Adenosine (Ado) is a crucial metabolite that affects a wide range of physiological processes. Key proteins regulating Ado signaling, transport and metabolism are conserved among vertebrates and invertebrates. It is well known that Ado influences proliferation of several vertebrate and invertebrate cells. Here we show that Ado negatively influences viability, changes morphology and mitochondrial polarity of the Drosophila imaginal disc cell line (Cl.8+) via a mechanism exclusively dependent on cellular Ado uptake. High transport of Ado is followed by phosphorylation and ATP production as a part of Ado salvation, which at higher concentrations may interfere with cellular homeostasis. In contrast, hematopoietic cell line Mbn2, which grows well in high Ado concentration, preferentially uses adenosine deaminase as a part of the purine catabolic pathway. Our results show that different types of Drosophila cell lines use different pathways for Ado conversion and suggest that such differences may be an important part of complex mechanisms maintaining energy homeostasis in the body.

• MeSH
• Adenosine metabolism   toxicity   MeSH
• Adenosine Kinase antagonists & inhibitors   metabolism   MeSH
• Adenosine Triphosphate metabolism   MeSH
• Cell Line MeSH
• Drosophila cytology   metabolism   MeSH
• Energy Metabolism MeSH
• Cell Proliferation MeSH
• Uridine metabolism   MeSH
• Cell Survival MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH

The in vitro induction of apoptosis by N6-substituted derivatives of adenosine and adenine was investigated in HL-60 cells. Using reversed phase HPLC/MS analysis we demonstrated that both N6-substituted derivatives of adenosine and adenine are phosphorylated within cells to the monophosphate level. While N6-substituted derivatives of adenosine were phosphorylated by adenosine kinase and corresponding mononucleotides were produced in large quantities, N6-substituted derivatives of adenine were converted into the corresponding mononucleotides via the phosphoribosyl transferase pathway, which yielded 50-100 times lower amounts of the mononucleotides than the adenosine kinase pathway. Accordingly, N6-substituted derivatives of adenine were relatively inefficient inductors of apoptosis at the concentrations applied. Inhibitors of adenosine kinase that abrogated the formation of monophosphates from N6-substituted derivatives of adenosine completely prevented cells from going into apoptosis. These results consistently support the idea that pro-apoptotic effects of N6-substituted derivatives of adenosine are related to their intracellular conversion into corresponding mononucleotides which eventually trigger apoptosis when accumulated beyond certain level. Intracellular accumulation of mononucleotides derived from the corresponding N6-substituted derivatives of adenosine led to a rapid decrease in ATP production and consequently to apoptosis induction. Nevertheless, the detailed mechanism is unknown and must be further elucidated. Apoptosis, induced by N6-substituted derivatives of adenosine, was accompanied by a distinct caspase-3 activation. However, a broad spectrum caspase inhibitor, z-VAD-fmk, failed to prevent cells from death, thereby indicating that caspases alone were not mediators of cell death.

• MeSH
• Adenine analogs & derivatives   toxicity   MeSH
• Adenine Phosphoribosyltransferase metabolism   MeSH
• Adenine Nucleotides metabolism   MeSH
• Adenosine analogs & derivatives   toxicity   MeSH
• Adenosine Kinase antagonists & inhibitors   metabolism   MeSH
• Adenosine Monophosphate metabolism   MeSH
• Apoptosis MeSH
• Amino Acid Chloromethyl Ketones pharmacology   MeSH
• Phosphorylation MeSH
• HL-60 Cells MeSH
• Enzyme Inhibitors pharmacology   MeSH
• Caspase Inhibitors MeSH
• Caspase 3 MeSH
• Caspases metabolism   MeSH
• Humans MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH