Characterization of Highly Immunogenic p66/p51 as the Reverse Transcriptase of HTLV-III/LAV

Veronese, Fulvia; Copeland, Terry D.; DeVico, Anthony L.; Rahman, Rukhsana; Oroszlan, Stephen; Gallo, Rosella; Sarngadharan, M. G.

doi:10.1126/science.2418504

Cited by 534 publications

(260 citation statements)

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“…The RT inhibitors used here, nevirapine and efavirenz, share a common biochemical mechanism of action by binding the hydrophobic pocket in the p66 subunit of RT enzymes (Di Marzo Veronese et al, 1986;Ren et al, 2001). Though being designed to target the HIVencoded RT, nevirapine proved able to inhibit the endogenous retrotranscriptase activity present in noninfected cells (Mangiacasale et al, 2003) in a highly sensitive in vitro assay (Pyra et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Inhibition of endogenous reverse transcriptase antagonizes human tumor growth

et al. 2005

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Undifferentiated cells and embryos express high levels of endogenous non-telomerase reverse transcriptase (RT) of retroposon/retroviral origin. We previously found that RT inhibitors modulate cell growth and differentiation in several cell lines. We have now sought to establish whether high levels of RT activity are directly linked to cell transformation. To address this possibility, we have employed two different approaches to inhibit RT activity in melanoma and prostate carcinoma cell lines: pharmacological inhibition by two characterized RT inhibitors, nevirapine and efavirenz, and downregulation of expression of RT-encoding LINE-1 elements by RNA interference (RNAi). Both treatments reduced proliferation, induced morphological differentiation and reprogrammed gene expression. These features are reversible upon discontinuation of the anti-RT treatment, suggesting that RT contributes to an epigenetic level of control. Most importantly, inhibition of RT activity in vivo antagonized tumor growth in animal experiments. Moreover, pretreatment with RT inhibitors attenuated the tumorigenic phenotype of prostate carcinoma cells inoculated in nude mice. Based on these data, the endogenous RT can be regarded as an epigenetic regulator of cell differentiation and proliferation and may represent a novel target in cancer therapy.

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Section: Discussionmentioning

confidence: 99%

Inhibition of endogenous reverse transcriptase antagonizes human tumor growth

et al. 2005

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“…However, in both virions (diMarzo Veronese ef al., 1986;Wondrak et al, 1986) and infected cells (Lightfoote ef al., 1986), HIV-1 RT has been characterized as a heterodimer consisting of 66 and 51 kDa chains. The p66/p51 HIV-1 RT is recognized by antibodies in about 80% of HIV-1 positive individuals (diMarzo Veronese et al, 1986). Mapping by monoclonal antibodies of the p66 subunit of HIV-1 with C-terminally truncated mutants revealed that p51 was derived from the p66 polypeptide and that p66 and p51 possess identical amino termini (Lightfoote et al, 1986).…”

Section: Expression Of Hiv-1 Reverse Transcriptasementioning

confidence: 99%

“…Mapping by monoclonal antibodies of the p66 subunit of HIV-1 with C-terminally truncated mutants revealed that p51 was derived from the p66 polypeptide and that p66 and p51 possess identical amino termini (Lightfoote et al, 1986). The tightly associated p66/p51 heterodimer is generated from a HIV-1 p66/p66 homodimer (Farmerie et al, 1987;Mous et al, 1988) in the presence of the HIV-1 PR (diMarzo Veronese et al, 1986;Lightfoote et al, 1986;McHenry, 1989), thus generating an additional polypeptide of 15 kDa from the C-terminus. Once the heterodimer is formed, it is not susceptible to further cleavage.…”

Section: Expression Of Hiv-1 Reverse Transcriptasementioning

confidence: 99%

Review

1996

Biological Chemistry Hoppe-Seyler

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Proteolytic enzymes have many physiological functions in plants, bacteria, viruses, protozoa and mammals. They play a role in processes such as food digestion, complement activation or blood coagulation. The action of proteolytic enzymes is biologically controlled by proteinase inhibitors and increasing attention is being paid to the physiological significance of these natural inhibitors in pathological processes. The reason for this growing interest is that uncontrolled proteolysis can lead to irreversible damage e.g. in chronic inflammation or tumor metastasis. This review focusses on the possible role of the cystatins, natural and specific inhibitors of the cysteine proteinases, in pathological processes. Key words: Cystatins / Cysteine proteinases / Inflammation / Inhibitors / Pathological processes. Cysteine ProteinasesCysteine Proteinases, synonymous with thiol proteinases, are small proteins with molecular masses varying from 23 to 24 kDa and with two catalytic residues, Cys25 and His159, which are involved in the hydrolytic reaction. Cysteine proteinases catalyze the hydrolysis of various polypeptide substrates and are most active under reducing and mildly acidic conditions (pH 5 -6.5). They have been detected in and isolated from a large number of biological sources including plants, bacteria, animals and humans. Bacterial cysteine proteinases are produced by Clostridium histolyticum, named clostripain, by hemolytic group A streptococci and by the pathogenic anaerobic Porphyromonas gingivalis, a bacterium associated with periodontitis. Bacterial cysteine proteinases probably play a role in the penetration of normal tissues by the bacteria and in the food digestion. Viral cysteine proteinases from picornaviruses, e.g. the poliovirus and rhinovirus type I, are involved in proteolytic cleavage of precursor proteins for virus replication and for the production of new virus particles. A virus-coded cysteine proteinase is involved in this process (Kay and Dunn, 1990; Körant et a/., 1985;. HIV-I also needs proteolytic processing by cysteine proteinases to regulate the expression of viral proteins (Guy ef a/., 1991). Protozoal cysteine proteinases are produced by a number of protozoan parasites to facilitate host invasion, metabolize host proteins, to degrade the host immune molecules or to use them for intracellular replication. Cysteine proteinases are produced by e.g. Trypanosoma cruzi, the causative agent of American trypanosomiasis or by Leishmania species, causing one of the six major parasitic diseases. Furthermore, human malarial parasites produce a broad scala of proteinases including cysteine proteinase which are involved in erythrocyte invasion and rupture (McKerrow, 1993). Mammalian cysteine proteinases are present in the lysosomes of cells. Lysosomes contain different cysteine proteinases, the most important being the cathepsins B, H, L and S Kirschke, 1981, Barrett et a/., 1988). These cathepsins have common ancestors and are related to papain. Cathepsin B has been detected in every tissue or cel...

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“…These proteins are an 18K protein with protease activity, a 66K reverse transcriptase (RT) protein and a 34K protein with endonuclease activity (Di Marzo Veronese et al, 1986;Lightfoote et al, 1986;Farmerie et al, 1987;Larder et al, 1987a, b;Mous et al, 1988;Hizi et al, 1990). The 66K RT protein encoded by the middle portion of the pol gene consists of 560 amino acids and it has both RT and RNase H enzymic activities (Hizi et al, 1987(Hizi et al, , 1990Larder et al, 1987a, b;Le Grice et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

“…The 66K RT protein encoded by the middle portion of the pol gene consists of 560 amino acids and it has both RT and RNase H enzymic activities (Hizi et al, 1987(Hizi et al, , 1990Larder et al, 1987a, b;Le Grice et al, 1988). The viral protease cleaves the 66K RT protein into an N-terminal 51K and a C-terminal 15K protein which are found in virions in equimolar amounts to the uncleaved 66K protein (Di Marzo Veronese et al, 1986;Farmerie et al, 1987;Lightfoote et al, 1986;Hansen et al, 1988;Mous et al, 1988;Ferris et al, 1990). In Moloney murine leukaemia virus (MMLV), the RNA-dependent DNA polymerase activity and RNase H activity are located in the N and C termini of the protein, respectively, and sequence comparisons have shown that overall organization of HIV-1 RT is the same (Johnson et al, 1986; 0001-0138 © 1991 SGM Kotewicz et al, 1988;Tanese & Goff, 1988).…”

Section: Introductionmentioning

confidence: 99%

Immunological Characterization Of The Human Immunodeficiency Virus Type 1 Reverse Transcriptase Protein By The Use Of Monoclonal Antibodies

Örvell

Unge

Bhikhabhai

et al. 1991

Journal of General Virology

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Eighteen monoclonal antibodies (MAbs) directed against the purified human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) protein were produced. The antibodies were characterized by competitive ELISAs and Western blot experiments, and with nested, nine amino acid long peptides representing the whole 560 amino acid RT protein. By ELISA, the MAbs react with a minimum of seven epitopes of the protein. Four of the epitopes were located on the Nterminal 51K subunit and the remaining three epitopes were located at the C-terminal end of the protein.Using synthetic peptides, two epitopes at the Nterminal part were located at amino acids 294 to 302 and 350 to 354, respectively, from the N-terminal start of the protein. One epitope was located at amino acids 442 to 450, just after the cleavage site between the Nterminal and C-terminal subunit at position 440. Antibodies located at amino acids 294 to 302 could inhibit the RT enzymic activity of the protein. Two other MAbs, directed at the N-terminal and C-terminal parts of the protein, could also inhibit RT activity.

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Characterization of Highly Immunogenic p66/p51 as the Reverse Transcriptase of HTLV-III/LAV

Cited by 534 publications

References 16 publications

Inhibition of endogenous reverse transcriptase antagonizes human tumor growth

Inhibition of endogenous reverse transcriptase antagonizes human tumor growth

Review

Immunological Characterization Of The Human Immunodeficiency Virus Type 1 Reverse Transcriptase Protein By The Use Of Monoclonal Antibodies

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