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Many natural proteins contain flexible loops utilizing well-defined complementary surface regions of their interacting partners and usually undergo major structural rearrangements to allow perfect binding. The molecular recognition of such flexible structures is still highly challenging due to the inherent conformational dynamics. Notably, protein-protein interactions are on the other hand characterized by a multivalent display of complementary binding partners to enhance molecular affinity and specificity. Imitating this natural concept, we here report the rational design of advanced multivalent supramolecular tweezers that allow addressing two lysine and arginine clusters on a flexible protein surface loop. The protease Taspase 1, which is involved in cancer development, carries a basic bipartite nuclear localization signal (NLS) and thus interacts with Importin α, a prerequisite for proteolytic activation. Newly established synthesis routes enabled us to covalently fuse several tweezer molecules into multivalent NLS ligands. The resulting bi- up to pentavalent constructs were then systematically compared in comprehensive biochemical assays. In this series, the stepwise increase in valency was robustly reflected by the ligands' gradually enhanced potency to disrupt the interaction of Taspase 1 with Importin α, correlated with both higher binding affinity and inhibition of proteolytic activity.

Despite considerable success in the treatment of epithelial ovarian cancer (EOC), therapy resistance counteracts improvement of long-term survival. The dual role of survivin as an apoptosis inhibitor and mitotic regulator has been associated with disease outcome. However, the molecular mechanisms involved in the deregulated expression in EOC of survivin need further investigation. Here, we show that high amounts of the nitric oxide (NO) donors, S-nitroso-N-acetyl-penicillamine (SNAP) and sodium nitroprusside (SNP) or strong overexpression of the inducible nitric oxide synthase (iNOS) suppressed survivin levels via the p38MAPK pathway and triggered apoptosis in ovarian cancer cell lines (OCC). Importantly, low NO concentrations conferred resistance against carboplatin/paclitaxel-induced apoptosis. Cytoprotection was mediated by survivin because we observed its up-regulation subsequent to low SNAP/SNP doses or ectopic expression of low amounts of iNOS. Also, RNAi-mediated depletion of survivin blocked the antiapoptotic effects of NO signaling. Induction of survivin involves activation of the phosphatidylinositol-3-kinase (PI3K)/Akt pathway, which was antagonized by the PI3K-inhibitor, LY294002. Interestingly, application of the iNOS-inhibitor 1400W together with RNAi-mediated survivin down-regulation cooperatively enhanced drug-induced apoptosis in OCCs. The iNOS/survivin interdependencies seem to be also of clinical relevance because immunohistochemistry revealed that low iNOS levels correlate with survivin expression (P < 0.01) in carboplatin/paclitaxel-treated EOC patients with minimal postoperative residual tumor (n = 54). Also, iNOS and survivin expression were associated with increased risk for disease progression. Our study uncovers a novel molecular mechanism of how NO signaling may contribute to therapy resistance in EOC by modulating survivin expression. Pharmacogenetic iNOS/survivin-targeting strategies may hence be pursued to complement current treatment modalities in EOC. [Cancer Res 2008;68(13):5159–65]

Supplementary Tables 1-3, Figure 1 from NO Signaling Confers Cytoprotectivity through the Survivin Network in Ovarian Carcinomas

Nanobodies are highly affine binders, often used to track disease-relevant proteins inside cells. However, they often fail to interfere with pathobiological functions, required for their clinical exploitation. Here, a nanobody targeting the disease-relevant apoptosis inhibitor and mitosis regulator Survivin (SuN) is utilized. Survivin's multifaceted functions are regulated by an interplay of dynamic cellular localization, dimerization, and protein–protein interactions. However, as Survivin harbors no classical “druggable” binding pocket, one must aim at blocking extended protein surface areas. Comprehensive experimental evidence demonstrates that intracellular expression of SuN allows to track Survivin at low nanomolar concentrations but failed to inhibit its biological functions. Small angle X-ray scattering of the Survivin-SuN complex locates the proposed interaction interface between the C-terminus and the globular domain, as such not blocking any pivotal interaction. By clicking multiple SuN to ultrasmall (2 nm) gold nanoparticles (SuN-N), not only intracellular uptake is enabled, but additionally, Survivin crosslinking and interference with mitotic progression in living cells are also enabled. In sum, it is demonstrated that coupling of nanobodies to nanosized scaffolds can be universally applicable to improve their function and therapeutic applicability. in press

A library of eight different cationic emitters with emission properties in solution and in solid-state (solution and solid-state emitters – SSSE) is presented. These compounds, bearing either ammonium or pyridinium groups, have been investigated regarding their photophysical properties as well as their potential application in biological imaging. Besides high quantum yields as well as a high degree of stability during the imaging process, it was additionally revealed that a broad range of biological targets can be addressed, such as different bacterial strains, human cells as well as protists. The reported SSSE approach employing the mentioned robust emitters for biological imaging, will contribute to a rapid and facile way to design and apply affordable emitters with outstanding properties. Additionally, these emitters will overcome the drawbacks of classical luminophores and agents featuring well-known aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ) properties. in press

Therapy resistance remains a challenge for the clinics. Here, dual-active chemicals that simultaneously inhibit independent functions in disease-relevant proteins are desired though highly challenging. As a model, we here addressed the unique protease threonine aspartase 1, involved in various cancers. We hypothesized that targeting basic residues in its bipartite nuclear localization signal (NLS) by precise bisphosphate ligands inhibits additional steps required for protease activity. We report the bisphosphate anionic bivalent inhibitor 11d, selectively binding to the basic NLS cluster (²²⁰KKRR²²³) with high affinity (KD = 300 nM), thereby disrupting its interaction and function with Importin α (IC₅₀ = 6 μM). Cell-free assays revealed that 11d additionally affected the protease's catalytic substrate trans-cleavage activity. Importantly, functional assays comprehensively demonstrated that 11d inhibited threonine aspartase 1 also in living tumor cells. We demonstrate for the first time that intracellular interference with independent key functions in a disease-relevant protein by an inhibitor binding to a single site is possible. CA Niemeyer und Knauer

We rationally designed a series of amphiphilic hepta-peptides enriched with a chemically conjugated guanidiniocarbonylpyrrole (GCP) unit at the lysine side chain. All peptides are composed of polar (GCP) and non-polar (cyclohexyl alanine) residues but differ in their sequence periodicity, resulting in different secondary as well as supramolecular structures. CD spectra revealed the assembly of β-sheet-, α-helical and random structures for peptides 1, 2 and 3, respectively. Consequently, this enabled the formation of distinct supramolecular assemblies such as fibres, nanorod-like or spherical aggregates. Notably, all three cationic peptides are equipped with the anion-binding GCP unit and thus possess a nucleic acid-binding centre. However, only the helical (2) and the unstructured (3) peptide were able to assemble into small virus-like DNA-polyplexes and effectively deliver DNA into cells. Notably, as both peptides (2 and 3) were also capable of siRNA-delivery, they could be utilized to downregulate expression of the caner-relevant protein Survivin.

In this contribution we report on the synthesis, characterization and application of water‐soluble zinc(II) phthalocyanines, which are decorated with four or eight umbelliferone moieties for photodynamic therapy (PDT). These compounds are linked peripherally to zinc(II) phthalocyanine by a triethylene glycol linker attached to pyridines, leading to cationic pyridinium units, able to increase the water solubility of the system. Beside their photophysical properties they were analyzed concerning their cellular distribution in human hepatocyte carcinoma (HepG2) cells as well as their phototoxicity towards HepG2 cells, Gram‐positive (S. aureus strain 3150/12 and B. subtilis strain DB104) and Gram‐negative bacteria (E. coli strain UTI89 and E. coli strain Nissle 1917). At low light doses and concentrations, they exhibit superb antimicrobial activity against Gram‐positive bacteria as well as anti‐tumor activity against HepG2. They are even capable to inactivate Gram‐negative bacteria, whereas the dark toxicity remains low. These unique water‐soluble compounds can be regarded as all‐in‐one type photosensitizers with broad applications ranges in the future., Presented here are umbelliferone substituted water‐soluble zinc(II) phthalocyanines, which are able to inactivate efficiently Gram‐positive and Gram‐negative bacteria and are also active against HepG2 cancer cells. The compounds were investigated concerning their phototoxicity as well as their photophysical properties and their aggregation behavior.

We report the characterization of amphiphilic aminoglycoside conjugates containing luminophores with aggregation‐induced emission properties as transfection reagents. These inherently luminescent transfection vectors are capable of binding plasmid DNA through electrostatic interactions; this binding results in an emission “on” signal due to restriction of intramolecular motion of the luminophore core. The luminescent cationic amphiphiles effectively transferred plasmid DNA into mammalian cells (HeLa, HEK 293T), as proven by expression of a red fluorescent protein marker. The morphologies of the aggregates were investigated by microscopy as well as ζ‐potential and dynamic light‐scattering measurements. The transfection efficiencies using luminescent cationic amphiphiles were similar to that of the gold‐standard transfection reagent Lipofectamine® 2000., Transfection tracker: Conjugates of luminophores with aggregation‐induced emission properties linked to the aminoglycoside tobramycin are reported. These compounds reveal an emission “on” behavior upon plasmid‐DNA binding and are able to transfect different mammalian cell lines. The cellular uptake was investigated using the emission properties of the formed plasmid DNA‐vector assemblies.

Background: To improve the biocompatibility of porous polyethylene (PPE) implants and expand their application range for reconstructive surgery in poorly vascularized environments, implants were coated with tumor necrosis factor α (TNFα) inhibitor Etanercept. While approved for systemic application, local application of the drug is a novel experimental approach. Microvascular and mechanical integration as well as parameters of inflammation were analyzed in vivo. Methods: PPE implants were coated with Etanercept and extracellular matrix (ECM) components prior to implantation into dorsal skinfold chambers of C57BL/6 mice. Fluorescence microscopy analyses of angiogenesis and local inflammatory response were thrice performed in vivo over a period of 14 days to assess tissue integration and biocompatibility. Uncoated implants and ECM-coated implants served as controls. Results: TNFα inhibition with Etanercept led to a reduced local inflammatory response: leukocyte-endothelial cell adherence was significantly lowered compared to both control groups (n = 6/group) on days 3 and 14, where the lowest values were reached: 3573.88 leukocytes/mm-2 ± 880.16 (uncoated implants) vs. 3939.09 mm-2 ± 623.34 (Matrigel only) vs. 637.98 mm-2 + 176.85 (Matrigel and Etanercept). Implant-coating with Matrigel alone and Matrigel and Etanercept led to significantly higher vessel densities 7 and 14 days vs. 3 days after implantation and compared to uncoated implants. Mechanical implant integration as measured by dynamic breaking strength did not differ after 14 days. Conclusion: Our data show a reduced local inflammatory response to PPE implants after immunomodulatory coating with Etanercept in vivo, suggesting improved biocompatibility. Application of this tissue engineering approach is therefore warranted in models of a compromised host environment.

A novel strategy to inhibit the oncologically relevant protease Taspase1 is explored by developing PEGylated macromolecular ligands presenting the supramolecular binding motif guanidiniocarbonylpyrrole (GCP). Taspase1 requires interaction of its nuclear localization signal (NLS) with import receptor Importin α. We show the synthesis and effective interference of PEGylated multivalent macromolecular ligands with Taspase1-Importin α-complex formation.

A strategy toward epitope-selective functionalized nanoparticles is introduced in the following: ultrasmall gold nanoparticles (diameter of the metallic core about 2 nm) were functionalized with molecular tweezers that selectively attach lysine and arginine residues on protein surfaces. Between 11 and 30 tweezer molecules were covalently attached to the surface of each nanoparticle by copper-catalyzed azide alkyne cycloaddition (CuAAC), giving multiavid agents to target proteins. The nanoparticles were characterized by high-resolution transmission electron microscopy, differential centrifugal sedimentation, and 1H NMR spectroscopy (diffusion-ordered spectroscopy, DOSY, and surface composition). The interaction of these nanoparticles with the model proteins hPin1 (WW domain; hPin1-WW) and Survivin was probed by NMR titration and by isothermal titration calorimetry (ITC). The binding to the WW domain of hPin1 occurred with a KD of 41 ± 2 μM, as shown by ITC. The nanoparticle-conjugated tweezers targeted cationic amino acids on the surface of hPin1-WW in the following order: N-terminus (G) ≈ R17 > R14 ≈ R21 > K13 > R36 > K6, as shown by NMR spectroscopy. Nanoparticle recognition of the larger protein Survivin was even more efficient and occurred with a KD of 8 ± 1 μM, as shown by ITC. We conclude that ultrasmall nanoparticles can act as versatile carriers for artificial protein ligands and strengthen their interaction with the complementary patches on the protein surface.

We report on a stabilizer of the interaction between 14‐3‐3ζ and the Estrogen Receptor alpha (ERα). ERα is a driver in the majority of breast cancers and 14‐3‐3 proteins are negative regulators of this nuclear receptor, making the stabilization of this protein‐protein interaction (PPI) an interesting strategy. The stabilizer (1) consists of three symmetric peptidic arms containing an arginine mimetic, previously described as the GCP motif. 1 stabilizes the 14‐3‐3ζ/ERα interaction synergistically with the natural product Fusicoccin‐A and was thus hypothesized to bind to a different site. This is supported by computational analysis of 1 binding to the binary complex of 14‐3‐3 and an ERα‐derived phosphopeptide. Furthermore, 1 shows selectivity towards 14‐3‐3ζ/ERα interaction over other 14‐3‐3 client‐derived phosphomotifs. These data provide a solid support of a new binding mode for a supramolecular 14‐3‐3ζ/ERα PPI stabilizer., A stabilizer of the interaction between the Estrogen Receptor alpha (ERα), a driver in the majority of breast cancers, and 14‐3‐3ζ, a negative regulator of ERα, is developed as anti‐cancer strategy. The stabilizer of this protein‐protein interaction (PPI) consists of three symmetric peptidic arms and stabilizes the 14‐3‐3ζ/ERα interaction synergistically with the natural product Fusicoccin‐A.

Tumor‐targeted drug delivery is highly important for improving chemotherapy, as it reduces the dose of cytotoxic agents and minimizes the death of healthy tissues. Towards this goal, a conjugate was synthesized of gossypol and a MCF‐7 cancer cell specific CPP (cell penetrating peptide), thus providing a selective drug delivery system. Utilizing the aldehyde moiety of gossypol, the tumor homing CPP RLYMRYYSPTTRRYG was attached through a semi‐labile imine linker, which was cleaved in a traceless fashion under aqueous conditions and had a half‐life of approximately 10 hours. The conjugate killed MCF‐7 cells to a significantly greater extent than HeLa cells or healthy fibroblasts., Selective drug delivery: A Cancer‐cell specific drug delivery system was developed by conjugating a tumor homing peptide and gossypol through a cleavable linker. The Schiff's base linked conjugate killed the targeted MCF‐7 cells selectively compared to HeLa cells used as a control (see figure).

In this communication we report on the synthesis and application of axially functionalized boron-subphthalocyanines (SubPC) which are able to form host-guest complexes with cyclodextrins. Here, a tert-butylphenyl substituted SubPC was investigated concerning its complexation with β-cyclodextrin (β-CD) and a β-cyclodextrin polymer. NMR-titrations showed the formation of a 1 : 1 complex with β-CD. These assemblies were analyzed for their cellular distribution as well as their phototoxicity towards HeLa cells.

Targeting specific protein binding sites to interfere with protein-protein interactions (PPIs) is crucial for the rational modulation of biologically relevant processes. Survivin, which is highly overexpressed in most cancer cells and considered to be a key player of carcinogenesis, features two functionally relevant binding sites. Here, we demonstrate selective disruption of the Survivin/Histone H3 or the Survivin/Crm1 interaction using a supramolecular approach. By rational design we identified two structurally related ligands (LNES and LHIS), capable of selectively inhibiting these PPIs, leading to a reduction in cancer cell proliferation.

Taspase1 is a unique protease not only pivotal for embryonic development but also implicated in leukemia as well as solid tumors. As such, it is a promising target in cancer therapy, although only a limited number of Taspase1 inhibitors lacking general applicability are currently available. Here we present a bivalent guanidiniocarbonyl-pyrrole (GCP)-containing supramolecular ligand that is capable of disrupting the essential interaction between Taspase1 and its cognate import receptor Importin α in a concentration-dependent manner in vitro with an IC₅₀ of 35 μM. Here, size of the bivalent vs the monovalent construct as well as its derivation with an aromatic cbz-group arose as critical determinants for efficient interference of 2GC. This was also evident when we investigated the effects in different tumor cell lines, resulting in comparable EC₅₀ values (∼40–70 μM). Of note, in higher concentrations, 2GC also interfered with Taspase1’s proteolytic activity. We thus believe to set the stage for a novel class of Taspase1 inhibitors targeting a pivotal protein-protein interaction prerequisite for its cancer-associated proteolytic function.

In bacteria, the monopolar localization of enzymes and protein complexes can result in a bi-modal distribution of enzyme activity between the dividing cells and heterogeneity of cellular behaviors. In Shewanella putrefaciens, the multidomain hybrid diguanylate cyclase/phosphodiesterase PdeB, which degrades the secondary messenger c-di-GMP, is located at the flagellated cell pole. Here we show how PdeB polar recruitment is mediated by direct interaction between the inactive diguanylate cyclase (GGDEF) domain of PdeB and the C-terminal FimV domain of the polar landmark protein HubP. We demonstrate that this interaction is crucial for full function of PdeB as a phosphodiesterase. Thus, the GGDEF domain serves as a spatially controlled on-switch that effectively restricts PdeBs activity to the flagellated cell pole. We further show that PdeB regulates abundance and activity of at least two crucial surface-interaction factors, the BpfA surface adhesion protein and the MSHA type IV pilus. The heterogeneity in c-di-GMP concentrations that is generated by differences in abundance and temporal polar appearance of PdeB as well as by bi-modal distribution after cell fission orchestrates the population behavior with respect to cell-surface interaction and environmental spreading.SignificancePhenotypic heterogeneity benefits the proliferation of microbial populations in changing environments. Such heterogeneity can be created by recruitment of enzymatic activity to specific cellular compartments, e.g., the cell pole. Here we show how a GGDEF domain of a multidomain phosphodiesterase has adopted the function as a spatial on-switch that is specifically activated upon direct interaction with a polar landmark protein.

Circulating tumor cells (CTCs) are disseminated cancer cells. The occurrence and circulation of CTCs seem key for metastasis, still the major cause of cancer-associated deaths. As such, CTCs are investigated as predictive biomarkers. However, due to their rarity and heterogeneous biology, CTCs' practical use has not made it into the clinical routine. Clearly, methods for the effective isolation and reliable detection of CTCs are urgently needed. With the development of nanotechnology, various nanosystems for CTC isolation and enrichment and CTC-targeted cancer therapy have been designed. Here, we summarize the relationship between CTCs and tumor metastasis, and describe CTCs' unique properties hampering their effective enrichment. We comment on nanotechnology-based systems for CTC isolation and recent achievements in microfluidics and lab-on-a-chip technologies. We discuss recent advances in CTC-targeted cancer therapy exploiting the unique properties of nanomaterials. We conclude by introducing developments in CTC-directed nanosystems and other advanced technologies currently in (pre)clinical research.

This article has been removed: please see Elsevier Policy on Article Withdrawal ( https://www.elsevier.com/about/our-business/policies/article-withdrawal ). This article has been removed at the request of the Editors. Parts of Figure 1 were obtained in conjunction with another group of researchers. This group does not wish to publish this data as part of this manuscript. As this data has been deemed critical to the manuscript, and permission to publish the data has not been obtained, the manuscript has been removed. One of the conditions of submission of a paper for publication is that the authors have the right to publish the materials within. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not resolved prior to publication.

Multidrug-resistant bacterial infections are a global health threat. Nanoparticles are thus investigated as novel antibacterial agents for clinical practice, including wound dressings and implants. We report that nanoparticles' bactericidal activity strongly depends on their physical binding to pathogens, including multidrug-resistant primary clinical isolates, such as Staphylococcus aureus , Klebsiella pneumoniae or Enterococcus faecalis . Using controllable nanoparticle models, we found that nanoparticle-pathogen complex formation was enhanced by small nanoparticle size rather than material or charge, and was prevented by 'stealth' modifications. Nanoparticles seem to preferentially bind to Gram-positive pathogens, such as Listeria monocytogenes, S. aureus or Streptococcus pyrogenes , correlating with enhanced antibacterial activity . Bacterial resistance to metal-based nanoparticles was mediated by biomolecule coronas acquired in pathophysiological environments, such as wounds, the lung, or the blood system. Biomolecule corona formation reduced nanoparticles' binding to pathogens, but did not impact nanoparticle dissolution. Our results provide a mechanistic explanation why nano-sized antibiotics may show reduced activity in clinically relevant environments, and may inspire future nanoantibiotic designs with improved and potentially pathogen-specific activity.

OA Förderung 2022 The unique threonine protease Tasp1 impacts not only ordered development and cell proliferation but also pathologies. However, its substrates and the underlying molecular mechanisms remain poorly understood. We demonstrate that the unconventional Myo1f is a Tasp1 substrate and unravel the physiological relevance of this proteolysis. We classify Myo1f as a nucleo-cytoplasmic shuttle protein, allowing its unhindered processing by nuclear Tasp1 and an association with chromatin. Moreover, we show that Myo1f induces filopodia resulting in increased cellular adhesion and migration. Importantly, filopodia formation was antagonized by Tasp1-mediated proteolysis, supported by an inverse correlation between Myo1f concentration and Tasp1 expression level. The Tasp1/Myo1f-axis might be relevant in human hematopoiesis as reduced Tasp1 expression coincided with increased Myo1f concentrations and filopodia in macrophages compared to monocytes and vice versa. In sum, we discovered Tasp1-mediated proteolysis of Myo1f as a mechanism to fine-tune filopodia formation, inter alia relevant for cells of the immune system.

Survivin’s dual function as apoptosis inhibitor and regulator of cell proliferation is mediated via its interaction with the export receptor CRM1. This protein–protein interaction represents an attractive target in cancer research and therapy. Here, we report a sophisticated strategy addressing Survivin’s nuclear export signal (NES), the binding site of CRM1, with advanced supramolecular tweezers for lysine and arginine. These were covalently connected to small peptides resembling the natural, self-complementary dimer interface which largely overlaps with the NES. Several biochemical methods demonstrated sequence-selective NES recognition and interference with the critical receptor interaction. These data were strongly supported by molecular dynamics simulations and multiscale computational studies. Rational design of lysine tweezers equipped with a peptidic recognition element thus allowed to address a previously unapproachable protein surface area. As an experimental proof-of-principle for specific transport signal interference, this concept should be transferable to any protein epitope with a flanking well-accessible lysine., Survivin’s dual function as apoptosis inhibitor and regulator of cell proliferation is mediated via its interaction with the export receptor CRM1. Here authors report a strategy addressing its dimer interface overlapping with the nuclear export signal, the binding site of CRM1, with advanced supramolecular tweezers for lysine and arginine.

The 14-3-3 protein family, one of the first discovered phosphoserine/phosphothreonine binding proteins, has attracted interest not only because of its important role in the cell regulatory processes but also due to its enormous number of interactions with other proteins. Here, we use a computational approach to find the binding sites of the designed hybrid compound featuring aggregation-induced emission luminophores as a potential supramolecular ligand for 14-3-3z in the presence and absence of C-Raf peptides. Our results suggest that the area above and below the central pore of the dimeric 14-3-3z protein is the most probable binding site for the ligand. Moreover, we predict that the position of the ligand is sensitive to the presence of phosphorylated C-Raf peptides.

BackgroundThe amyloid precursor protein (APP) is a type I transmembrane protein with unknown physiological function. Amyloidogenic processing of APP causes the generation of different cleavage products amongst b-amyloid and the APP C-terminal (APP-CT) fragment.METHODS1D, cerebral organoid 3D cell culture and human hippocampal post-mortem tissue were used to study APP-CT signalling in combination with immunofluorescence, -precipitation, confocal and STED imaging.RESULTSThe current study demonstrates that APP-CT signals to the nucleus causing the generation of dynamic aggregates consisting of FE65 and the tumour suppressors p53 and PML. PML aggregates fuse over time depending on the APP nuclear signalling and complexes of the APP-CT/p53/PML and FE65 are present in the aged human post-mortem brain but not in cerebral organoids. Precise quantification revealed that AD brains show a significant loss of these nuclear aggregates in areas with high plaque load. The PML aggregates are co-localized to the herpes simplex virus in the human brain.CONCLUSIONSOur data show that APP-CT signalling recruits the nuclear PML body machinery and is of central relevance for neurodegeneration in AD with a potential function in viral defence.

When nanoparticles enter a physiological environment, they rapidly adsorb biomolecules, in particular cellular proteins. This biological coating, the so-called nanoparticle protein corona, undoubtedly affects the biological identity and potential cytotoxicity of the nanomaterial. To elucidate a possible impact on the adsorbed biomolecules, we focused on an important group of players in cellular homeostasis, namely proteolytic enzymes. We could demonstrate that amorphous silica nanoparticles are not only able to bind to the oncologically relevant threonine protease Taspase1 as revealed by microscale thermophoresis and fluorescence anisotropy measurements, but moreover inhibit its proteolytic activity in a non-competitive manner. As revealed by temperature-dependent unfolding and CD spectroscopy, binding did not alter the stability of Taspase1 or its secondary structure. Noteworthy, inhibition of protein function seems not a general feature of nanoparticles, as several control enzymes were not affected in their proteolytic activity. Our data suggests that nanoparticles bind Taspase1 as an αβ-dimer in a single layer without conformational change, resulting in noncompetitive inhibition that is either allostery-like or occludes the active site. Nanoparticle-based inhibition of Taspase1 could be also achieved in cell lysates and in live cells as shown by the use of a protease-specific cellular cleavage biosensor. Collectively, we could demonstrate that nanoparticles could not only bind but also selectively inhibit cellular enzymes, which might explain observed cytotoxicity but might serve as a starting point for the development of nanoparticle-based inhibitors as therapeutics.

The amyloid precursor protein (APP) is a type I transmembrane protein with unknown physiological function but potential impact in neurodegeneration. The current study demonstrates that APP signals to the nucleus causing the generation of aggregates comprising its adapter protein FE65 and the tumour suppressor proteins p53 and PML. The PML nuclear body generation, known to be of relevance in virus defence and cell division, is induced and fusion occurs over time depending on APP signalling. We further show that the nuclear aggregates of APP C-terminal (APP-CT) fragments together with PML and FE65 are present in the aged human brain but not in cerebral organoids differentiated from iPS cells. Notably, human Alzheimer’s disease brains reveal a highly significant loss of these nuclear aggregates in areas with high plaque load compared to plaque-free areas of the same individual. Based on these results we conclude that APP-CT signalling to the nucleus takes place in the aged human brain and is potentially involved in the pathophysiology of AD. Taken the current knowledge on PML bodies into account, we hypothesize a new role for APP as a twofold virus response protein. The APP-dependent defence strategy includes Aß-virus interaction at the extracellular matrix and APP-CT driven PML aggregation in the nucleus to encapsulate the viral nucleic acid. This defence strategy preferentially occurs in high-plaque regions of the human brain and overstimulation of this pathway results in a pyrrhic victory.

The synthesis and self-assembly of a polymer featuring a self-complementary supramolecular binding motif guanidiniocarbonyl pyrrole carboxylate zwitterion (GCP-zwitterion) bearing lactose moieties are reported. The GCP-zwitterion acts as a cross-linker to facilitate self-assembly of the polymeric chain into nanoparticles (NPs) at neutral pH in an aqueous medium. The formation of polymeric NPs can be controlled by addition of external stimuli (acid or base), which disfavors self-assembly of the GCP-zwitterion because of protonation or deprotonation of the GCP units in the polymer chain. The small-sized (40 nm) NPs have a hydrophobic cavity and accessible lactose units on the outer shell for multivalent lectin binding. The multivalent interaction between NPs and the lectin peanut agglutinin was confirmed by agglutination experiments. In addition, the stimuli-responsive property of NPs was exploited for the uptake and release of a hydrophobic guest Nile red. Furthermore, the selectivity toward different cell lines (HEK 296T, HeLa, and Hep2G) was tested, and a cellular uptake of cargo-loaded NPs was found for Hep2G cells bearing the lactose-specific asialogylcoprotein receptor, whereas all other cells showed no NP interaction.

Whereas nanotoxicity is intensely studied in mammalian systems, our knowledge of desired or unwanted nano-based effects for microbes is still limited. Fungal infections are global socio-economic health and agricultural problems, and current chemical antifungals may induce adverse side-effects in humans and ecosystems. Thus, nanoparticles are discussed as potential novel and sustainable antifungals via the desired nanotoxicity but often fail in practical applications. In our study, we found that nanoparticles' toxicity strongly depends on their binding to fungal spores, including the clinically relevant pathogen

The protein Survivin is highly upregulated in most cancers and considered to be a key player in carcinogenesis. We explored a supramolecular approach to address Survivin as a drug target by inhibiting the protein–protein interaction of Survivin and its functionally relevant binding partner Histone H3. Ligand L1 is based on the guanidiniocarbonyl pyrrole cation and serves as a highly specific anion binder in order to target the interaction between Survivin and Histone H3. NMR titration confirmed binding of L1 to Survivin's Histone H3 binding site. The inhibition of the Survivin–Histone H3 interaction and consequently a reduction of cancer cell proliferation were demonstrated by microscopic and cellular assays., Effective interruption: The supramolecular guanidiniocarbonyl pyrrole ligand L1 targets the Histone H3 binding site of the protein Survivin, which is highly upregulated in cancer. Inhibiting the interaction between the two proteins successfully reduced cancer cell proliferation.

In this communication we present the use of a novel class of luminophores with aggregation-induced emission (AIE) properties based on the steroid estrone. These molecules were equipped with cationic residues yielding amphiphiles suitable for lipofection. To this end, self-assembled luminescent structures were formed in aqueous media and mixed with a red-fluorescent protein expressing plasmid, yielding lipoplexes with increased emission intensity. These luminescent lipoplexes were able to efficiently transfect HeLa and HEK 293T cells and were able to be tracked due to the aggregation induced-emission properties. CA - Voskuhl

Nanomaterials are promising novel antibiotics, but often ineffective. We found that nanomaterial-bacteria complex formation occurred with various nanomaterials. The bactericidal activity of NMs strongly depends on their physical binding to (multidrug-resistant) bacteria. Nanomaterials' binding and antibiotic effect was reduced by various pathophysiological biomolecule coronas strongly inhibiting their antibiotic effects. We show from analytical to in vitro to in vivo that nanomaterial-based killing could be restored by acidic pH treatments. Here, complex formation of negatively-charged, plasma corona-covered, nanomaterials with bacteria was electrostatically enhanced by reducing bacteria's negative surface charge. Employing in vivo skin infection models, acidic pH-induced complex formation was critical to counteract Staphylococcus aureus infections by silver nanomaterials. We explain why nano-antibiotics show reduced activity and provide a clinically practical solution. This journal is CA - Knauer

Airborne fungal pathogens, predominantly Aspergillus fumigatus, can cause severe respiratory tract diseases. Here we show that in environments, fungal spores can already be decorated with nanoparticles. Using representative controlled nanoparticle models, we demonstrate that various nanoparticles, but not microparticles, rapidly and stably associate with spores, without specific functionalization. Nanoparticle-spore complex formation was enhanced by small nanoparticle size rather than by material, charge, or "stealth" modifications and was concentration-dependently reduced by the formation of environmental or physiological biomolecule coronas. Assembly of nanoparticle-spore surface hybrid structures affected their pathobiology, including reduced sensitivity against defensins, uptake into phagocytes, lung cell toxicity, and TLR/cytokine-mediated inflammatory responses. Following infection of mice, nanoparticle-spore complexes were detectable in the lung and less efficiently eliminated by the pulmonary immune defense, thereby enhancing A. fumigatus infections in immunocompromised animals. Collectively, self-assembly of nanoparticle-fungal complexes affects their (patho)biological identity, which may impact human health and ecology.

Irinotecan (CPT-11) and oxaliplatin (L-OHP) are among the most frequently used drugs against colorectal tumors. Therefore, it is important to define the molecular mechanisms that these agents modulate in colon cancer cells. Here we demonstrate that CPT-11 stalls such cells in the G₂/M phase of the cell cycle, induces an accumulation of the tumor suppressor p53, the replicative stress/DNA damage marker γH2AX, phosphorylation of the checkpoint kinases ATM and ATR, and an ATR-dependent accumulation of the pro-survival molecule survivin. L-OHP reduces the number of cells in S-phase, stalls cell cycle progression, transiently triggers an accumulation of low levels of γH2AX and phosphorylated checkpoint kinases, and L-OHP suppresses survivin expression at the mRNA and protein levels. Compared to CPT-11, L-OHP is a stronger inducer of caspases and p53-dependent apoptosis. Overexpression and RNAi against survivin reveal that this factor critically antagonizes caspase-dependent apoptosis in cells treated with CPT-11 and L-OHP. We additionally show that L-OHP suppresses survivin through p53 and its downstream target p21, which stalls cell cycle progression as a cyclin-dependent kinase inhibitor (CDKi). These data shed new light on the regulation of survivin by two clinically significant drugs and its biological and predictive relevance in drug-exposed cancer cells. CA extern

Herein, we report a rather simple strategy to enhance the anion binding ability of a dipeptide to achieve cell uptake and also protein delivery. Peptide 1, composed of only two synthetic amino acids with an artificial anion binding site in the side chains, has an overall molecular weight of only 630 Da and demonstrated strong binding affinity (107 M-1) and clustering ability with heparin as a model for cell surface sugars. Furthermore, peptide 1 is also efficiently taken up by cells most likely via endocytosis. The uptake efficiency is dependent on the amount of glycosaminoglycans on the cell surface. Cells with reduced amounts of surface bound glycosaminoglycans show significantly less uptake of peptide 1. Moreover, 1 induced the uptake of a model protein (avidin, around 67 kDa) into cells, which makes 1 a highly attractive candidate for drug and protein delivery, especially as 1 has negligible cytotoxicity.