Stolte, J. | Search bioRxiv

bioRxiv2021

Accelerated Antibody Discovery Targeting the SARS-CoV-2 Spike Protein for COVID-19 Therapeutic Potential

Rapid deployment of technologies capable of high-throughput and high-resolution screening is imperative for timely response to viral outbreaks. Risk mitigation in the form of leveraging multiple advanced technologies further increases the likelihood of identifying efficacious treatments in an aggressive timeline. In this study, we describe two parallel, yet distinct, in vivo approaches for accelerated discovery of antibodies targeting the SARS-CoV-2 spike protein. Working with human transgenic Alloy-GK mice, we detail a single B-cell discovery workflow to directly interrogate antibodies secreted from plasma cells for binding specificity and ACE2 receptor blocking activity. Additionally, we describe a concurrent accelerated hybridoma-based workflow utilizing a DiversimAb mouse model for increased diversity. The panel of antibodies isolated from both workflows revealed binding to distinct epitopes with both blocking and non-blocking profiles. Sequence analysis of the resulting lead candidates uncovered additional diversity with the opportunity for straightforward engineering and affinity maturation. By combining in vivo models with advanced integration of screening and selection platforms, lead antibody candidates can be sequenced and fully characterized within one to three months.

immunology↗

bioRxiv2021

Compound- and fiber type-selective requirement of AMPKγ3 for insulin-independent glucose uptake in skeletal muscle

Objective: The metabolic master-switch AMP-activated protein kinase (AMPK) mediates insulin-independent glucose uptake in muscle and regulates the metabolic activity of brown and beige adipose tissue (BAT). The regulatory AMPK{gamma}3 isoform is uniquely expressed in skeletal muscle and also potentially in BAT. Here, we investigated the role that AMPK{gamma}3 plays in mediating skeletal muscle glucose uptake and whole-body glucose clearance in response to small-molecule activators that act on AMPK via distinct mechanisms. We also assessed if {gamma}3 plays a role in adipose thermogenesis and browning. Methods: Global AMPK{gamma}3 knockout (KO) mice were generated. A systematic whole-body, tissue and molecular phenotyping linked to glucose homeostasis was performed in {gamma}3 KO and wild type (WT) mice. Glucose uptake in glycolytic and oxidative skeletal muscle ex vivo, as well as blood glucose clearance in response to small molecule AMPK activators that target nucleotide-binding domain of {gamma} subunit (AICAR) and allosteric drug and metabolite (ADaM) site located at the interface of the and {beta} subunit (991, MK-8722) were assessed. Oxygen consumption, thermography, and molecular phenotyping with a {beta}3-adrenergic receptor agonist (CL-316,243) treatment were performed to assess BAT thermogenesis, characteristics and function. Results: Genetic ablation of {gamma}3 did not affect body weight, body composition, physical activity, and parameters associated with glucose homeostasis under chow or high fat diet. {gamma}3 deficiency had no effect on fiber-type composition, mitochondrial content and components, or insulin-stimulated glucose uptake in skeletal muscle. Glycolytic muscles in {gamma}3 KO mice showed a partial loss of AMPK2 activity, which was associated with reduced levels of AMPK2 and {beta}2 subunit isoforms. Notably, {gamma}3 deficiency resulted in a selective loss of AICAR-, but not MK-8722-induced blood glucose-lowering in vivo and glucose uptake specifically in glycolytic muscle ex vivo. We detected {gamma}3 in BAT and found that it preferentially interacts with 2 and {beta}2. We observed no differences in oxygen consumption, thermogenesis, morphology of BAT and inguinal white adipose tissue (iWAT), or markers of BAT activity between WT and {gamma}3 KO mice. Conclusions: These results demonstrate that {gamma}3 plays a key role in mediating AICAR- but not ADaM site binding drug-stimulated blood glucose clearance and glucose uptake specifically in glycolytic skeletal muscle. We also showed that {gamma}3 is dispensable for thermogenesis and browning of iWAT.

physiology↗