• The disabled 1 phosphotyrosine-binding domain binds to the internalization signals of transmembrane glycoproteins and to phospholipids.

      Howell, B W; Lanier, L M; Frank, R; Gertler, F B; Cooper, J A; Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA (1999-07)
      Disabled gene products are important for nervous system development in drosophila and mammals. In mice, the Dab1 protein is thought to function downstream of the extracellular protein Reln during neuronal positioning. The structures of Dab proteins suggest that they mediate protein-protein or protein-membrane docking functions. Here we show that the amino-terminal phosphotyrosine-binding (PTB) domain of Dab1 binds to the transmembrane glycoproteins of the amyloid precursor protein (APP) and low-density lipoprotein receptor families and the cytoplasmic signaling protein Ship. Dab1 associates with the APP cytoplasmic domain in transfected cells and is coexpressed with APP in hippocampal neurons. Screening of a set of altered peptide sequences showed that the sequence GYXNPXY present in APP family members is an optimal binding sequence, with approximately 0.5 microM affinity. Unlike other PTB domains, the Dab1 PTB does not bind to tyrosine-phosphorylated peptide ligands. The PTB domain also binds specifically to phospholipid bilayers containing phosphatidylinositol 4P (PtdIns4P) or PtdIns4,5P2 in a manner that does not interfere with protein binding. We propose that the PTB domain permits Dab1 to bind specifically to transmembrane proteins containing an NPXY internalization signal.
    • High immune response rates and decreased frequencies of regulatory T cells in metastatic renal cell carcinoma patients after tumor cell vaccination.

      Pohla, Heike; Buchner, Alexander; Stadlbauer, Birgit; Frankenberger, Bernhard; Stevanovic, Stefan; Walter, Steffen; Frank, Ronald; Schwachula, Tim; Olek, Sven; Kopp, Joachim; et al. (2013-02-08)
      Our previously reported phase I clinical trial with the allogeneic gene-modified tumor cell line RCC-26/CD80/IL-2 showed that vaccination was well tolerated and feasible in metastatic renal cell carcinoma (RCC) patients. Substantial disease stabilization was observed in most patients despite a high tumor burden at study entry. To investigate alterations in immune responses that might contribute to this effect, we performed an extended immune monitoring that included analysis of reactivity against multiple antigens, cytokine/chemokine changes in serum and determination of the frequencies of immune suppressor cell populations, including natural regulatory T cells (nTregs) and myeloid-derived suppressor cell subsets (MDSCs). An overall immune response capacity to virus-derived control peptides was present in 100% of patients before vaccination. Vaccine-induced immune responses to tumor-associated antigens occurred in 75% of patients, demonstrating the potent immune stimulatory capacity of this generic vaccine. Furthermore, some patients reacted to peptide epitopes of antigens not expressed by the vaccine, showing that epitope-spreading occurred in vivo. Frequencies of nTregs and MDSCs were comparable to healthy donors at the beginning of study. A significant decrease of nTregs was detected after vaccination (p = 0.012). High immune response rates, decreased frequencies of nTregs and a mixed T helper 1/T helper 2 (T(H)1/T(H)2)-like cytokine pattern support the applicability of this RCC generic vaccine for use in combination therapies.
    • Identification of high-affinity PB1-derived peptides with enhanced affinity to the PA protein of influenza A virus polymerase.

      Wunderlich, Kerstin; Juozapaitis, Mindaugas; Ranadheera, Charlene; Kessler, Ulrich; Martin, Arnold; Eisel, Jessica; Beutling, Ulrike; Frank, Ronald; Schwemmle, Martin; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2011-02)
      The influenza A virus polymerase complex, consisting of the subunits PB1, PB2, and PA, represents a promising target for the development of new antiviral drugs. We have previously demonstrated the feasibility of targeting the protein-protein interaction domain between PA and PB1 using peptides derived from the extreme N terminus of PB1 (amino acids [aa] 1 to 15), comprising the PA-binding domain of PB1. To increase the binding affinity of these peptides, we performed a systematic structure-affinity relationship analysis. Alanine and aspartic acid scans revealed that almost all amino acids in the core binding region (aa 5 to 11) are indispensable for PA binding. Using a library of immobilized peptides representing all possible single amino acid substitutions, we were able to identify amino acid positions outside the core PA-binding region (aa 1, 3, 12, 14, and 15) that are variable and can be replaced by affinity-enhancing residues. Surface plasmon resonance binding studies revealed that combination of several affinity-enhancing mutations led to an additive effect. Thus, the feasibility to enhance the PA-binding affinity presents an intriguing possibility to increase antiviral activity of the PB1-derived peptide and one step forward in the development of an antiviral drug against influenza A viruses.
    • Multiple antibody targets on herpes B glycoproteins B and D identified by screening sera of infected rhesus macaques with peptide microarrays.

      Hotop, Sven-Kevin; Abd El Wahed, Ahmed; Beutling, Ulrike; Jentsch, Dieter; Motzkus, Dirk; Frank, Ronald; Hunsmann, Gerhard; Stahl-Hennig, Christiane; Fritz, Hans-Joachim; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2014)
      Herpes B virus (or Herpesvirus simiae or Macacine herpesvirus 1) is endemic in many populations of macaques, both in the wild and in captivity. The virus elicits only mild clinical symptoms (if any) in monkeys, but can be transmitted by various routes, most commonly via bites, to humans where it causes viral encephalitis with a high mortality rate. Hence, herpes B constitutes a considerable occupational hazard for animal caretakers, veterinarians and laboratory personnel. Efforts are therefore being made to reduce the risk of zoonotic infection and to improve prognosis after accidental exposure. Among the measures envisaged are serological surveillance of monkey colonies and specific diagnosis of herpes B zoonosis against a background of antibodies recognizing the closely related human herpes simplex virus (HSV). 422 pentadecapeptides covering, in an overlapping fashion, the entire amino acid sequences of herpes B proteins gB and gD were synthesized and immobilized on glass slides. Antibodies present in monkey sera that bind to subsets of the peptide collection were detected by microserological techniques. With 42 different rhesus macaque sera, 114 individual responses to 18 different antibody target regions (ATRs) were recorded, 17 of which had not been described earlier. This finding may pave the way for a peptide-based, herpes B specific serological diagnostic test.
    • Novel peptidomimetic compounds containing redox active chalcogens and quinones as potential anticancer agents.

      Shaaban, Saad; Diestel, Randi; Hinkelmann, Bettina; Muthukumar, Yazh; Verma, Rajeshwar P; Sasse, Florenz; Jacob, Claus; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2012-12)
      Many types of cancer cells are associated with a disturbed intracellular redox balance and oxidative stress (OS). Among the various agents employed to modulate the intracellular redox state of cells, certain redox catalysts containing quinone and chalcogen moieties have shown considerable promise. Passerini multicomponent reaction has been developed for the synthesis of agents combining two, three or even four redox centers in one molecule in a good yield. When incubated with cancer cells these agents inhibited cell proliferation and induced apoptotic cell death. Interestingly, some of these redox active compounds exhibited quite low toxicity with normal cells. The cause was obviously OS, which was reflected by significant decrease in reduced glutathione, subsequently cell cycle arrest and induction of apoptosis.
    • Peptide-mediated interference with influenza A virus polymerase.

      Ghanem, Alexander; Mayer, Daniel; Chase, Geoffrey; Tegge, Werner; Frank, Ronald; Kochs, Georg; García-Sastre, Adolfo; Schwemmle, Martin; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2007-07)
      The assembly of the polymerase complex of influenza A virus from the three viral polymerase subunits PB1, PB2, and PA is required for viral RNA synthesis. We show that peptides which specifically bind to the protein-protein interaction domains in the subunits responsible for complex formation interfere with polymerase complex assembly and inhibit viral replication. Specifically, we provide evidence that a 25-amino-acid peptide corresponding to the PA-binding domain of PB1 blocks the polymerase activity of influenza A virus and inhibits viral spread. Targeting polymerase subunit interactions therefore provides a novel strategy to develop antiviral compounds against influenza A virus or other viruses.
    • Sulfur, selenium and tellurium pseudopeptides: synthesis and biological evaluation.

      Shaaban, Saad; Sasse, Florenz; Burkholz, Torsten; Jacob, Claus; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2014-07-15)
      A new series of sulfur, selenium and tellurium peptidomimetic compounds was prepared employing the Passerini and Ugi isocyanide based multicomponent reactions (IMCRs). These reactions were clearly superior to conventional methods traditionally used for organoselenium and organotellurium synthesis, such as classical nucleophilic substitution and coupling methods. From the biological point of view, these compounds are of considerable interest because of suspected anticancer and antimicrobial activities. While the sulfur and selenium containing compounds generally did not show either anticancer or antimicrobial activities, their tellurium based counterparts frequently exhibited antimicrobial activity and were also cytotoxic. Some of the compounds synthesized even showed selective activity against certain cancer cells in cell culture. These compounds induced a cell cycle delay in the G0/G1 phase. At closer inspection, the ER and the actin cytoskeleton appeared to be the primary cellular targets of these tellurium compounds, in line with some of our previous studies. As most of these peptidomimetic compounds also comply with Lipinski's Rule of Five, they promise good bioavailability, which needs to be studied as part of future investigations.