Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
Add more filters

Database
Language
Affiliation country
Publication year range
1.
J Cell Physiol ; 238(7): 1558-1566, 2023 07.
Article in English | MEDLINE | ID: mdl-37183313

ABSTRACT

Pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6, participates as a cofactor to one carbon (1C) pathway that produces precursors for DNA metabolism. The concerted action of PLP-dependent serine hydroxymethyltransferase (SHMT) and thymidylate synthase (TS) leads to the biosynthesis of thymidylate (dTMP), which plays an essential function in DNA synthesis and repair. PLP deficiency causes chromosome aberrations (CABs) in Drosophila and human cells, rising the hypothesis that an altered 1C metabolism may be involved. To test this hypothesis, we used Drosophila as a model system and found, firstly, that in PLP deficient larvae SHMT activity is reduced by 40%. Second, we found that RNAi-induced SHMT depletion causes chromosome damage rescued by PLP supplementation and strongly exacerbated by PLP depletion. RNAi-induced TS depletion causes severe chromosome damage, but this is only slightly enhanced by PLP depletion. dTMP supplementation rescues CABs in both PLP-deficient and PLP-proficient SHMTRNAi . Altogether these data suggest that a reduction of SHMT activity caused by PLP deficiency contributes to chromosome damage by reducing dTMP biosynthesis. In addition, our work brings to light a gene-nutrient interaction between SHMT decreased activity and PLP deficiency impacting on genome stability that may be translated to humans.


Subject(s)
Chromosome Aberrations , Glycine Hydroxymethyltransferase , Vitamin B 6 , Animals , Humans , DNA , Drosophila/metabolism , Glycine Hydroxymethyltransferase/metabolism , Pyridoxal Phosphate , Thymidine Monophosphate/biosynthesis , Vitamin B 6/pharmacology
2.
J Cell Physiol ; 237(9): 3578-3586, 2022 09.
Article in English | MEDLINE | ID: mdl-35678366

ABSTRACT

The insulin signaling pathway controls cell growth and metabolism, thus its deregulation is associated with both cancer and diabetes. Phosphatidylinositol 3-kinase (PI3K) contributes to the cascade of phosphorylation events occurring in the insulin pathway by activating the protein kinase B (PKB/AKT), which phosphorylates several substrates, including those involved in glucose uptake and storage. PI3K inactivating mutations are associated with insulin resistance while activating mutations are identified in human cancers. Here we show that RNAi-induced depletion of the Drosophila PI3K catalytic subunit (Dp110) results in diabetic phenotypes such as hyperglycemia, body size reduction, and decreased glycogen content. Interestingly, we found that hyperglycemia produces chromosome aberrations (CABs) triggered by the accumulation of advanced glycation end-products and reactive oxygen species. Rearing PI3KRNAi flies in a medium supplemented with pyridoxal 5'-phosphate (PLP; the catalytically active form of vitamin B6) rescues DNA damage while, in contrast, treating PI3KRNAi larvae with the PLP inhibitor 4-deoxypyridoxine strongly enhances CAB frequency. Interestingly, PLP supplementation rescues also diabetic phenotypes. Taken together, our results provide a strong link between impaired PI3K activity and genomic instability, a crucial relationship that needs to be monitored not only in diabetes due to impaired insulin signaling but also in cancer therapies based on PI3K inhibitors. In addition, our findings confirm the notion that vitamin B6 is a good natural remedy to counteract insulin resistance and its complications.


Subject(s)
DNA Damage , Phosphatidylinositol 3-Kinase , Vitamin B 6 , Animals , DNA Damage/drug effects , Disease Models, Animal , Drosophila/drug effects , Drosophila/metabolism , Glucose/pharmacology , Humans , Hyperglycemia , Insulin/metabolism , Insulin Resistance , Phosphatidylinositol 3-Kinase/genetics , Proto-Oncogene Proteins c-akt/metabolism , Pyridoxal Phosphate/pharmacology , Vitamin B 6/pharmacology
3.
Int J Mol Sci ; 22(23)2021 Dec 04.
Article in English | MEDLINE | ID: mdl-34884931

ABSTRACT

Neuroblastoma is a severe childhood disease, accounting for ~10% of all infant cancers. The amplification of the MYCN gene, coding for the N-Myc transcription factor, is an essential marker correlated with tumor progression and poor prognosis. In neuroblastoma cells, the mitotic kinase Aurora-A (AURKA), also frequently overexpressed in cancer, prevents N-Myc degradation by directly binding to a highly conserved N-Myc region. As a result, elevated levels of N-Myc are observed. During recent years, it has been demonstrated that some ATP competitive inhibitors of AURKA also cause essential conformational changes in the structure of the activation loop of the kinase that prevents N-Myc binding, thus impairing the formation of the AURKA/N-Myc complex. In this study, starting from a screening of crystal structures of AURKA in complexes with known inhibitors, we identified additional compounds affecting the conformation of the kinase activation loop. We assessed the ability of such compounds to disrupt the interaction between AURKA and N-Myc in vitro, using Surface Plasmon Resonance competition assays, and in tumor cell lines overexpressing MYCN, by performing Proximity Ligation Assays. Finally, their effects on N-Myc cellular levels and cell viability were investigated. Our results identify PHA-680626 as an amphosteric inhibitor both in vitro and in MYCN overexpressing cell lines, thus expanding the repertoire of known conformational disrupting inhibitors of the AURKA/N-Myc complex and confirming that altering the conformation of the activation loop of AURKA with a small molecule is an effective strategy to destabilize the AURKA/N-Myc interaction in neuroblastoma cancer cells.


Subject(s)
Aurora Kinase A/metabolism , N-Myc Proto-Oncogene Protein/metabolism , Protein Kinase Inhibitors/pharmacology , Pyrazoles/pharmacology , Pyrroles/pharmacology , Adenosine Triphosphate/metabolism , Antineoplastic Agents/pharmacology , Aurora Kinase A/antagonists & inhibitors , Aurora Kinase A/chemistry , Azepines/metabolism , Azepines/pharmacology , Benzazepines/metabolism , Benzazepines/pharmacology , Binding Sites , Binding, Competitive , Cell Line , Drug Evaluation, Preclinical/methods , Humans , N-Myc Proto-Oncogene Protein/chemistry , Neuroblastoma/drug therapy , Neuroblastoma/metabolism , Protein Conformation , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Pyrazoles/metabolism , Pyrimidines/metabolism , Pyrimidines/pharmacology , Pyrroles/metabolism , Surface Plasmon Resonance
SELECTION OF CITATIONS
SEARCH DETAIL