Discovery by Virtual Screening of an Inhibitor of CDK5-Mediated PPARγ Phosphorylation

VSP-2 attenuates secretion of inflammatory cytokines induced by LPS in BV2 cells by mediating the PPARγ/NF-κB signaling pathway

Neuroinflammation, characterized by microglial activation and the subsequent secretion of inflammatory cytokines, plays a pivotal role in neurodegenerative diseases and brain injuries, often leading to neuronal damage and death. Alleviating neuroinflammation has thus emerged as a promising strategy to protect neurons and ameliorate neurodegenerative disorders. While peroxisome proliferator-activated receptor gamma (PPARγ) agonists have demonstrated potential therapeutic actions on neuroinflammation, their prolonged use, such as with rosiglitazone, can lead to cardiac risks and lipid differentiation disorders. In this study, we investigated the effects of a newly synthesized PPARγ agonist, VSP-2, on secretion of inflammatory cytokines in BV2 cells. Treatment with VSP-2 significantly reduced the mRNA and protein levels of proinflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Furthermore, VSP-2 attenuated the phosphorylation of nuclear factor kappa B (NF-κB) (65 kD) and IκBα, as well as the nuclear translocation of NF-κB (65 kD). Additionally, the use of PPARγ small interfering RNA was able to attenuate the effects of VSP-2 on proinflammatory cytokines and the NF-κB pathway. In conclusion, our findings suggest that VSP-2 effectively suppressed the expressions of IL-1β, IL-6, and TNF-α via the PPARγ/NF-κB signaling pathway. Given its potential therapeutic benefits, VSP-2 may emerge as a promising candidate for the treatment of neurodegenerative diseases or brain injuries associated with neuroinflammation.

Raloxifene-driven benzothiophene derivatives: Discovery, structural refinement, and biological evaluation as potent PPARγ modulators based on drug repurposing

By virtue of the drug repurposing strategy, the anti-osteoporosis drug raloxifene was identified as a novel PPARγ ligand through structure-based virtual high throughput screening (SB-VHTS) of FDA-approved drugs and TR-FRET competitive binding assay. Subsequent structural refinement of raloxifene led to the synthesis of a benzothiophene derivative, YGL-12. This compound exhibited potent PPARγ modulation with partial agonism, uniquely promoting adiponectin expression and inhibiting PPARγ Ser273 phosphorylation by CDK5 without inducing the expression of adipongenesis associated genes, including PPARγ, aP2, CD36, FASN and C/EBPα. This specific activity profile resulted in effective hypoglycemic properties, avoiding major TZD-related adverse effects like weight gain and hepatomegaly, which were demonstrated in db/db mice. Molecular docking studies showed that YGL-12 established additional hydrogen bonds with Ile281 and enhanced hydrogen-bond interaction with Ser289 as well as PPARγ Ser273 phosphorylation-related residues Ser342 and Glu343. These findings suggested YGL-12 as a promising T2DM therapeutic candidate, thereby providing a molecular framework for the development of novel PPARγ modulators with an enhanced therapeutic index.

The Role of Type 2 Diabetes Mellitus-Related Risk Factors and Drugs in Hepatocellular Carcinoma

With changes in modern lifestyles, type 2 diabetes mellitus (T2DM) has become a global epidemic metabolic disease, and hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. T2DM is a complex metabolic disorder and has been considered an independent risk factor for HCC. Growing evidence supports that T2DM-related risk factors facilitate hepatocarcinogenesis via abundant mechanisms. With the wide implementation of microbiomics, transcriptomics, and immunotherapy, the understanding of the complex mechanisms of intestinal flora and immune cell subsets have advanced tremendously in T2DM-related HCC, uncovering new findings in T2DM-related HCC patients. In addition, reports have indicated the different effects of anti-DM drugs on the progression of HCC. In this review, we summarize the effects of major T2DM-related risk factors (including hyperglycemia, hyperinsulinemia, insulin, chronic inflammation, obesity, nonalcoholic fatty liver disease, gut microbiota and immunomodulation), and anti-DM drugs on the carcinogensis and progression of HCC, as well as their potential molecular mechanisms. In addition, other factors (miRNAs, genes, and lifestyle) related to T2DM-related HCC are discussed. We propose a refined concept by which T2DM-related risk factors and anti-DM drugs contribute to HCC and discuss research directions prompted by such evidence worth pursuing in the coming years. Finally, we put forward novel therapeutic approaches to improve the prognosis of T2DM-related HCC, including exploiting novel diagnostic biomarkers, combination therapy with immunocheckpoint inhibitors, and enhancement of the standardized management of T2DM patients.

Effect of Different Medium-Chain Triglycerides on Glucose Metabolism in High-Fat-Diet Induced Obese Rats

Obesity can be associated with significant metabolic disorders. Our previous study found that medium-chain triglycerides (MCTs) improved lipid metabolism in obese rats. However, scant attention has been given to exploring the impact of MCTs on glucose metabolism in obese rats. This study is designed to examine the effects and mechanisms of three distinct MCTs on glucose metabolism in obese rats. To induce obesity, Sprague-Dawley (SD) rats were fed a high-fat diet, followed by a 12-week treatment with caprylic triglyceride (CYT), capric triglyceride (CT), and lauric triglyceride (LT). The results showed that three types of MCT intervention reduced the levels of lipids (TC, TG, LDL-c, and HDL-c), hyperglycemia, insulin resistance (insulin, OGTT, HOMA-IR, and ISI), and inflammatory markers (IL-4, IL-1β, and TNF-α) in obese rats (p < 0.01), The above parameters have been minimally improved in the high-fat restoring group (HR) group. MCTs can modulate the PI3K/AKT signaling pathways to alleviate insulin resistance and improve glucose metabolism in obese rats. Furthermore, MCTs can activate peroxisome proliferator-activated receptor (PPAR) γ and reduce the phosphorylation of PPARγser237 mediated by CDK5, which can improve insulin sensitivity without lipid deposition in obese rats. Among the MCT group, CT administration performed the best in the above pathways, with the lowest blood glucose level and insulin resistance. These findings contribute to a deeper understanding of the connection between health benefits and the specific type of MCT employed.

The global perspective on peroxisome proliferator-activated receptor γ (PPARγ) in ectopic fat deposition: A review

Excessive expansion of adipocytes can have unhealthy consequences as excess free fatty acids enter other tissues and cause ectopic fat deposition by resynthesizing triglycerides. This lipid accumulation in various tissues is harmful and can increase the risk of related metabolic diseases such as type II diabetes, cardiovascular disease, and insulin resistance. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that play a key role in energy metabolism as fatty acid metabolism sensors, and peroxisome proliferator-activated receptor γ (PPARγ) is the main subtype responsible for fat cell differentiation and adipogenesis. In this paper, we introduce the main structure and function of PPARγ and its regulatory role in the process of lipogenesis in the liver, kidney, skeletal muscle, and pancreas. This information can serve as a reference for further understanding the regulatory mechanisms and measures of the PPAR family in the process of ectopic fat deposition.

Discovery of FXR/PPARγ dual partial agonist

Farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR)γ are nuclear receptor 1 superfamily of transcription factors. FXR and PPARγ agonists have been individually investigated in clinical trial of anti-diabetic agents in the patients with nonalcoholic fatty liver disease (NAFLD). Regarding recent agonist development, the partial agonists for FXR and PPARγ are drawing attention from the standpoint of avoiding overactive responses caused by full agonists. In this article, we report that 18 with a benzimidazole scaffold possesses FXR/PPARγ dual partial agonistic activity. In addition, 18 shares the ability to reduce cyclin-dependent kinase 5-mediated phosphorylation of PPARγ-Ser273 and the metabolic stability in mouse liver microsome assay. To date, there are no published reports on FXR/PPARγ dual partial agonists with biological profiles similar to 18. Thus, the analog would be a feasible candidate as an unprecedented approach to NAFLD associated with type 2 diabetes mellitus.

Obesity-Linked PPARγ Ser273 Phosphorylation Promotes Beneficial Effects on the Liver, despite Reduced Insulin Sensitivity in Mice

Since the removal of thiazolidinediones (TZDs) from the market, researchers have been exploring alternative anti-diabetic drugs that target PPARγ without causing adverse effects while promoting insulin sensitization by blocking serine 273 phosphorylation (Ser273 or S273). Nonetheless, the underlying mechanisms of the relationship between insulin resistance and S273 phosphorylation are still largely unknown, except for the involvement of growth differentiation factor (GDF3) regulation in the process. To further investigate potential pathways, we generated a whole organism knockin mouse line with a single S273A mutation (KI) that blocks the occurrence of its phosphorylation. Our observations of KI mice on different diets and feeding schedules revealed that they were hyperglycemic, hypoinsulinemic, presented more body fat at weaning, and presented an altered plasma and hepatic lipid profile, distinctive liver morphology and gene expression. These results suggest that total blockage of S273 phosphorylation may have unforeseen effects that, in addition to promoting insulin sensitivity, could lead to metabolic disturbances, particularly in the liver. Therefore, our findings demonstrate both the beneficial and detrimental effects of PPAR S273 phosphorylation and suggest selective modulation of this post translational modification is a viable strategy to treat type 2 diabetes.

A Comprehensive Survey of Prospective Structure-Based Virtual Screening for Early Drug Discovery in the Past Fifteen Years

Structure-based virtual screening (SBVS), also known as molecular docking, has been increasingly applied to discover small-molecule ligands based on the protein structures in the early stage of drug discovery. In this review, we comprehensively surveyed the prospective applications of molecular docking judged by solid experimental validations in the literature over the past fifteen years. Herein, we systematically analyzed the novelty of the targets and the docking hits, practical protocols of docking screening, and the following experimental validations. Among the 419 case studies we reviewed, most virtual screenings were carried out on widely studied targets, and only 22% were on less-explored new targets. Regarding docking software, GLIDE is the most popular one used in molecular docking, while the DOCK 3 series showed a strong capacity for large-scale virtual screening. Besides, the majority of identified hits are promising in structural novelty and one-quarter of the hits showed better potency than 1 μM, indicating that the primary advantage of SBVS is to discover new chemotypes rather than highly potent compounds. Furthermore, in most studies, only in vitro bioassays were carried out to validate the docking hits, which might limit the further characterization and development of the identified active compounds. Finally, several successful stories of SBVS with extensive experimental validations have been highlighted, which provide unique insights into future SBVS drug discovery campaigns.

Identification of a novel PPARγ modulator with good anti-diabetic therapeutic index via structure-based screening, optimization and biological validation

PPARγ is well-known as the target receptor of TZD anti-diabetic drugs. However, recently the therapeutic benefits of these TZD drugs have been compromised by many severe side effects because of their full PPARγ agonistic action to lock the AF-2 helix. Herein, we conducted a virtual screening in the combination with structure-based design, synthesis and biological evaluation both in vitro and in vivo, leading to the identification of a potent candidate YG-C-20 as the SPPARγM with improved and safer anti-diabetic therapeutics. Mechanistically, this compound presented such desired pharmacological profiles (e.g., preferable anti-diabetic efficiencies and minimized side effects) mainly via selectively inhibiting the CDK5-mediated phosphorylation of PPARγ-Ser273 and up-regulating the expression of insulin-sensitive genes Adiponectin and Glut4, yet lacking the classical full agonism to induce the adipogenesis and the expression of key adipogenic genes including PPARγ, aP2, CD36, LPL, C/EBPα and FASN. Further validation led to the final recognition of its (R)-configured isomer as the potential conformational form. Subsequent molecular docking studies revealed a unique hydrogen-bonding network of (R)-YG-C-20 with three full PPARγ agonism-unrelated residues, especially with PPARγ-Ser273 phosphorylation-associated site Ser342, which not only gives a clear verification for our structure-based design but also provides a proof of concept for the abovementioned molecular mechanism.

The assembly of integrated continuous flow platform for on-demand rosiglitazone and pioglitazone synthesis

Manufacturing thiazolidinediones in a batch process is often carried out at different locations, where each successive batch collects a certain amount of intermediate followed by its transportation to another location.