the peptides, PTD-4 and PTD-5, mediated transduction nearly 600-fold more efficiently than a random control peptide, but with an efficiency similar to the TAT PTD and the 12 mers of polylysine and polyarginine. Furthermore, confocal analysis of biotinylated peptide-streptavidin-Cy3 conjugates demonstrated that the internalized PTDs are found in both the nuclei and the cytoplasm of treated cells. When tested in vivo, the PTDs were able to facilitate efficient and rapid protein delivery into rabbit synovium and mouse solid tumors following intraarticular and intratumoral administration, respectively. These novel PTDs can be used to transfer therapeutic proteins and DNA for the treatment of a wide variety of diseases, including arthritis and cancer.
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PMID:Characterization of a class of cationic peptides able to facilitate efficient protein transduction in vitro and in vivo. 1102 Mar 49

The interactions among sex, HIV infection, and body fat redistribution are uncertain. We retrospectively compared total, subcutaneous, and visceral adipose tissue (TAT, SAT, VAT) contents, as determined by whole body MRI, in 85 HIV-infected persons, including 48 HIV-positive persons with self-reported changes in body shape, and matched healthy controls. The effect of sex on regional fat contents differed among HIV-infected persons with and without self-reported changes in body shape. Women without changes had significantly less SAT and TAT than did controls, while men with changes had significantly less SAT and TAT than did controls. Higher contents of VAT were found in both men and women with self-reported changes in body shape.
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PMID:Interactions among sex, HIV infection, and fat redistribution. 1106 5

Stress conditions and proinflammatory cytokines activate the c-Jun NH2-terminal kinase (JNK), a member of the stress-activated group of mitogen-activated protein kinases (MAPKs). We recently demonstrated that inhibition of JNK signaling with the use of the islet-brain (IB) 1 and 2 proteins prevented interleukin (IL)-1beta-induced pancreatic beta-cell death. Bioactive cell-permeable peptide inhibitors of JNK were engineered by linking the minimal 20-amino acid inhibitory domains of the IB proteins to the 10-amino acid HIV-TAT sequence that rapidly translocates inside cells. Kinase assays indicate that the inhibitors block activation of the transcription factor c-Jun by JNK. Addition of the peptides to the insulin-secreting betaTC-3 cell line results in a marked inhibition of IL-1beta-induced c-jun and c-fos expression. The peptides protect betaTC-3 cells against apoptosis induced by IL-1beta. All-D retro-inverso peptides penetrate cells as efficiently as the L-enantiomers, decrease c-Jun activation by JNK, and remain highly stable inside cells. These latter peptides confer full protection against IL-1beta-induced apoptosis for up to 2 weeks of continual treatment with IL-1beta. These data establish these bioactive cell-permeable peptides as potent pharmacological compounds that decrease intracellular JNK signaling and confer long-term protection to pancreatic beta-cells from IL-1beta-induced apoptosis.
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PMID:Cell-permeable peptide inhibitors of JNK: novel blockers of beta-cell death. 1114 98

We previously defined a cholesterol recognition/interaction amino acid consensus (CRAC; ATVLNYYVWRDNS) in the carboxyl terminus of the peripheral-type benzodiazepine receptor (PBR), an outer mitochondrial membrane protein involved in the regulation of cholesterol transport into the mitochondria, the rate-determining step in steroid biosynthesis. We examined (i) the PBR-cholesterol interaction by UV crosslinking of the C17 side-chain containing progestin, promegestone, and (ii) the role of the CRAC domain of PBR in Leydig cell steroidogenesis by using a transducible peptide composed of the TAT domain of HIV and the CRAC domain of PBR. [(3)H]Promegestone photoincorporated into recombinant PBR, and this labeling was displaced by cholesterol. [(3)H]Promegestone also photoincorporated into the TAT-CRAC peptide. [(3)H]Promegestone crosslinking to TAT-CRAC could be displaced by cholesterol and promegestone, with IC50 values of 1 and 200 microM, respectively. TAT-CRAC efficiently transduced into MA-10 Leydig cells and inhibited the hCG- and cAMP-stimulated steroid production in a dose-dependent manner. TAT-CRAC did not affect the hCG-induced cAMP synthesis and the 22R-hydroxycholesterol-supported steroidogenesis. Mutated TAT-CRAC lost its ability to bind [(3)H]promegestone and to inhibit the hCG-stimulated steroidogenesis. These results show that TAT-CRAC binds cholesterol and competes for cholesterol interaction with endogenous PBR, suggesting that the cytosolic carboxyl-terminal domain of PBR is responsible for taking up and bringing steroidogenic cholesterol into the mitochondria.
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PMID:Cholesterol binding at the cholesterol recognition/ interaction amino acid consensus (CRAC) of the peripheral-type benzodiazepine receptor and inhibition of steroidogenesis by an HIV TAT-CRAC peptide. 1115 28

HIV-1 expresses a multifunctional protein called TAT (trans-acting transcriptional activator), the function of which in vivo is tightly correlated with the incidence of Kaposi's sarcoma in AIDS patients. TAT is angiogenic and apparently binds to receptors specific for vascular endothelial growth factor (VEGF). Amino acids 46-60 of HIV-TAT, known as the basic peptide, have been shown to be responsible for its functional interaction with VEGF receptors. To characterize further the binding properties of this peptide, its coding sequence was fused to the reading frame of bacterial thioredoxin, allowing the production of large amounts of chimaeric polypeptides in bacteria in a biologically active form. Binding of chimaeric proteins to VEGF receptors was studied in vitro in endothelial cell cultures expressing either of the two receptors. Chimaeric thioredoxin proteins carrying the basic domain of TAT bound to both VEGF receptors with affinities similar to those of HIV-TAT or VEGF. Interestingly, these polypeptides competed only partially with VEGF for receptor binding, implying different binding sites for the TAT peptide and VEGF. This suggests that TAT binds VEGF receptors at new sites that might be useful targets for pharmacological intervention during pathological angiogenesis. The thioredoxin/basic-peptide chimaeras are functional agonists that mediate VEGF receptor signalling: (1) they stimulate the growth of endothelial cells; (2) together with basic fibroblast growth factor they cause tube formation of endothelial cells in collagen gels; (3) they induce blood vessel formation on the chicken chorioallantoic membrane; and (4) they activate VEGF receptor kinase and mitogen-activated protein kinase activity.
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PMID:Signalling properties of an HIV-encoded angiogenic peptide mimicking vascular endothelial growth factor activity. 1117 Oct 54

The protein transduction domain (PTD) embedded in the HIV TAT protein (amino acids 47-57) has been shown to successfully mediate the introduction of heterologous peptides and proteins in excess of Mr 100,000 into mammalian cells in vitro and in vivo. We report here that the modeled structure of the TAT PTD is a strong amphipathic helix. On the basis of this information, we synthesized a series of synthetic PTDs that strengthen the alpha-helical content and optimize the placement of arginine residues. Several PTD peptides possessed significantly enhanced protein transduction potential compared with TAT in vitro and in vivo. These optimized PTDs have the potential to deliver both existing and novel anticancer therapeutics.
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PMID:Synthetic protein transduction domains: enhanced transduction potential in vitro and in vivo. 1121 34

The von Hippel-Lindau (VHL) tumor suppressor gene is mutated in patients with VHL disease and in the majority of patients with sporadic renal cell carcinomas (RCCs). RCCs are dependent on insulin-like growth factor-1 receptor-mediated signaling for tumor growth and invasion in vivo. Reintroduction of the VHL gene product (pVHL) can inhibit on insulin-like growth factor-I receptor-mediated signaling in RCC cells in vitro through interaction with protein kinase C delta and is mediated by a specific amino acid sequence (104-123) in the beta-domain of the pVHL. In the present study, the amino acid sequence (104-123) of the pVHL was conjugated to the protein transduction domain of HIV-TAT protein (TATFLAGVHL-peptide) to facilitate entry into cells, and we demonstrate that this amino acid region of VHL is sufficient to block proliferation and invasion of 786-O renal cancer cells in vitro. Furthermore, daily i.p. injections with the TATFLAGVHL peptide retarded and, in some cases, caused partial regression of renal tumors that were implanted in the dorsal flank of nude mice. Treatment with this peptide also inhibits the invasiveness of renal tumors. A 56% decrease in the proliferative index in tumors treated with the TATFLAGVHL-peptide versus control-peptide-treated mice was observed. Taken together, these results show the novel importance of a 20-amino acid sequence of the beta-domain of the VHL gene product capable of inhibiting tumor growth and invasion. These results lay the foundation for a unique approach toward treating RCCs using this small-molecular-weight peptide fused to the TAT-sequence, which may, in the future, be used alone or in conjunction with other therapies.
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PMID:The 104-123 amino acid sequence of the beta-domain of von Hippel-Lindau gene product is sufficient to inhibit renal tumor growth and invasion. 1128 Jul 20


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