Multi-platform quantitation of alpha-synuclein human brain proteoforms suggests disease-specific biochemical profiles of synucleinopathies.

Based on immunostainings and biochemical analyses, certain post-translationally modified alpha-synuclein (aSyn) variants, including C-terminally truncated (CTT) and Serine-129 phosphorylated (pSer129) aSyn, are proposed to be involved in the pathogenesis of synucleinopathies such as Parkinson's disease with (PDD) and without dementia (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). However, quantitative information about aSyn proteoforms in the human brain in physiological and different pathological conditions is still limited. To address this, we generated sequential biochemical extracts of the substantia nigra, putamen and hippocampus from 28 donors diagnosed and neuropathologically-confirmed with different synucleinopathies (PD/PDD/DLB/MSA), as well as Alzheimer's disease, progressive supranuclear palsy, and aged normal subjects.

The subcellular arrangement of alpha-synuclein proteoforms in the Parkinson's disease brain as revealed by multicolor STED microscopy.

Various post-translationally modified (PTM) proteoforms of alpha-synuclein (aSyn)-including C-terminally truncated (CTT) and Serine 129 phosphorylated (Ser129-p) aSyn-accumulate in Lewy bodies (LBs) in different regions of the Parkinson's disease (PD) brain. Insight into the distribution of these proteoforms within LBs and subcellular compartments may aid in understanding the orchestration of Lewy pathology in PD. We applied epitope-specific antibodies against CTT and Ser129-p aSyn proteoforms and different aSyn domains in immunohistochemical multiple labelings on post-mortem brain tissue from PD patients and non-neurological, aged controls, which were scanned using high-resolution 3D multicolor confocal and stimulated emission depletion (STED) microscopy.

Sensitization of Tumors for Attack by Virus-Specific CD8+ T-Cells Through Antibody-Mediated Delivery of Immunogenic T-Cell Epitopes.

Anti-tumor immunity is limited by a number of factors including the lack of fully activated T-cells, insufficient antigenic stimulation and the immune-suppressive tumor microenvironment. We addressed these hurdles by developing a novel class of immunoconjugates, Antibody-Targeted Pathogen-derived Peptides (ATPPs), which were designed to efficiently deliver viral T-cell epitopes to tumors with the aim of redirecting virus-specific memory T-cells against the tumor. ATPPs were generated through covalent binding of mature MHC class I peptides to antibodies specific for cell surface-expressed tumor antigens that mediate immunoconjugate internalization.

Antibody-targeted chromatin enables effective intracellular delivery and functionality of CRISPR/Cas9 expression plasmids.

We report a novel system for efficient and specific targeted delivery of large nucleic acids to and into cells. Plasmid DNA and core histones were assembled to chromatin by salt gradient dialysis and subsequently connected to bispecific antibody derivatives (bsAbs) via a nucleic acid binding peptide bridge. The resulting reconstituted vehicles termed 'plasmid-chromatin' deliver packaged nucleic acids to and into cells expressing antigens that are recognized by the bsAb, enabling intracellular functionality without detectable cytotoxicity.

Quantitative fluorescence imaging determines the absolute number of locked nucleic acid oligonucleotides needed for suppression of target gene expression.

Locked nucleic acid based antisense oligonucleotides (LNA-ASOs) can reach their intracellular RNA targets without delivery modules. Functional cellular uptake involves vesicular accumulation followed by translocation to the cytosol and nucleus. However, it is yet unknown how many LNA-ASO molecules need to be delivered to achieve target knock down.

Diphthamide affects selenoprotein expression: Diphthamide deficiency reduces selenocysteine incorporation, decreases selenite sensitivity and pre-disposes to oxidative stress.

The diphthamide modification of translation elongation factor 2 is highly conserved in eukaryotes and archaebacteria. Nevertheless, cells lacking diphthamide can carry out protein synthesis and are viable. We have analyzed the phenotypes of diphthamide deficient cells and found that diphthamide deficiency reduces selenocysteine incorporation into selenoproteins.

Transcytosis of payloads that are non-covalently complexed to bispecific antibodies across the hCMEC/D3 blood-brain barrier model.

A transcellular shuttle system was generated for the delivery of non-covalently linked payloads across blood-brain barrier (BBB) endothelial cells. Transcytosis-enabling shuttles are composed of bispecific antibodies (bsAbs) that simultaneously bind transferrin receptor (TfR) and haptens such as digoxigenin or biocytinamide. Haptenylated payloads are attached to these vehicles via non-covalent hapten-antibody complexation.

Charge-mediated influence of the antibody variable domain on FcRn-dependent pharmacokinetics.

Here, we investigated the influence of the variable fragment (Fv) of IgG antibodies on the binding to the neonatal Fc receptor (FcRn) as well as on FcRn-dependent pharmacokinetics (PK). FcRn plays a key role in IgG homeostasis, and specific manipulation in the crystallizable fragment (Fc) is known to affect FcRn-dependent PK. Although the influence of the antigen-binding fragment (Fab) on FcRn interactions has been reported, the underlying mechanism is hitherto only poorly understood.

Committing Cytomegalovirus-Specific CD8 T Cells to Eliminate Tumor Cells by Bifunctional Major Histocompatibility Class I Antibody Fusion Molecules.

Tumor cells escape immune eradication through multiple mechanisms, including loss of antigenicity and local suppression of effector lymphocytes. To counteract these obstacles, we aimed to direct the unique cytomegalovirus (CMV)-specific immune surveillance against tumor cells. We developed a novel generation of fusion proteins composed of a tumor antigen-specific full immunoglobulin connected to a single major histocompatibility class I complex bearing a covalently linked virus-derived peptide (pMHCI-IgG).

Hapten-directed spontaneous disulfide shuffling: a universal technology for site-directed covalent coupling of payloads to antibodies.

Humanized hapten-binding IgGs were designed with an accessible cysteine close to their binding pockets, for specific covalent payload attachment. Individual analyses of known structures of digoxigenin (Dig)- and fluorescein (Fluo) binding antibodies and a new structure of a biotin (Biot)-binder, revealed a "universal" coupling position (52(+2)) in proximity to binding pockets but without contributing to hapten interactions. Payloads that carry a free thiol are positioned on the antibody and covalently linked to it via disulfides.

Quantification of cell surface proteins with bispecific antibodies.

Flow cytometry is an established method for fast and accurate quantitation of cellular protein levels and requires fluorescently labeled antibodies as well as calibration standards. A critical step for quantitation remains the production of suitable detection antibodies with a precisely defined ratio of antigen-binding sites to fluorophores. Problems often arise as a consequence of inefficient and unspecific labeling which can influence antibody properties.

Preclinical activity of the type II CD20 antibody GA101 (obinutuzumab) compared with rituximab and ofatumumab in vitro and in xenograft models.

We report the first preclinical in vitro and in vivo comparison of GA101 (obinutuzumab), a novel glycoengineered type II CD20 monoclonal antibody, with rituximab and ofatumumab, the two currently approved type I CD20 antibodies. The three antibodies were compared in assays measuring direct cell death (AnnexinV/PI staining and time-lapse microscopy), complement-dependent cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), and internalization. The models used for the comparison of their activity in vivo were SU-DHL4 and RL xenografts.

Targeted near-infrared imaging of the erythropoietin receptor in human lung cancer xenografts.

Unlabelled: The putative presence of the erythropoietin receptor (EpoR) on human cancer cells has given rise to controversial discussion about the use of recombinant human erythropoietin (rhuEpo) for treatment of patients with chemotherapy-induced anemia. In vivo analysis of the EpoR status in tumors could help in elucidating the role of erythropoietin in cancer. Thus, the aim of this study was to develop a targeted EpoR probe for the investigation of EpoR expression in human lung cancer xenografts by fluorescence-mediated tomography.

Allosteric antibody inhibition of human hepsin protease.

Hepsin is a type II transmembrane serine protease that is expressed in several human tissues. Overexpression of hepsin has been found to correlate with tumour progression and metastasis, which is so far best studied for prostate cancer, where more than 90% of such tumours show this characteristic. To enable improved future patient treatment, we have developed a monoclonal humanized antibody that selectively inhibits human hepsin and does not inhibit other related proteases.

Bispecific digoxigenin-binding antibodies for targeted payload delivery.

Bispecific antibodies that bind cell-surface targets as well as digoxigenin (Dig) were generated for targeted payload delivery. Targeting moieties are IgGs that bind the tumor antigens Her2, IGF1R, CD22, or LeY. A Dig-binding single-chain Fv was attached in disulfide-stabilized form to C termini of CH3 domains of targeting antibodies.

Epitope characterization and crystal structure of GA101 provide insights into the molecular basis for type I/II distinction of CD20 antibodies.

CD20 is a cell-surface marker of normal and malignant B cells. Rituximab, a monoclonal antibody targeting CD20, has improved the treatment of malignant lymphomas. Therapeutic CD20 antibodies are classified as either type I or II based on different mechanisms of killing malignant B cells.

Expression and targeting of the tight junction protein CLDN1 in CLDN1-negative human breast tumor cells.

Claudins and occludin constitute the major transmembrane proteins of tight junctions (TJs). We have previously identified the human homologue of the murine Cldn1, CLDN1 (SEMP1) that is expressed in normal, mammary gland-derived epithelial cells but is absent in most human breast cancer cell lines. To investigate the potential functions of CLDN1 protein in tumor and normal epithelial cells, we developed an I-NGFR retroviral vector and monoclonal anti-CLDN1 antibody.

Digital imaging microscopy of firefly luciferase activity to directly monitor differences in cell transduction efficiencies between AdCMVLuc and Ad5LucRGD vectors having different cell binding properties.

The luciferase reporter gene incorporated into adenoviral vectors is very useful for monitoring viral transduction of different cell types or for comparing the transduction efficiency of different viral constructs of one cell type. Luciferase protein expression can be detected and quantified with very high sensitivity from whole cells or organ extracts. However, its disadvantages become obvious when aiming at evaluation of transduction events at the single cell level.

Amphiphysin I antisense oligonucleotides inhibit neurite outgrowth in cultured hippocampal neurons.

Amphiphysin I is an SH3 domain-containing neuronal protein, enriched in axon terminals, which was reported to act as a physiological binding partner for dynamin I in synaptic vesicle endocytosis. Rvs167 and Rvs161, the yeast homologs of amphiphysin I, have been implicated in endocytosis, actin function, and cell polarity. Now we have explored the possibility that amphiphysin I also may have a role in actin dynamics and cell polarity by testing the effect of amphiphysin I suppression on neurite outgrowth.

Mobility of synaptic vesicles in nerve endings monitored by recovery from photobleaching of synaptic vesicle-associated fluorescence.

In nerve terminals, synaptic vesicles form large clusters anchored to the presynaptic plasmalemma. Recently, FM1-43 photobleaching experiments carried out a frog motor end-plates demonstrated lack of lateral intermixing of synaptic vesicles within clusters, even during sustained nerve terminal stimulation (Henkel and Betz, 1995; Henkel et al., 1996b).

The synaptic vesicle cycle: a single vesicle budding step involving clathrin and dynamin.

Strong evidence implicates clathrin-coated vesicles and endosome-like vacuoles in the reformation of synaptic vesicles after exocytosis, and it is generally assumed that these vacuoles represent a traffic station downstream from clathrin-coated vesicles. To gain insight into the mechanisms of synaptic vesicle budding from endosome-like intermediates, lysed nerve terminals and nerve terminal membrane subfractions were examined by EM after incubations with GTP gamma S. Numerous clathrin-coated budding intermediates that were positive for AP2 and AP180 immunoreactivity and often collared by a dynamin ring were seen.

Polarized expression of GABA transporters in Madin-Darby canine kidney cells and cultured hippocampal neurons.

At least three high affinity Na+- and Cl--dependent gamma-aminobutyric acid (GABA) transporters are known to exist in the rat and mouse brain. These transporters share 50-65% amino acid sequence identity with the kidney betaine transporter which also transports GABA but with lower affinity. The betaine transporter (BGT) is expressed on the basolateral surface of polarized Madin-Darby canine kidney (MDCK) cells.

A role of amphiphysin in synaptic vesicle endocytosis suggested by its binding to dynamin in nerve terminals.

Amphiphysin, a major autoantigen in paraneoplastic Stiff-Man syndrome, is an SH3 domain-containing neuronal protein, concentrated in nerve terminals. Here, we demonstrate a specific, SH3 domain-mediated, interaction between amphiphysin and dynamin by gel overlay and affinity chromatography. In addition, we show that the two proteins are colocalized in nerve terminals and are coprecipitated from brain extracts consistent with their interactions in situ.

v- and t-SNAREs in neuronal exocytosis: a need for additional components to define sites of release.

Synaptic vesicle recycling is a specialized form of membrane recycling which takes place in all cells between early endosomes and the plasmalemma. Synaptic vesicles exocytosis is highly regulated and occurs only at presynaptic active zones. In contrast, exocytosis of endosome-derived vesicles of the housekeeping recycling pathway takes place constitutively and throughout the cell surface.