Caffeine mimics adenine and 2'-deoxyadenosine, both of which inhibit the guanine-nucleotide exchange activity of RCC1 and the kinase activity of ATR.
BACKGROUND
Both caffeine and the inactivation of RCC1, the guanine-nucleotide exchange factor (GEF) of Ran, induce premature chromatin condensation (PCC) in hamster BHK21 cells arrested in the S-phase, suggesting that RCC1 is a target for caffeine.


RESULTS
Caffeine inhibited the Ran-GEF activity of RCC1 by preventing the binary complex formation of Ran-RCC1. Inhibition of the Ran-GEF activity of RCC1 by caffeine and its derivatives was correlated with their ability to induce PCC. Since caffeine is a derivative of xanthine, the bases and nucleosides were screened for their ability to inhibit RCC1. Adenine, adenosine, and all of the 2'-deoxynucleosides inhibited the Ran-GEF activity of RCC1; however, only adenine and 2'-deoxyadenosine (2'-dA) induced PCC. A factor(s) other than RCC1, should therefore be involved in PCC-induction. We found that both adenine and 2'-dA, but none of the other 2'-deoxynucleosides, inhibited the kinase activity of ATR, similar to that of caffeine. The ATR pathway was also abrogated by the inactivation of RCC1 in tsBN2 cells.


CONCLUSIONS
The effect of caffeine on cell-cycle control mimics the biological effect of adenine and 2'-dA, both of which inhibit ATR. dATP, a final metabolite of adenine and 2'-dA, is suggested to inhibit ATR, resulting in PCC.
Nishijima
Hitoshi
H
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Nishitani
Hideo
H
Saito
Noriko
N
Nishimoto
Takeharu
T
D000225:Adenine / Q000494:pharmacology*; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology*; D018797:Cell Cycle Proteins; D002460:Cell Line; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002843:Chromatin / Q000502:physiology; D006224:Cricetinae; D003839:Deoxyadenosines / Q000494:pharmacology*; D020662:Guanine Nucleotide Exchange Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006150:Guanine Nucleotides / Q000494:pharmacology; D006801:Humans; D018716:Molecular Mimicry; D009687:Nuclear Proteins; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D015398:Signal Transduction; D013696:Temperature; D020931:ran GTP-Binding Protein / Q000378:metabolism*
D018797:Cell Cycle Proteins; D000697:Central Nervous System Stimulants; D002843:Chromatin; D003839:Deoxyadenosines; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides; D009687:Nuclear Proteins; C062521:RCC1 protein, human; D011994:Recombinant Proteins; D002110:Caffeine; D011494:Protein Kinases; C102333:histone H1 kinase; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D020931:ran GTP-Binding Protein; D000225:Adenine