Heart-Type Fatty Acid Binding Protein Binds Long-Chain Acylcarnitines and Protects against Lipotoxicity

Funding Information: This research was funded by the European Union’s Horizon 2020 research and innovation program project FAT4BRAIN under grant agreement No. 857394 and by Latvian Institute of Organic Synthesis internal student grants IG-2022-04 and IG-2023-04 (to D.Z.-G.). Publisher Copyright: © 2023 by the authors.Heart-type fatty-acid binding protein (FABP3) is an essential cytosolic lipid transport protein found in cardiomyocytes. FABP3 binds fatty acids (FAs) reversibly and with high affinity. Acylcarnitines (ACs) are an esterified form of FAs that play an important role in cellular energy metabolism. However, an increased concentration of ACs can exert detrimental effects on cardiac mitochondria and lead to severe cardiac damage. In the present study, we evaluated the ability of FABP3 to bind long-chain ACs (LCACs) and protect cells from their harmful effects. We characterized the novel binding mechanism between FABP3 and LCACs by a cytotoxicity assay, nuclear magnetic resonance, and isothermal titration calorimetry. Our data demonstrate that FABP3 is capable of binding both FAs and LCACs as well as decreasing the cytotoxicity of LCACs. Our findings reveal that LCACs and FAs compete for the binding site of FABP3. Thus, the protective mechanism of FABP3 is found to be concentration dependent.publishersversionPeer reviewe

Aziridine-2-carboxylic acid derivatives and its open-ring isomers as a novel PDIA1 inhibitors

Acyl derivatives of aziridine-2-carboxylic acid have been synthesized and tested as PDIA1 inhibitors. Calculations of charge value and distribution in aziridine ring system and some alkylating agents were performed. For the first time was found that acyl derivatives of aziridine-2-carboxylic acid are weak to moderately active PDIA1 inhibitors

Exploring aspartic protease inhibitor binding to design selective antimalarials

Selectivity is a major issue in the development of drugs targeting pathogen aspartic proteases. Here we explore the selectivity determining factors by studying specifically designed malaria aspartic protease (plasmepsin) open-flap inhibitors. Metadynamics simulations are used to uncover the complex binding/unbinding pathways of these inhibitors, and describe the critical transition states in atomistic resolution. The simulation results are compared to experimentally determined enzymatic activities. Our findings demonstrate that plasmepsin inhibitor selectivity can be achieved by targeting the flap loop with hydrophobic substituents that enable ligand binding under the flap loop, as such behaviour is not observed for several other aspartic proteases. The ability to estimate compound selectivity before they are synthesized is of great importance in drug design, therefore, we expect that our approach will be useful in selective inhibitor design not only against aspartic proteases, but other enzyme classes as well

Novel Scaffolds for Dual Specificity Tyrosine-Phosphorylation-Regulated Kinase (DYRK1A) Inhibitors

DYRK1A is one of five members of the dual-specificity tyrosine (Y) phosphorylation-regulated kinase (DYRK) family. The DYRK1A gene is located in the Down syndrome critical region and regulates cellular processes related to proliferation and differentiation of neuronal progenitor cells during early development. This has focused research on its role in neuronal degenerative diseases, including Alzheimer’s and Down syndrome. Recent studies have also shown a possible role of DYRK1A in diabetes. Here we report a variety of scaffolds not generally known for DYRK1A inhibition, demonstrating their effects in in vitro assays and also in cell cultures. These inhibitors effectively block the tau phosphorylation that is a hallmark of Alzheimer’s disease. The crystal structures of these inhibitors support the design of optimized and novel therapeutics

Targeting Carnitine Biosynthesis: Discovery of New Inhibitors against γ‑Butyrobetaine Hydroxylase

γ-Butyrobetaine hydroxylase (BBOX) catalyzes the conversion of gamma butyrobetaine (GBB) to l-carnitine, which is involved in the generation of metabolic energy from long-chain fatty acids. BBOX inhibitor 3-(1,1,1-trimethylhydrazin-1-ium-2-yl)­propanoate (mildronate), which is an approved, clinically used cardioprotective drug, is a relatively poor BBOX inhibitor and requires high daily doses. In this paper we describe the design, synthesis, and properties of 51 compounds, which include both GBB and mildronate analogues. We have discovered novel BBOX inhibitors with improved IC₅₀ values; the best examples are in the nanomolar range and about 2 orders of magnitude better when compared to mildronate. For six inhibitors, crystal structures in complex with BBOX have been solved to explain their activities and pave the way for further inhibitor design