Nerve growth factor-induced phosphorylation of amphiphysin-1 by casein kinase 2 regulates clathrin-amphiphysin interactions

Amphiphysins interact directly with clathrin and have a function in clathrin-mediated synaptic vesicle recycling and clathrin-mediated endocytosis. The neuronal isoform amphiphysin-1 is a serine/threonine phosphoprotein that is dephosphorylated upon stimulation of synaptic vesicle endocytosis. Rephosphorylation was stimulated by nerve growth factor. We analysed the regulation of amphiphysin-clathrin interactions by phosphorylation. The N-terminal domain of clathrin bound to unphosphorylated amphiphysin-1, but not to the phosphorylated protein. A search for possible phosphorylation sites revealed two casein kinase 2 consensus motifs in close proximity to the clathrin binding sites in amphiphysin-1 and -2. We mutagenized these residues (T350 and T387) to glutamate, mimicking a constitutive phosphorylation. The double mutant showed a strong reduction in clathrin binding. The assumption that casein kinase 2 phosphorylates amphiphysin-1 at T350 and T387 was corroborated by experiments showing that: (i) casein kinase 2 phosphorylated these residues directly in vitro, (ii) when expressed in HeLa cells, the glutamate mutant showed reduced phosphorylation, and (iii) casein kinase 2 inhibitors blocked nerve growth factor-induced phosphorylation of endogenous amphiphysin-1 in PC12 cells. These observations are consistent with the hypothesis that, upon activation by nerve growth factor, casein kinase 2 phosphorylates amphiphysin-1 and thereby regulates the endocytosis of clathrin-coated vesicles via the interaction between clathrin and amphiphysin.     

Structural and functional characterization of an anti‐West Nile virus monoclonal antibody and its single‐chain variant produced in glycoengineered plants

Previously, our group engineered a plant‐derived monoclonal antibody (MAb pE16) that efficiently treated West Nile virus (WNV) infection in mice. In this study, we developed a pE16 variant consisting of a single‐chain variable fragment (scFv) fused to the heavy chain constant domains (C_H) of human IgG (pE16scFv‐C_H). pE16 and pE16scFv‐C_H were expressed and assembled efficiently in Nicotiana benthamiana ?XF plants, a glycosylation mutant lacking plant‐specific N‐glycan residues. Glycan analysis revealed that ?XF plant‐derived pE16scFv‐C_H (?XFpE16scFv‐C_H) and pE16 (?XFpE16) both displayed a mammalian glycosylation profile. ?XFpE16 and ?XFpE16scFv‐C_H demonstrated equivalent antigen‐binding affinity and kinetics, and slightly enhanced neutralization of WNV in vitro compared with the parent mammalian cell‐produced E16 (mE16). A single dose of ?XFpE16 or ?XFpE16scFv‐C_H protected mice against WNV‐induced mortality even 4 days after infection at equivalent rates as mE16. This study provides a detailed tandem comparison of the expression, structure and function of a therapeutic MAb and its single‐chain variant produced in glycoengineered plants. Moreover, it demonstrates the development of anti‐WNV MAb therapeutic variants that are equivalent in efficacy to pE16, simpler to produce, and likely safer to use as therapeutics due to their mammalian N‐glycosylation. This platform may lead to a more robust and cost‐effective production of antibody‐based therapeutics against WNV infection and other infectious, inflammatory or neoplastic diseases.     

Vacuolar targeting of recombinant antibodies in Nicotiana benthamiana

Plant‐based platforms are extensively used for the expression of recombinant proteins, including monoclonal antibodies. However, to harness the approach effectively and leverage it to its full potential, a better understanding of intracellular processes that affect protein properties is required. In this work, we examined vacuolar (vac) targeting and deposition of the monoclonal antibody (Ab) 14D9 in Nicotiana benthamiana leaves. Two distinct vacuolar targeting signals (KISIA and NIFRGF) were C‐terminal fused to the heavy chain of 14D9 (vac‐Abs) and compared with secreted and ER‐retained variants (sec‐Ab, ER‐Ab, respectively). Accumulation of ER‐ and vac‐Abs was 10‐ to 15‐fold higher than sec‐Ab. N‐glycan profiling revealed the predominant presence of plant typical complex fucosylated and xylosylated GnGnXF structures on sec‐Ab while vac‐Abs carried mainly oligomannosidic (Man 7‐9) next to GnGnXF forms. Paucimannosidic glycans (commonly assigned as typical vacuolar) were not detected. Confocal microscopy analysis using RFP fusions showed that sec‐Ab‐RFP localized in the apoplast while vac‐Abs‐RFP were exclusively detected in the central vacuole. The data suggest that vac‐Abs reached the vacuole by two different pathways: direct transport from the ER bypassing the Golgi (Ab molecules containing Man structures) and trafficking through the Golgi (for Ab molecules containing complex N‐glycans). Importantly, vac‐Abs were correctly assembled and functionally active. Collectively, we show that the central vacuole is an appropriate compartment for the efficient production of Abs with appropriate post‐translational modifications, but also point to a reconsideration of current concepts in plant glycan processing.     

Studies on the interaction of C1q, a subcomponent of the first component of complement, with porins from Salmonella minnesota incorporated into artificial membranes.

Purified outer membrane proteins (OMP) of Salmonella minnesota, Re-form, were incorporated into liposomes. These induced in macrophages a chemiluminescence signal identical to that of the intact Re-form. This signal was abolished by preincubation of porin-containing liposomes with purified C1q. Incorporation of isolated OMP into black lipid membranes (BLM) resulted in channel-formation which could not be inhibited by isolated C1q. Additionally, incubation of OMP-containing liposomes with BLM resulted in pore-formation within the BLM. This was amplified when lipid A was present within the liposomes. Preincubation of OMP-containing liposomes with purified C1q abolished pore-formation within the BLM.     

The use of enhanced polymer one-step staining reagents for immunoenzyme double-labelling

Summary The newly developed peroxidase-labelled Enhanced Polymer One-Step (EPOS) reagents were applied, together with an unlabelled primary mouse antibody, in a multistep double-labelling protocol. Enzyme label reporter combinations consisted of either peroxidase and alkaline phosphatase in red and blue, respectively, or β-galactosidase and alkaline phosphatase in turquoise and red, respectively. The latter enzyme combination was introduced using a rabbit antiperoxidase antibody and an enzyme-labelled anti-rabbit immunoglobulin antibody. The multistep procedure was tested using five different antibody combinations on cryostat and Carnoy- or formalin-fixed, paraffin-embedded sections. In each instance, clear and distinct labelling was obtained, either with the two antigens at separate sites, or with an overlap in distribution. In the latter situation, the sites of co-localization were marked by mixed colours, which were distinct and readily discriminated from the two basic colours.     

The animal research kit (ARK) can be used in a multistep double staining method for human tissue specimens.

The newly developed Animal Research Kit (ARK) offers a simple and economic way of biotinylating mouse primary antibodies for background-free immunostaining of mouse and rat tissue specimens. Biotinylation involves the use of a biotinylated goat anti-mouse immunoglobulin Fab fragment mixed with a mouse primary antibody and subsequent blocking with normal mouse immunoglobulin. Because a reliable immunoenzyme double staining procedure on human tissue specimens with two unlabeled mouse primary antibodies of identical subclass is almost impossible, we have tested the performance of ARK biotinylation of one primary antibody in a multistep indirect/direct staining protocol. The multistep double staining procedure involved the subsequent application of an unlabeled mouse monoclonal antibody (MAb) 1 detected with an enzyme-labeled EnVision reagent, normal mouse serum for blocking, followed by a biotinylated mouse MAb 2 and enzyme-labeled streptavidin. Alkaline phosphatase and peroxidase enzymatic activities were developed last. Double staining results obtained with an ARK biotinylated reagent were compared with a truly biotinylated reagent using N-hydroxy succinimide-biotin for conjugation. It appeared that both biotinylation procedures revealed identical double staining results. Although a limited number of antibody combinations have been tested, it is clear that this double staining procedure will be successful for many antibody pairs.     

More fibrosis and thrombotic complications but similar expression patterns of markers for coagulation and inflammation in symptomatic plaques from DM2 patients.

OBJECTIVE: One of the possible pathological mechanisms behind the increased vascular injury in diabetes mellitus type 2 (DM2) is the formation of advanced glycation end products (AGEs). The aim of this study was to investigate whether the presence of AGEs and specific markers for coagulation and inflammation in symptomatic atherosclerotic plaques from DM2 patients differs from plaques from nondiabetics. METHODS AND RESULTS: Carotid atherectomies were obtained from DM2 patients (n=11) and controls without DM2 matched for age and other cardiovascular risk factors (n=12) who were treated for symptomatic carotid artery stenosis. Plaques were graded according to the American Heart Association classification of lesions. More fibrosis and more thrombotic complications (p=0.007) were observed in carotid atherectomies from DM2 patients. Percentages of immunostained smooth muscle cells and macrophages in the lesions, quantified planimetrically, did not differ between the two groups. No differences were found in the immunostaining for T cells, tissue factor (TF), endothelial protein C receptor (EPCR), nuclear factor kappaB, and the AGE carboxymethyllysine. CONCLUSIONS: These findings demonstrate that DM2 is associated with increased plaque complications; however, a local changed presence of AGEs, TF, and EPCR seems not to be involved in this end stage of atherosclerosis.     

Strategies to enable the adoption of animal biotechnology to sustainably improve global food safety and security

The ability to generate transgenic animals has existed for over 30 years, and from those early days many predicted that the technology would have beneficial applications in agriculture. Numerous transgenic agricultural animals now exist, however to date only one product from a transgenic animal has been approved for the food chain, due in part to cumbersome regulations. Recently, new techniques such as precision breeding have emerged, which enables the introduction of desired traits without the use of transgenes. The rapidly growing human population, environmental degradation, and concerns related to zoonotic and pandemic diseases have increased pressure on the animal agriculture sector to provide a safe, secure and sustainable food supply. There is a clear need to adopt transgenic technologies as well as new methods such as gene editing and precision breeding to meet these challenges and the rising demand for animal products. To achieve this goal, cooperation, education, and communication between multiple stakeholders—including scientists, industry, farmers, governments, trade organizations, NGOs and the public—is necessary. This report is the culmination of concepts first discussed at an OECD sponsored conference and aims to identify the main barriers to the adoption of animal biotechnology, tactics for navigating those barriers, strategies to improve public perception and trust, as well as industry engagement, and actions for governments and trade organizations including the OECD to harmonize regulations and trade agreements. Specifically, the report focuses on animal biotechnologies that are intended to improve breeding and genetics and currently are not routinely used in commercial animal agriculture. We put forward recommendations on how scientists, regulators, and trade organizations can work together to ensure that the potential benefits of animal biotechnology can be realized to meet the future needs of agriculture to feed the world.