Dimerization and antidepressant recognition at noradrenaline transporter.

The noradrenaline transporter has a pivotal role in regulating neurotransmitter balance and is crucial for normal physiology and neurobiology1. Dysfunction of noradrenaline transporter has been implicated in numerous neuropsychiatric diseases, including depression and attention deficit hyperactivity disorder2. Here we report cryo-electron microscopy structures of noradrenaline transporter in apo and substrate-bound forms, and as complexes with six antidepressants. The structures reveal a noradrenaline transporter dimer interface that is mediated predominantly by cholesterol and lipid molecules. The substrate noradrenaline binds deep in the central binding pocket, and its amine group interacts with a conserved aspartate residue. Our structures also provide insight into antidepressant recognition and monoamine transporter selectivity. Together, these findings advance our understanding of noradrenaline transporter regulation and inhibition, and provide templates for designing improved antidepressants to treat neuropsychiatric disorders.

Mechanisms of ligand recognition and activation of melanin-concentrating hormone receptors.

Melanin-concentrating hormone (MCH) is a cyclic neuropeptide that regulates food intake, energy balance, and other physiological functions by stimulating MCHR1 and MCHR2 receptors, both of which are class A G protein-coupled receptors. MCHR1 predominately couples to inhibitory G protein, Gi/o, and MCHR2 can only couple to Gq/11. Here we present cryo-electron microscopy structures of MCH-activated MCHR1 with Gi and MCH-activated MCHR2 with Gq at the global resolutions of 3.01 Å and 2.40 Å, respectively. These structures reveal that MCH adopts a consistent cysteine-mediated hairpin loop configuration when bound to both receptors. A central arginine from the LGRVY core motif between the two cysteines of MCH penetrates deeply into the transmembrane pocket, triggering receptor activation. Integrated with mutational and functional insights, our findings elucidate the molecular underpinnings of ligand recognition and MCH receptor activation and offer a structural foundation for targeted drug design.

Molecular recognition and activation of the prostacyclin receptor by anti-pulmonary arterial hypertension drugs.

The prostacyclin (PGI2) receptor (IP) is a Gs-coupled receptor associated with blood pressure regulation, allergy, and inflammatory response. It is a main therapeutic target for pulmonary arterial hypertension (PAH) and several other diseases. Here we report cryo-electron microscopy (cryo-EM) structures of the human IP-Gs complex bound with two anti-PAH drugs, treprostinil and MRE-269 (active form of selexipag), at global resolutions of 2.56 and 2.41 angstrom, respectively. These structures revealed distinct features governing IP ligand binding, receptor activation, and G protein coupling. Moreover, comparison of the activated IP structures uncovered the mechanism and key residues that determine the superior selectivity of MRE-269 over treprostinil. Combined with molecular docking and functional studies, our structures provide insight into agonist selectivity, ligand recognition, receptor activation, and G protein coupling. Our results provide a structural template for further improving IP-targeting drugs to reduce off-target activation of prostanoid receptors and adverse effects.

Ligand-induced activation and G protein coupling of prostaglandin F2α receptor.

Prostaglandin F2α (PGF2α), an endogenous arachidonic acid metabolite, regulates diverse physiological functions in many tissues and cell types through binding and activation of a G-protein-coupled receptor (GPCR), the PGF2α receptor (FP), which also is the primary therapeutic target for glaucoma and several other diseases. Here, we report cryo-electron microscopy (cryo-EM) structures of the human FP bound to endogenous ligand PGF2α and anti-glaucoma drugs LTPA and TFPA at global resolutions of 2.67 Å, 2.78 Å, and 3.14 Å. These structures reveal distinct features of FP within the lipid receptor family in terms of ligand binding selectivity, its receptor activation, and G protein coupling mechanisms, including activation in the absence of canonical PIF and ERY motifs and Gq coupling through direct interactions with receptor transmembrane helix 1 and intracellular loop 1. Together with mutagenesis and functional studies, our structures reveal mechanisms of ligand recognition, receptor activation, and G protein coupling by FP, which could facilitate rational design of FP-targeting drugs.

The pathological and therapeutic roles of mesenchymal stem cells in preeclampsia.

Mesenchymal stem cells (MSCs) have made progress in the treatment of ischemic and inflammatory diseases. Preeclampsia (PE) is characterized by placenta ischemic and inflammatory injury. Our paper summarized the new role of MSCs in PE pathology and its potency in PE therapy and analyzed its current limitations. Intravenously administered MSCs dominantly distributed in perinatal tissues. There may be additional advantages to using MSCs-based therapies for reproductive disorders. It will provide new ideas for future research in this field.

Structural and biochemical mechanism for increased infectivity and immune evasion of Omicron BA.2 variant compared to BA.1 and their possible mouse origins.

The Omicron BA.2 variant has become a dominant infective strain worldwide. Receptor binding studies show that the Omicron BA.2 spike trimer exhibits 11-fold and 2-fold higher potency in binding to human ACE2 than the spike trimer from the wildtype (WT) and Omicron BA.1 strains. The structure of the BA.2 spike trimer complexed with human ACE2 reveals that all three receptor-binding domains (RBDs) in the spike trimer are in open conformation, ready for ACE2 binding, thus providing a basis for the increased infectivity of the BA.2 strain. JMB2002, a therapeutic antibody that was shown to efficiently inhibit Omicron BA.1, also shows potent neutralization activities against Omicron BA.2. In addition, both BA.1 and BA.2 spike trimers are able to bind to mouse ACE2 with high potency. In contrast, the WT spike trimer binds well to cat ACE2 but not to mouse ACE2. The structures of both BA.1 and BA.2 spike trimer bound to mouse ACE2 reveal the basis for their high affinity interactions. Together, these results suggest a possible evolution pathway for Omicron BA.1 and BA.2 variants via a human-cat-mouse-human circle, which could have important implications in establishing an effective strategy for combating SARS-CoV-2 viral infections.

Structures of the Omicron spike trimer with ACE2 and an anti-Omicron antibody.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has become the dominant infective strain. We report the structures of the Omicron spike trimer on its own and in complex with angiotensin-converting enzyme 2 (ACE2) or an anti-Omicron antibody. Most Omicron mutations are located on the surface of the spike protein and change binding epitopes to many current antibodies. In the ACE2-binding site, compensating mutations strengthen receptor binding domain (RBD) binding to ACE2. Both the RBD and the apo form of the Omicron spike trimer are thermodynamically unstable. An unusual RBD-RBD interaction in the ACE2-spike complex supports the open conformation and further reinforces ACE2 binding to the spike trimer. A broad-spectrum therapeutic antibody, JMB2002, which has completed a phase 1 clinical trial, maintains neutralizing activity against Omicron. JMB2002 binds to RBD differently from other characterized antibodies and inhibits ACE2 binding.

Structure genomics of SARS-CoV-2 and its Omicron variant: drug design templates for COVID-19.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has brought an unprecedented public health crisis and persistently threatens to humanity. With tireless efforts from scientists around the world, understanding of the biology of coronavirus has been greatly enhanced over the past 2 years. Structural biology has demonstrated its powerful impact on uncovering structures and functions for the vast majority of SARS-CoV-2 proteins and guided the development of drugs and vaccines against COVID-19. In this review, we summarize current progress in the structural biology of SARS-CoV-2 and discuss important biological issues that remain to be addressed. We present the examples of structure-based design of Pfizer's novel anti-SARS-CoV-2 drug PF-07321332 (Paxlovid), Merck's nucleotide inhibitor molnupiravir (Lagevrio), and VV116, an oral drug candidate for COVID-19. These examples highlight the importance of structure in drug discovery to combat COVID-19. We also discussed the recent variants of Omicron and its implication in immunity escape from existing vaccines and antibody therapies.

Rational Design and Synthesis of Novel Dual PROTACs for Simultaneous Degradation of EGFR and PARP.

Inspired by the success of dual-targeting drugs, especially bispecific antibodies, we propose to combine the concept of proteolysis targeting chimera (PROTAC) and dual targeting to design and synthesize dual PROTAC molecules with the function of degrading two completely different types of targets simultaneously. A library of novel dual-targeting PROTAC molecules has been rationally designed and prepared. A convergent synthetic strategy has been utilized to achieve high synthetic efficiency. These dual PROTAC structures are characterized using trifunctional natural amino acids as star-type core linkers to connect two independent inhibitors and E3 ligands together. In this study, gefitinib, olaparib, and CRBN or VHL E3 ligands were used as substrates to synthesize novel dual PROTACs. They successfully degraded both the epidermal growth factor receptor (EGFR) and poly(ADP-ribose) polymerase (PARP) simultaneously in cancer cells. Being the first successful example of dual PROTACs, this technique will greatly widen the range of application of the PROTAC method and open up a new field for drug discovery.

3-Phosphoglycerate dehydrogenase: a potential target for cancer treatment.

BACKGROUND: Metabolic changes have been recognized as an important hallmark of cancer cells. Cancer cells can promote their own growth and proliferation through metabolic reprogramming. Particularly, serine metabolism has frequently been reported to be dysregulated in tumor cells. 3-Phosphoglycerate dehydrogenase (PHGDH) catalyzes the first step in the serine biosynthesis pathway and acts as a rate-limiting enzyme involved in metabolic reprogramming. PHGDH upregulation has been observed in many tumor types, and inhibition of PHGDH expression has been reported to inhibit the proliferation of PHGDH-overexpressing tumor cells, indicating that it may be utilized as a target for cancer treatment. Recently identified inhibitors targeting PHGDH have already shown effectiveness. A further in-depth analysis and concomitant development of PHGDH inhibitors will be of great value for the treatment of cancer. CONCLUSIONS: In this review we describe in detail the role of PHGDH in various cancers and inhibitors that have recently been identified to highlight progression in cancer treatment. We also discuss the development of new drugs and treatment modalities based on PHGDH targets. Overexpression of PHGDH has been observed in melanoma, breast cancer, nasopharyngeal carcinoma, parathyroid adenoma, glioma, cervical cancer and others. PHGDH may serve as a molecular biomarker for the diagnosis, prognosis and treatment of these cancers. The design and development of novel PHGDH inhibitors may have broad implications for cancer treatment. Therapeutic strategies of PHGDH inhibitors in combination with traditional chemotherapeutic drugs may provide new perspectives for precision medicine and effective personalized treatment for cancer patients.

Novel PROTACs for degradation of SHP2 protein.

Protein tyrosine phosphatase SHP2 is a member of PTPs family associated with cancer such as leukemia, non-small cell lung cancer, breast cancer, and so on. SHP2 is a promising target for drug development, and consequently it is of great significance to develop SHP2 inhibitors. Herein, we report CRBN-recruiting PROTAC molecules targeting SHP2 by connecting pomalidomide with SHP099, an allosteric inhibitor of SHP2. Among them, SP4 significantly inhibited the growth of Hela cells, compared with SHP099, its activity increased 100 times. In addition, it can significantly induce SHP2 degradation and cell apoptosis. Further study of SHP2-protac may have important significance for the treatment of SHP2 related diseases.

Novel selective hexokinase 2 inhibitor Benitrobenrazide blocks cancer cells growth by targeting glycolysis.

Accelerated glucose metabolism is a common feature of cancer cells. Hexokinase 2 (HK2) as the rate-limiting enzyme catalyzes the first step of glucose metabolism. It is overexpressed in most of the human cancers and has been a promising target for cancer therapy. Here, we report a novel selective HK2 inhibitor Benitrobenrazide (BNBZ), with nanomolar inhibitory potency. In vitro, BNBZ directly binds to HK2, induces apoptosis, and inhibits proliferation of HK2-overexpressed cancer cells. BNBZ also significantly inhibits the glycolysis of SW1990 cells by targeting HK2. The knockdown or knockout of HK2 expression in SW1990 cells can reduce their sensitivity to BNBZ. Additionally, oral administration of BNBZ can effectively inhibit tumor growth in SW1990 and SW480 xenograft models. In general, BNBZ significantly inhibited glycolysis and cancer cell proliferation in vitro and in vivo by directly targeting HK2 with high potency and low toxicity, and can be developed as a novel HK2 small-molecule candidate drug for future cancer therapeutics.

Furin: A Potential Therapeutic Target for COVID-19.

COVID-19 broke out in the end of December 2019 and is still spreading rapidly, which has been listed as an international concerning public health emergency. We found that the Spike protein of SARS-CoV-2 contains a furin cleavage site, which did not exist in any other betacoronavirus subtype B. Based on a series of analysis, we speculate that the presence of a redundant furin cut site in its Spike protein is responsible for SARS-CoV-2's stronger infectious nature than other coronaviruses, which leads to higher membrane fusion efficiency. Subsequently, a library of 4,000 compounds including approved drugs and natural products was screened against furin through structure-based virtual screening and then assayed for their inhibitory effects on furin activity. Among them, an anti-parasitic drug, diminazene, showed the highest inhibition effects on furin with an IC50 of 5.42 ± 0.11 µM, which might be used for the treatment of COVID-19.

Discovery of an Orally Active Small-Molecule Tumor Necrosis Factor-α Inhibitor.

Tumor necrosis factor α (TNF-α) is an important therapeutic target for rheumatoid arthritis, inflammatory bowel disease, and septic hepatitis. In this study, structure-based virtual ligand screening combined with in vitro and in vivo assays were applied. A lead compound, benpyrine, could directly bind to TNF-α and block TNF-α-trigged signaling activation. Furthermore, the endotoxemic murine model showed that benpyrine could attenuate TNF-α-induced inflammation, thereby reducing liver and lung injury. Meanwhile, administration of benpyrine by gavage significantly relieved the symptoms of collagen-induced arthritis and imiquimod-induced psoriasiform inflammation in mice. Thus, our study discovered a novel, highly specific, and orally active small-molecule TNF-α inhibitor that is potentially useful for treating TNF-α-mediated inflammatory and autoimmune disease.

Analysis of therapeutic targets for SARS-CoV-2 and discovery of potential drugs by computational methods.

SARS-CoV-2 has caused tens of thousands of infections and more than one thousand deaths. There are currently no registered therapies for treating coronavirus infections. Because of time consuming process of new drug development, drug repositioning may be the only solution to the epidemic of sudden infectious diseases. We systematically analyzed all the proteins encoded by SARS-CoV-2 genes, compared them with proteins from other coronaviruses, predicted their structures, and built 19 structures that could be done by homology modeling. By performing target-based virtual ligand screening, a total of 21 targets (including two human targets) were screened against compound libraries including ZINC drug database and our own database of natural products. Structure and screening results of important targets such as 3-chymotrypsin-like protease (3CLpro), Spike, RNA-dependent RNA polymerase (RdRp), and papain like protease (PLpro) were discussed in detail. In addition, a database of 78 commonly used anti-viral drugs including those currently on the market and undergoing clinical trials for SARS-CoV-2 was constructed. Possible targets of these compounds and potential drugs acting on a certain target were predicted. This study will provide new lead compounds and targets for further in vitro and in vivo studies of SARS-CoV-2, new insights for those drugs currently ongoing clinical studies, and also possible new strategies for drug repositioning to treat SARS-CoV-2 infections.

Structure based discovery of novel hexokinase 2 inhibitors.

Hexokinase 2 (HK2) is over-expressed in most of human cancers and has been proved to be a promising target for cancer therapy. In this study, based on the structure of HK2, we screened over 6 millions of compounds to obtain the lead. A total of 26 (E)-N'-(2,3,4-trihydroxybenzylidene) arylhydrazide derivatives were then designed, synthesized, and evaluated for their HK2 enzyme activity and IC50 values against two cancer cell lines. Most of the 26 target compounds showed excellently in vitro activity. Among them, compound 3j showed the strongest inhibitory effects on HK2 enzyme activity with an IC50 of 0.53 ± 0.13 µM and exhibited the most potent growth inhibition against SW480 cells with an IC50 of 7.13 ± 1.12 µM, which deserves further studies.

Physapubescin I from husk tomato suppresses SW1990 cancer cell growth by targeting kidney-type glutaminase.

Kidney-type glutaminase (KGA), catalyzing the hydrolysis of glutamine to glutamate for energy supply, is over-expressed in many cancers and has been regarded as a new therapeutic target for cancers. Physapubescin I was isolated from the fruits of the edible herb Physalis pubescens L., commonly named as "husk tomato or hairy groundcherry", and was predicted to be a potential KGA inhibitor through structure-based virtual ligand screening. Enzyme inhibition assays, microscale thermophoresis (MST) and cellular thermal shift assay (CETSA) experiments have demonstrated the high efficiency and specificity of physapubescin I targeting KGA. EdU proliferation, Hoechst 33258 staining and cytotoxicity assays indicated that physapubescin I could inhibit cancer cell proliferation and promote apoptosis more effectively than the known KGA inhibitor, BPTES. Knockdown of KGA by siRNA reduced the inhibition of physapubescin I to SW1990 cells. Meanwhile, physapubescin I impaired glutamine metabolism in SW1990 cells with increasing intracellular level of glutamine, and correspondingly decreasing glutamate and its downstream metabolites, which may account for its inhibition of cancer cell proliferation and proapoptosis. Physapubescin I also showed significant tumor growth inhibition and low toxicity in a SW1990 xenograft mouse model. Collectively, physapubescin I may serve as a potential drug candidate or lead compound for cancer therapy by targeting KGA.

Synthesis of novel andrographolide beckmann rearrangement derivatives and evaluation of their HK2-related anti-inflammatory activities.

Two series of andrographolide derivatives with introduction of amide moiety into ring A by Beckmann rearrangement were synthesized. In series 1, the ring A was converted to caprolactam, and an amide moiety was linked to C-19 of ring A in series 2. Among them, compound 8h exhibited obvious inhibition on HK2 enzyme activity (IC50 = 9.36 ±â€¯0.08 µM) and LPS-induced NO production in RAW264.7 cells (IC50 = 22.38 ±â€¯3.57 µM), and potent binding affinity with HK2 (Kd = 5.12 ±â€¯0.82 µM). The preliminary structure-activity relationships (SARs) suggested that the formation of caprolactam of ring A and esterification of C-19-hydroxyl could improve the inhibitory effects on HK2 enzyme of andrographolide derivatives. Furthermore, compound 8h significantly reduced the levels of IL-1ß and IL-6, down-regulated the expressions of iNOS and COX-2. Its anti-inflammatory effect was related to the inhibition of both NF-κB pathway and glycolysis enzyme HK2. Since HK2 could be a novel and effective target for anti-inflammation, compound 8h might be a new anti-inflammatory agent targeting at HK2, or serve as a lead compound to design and synthesize more HK2 inhibitors with better inflammatory effects.

Glutaminase inhibitors: a patent review.

INTRODUCTION: The kidney-type glutaminase (GLS) controlling the first step of glutamine metabolism is overexpressed in many cancer cells. Targeting inhibition of GLS shows obvious inhibitory effects on cancer cell proliferation. Therefore, extensive research and development of GLS inhibitors have been carried out in industrial and academic institutions over the past decade to address this unmet medical need. AREAS COVERED: This review covers researches and patent literatures in the field of discovery and development of small molecule inhibitors of GLS for cancer therapy over the past 16 years. EXPERT OPINION: The detailed ligand-receptor interaction information from their complex structure not only guides the rational drug design, but also facilitates in silico structure-based virtual ligand screening of novel GLS inhibitors. Multi-drug combination administration is of great significance both in terms of safety and efficacy.