ABSTRACT
Alzheimer's disease (AD) is a severe neurodegenerative disorder for which identification of differentially expressed genes is one way to find new therapeutic targets. Here, we conducted analysis to identify age-independent, AD-specific genes. We found that the MET, WIF1, and NPTX2 genes are downregulated in AD. WIF1 and MET are implicated in Wnt and MET signaling and regulate GSK3ß activity and are thus linked with AD. Importantly, we found that the GMPR gene exhibited a gradual increase in AD progression. A logistic model based on GMPR has good ability to classify AD cases. GMPR's product GMPR1 is in the AMPK and adenosine receptor pathways and is thus associated with Tau phosphorylation in AD. This allows GMPR1 to be a therapeutic target. Therefore, we screened five possible inhibitors to GMPR1 by docking GMPR1 with 1,174 approved drugs. Among them, lumacaftor is ideal. We then tested the effects of lumacaftor on AD model mice. After 20 days of oral administration, we observed that ß-Amyloid accumulation was slowed down, and phosphorylation of Tau was almost eliminated in the treated mice. We highlight the elevated expression level of GMPR in AD and propose a therapeutic strategy of inhibiting GMPR1 with lumacaftor.
Subject(s)
Alzheimer Disease/drug therapy , Aminopyridines/therapeutic use , Amyloid beta-Peptides/metabolism , Benzodioxoles/therapeutic use , Enzyme Inhibitors/therapeutic use , GMP Reductase/antagonists & inhibitors , Molecular Targeted Therapy , tau Proteins/metabolism , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Aminopyridines/pharmacology , Animals , Benzodioxoles/pharmacology , C-Reactive Protein/genetics , C-Reactive Protein/metabolism , Databases, Genetic , Disease Models, Animal , GMP Reductase/genetics , Glycogen Synthase Kinase 3 beta/genetics , Glycogen Synthase Kinase 3 beta/metabolism , Mice , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Phosphorylation/drug effects , Proto-Oncogene Proteins c-met/genetics , Proto-Oncogene Proteins c-met/metabolism , Repressor Proteins/genetics , Repressor Proteins/metabolism , Wnt Signaling Pathway/geneticsABSTRACT
Trypanosoma congolense is one of the most prevalent pathogens which causes trypanosomosis in African animals, resulting in a significant economic loss. In its life cycle, T. congolense is incapable of synthesizing purine nucleotides via a de novo pathway, and thus relies on a salvage pathway to survive. In this study, we identified a gene from T. congolense, TcIL3000_5_1940, as a guanosine 5'-monophosphate reductase (GMPR), an enzyme that modulates the concentration of intracellular guanosine in the pathogen. The recombinant protein was expressed in Escherichia coli, and the gene product was enzymatically confirmed as a unique GMPR, designated as rTcGMPR. This enzyme was constitutively expressed in glycosomes at all of the parasite's developmental stages similar to other purine nucleotide metabolic enzymes. Mycophenolic acid (MPA) was found to inhibit rTcGMPR activity. Hence, it is a potential lead compound for the design of trypanocidal agents, specifically GMPR inhibitor.
Subject(s)
GMP Reductase/antagonists & inhibitors , GMP Reductase/genetics , Trypanocidal Agents/pharmacology , Trypanosoma congolense/drug effects , Trypanosoma congolense/enzymology , Animals , Enzyme Inhibitors/pharmacology , Escherichia coli/genetics , GMP Reductase/isolation & purification , Guanosine/metabolism , Mycophenolic Acid/pharmacology , Purines/metabolism , Recombinant Proteins/metabolism , Trypanosomiasis, African/drug therapy , Trypanosomiasis, African/parasitologyABSTRACT
Melanoma is one of the most aggressive types of human cancers, and the mechanisms underlying melanoma invasive phenotype are not completely understood. Here, we report that expression of guanosine monophosphate reductase (GMPR), an enzyme involved in de novo biosynthesis of purine nucleotides, was downregulated in the invasive stages of human melanoma. Loss- and gain-of-function experiments revealed that GMPR downregulates the amounts of several GTP-bound (active) Rho-GTPases and suppresses the ability of melanoma cells to form invadopodia, degrade extracellular matrix, invade in vitro, and grow as tumor xenografts in vivo. Mechanistically, we demonstrated that GMPR partially depletes intracellular GTP pools. Pharmacological inhibition of de novo GTP biosynthesis suppressed whereas addition of exogenous guanosine increased invasion of melanoma cells as well as cells from other cancer types. Our data identify GMPR as a melanoma invasion suppressor and establish a link between guanosine metabolism and Rho-GTPase-dependent melanoma cell invasion.
