Synthetic peptide AT20 coupled to KLH elicits antibodies against a conserved conformational epitope from a major functional area of the HIV-1 matrix protein p17

Fiorentini, Simona; Marsico, Stefania; Becker, Pablo D.; Iaria, Maria Luisa; Bruno, Rosalinda; Guzmán, Carlos A.; Caruso, Arnaldo

doi:10.1016/j.vaccine.2008.06.082

Cited by 20 publications

(20 citation statements)

References 36 publications

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“…7, the functional region responsible for SIV MA and p17 binding to their receptors (AT20 loop) is structurally unchanged. This finding is in line with previous data showing that the functional loop is a structural constraint being an hot spot for viral proteins interaction with several host cell proteins (25,(41)(42)(43) and that critical mutations in this highly basic domain do not affect the spatial conformation of the AT20 epitope to an extent that the folded state is destabilized (25).…”

Section: Discussionsupporting

confidence: 92%

“…The structural analysis was based on the following input data: for the p17 model, we used UniProtKB locus GAG_HV1N5 (accession number P12493) and the X-ray structure PDB code 1hiw (23), and for SIV MA, we used UniProtKB locus Q03859_ SIVCZ (accession number Q03859) and the X-ray structure PDB code 1ed1 (24). For S75X, we used its amino acid primary sequence (25). To understand and find the local interactions of p17 and SIV MA, both proteins were analyzed using BPlus (26).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Simian Immunodeficiency Virus and Human Immunodeficiency Virus Type 1 Matrix Proteins Specify Different Capabilities To Modulate B Cell Growth

Caccuri

Giagulli

Reichelt

et al. 2014

J Virol

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Exogenous HIV-1 matrix protein p17 (p17) deregulates the function of different cells after its N-terminal loop (AT20) binding to the chemokine receptors CXCR1 and CXCR2. One site within AT20 has been recently found to be the major determinant of viral fitness following transmission of simian immunodeficiency virus (SIV) to the human host. Therefore, we sought to determine whether SIV matrix protein (MA) was already capable of interacting with CXCR1 and CXCR2 and mimic p17 biological activities rather than this being a newly acquired function during host adaptation. We show here that SIV MA binds with the same affinity of p17 to CXCR1 and CXCR2 and displays both p17 proangiogenic on human primary endothelial cells and chemotactic activity on human primary monocytes and B cells. However, SIV MA exhibited a higher degree of plasticity than p17 in the C terminus, a region known to play a role in modulating B cell growth. Indeed, in contrast to p17, SIV MA was found to activate the phosphatidylinositol 3-kinase/Akt signaling pathway and strongly promote B cell proliferation and clonogenic activity. Interestingly, we have recently highlighted the existence of a Ugandan HIV-1 strain-derived p17 variant (S75X) with the same B cell growth-promoting activity of SIV MA. Computational modeling allowed us to hypothesize an altered C terminus/core region interaction behind SIV MA and S75X activity. Our findings suggest the appearance of a structural constraint in the p17 C terminus that controls B cell growth, which may help to elucidate the evolutionary trajectory of HIV-1. IMPORTANCEThe HIV-1 matrix protein p17 (p17) deregulates the biological activities of different cells after binding to the chemokine receptors CXCR1 and CXCR2. The p17 functional domain responsible for receptors interaction includes an amino acid which is considered the major determinant of SIV replication in humans. Therefore, we sought to determine whether SIV matrix protein (SIV MA) already had the ability to bind to both chemokine receptors rather than being a function newly acquired during host adaptation. We show here that SIV MA binds to CXCR1 and CXCR2 and fully mimics the p17 proangiogenic and chemokine activity. However, it differs from p17 in its ability to signal into B cells and promote B cell growth and clonogenicity. Computational analysis suggests that the accumulation of mutations in the C-terminal region may have led to a further SIV MA adaptation to the human host. This finding in turn sheds light on the evolutionary trajectory of HIV-1.

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Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Simian Immunodeficiency Virus and Human Immunodeficiency Virus Type 1 Matrix Proteins Specify Different Capabilities To Modulate B Cell Growth

Caccuri

Giagulli

Reichelt

et al. 2014

J Virol

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“…As expected, p17 binding to Raji cells (Figure 3A) was completely blocked by mAb MBS-3 (Figure 3B), which recognizes a linear epitope (aa 9–18) within the BH10-derived AT20 functional epitope [18], [26]. Other anti-p17 mAbs, and among them one named MK-1 [18], didn't show any neutralizing activity (data not shown).…”

Section: Resultssupporting

confidence: 67%

“…This finding allowed us to study the development of the p17 oligomerization process in solution under different NaCl concentrations (0.5, 0.2 and 0.1 M) by western blot and to establish the molecular weight of the resulting oligomers. Western blot analysis, performed using the monoclonal antibody (mAb) MBS-3 which recognizes the functional epitope AT20 (aa 9–28) in the p17 NH 2 -terminal region [18], [26], revealed that both monomeric and trimeric p17 are recognized by this mAb (Figure 1B). Under reducing conditions, p17 is mostly in monomeric form in a solution containing 0.5 M NaCl (lane a), whereas it is detected as an approximately 40.000 Daltons band in solutions containing lower NaCl concentrations, i.e., 0.2 M (lane b) and 0.1 M (lane c).…”

Section: Resultsmentioning

confidence: 99%

Opposite Effects of HIV-1 p17 Variants on PTEN Activation and Cell Growth in B Cells

Giagulli

Marsico

Magiera³

et al. 2011

PLoS ONE

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The HIV-1 matrix protein p17 is a structural protein that can act in the extracellular environment to deregulate several functions of immune cells, through the interaction of its NH2-terminal region with a cellular surface receptor (p17R). The intracellular events triggered by p17/p17R interaction have been not completely characterized yet. In this study we analyze the signal transduction pathways induced by p17/p17R interaction and show that in Raji cells, a human B cell line stably expressing p17R on its surface, p17 induces a transient activation of the transcriptional factor AP-1. Moreover, it was found to upregulate pERK1/2 and downregulate pAkt, which are the major intracellular signalling components involved in AP-1 activation. These effects are mediated by the COOH-terminal region of p17, which displays the capability of keeping PTEN, a phosphatase that regulates the PI3K/Akt pathway, in an active state through the serin/threonin (Ser/Thr) kinase ROCK. Indeed, the COOH-terminal truncated form of p17 (p17Δ36) induced activation of the PI3K/Akt pathway by maintaining PTEN in an inactive phosphorylated form. Interestingly, we show that among different p17s, a variant derived from a Ugandan HIV-1 strain, named S75X, triggers an activation of PI3K/Akt signalling pathway, and leads to an increased B cell proliferation and malignant transformation. In summary, this study shows the role of the COOH-terminal region in modulating the p17 signalling pathways so highlighting the complexity of p17 binding to and signalling through its receptor(s). Moreover, it provides the first evidence on the presence of a p17 natural variant mimicking the p17Δ36-induced signalling in B cells and displaying the capacity of promoting B cell growth and tumorigenesis.

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“…The absence of endotoxin contamination (<0.25 endotoxin units/mL) in protein preparations was assessed by Limulus amoebocyte assay (Associates of Cape Cod, East Falmouth, MA). Monoclonal antibodies (mAbs) to p17 capable of neutralizing (MBS-3 and MBS-34) or not (MBS-15) p17/receptors interaction, and therefore all the p17 biological activities, were produced in our laboratory1364. Mab MBS-34 was also biotinylated using AH-N-Hydroxysuccinimido-biotin reagent (AH–NHS–biotin; SPA, Milan, Italy) according to the manufacturer’s instructions.…”

Section: Methodsmentioning

confidence: 99%

Cellular aspartyl proteases promote the unconventional secretion of biologically active HIV-1 matrix protein p17

Caccuri

Iaria

Campilongo

et al. 2016

Sci Rep

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The human immune deficiency virus type 1 (HIV-1) matrix protein p17 (p17), although devoid of a signal sequence, is released by infected cells and detected in blood and in different organs and tissues even in HIV-1-infected patients undergoing successful combined antiretroviral therapy (cART). Extracellularly, p17 deregulates the function of different cells involved in AIDS pathogenesis. The mechanism of p17 secretion, particularly during HIV-1 latency, still remains to be elucidated. A recent study showed that HIV-1-infected cells can produce Gag without spreading infection in a model of viral latency. Here we show that in Gag-expressing cells, secretion of biologically active p17 takes place at the plasma membrane and occurs following its interaction with phosphatidylinositol-(4,5)-bisphosphate and its subsequent cleavage from the precursor Gag (Pr55Gag) operated by cellular aspartyl proteases. These enzymes operate a more complex Gag polypeptide proteolysis than the HIV-1 protease, thus hypothetically generating slightly truncated or elongated p17s in their C-terminus. A 17 C-terminal residues excised p17 was found to be structurally and functionally identical to the full-length p17 demonstrating that the final C-terminal region of p17 is irrelevant for the protein’s biological activity. These findings offer new opportunities to identify treatment strategies for inhibiting p17 release in the extracellular microenvironment.

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Synthetic peptide AT20 coupled to KLH elicits antibodies against a conserved conformational epitope from a major functional area of the HIV-1 matrix protein p17

Cited by 20 publications

References 36 publications

Simian Immunodeficiency Virus and Human Immunodeficiency Virus Type 1 Matrix Proteins Specify Different Capabilities To Modulate B Cell Growth

Simian Immunodeficiency Virus and Human Immunodeficiency Virus Type 1 Matrix Proteins Specify Different Capabilities To Modulate B Cell Growth

Opposite Effects of HIV-1 p17 Variants on PTEN Activation and Cell Growth in B Cells

Cellular aspartyl proteases promote the unconventional secretion of biologically active HIV-1 matrix protein p17

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