Structural Requirements for Agonist Activity of a Murine Interferon-γ Peptide

Szente, Brian E.; Weiner, I.J.; Jablonsky, Michael J.; Krishna, N. Rama; Torres, Barbara A.; Johnson, Howard M.

doi:10.1089/jir.1996.16.813

Cited by 28 publications

(44 citation statements)

References 15 publications

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“…A peptide encompassing residues 95 through 125 of murine IFN-␥, [MuIFN-␥(95-125)], to which the lipophilic moiety was similarly added, was used as a negative control. We have previously shown that MuIFN-␥(95-125) lacked a required nuclear localization sequence for mimetic activity (26). Data presented below demonstrate that mimetics, whether expressed intracellularly or via delivery of chemically synthesized lipopeptides, possessed similar qualitative IFN-␥ mimetic activity.…”

Section: Resultsmentioning

confidence: 73%

“…Peptides corresponding to residues 95 through 133 and 95 through 125 of murine IFN-␥ were synthesized on an Applied Biosystems 9050 automated peptide synthesizer (Foster City, CA) using conventional fluorenylmethyloxycarbonyl chemistry as described previously (26). The addition of a lipophilic group (palmitoyl-lysine) to the N terminus of the synthetic peptide was performed as the last step by using semiautomated protocol.…”

Section: Cellmentioning

confidence: 99%

“…These peptides, consisting of IFN-␥ C terminus and C terminus analogs, HuIFN-␥(95-134) (from amino acid 95 to 134) for humans and MuIFN-␥(95-133) (from amino acid 95 to 133) for mice, possess potent antiviral activity against vesicular stomatitis virus (VSV) (25)(26)(27)(28). VSV is commonly used in the detection and quantitation of IFN activity.…”

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confidence: 99%

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Peptide Mimetics of Gamma Interferon Possess Antiviral Properties against Vaccinia Virus and Other Viruses in the Presence of Poxvirus B8R Protein

Ahmed

Burkhart

Subramaniam

et al. 2005

J Virol

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We have developed peptide mimetics of gamma interferon (IFN-␥) that play a direct role in the activation and nuclear translocation of STAT1␣ transcription factor. These mimetics do not act through recognition by the extracellular domain of IFN-␥ receptor but rather bind to the cytoplasmic domain of the receptor chain 1, IFNGR-1, and thereby initiate the cellular signaling. Thus, we hypothesized that these mimetics would bypass the poxvirus virulence factor B8R protein that binds to intact IFN-␥ and prevents its interaction with the receptor. Human and murine IFN-␥ mimetic peptides were introduced into an adenoviral vector for intracellular expression. There are several studies using mostly nucleoside analogs to test their efficacy against acute exposure to smallpox and other poxviruses (5,6,17). The most promising of these analogs appears to be cidofovir (5). However, undesirable toxic effects, particularly those involving kidneys, have been observed in animal studies (17). Perhaps this is because these drugs do not appear to be virus specific. Thus, there is a timely need for other approaches to the development of poxvirus therapeutic agents. Vaccinia virus, which is used worldwide to vaccinate against smallpox infections, is a prototype of the poxvirus family. These viruses are particularly effective in neutralizing host innate antiviral defense mechanisms, such as the interferon (IFN) system. A major reason for this is the production by these viruses of soluble secreted proteins that bind to and prevent alpha/beta IFN (IFN-␣/␤) and IFN-␥ from binding to their respective receptors on the cell membrane (16). An important virulence factor of poxviruses is the B8R protein, which is a homolog of the extracellular domain of the IFN-␥ receptor and can therefore bind to intact IFN-␥ and prevent its interaction with the receptor (24).We have discovered, characterized, and synthesized small peptide agonists/mimetics of IFN-␥. These peptides, consisting of IFN-␥ C terminus and C terminus analogs, HuIFN-␥(95-134) (from amino acid 95 to 134) for humans and MuIFN-␥(95-133) (from amino acid 95 to 133) for mice, possess potent antiviral activity against vesicular stomatitis virus (VSV) (25)(26)(27)(28). VSV is commonly used in the detection and quantitation of IFN activity. The structural motif required for the recognition of the extracellular domain of the IFN-␥ receptor chain IFNGR-1 and that involved in intracellular signaling are contained in two separate domains on the N terminus and C terminus, respectively, of the IFN-␥ molecule (28, 31). The peptide mimetics act intracellularly to activate the Jak/STAT signaling apparatus and, thus, do not recognize the IFN-␥ receptor extracellular domain (28). Therefore, smallpox and vaccinia virus virulence factor B8R should not interact with the IFN-␥ mimetics and, thus, should not block mimetic antiviral activity. The mimetics were delivered into the cell via penetration by attachment of a lipophilic residue to chemically synthesized peptides, as described earlier for the deliver...

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Section: Resultsmentioning

confidence: 73%

Section: Cellmentioning

confidence: 99%

See 1 more Smart Citation

Peptide Mimetics of Gamma Interferon Possess Antiviral Properties against Vaccinia Virus and Other Viruses in the Presence of Poxvirus B8R Protein

Ahmed

Burkhart

Subramaniam

et al. 2005

J Virol

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“…The peptides used in this study are listed in Table I and were synthesized in our laboratory on an Applied Biosystems 9050 automated peptide synthesizer using conventional fluorenylmethyoxycarbonyl chemistry as described previously (18). A lipophilic (lipo) group (palmitoyl-lysine) was added to the N terminus of peptides to facilitate entry into cells as a last step using a semiautomated protocol.…”

Section: Peptidesmentioning

confidence: 99%

Both the Suppressor of Cytokine Signaling 1 (SOCS-1) Kinase Inhibitory Region and SOCS-1 Mimetic Bind to JAK2 Autophosphorylation Site: Implications for the Development of a SOCS-1 Antagonist

Waiboci

Ahmed

Mujtaba

et al. 2007

The Journal of Immunology

106

133

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Suppressor of cytokine signaling (SOCS)-1 protein modulates signaling by IFN-γ by binding to the autophosphorylation site of JAK2 and by targeting bound JAK2 to the proteosome for degradation. We have developed a small tyrosine kinase inhibitor peptide (Tkip) that is a SOCS-1 mimetic. Tkip is compared in this study with the kinase inhibitory region (KIR) of SOCS-1 for JAK2 recognition, inhibition of kinase activity, and regulation of IFN-γ-induced biological activity. Tkip and a peptide corresponding to the KIR of SOCS-1, (53)DTHFRTFRSHSDYRRI(68) (SOCS1-KIR), both bound similarly to the autophosphorylation site of JAK2, JAK2(1001–1013). The peptides also bound to JAK2 peptide phosphorylated at Tyr1007, pJAK2(1001–1013). Dose-response competitions suggest that Tkip and SOCS1-KIR similarly recognize the autophosphorylation site of JAK2, but probably not precisely the same way. Although Tkip inhibited JAK2 autophosphorylation as well as IFN-γ-induced STAT1-α phosphorylation, SOCS1-KIR, like SOCS-1, did not inhibit JAK2 autophosphorylation but inhibited STAT1-α activation. Both Tkip and SOCS1-KIR inhibited IFN-γ activation of Raw 264.7 murine macrophages and inhibited Ag-specific splenocyte proliferation. The fact that SOCS1-KIR binds to pJAK2(1001–1013) suggests that the JAK2 peptide could function as an antagonist of SOCS-1. Thus, pJAK2(1001–1013) enhanced suboptimal IFN-γ activity, blocked SOCS-1-induced inhibition of STAT3 phosphorylation in IL-6-treated cells, enhanced IFN-γ activation site promoter activity, and enhanced Ag-specific proliferation. Furthermore, SOCS-1 competed with SOCS1-KIR for pJAK2(1001–1013). Thus, the KIR region of SOCS-1 binds directly to the autophosphorylation site of JAK2 and a peptide corresponding to this site can function as an antagonist of SOCS-1.

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“…DU145 cells were therefore treated with 1-8 mM lipophilic Tkip as shown in Figure 2a, and constitutive phosphorylation of 95 AKFEVNNPQVQRQAFNELIRVVHQLLPESSL 125 a The peptides used in this study were synthesized in our laboratory using conventional fluorenylmethyloxycarbonyl (Fmoc) chemistry as described previously (Szente et al, 1996;Flowers et al, 2004). A lipophilic group (palmitoyl-lysine) was added to the N-terminus of the synthetic peptides during peptide synthesis to enhance cellular uptake (Thiam et al, 1999) STAT3 was determined.…”

mentioning

confidence: 99%

A SOCS-1 peptide mimetic inhibits both constitutive and IL-6 induced activation of STAT3 in prostate cancer cells

2005

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Prostate cancer is the second highest cause of cancerrelated deaths of men in the US. Signal transducers and activators of transcription (STATs) proteins are a small family of latent cytoplasmic transcription factors that act downstream of Janus kinase (JAK) activation and mediate intracellular signaling from a wide variety of cytokines, growth factors, and hormones. Aberrant activation of STAT3 has been implicated in the progression of many human carcinomas, including prostate cancer. Previously, we have characterized a novel tyrosine kinase inhibitor peptide, Tkip, that is a mimetic of suppressor of cytokine signaling 1 (SOCS-1). Similar to SOCS-1, Tkip binds to the autophosphorylation site of JAK2 and inhibits phosphorylation of STAT1a. In this study, we determined the inhibitory effects of Tkip on the human prostate cancer cell lines DU145 and LNCaP. Tkip inhibited cellular proliferation of both DU145 and LNCaP cells, with a slightly greater antiproliferative effect on DU145 cells. Cell cycle analysis using flow cytometry showed Tkip blockage of progression into the S phase of the cell cycle. Tkip also inhibited constitutive (DU145) and IL-6-induced (LNCaP) activation of STAT3, consistent with the fact that STAT3 activation is mediated by JAK2. Tkip also slightly reduced the levels of cyclin D1, an important regulator of cell cycle progression into S phase, in DU145 and LNCaP cancer cell lines. These data describe a potentially important therapeutic that targets both constitutive and IL-6-induced STAT3 activation in human prostate cancer cell lines.

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Structural Requirements for Agonist Activity of a Murine Interferon-γ Peptide

Cited by 28 publications

References 15 publications

Peptide Mimetics of Gamma Interferon Possess Antiviral Properties against Vaccinia Virus and Other Viruses in the Presence of Poxvirus B8R Protein

Peptide Mimetics of Gamma Interferon Possess Antiviral Properties against Vaccinia Virus and Other Viruses in the Presence of Poxvirus B8R Protein

Both the Suppressor of Cytokine Signaling 1 (SOCS-1) Kinase Inhibitory Region and SOCS-1 Mimetic Bind to JAK2 Autophosphorylation Site: Implications for the Development of a SOCS-1 Antagonist

A SOCS-1 peptide mimetic inhibits both constitutive and IL-6 induced activation of STAT3 in prostate cancer cells

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