Daria Mochly-Rosen, Postdoctoral Faculty Sponsor
Boosting the Discovery of Small Molecule Inhibitors of Glucose-6-Phosphate Dehydrogenase for the Treatment of Cancer, Infectious Diseases, and Inflammation.
Journal of medicinal chemistry
We present an overview of small molecule glucose-6-phosphate dehydrogenase (G6PD) inhibitors that have potential for use in the treatment of cancer, infectious diseases, and inflammation. Both steroidal and nonsteroidal inhibitors have been identified with steroidal inhibitors lacking target selectivity. The main scaffolds encountered in nonsteroidal inhibitors are quinazolinones and benzothiazinones/benzothiazepinones. Three molecules show promise for development as antiparasitic (25 and 29) and anti-inflammatory (32) agents. Regarding modality of inhibition (MOI), steroidal inhibitors have been shown to be uncompetitive and reversible. Nonsteroidal small molecules have exhibited all types of MOI. Strategies to boost the discovery of small molecule G6PD inhibitors include exploration of structure-activity relationships (SARs) for established inhibitors, employment of high-throughput screening (HTS), and fragment-based drug discovery (FBDD) for the identification of new hits. We discuss the challenges and gaps associated with drug discovery efforts of G6PD inhibitors from in silico, in vitro, and in cellulo to in vivo studies.
View details for DOI 10.1021/acs.jmedchem.1c01577
View details for PubMedID 35239352
Mitochondrial fusion, fission and mitophagy in cardiac diseases: challenges and therapeutic opportunities.
Antioxidants & redox signaling
SIGNIFICANCE: Mitochondria play a critical role in the physiology of the heart by controlling cardiac metabolism, function, and remodeling. Accumulation of fragmented and damaged mitochondria is a hallmark of cardiac diseases. Recent Advances: Disruption of quality control systems that maintain mitochondrial number, size, and shape through fission-fusion balance and mitophagy results in dysfunctional mitochondria, defective mitochondrial segregation, impaired cardiac bioenergetics, and excessive oxidative stress.CRITICAL ISSUES: Pharmacological tools that improve the cardiac pool of healthy mitochondria through inhibition of excessive mitochondrial fission, boosting mitochondrial fusion, or increasing the clearance of damaged mitochondria have emerged as promising approaches to improve the prognosis of heart diseases.FUTURE DIRECTIONS: There is a reasonable amount of pre-clinical evidence supporting the effectiveness of molecules targeting mitochondrial fission and fusion to treat cardiac diseases. The current and future challenges are turning these lead molecules into treatments. Clinical studies focusing on acute (i.e., myocardial infarction) and chronic (i.e., heart failure) cardiac diseases are needed to validate the effectiveness of such strategies in improving mitochondrial morphology, metabolism, and cardiac function.
View details for DOI 10.1089/ars.2021.0145
View details for PubMedID 35044229
Stabilization of glucose-6-phosphate dehydrogenase oligomers enhances catalytic activity and stability of clinical variants.
The Journal of biological chemistry
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic trait that can cause hemolytic anemia. To date, over 150 non-synonymous mutations have been identified in G6PD, with pathogenic mutations clustering near the dimer and/or tetramer interface and the allosteric NADP+-binding site. Recently, our lab identified a small molecule which activates G6PD variants by stabilizing the allosteric NADP+ and dimer complex, suggesting therapeutics that target these regions may improve structural defects. Here, we elucidated the connection between allosteric NADP+ binding, oligomerization, and pathogenicity to determine whether oligomer stabilization can be used as a therapeutic strategy for G6PD deficiency (G6PDdef). We first solved the crystal structure for G6PDK403Q, a mutant which mimics the physiological acetylation of wildtype G6PD in erythrocytes, and demonstrated that loss of allosteric NADP+ binding induces conformational changes in the dimer. These structural changes prevent tetramerization, are unique to Class I variants (the most severe form of G6PDdef), and cause the deactivation and destabilization of G6PD. We also introduced non-native cysteines at the oligomer interfaces and found that the tetramer complex is more catalytically active and stable than the dimer. Furthermore, stabilizing the dimer and tetramer improved protein stability in clinical variants, regardless of clinical classification, with tetramerization also improving the activity of G6PDK403Q and Class I variants. These findings were validated using enzyme activity and thermostability assays, analytical size exclusion chromatography (SEC), and SEC coupled with small-angle X-ray scattering (SEC-SAXS). Taken together, our findings suggest a potential therapeutic strategy for G6PDdef and provide a foundation for future drug discovery efforts.
View details for DOI 10.1016/j.jbc.2022.101610
View details for PubMedID 35065072
Treatment strategies for glucose-6-phosphate dehydrogenase deficiency: past and future perspectives.
Trends in pharmacological sciences
Glucose-6-phosphate dehydrogenase (G6PD) maintains redox balance in a variety of cell types and is essential for erythrocyte resistance to oxidative stress. G6PD deficiency, caused by mutations in the G6PD gene, is present in ~400 million people worldwide, and can cause acute hemolytic anemia. Currently, there are no therapeutics for G6PD deficiency. We discuss the role of G6PD in hemolytic and nonhemolytic disorders, treatment strategies attempted over the years, and potential reasons for their failure. We also discuss potential pharmacological pathways, including glutathione (GSH) metabolism, compensatory NADPH production routes, transcriptional upregulation of the G6PD gene, highlighting potential drug targets. The needs and opportunities described here may motivate the development of a therapeutic for hematological and other chronic diseases associated with G6PD deficiency.
View details for DOI 10.1016/j.tips.2021.07.002
View details for PubMedID 34389161
Long-range structural defects by pathogenic mutations in most severe glucose-6-phosphate dehydrogenase deficiency.
Proceedings of the National Academy of Sciences of the United States of America
2021; 118 (4)
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common blood disorder, presenting multiple symptoms, including hemolytic anemia. It affects 400 million people worldwide, with more than 160 single mutations reported in G6PD. The most severe mutations (about 70) are classified as class I, leading to more than 90% loss of activity of the wild-type G6PD. The crystal structure of G6PD reveals these mutations are located away from the active site, concentrating around the noncatalytic NADP+-binding site and the dimer interface. However, the molecular mechanisms of class I mutant dysfunction have remained elusive, hindering the development of efficient therapies. To resolve this, we performed integral structural characterization of five G6PD mutants, including four class I mutants, associated with the noncatalytic NADP+ and dimerization, using crystallography, small-angle X-ray scattering (SAXS), cryogenic electron microscopy (cryo-EM), and biophysical analyses. Comparisons with the structure and properties of the wild-type enzyme, together with molecular dynamics simulations, bring forward a universal mechanism for this severe G6PD deficiency due to the class I mutations. We highlight the role of the noncatalytic NADP+-binding site that is crucial for stabilization and ordering two β-strands in the dimer interface, which together communicate these distant structural aberrations to the active site through a network of additional interactions. This understanding elucidates potential paths for drug development targeting G6PD deficiency.
View details for DOI 10.1073/pnas.2022790118
View details for PubMedID 33468660
- Structural defect leads to human severe (Class I) loss of function in glucose-6-phosphate dehydrogenase WILEY. 2020