Comprehensive mapping of the Interaction of levodopa and iron metabolism in Parkinson's disease

Levodopa remains the primary treatment for Parkinson's disease (PD), yet its long-term use has been associated with iron accumulation in the brain, a phenomenon linked to neurodegeneration. We utilize deep machine learning to determine plausible molecular mechanisms that may underlie the effects of levodopa on iron metabolism. Using the DRIFT platform, we performed a proteome-wide target identification of levodopa and uncovered significant interactions potentially involved in cellular iron transport. Pathway analysis revealed that levodopa may influence critical iron-related pathways, including the response of EIF2AK1 to heme deficiency, heme signaling, and ABC-family protein-mediated transport. These findings suggest that levodopa may contribute to iron dysregulation in PD by interacting with iron transporters and modulating iron-related pathways. Because levodopa is used at relatively high doses in PD, our findings provide new insight into secondary effects unrelated to being a precursor of dopamine. This highlights the need for careful consideration of its effects on iron metabolism as a consequence of use in the long-term management of PD. Further experimental validation is required to confirm these interactions, and also to explore potential strategies to mitigate iron-related side effects while preserving therapeutic efficacy.

Anti-echinococcal effect of metformin in advanced experimental cystic echinococcosis: reprogrammed intermediary carbon metabolism in the parasite

Metformin, a safe biguanide derivative with antiproliferative properties, has shown antiparasitic efficacy against the Echinococcus larval stage. Hence, we assessed the efficacy of a dose of 250 mg kg-1 day-1 in experimental models of advanced CE, at 6 and 12 months post-infection with oral and intraperitoneal administration, respectively. At this high dose, metformin reached intracystic concentrations between 0.7 and 1.7 mM and triggered Eg-TOR inhibition through AMPK activation by AMP-independent and -dependent mechanisms, which are dependent on drug dose. Cystic metformin uptake was controlled by increased expression of organic cation transporters in the presence of the drug. In both experimental models, metformin reduced the weight of parasite cysts, altered the ultrastructural integrity of their germinal layers, and reduced the intracystic availability of glucose, limiting the cellular carbon and energy charge and the proliferative capacity of metacestodes. This glucose depletion in the parasite was associated with a slight increase in cystic uptake of 2-deoxiglucose and the transcriptional induction of GLUT genes in metacestodes. In this context, drastic glycogen consumption led to increased lactate production and altered intermediary metabolism in treated metacestodes. Specifically, the fraction of reducing soluble sugars decreased twofold, and the levels of non-reducing soluble sugars, such as sucrose and trehalose, were modified in both cystic fluid and germinal cells. Taken together, our findings highlight the relevance of metformin as a promising candidate for CE treatment and warrant further research to improve the therapeutic conditions of this chronic zoonosis in humans.

The SGLT2 inhibitor dapagliflozin ameliorates renal fibrosis in hyperuricemic nephropathy

Hyperuricemic nephropathy (HN) is a global metabolic disorder characterized by uric acid (UA) metabolism dysfunction, resulting in hyperuricemia (HUA) and tubulointerstitial fibrosis (TIF). Sodium-dependent glucose transporter 2 inhibitor, dapagliflozin, has shown potential in reducing serum UA levels in patients with chronic kidney disease (CKD), though its protective effects against HN remain uncertain. This study investigates the functional, pathological, and molecular changes in HN through histological, biochemical, and transcriptomic analyses in patients, HN mice, and UA-stimulated HK-2 cells. Findings indicate UA-induced tubular dysfunction and fibrotic activation, which dapagliflozin significantly mitigates. Transcriptomic analysis identifies estrogen-related receptor α (ERRα), a downregulated transcription factor in HN. ERRα knockin mice and ERRα-overexpressed HK-2 cells demonstrate UA resistance, while ERRα inhibition exacerbates UA effects. Dapagliflozin targets ERRα, activating the ERRα-organic anion transporter 1 (OAT1) axis to enhance UA excretion and reduce TIF. Furthermore, dapagliflozin ameliorates renal fibrosis in non-HN CKD models, underscoring the therapeutic significance of the ERRα-OAT1 axis in HN and CKD.

The Human OCTN Sub-Family: Gene and Protein Structure, Expression, and Regulation

OCTN1 and OCTN2 are membrane transport proteins encoded by the SLC22A4 and SLC22A5 genes, respectively. Even though several transcripts have been predicted by bioinformatics for both genes, only one functional protein isoform has been described for each of them. Both proteins are ubiquitous, and depending on the physiopathological state of the cell, their expression is regulated by well-known transcription factors, although some aspects have been neglected. A plethora of missense variants with uncertain clinical significance are reported both in the dbSNP and the Catalogue of Somatic Mutations in Cancer (COSMIC) databases for both genes. Due to their involvement in human pathologies, such as inflammatory-based diseases (OCTN1/2), systemic primary carnitine deficiency (OCTN2), and drug disposition, it would be interesting to predict the impact of variants on human health from the perspective of precision medicine. Although the lack of a 3D structure for these two transport proteins hampers any speculation on the consequences of the polymorphisms, the already available 3D structures for other members of the SLC22 family may provide powerful tools to perform structure/function studies on WT and mutant proteins.

Unveiling genetic signatures associated with resilience to neonatal diarrhea in lambs through two GWAS approaches

Neonatal diarrhea presents a significant global challenge due to its multifactorial etiology, resulting in high morbidity and mortality rates, and substantial economic losses. While molecular-level studies on genetic resilience/susceptibility to neonatal diarrhea in farm animals are scarce, prior observations indicate promising research directions. Thus, the present study utilizes two genome-wide association approaches, pKWmEB and MLM, to explore potential links between genetic variations in innate immunity and neonatal diarrhea in Karacabey Merino lambs. Analyzing 707 lambs, including 180 cases and 527 controls, revealed an overall prevalence rate of 25.5%. The pKWmEB analysis identified 13 significant SNPs exceeding the threshold of ≥ LOD 3. Moreover, MLM detected one SNP (s61781.1) in the SLC22A8 gene (p-value, 1.85eE-7), which was co-detected by both methods. A McNemar's test was conducted as the final assessment to identify whether there are any major effective markers among the detected SNPs. Results indicate that four markers-oar3_OAR1_122352257, OAR17_77709936.1, oar3_OAR18_17278638, and s61781.1-have a substantial impact on neonatal diarrhea prevalence (odds ratio: 2.03 to 3.10; statistical power: 0.88 to 0.99). Therefore, we propose the annotated genes harboring three of the associated markers, TIAM1, YDJC, and SLC22A8, as candidate major genes for selective breeding against neonatal diarrhea.

Niujiao Dihuang Jiedu decoction promotes SLC7A11 m5C methylation modification against ferroptosis in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) constitutes a prevalent manifestation of liver failure within clinical settings. This condition manifests swiftly and is characterized by an exceedingly elevated fatality rate.

OBJECTIVE

While numerous investigations have delved into the role of RNA methylation in ferroptosis, the impact of such methylation on ACLF-associated ferroptosis remains notably underexplored. This study aimed to elucidate the molecular mechanism underlying the efficacy of Niujiao Dihuang Jiedu decoction (NDD) in mitigating ferroptosis in ACLF, with a specific focus on RNA 5-methylcytosine (m5C) methylation.

MATERIALS AND METHODS

An ACLF rat model was established alongside an erastin-induced ferroptosis model in LO2 cells. Both in vitro and in vivo experiments were conducted to substantiate NDD's influence on ferroptosis. The modifying influence of methylase NOL1/NOP2/sun domain (NSUN5) upon SLC7A11, a key ferroptosis-associated gene, was probed through dot blot, immunofluorescence co-localization, and RNA binding protein immunoprecipitation (RIP) experiments.

RESULTS

Serological and hepatic histopathological findings indicated NDD's discernible therapeutic impact on ACLF. Furthermore, ferroptosis phenotype experiments revealed NDD's proficiency in effectively impeding the occurrence and development of ferroptosis. Dot blot assays demonstrated a reduction in the overall RNA m5C levels during cellular ferroptosis. Furthermore, through immunofluorescence co-localization and RIP techniques, we found that the propensity of methylase NSUN5 to associate with SLC7A11 mRNA, thereby enhancing its protein translation and conferring resistance against ferroptosis.

CONCLUSION

RNA methylation is involved in the process of ACLF-associated ferroptosis, and NDD can inhibit ACLF-associated ferroptosis by fostering SLC7A11 m5C methylation.

Effect of changes in metabolic enzymes and transporters on drug metabolism in the context of liver disease: Impact on pharmacokinetics and drug-drug interactions

Changes in the pharmacokinetic and resulting pharmacodynamic properties of drugs are common in many chronic liver diseases, leading to adverse effects, drug interactions and increased risk of over- or underdosing of medications. Structural and functional hepatic impairment can have major effects on drug metabolism and transport. This review summarizes research on the functional changes in phase I and II metabolic enzymes and in transport proteins in patients with metabolic diseases such as type 2 diabetes, metabolic dysfunction-associated steatotic liver disease, metabolic dysfunction-associated steatohepatitis and cirrhosis, providing a clinical perspective on how these changes affect drug uptake and metabolism. Generally, a decrease in expression and/or activity of many enzymes of the cytochrome P450 family (e.g. CYP2E1 and CYP3A4), and of influx and efflux transporters (e.g. organic anion-transporting polypeptide [OATP]1B1, OATP2B1, OAT2 and bile salt export pump), has been recently documented in patients with liver disease. Decreased enzyme levels often correlate with increased severity of chronic liver disease. In subjects with hepatic impairment, there is potential for strong alterations of drug pharmacokinetics due to reduced absorption, increased volume of distribution, metabolism and extraction. Due to the altered pharmacokinetics, specific drug-drug interactions are also a potential issue to consider in patients with liver disease. Given the huge burden of liver disease in western societies, there is a need to improve awareness among all healthcare professionals and patients with liver disease to ensure appropriate drug prescriptions.

Membrane transporters in cell physiology, cancer metabolism and drug response

By controlling the passage of small molecules across lipid bilayers, membrane transporters influence not only the uptake and efflux of nutrients, but also the metabolic state of the cell. With more than 450 members, the Solute Carriers (SLCs) are the largest transporter super-family, clustering into families with different substrate specificities and regulatory properties. Cells of different types are, therefore, able to tailor their transporter expression signatures depending on their metabolic requirements, and the physiological importance of these proteins is illustrated by their mis-regulation in a number of disease states. In cancer, transporter expression is heterogeneous, and the SLC family has been shown to facilitate the accumulation of biomass, influence redox homeostasis, and also mediate metabolic crosstalk with other cell types within the tumour microenvironment. This Review explores the roles of membrane transporters in physiological and malignant settings, and how these roles can affect drug response, through either indirect modulation of sensitivity or the direct transport of small-molecule therapeutic compounds into cells.

Renal Organic Anion Transporters 1 and 3 In Vitro: Gone but Not Forgotten

Organic anion transporters 1 and 3 (OAT1 and OAT3) play a crucial role in kidney function by regulating the secretion of multiple renally cleared small molecules and toxic metabolic by-products. Assessing the activity of these transporters is essential for drug development purposes as they can significantly impact drug disposition and safety. OAT1 and OAT3 are amongst the most abundant drug transporters expressed in human renal proximal tubules. However, their expression is lost when cells are isolated and cultured in vitro, which is a persistent issue across all human and animal renal proximal tubule cell models, including primary cells and cell lines. Although it is well known that the overall expression of drug transporters is affected in vitro, the underlying reasons for the loss of OAT1 and OAT3 are still not fully understood. Nonetheless, research into the regulatory mechanisms of these transporters has provided insights into the molecular pathways underlying their expression and activity. In this review, we explore the regulatory mechanisms that govern the expression and activity of OAT1 and OAT3 and investigate the physiological changes that proximal tubule cells undergo and that potentially result in the loss of these transporters. A better understanding of the regulation of these transporters could aid in the development of strategies, such as introducing microfluidic conditions or epigenetic modification inhibitors, to improve their expression and activity in vitro and to create more physiologically relevant models. Consequently, this will enable more accurate assessment for drug development and safety applications.

Interactions of human drug transporters with chemical additives present in plastics: Potential consequences for toxicokinetics and health

Human membrane drug transporters are recognized as major actors of pharmacokinetics; they also handle endogenous compounds, including hormones and metabolites. Chemical additives present in plastics interact with human drug transporters, which may have consequences for the toxicokinetics and toxicity of these widely-distributed environmental and/or dietary pollutants, to which humans are highly exposed. The present review summarizes key findings about this topic. In vitro assays have demonstrated that various plastic additives, including bisphenols, phthalates, brominated flame retardants, poly-alkyl phenols and per- and poly-fluoroalkyl substances, can inhibit the activities of solute carrier uptake transporters and/or ATP-binding cassette efflux pumps. Some are substrates for transporters or can regulate their expression. The relatively low human concentration of plastic additives from environmental or dietary exposure is a key parameter to consider to appreciate the in vivo relevance of plasticizer-transporter interactions and their consequences for human toxicokinetics and toxicity of plastic additives, although even low concentrations of pollutants (in the nM range) may have clinical effects. Existing data about interactions of plastic additives with drug transporters remain somewhat sparse and incomplete. A more systematic characterization of plasticizer-transporter relationships is needed. The potential effects of chemical additive mixtures towards transporter activities and the identification of transporter substrates among plasticizers, as well as their interactions with transporters of emerging relevance deserve particular attention. A better understanding of the human toxicokinetics of plastic additives may help to fully integrate the possible contribution of transporters to the absorption, distribution, metabolism and excretion of plastics-related chemicals, as well as to their deleterious effects towards human health.

The Role of Solute Carrier Transporters in Efficient Anticancer Drug Delivery and Therapy

Transporter-mediated drug resistance is a major obstacle in anticancer drug delivery and a key reason for cancer drug therapy failure. Membrane solute carrier (SLC) transporters play a crucial role in the cellular uptake of drugs. The expression and function of the SLC transporters can be down-regulated in cancer cells, which limits the uptake of drugs into the tumor cells, resulting in the inefficiency of the drug therapy. In this review, we summarize the current understanding of low-SLC-transporter-expression-mediated drug resistance in different types of cancers. Recent advances in SLC-transporter-targeting strategies include the development of transporter-utilizing prodrugs and nanocarriers and the modulation of SLC transporter expression in cancer cells. These strategies will play an important role in the future development of anticancer drug therapies by enabling the efficient delivery of drugs into cancer cells.

Recent Advances in Novel Recombinant RNAs for Studying Post-transcriptional Gene Regulation in Drug Metabolism and Disposition

Drug-metabolizing enzymes and transporters are major determinants of the absorption, disposition, metabolism, and excretion (ADME) of drugs, and changes in ADME gene expression or function may alter the pharmacokinetics/ pharmacodynamics (PK/PD) and further influence drug safety and therapeutic outcomes. ADME gene functions are controlled by diverse factors, such as genetic polymorphism, transcriptional regulation, and coadministered medications. MicroRNAs (miRNAs) are a superfamily of regulatory small noncoding RNAs that are transcribed from the genome to regulate target gene expression at the post-transcriptional level. The roles of miRNAs in controlling ADME gene expression have been demonstrated, and such miRNAs may consequently influence cellular drug metabolism and disposition capacity. Several types of miRNA mimics and small interfering RNA (siRNA) reagents have been developed and widely used for ADME research. In this review article, we first provide a brief introduction to the mechanistic actions of miRNAs in post-transcriptional gene regulation of drug-metabolizing enzymes, transporters, and transcription factors. After summarizing conventional small RNA production methods, we highlight the latest advances in novel recombinant RNA technologies and applications of the resultant bioengineered RNA (BioRNA) agents to ADME studies. BioRNAs produced in living cells are not only powerful tools for general biological and biomedical research but also potential therapeutic agents amenable to clinical investigations.

Transport of Biologically Active Ultrashort Peptides Using POT and LAT Carriers

Ultrashort peptides (USPs), consisting of 2–7 amino-acid residues, are a group of signaling molecules that regulate gene expression and protein synthesis under normal conditions in various diseases and ageing. USPs serve as a basis for the development of drugs with a targeted mechanism of action. The purpose of this review is to systematize the available data on USP transport involving POT and LAT transporters in various organs and tissues under normal, pathological and ageing conditions. The carriers of the POT family (PEPT1, PEPT2, PHT1, PHT2) transport predominantly di- and tripeptides into the cell. Methods of molecular modeling and physicochemistry have demonstrated the ability of LAT1 to transfer not only amino acids but also some di- and tripeptides into the cell and out of it. LAT1 and 2 are involved in the regulation of the antioxidant, endocrine, immune and nervous systems’ functions. Analysis of the above data allows us to conclude that, depending on their structure, di- and tripeptides can be transported into the cells of various tissues by POT and LAT transporters. This mechanism is likely to underlie the tissue specificity of peptides, their geroprotective action and effectiveness in the case of neuroimmunoendocrine system disorders.