The significance of ribose metabolism mediated by ribokinase in purine metabolic pathway.

1988 Fiscal Year Final Research Report Summary

• Project/Area Number: 61480184
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: 内科学一般
• Research Institution: Teikyo University
• Principal Investigator: AKAOKA Ieo The second department of internal medicine,University of Teikyo, 医学部第二内科, 教授 (00000919)
• Co-Investigator(Kenkyū-buntansha): 高岡 佳代 帝京大学, 医学部第二内科, 実験助手 ; YAMANOUCHI Toshikazu The second department of internal medicine,University of Teikyo, 医学部第二内科, 講師 (40191374) ; TAKAOKA Kayo The second department of internal medicine,University of Teikyo
• Project Period (FY): 1986 – 1987
• Keywords: ribose / ribokinase / purine metabolism / erythrocyte / erythroblast / K 562 cell line / cell differentiation / プリン代謝異常症

Research Abstract

Although ribose is one of the essential components in the body, little has been known about its metabolism and kinetics, partially because of its metabolic ineartness. In this study, we demonstrated that ribose was uptaken by differenciated K-562 cells several to few hundred times more than ordinary cells. The metabolic pathyway of uptaken ribose had not been clarified. However, the uptake of ribose by this cell line seemed to have physciological significance since (1) it accampanied with a parallel inhibition of cell growth, which was reversible according to the removal of ribose, (2) these changes occured without morphological alteration, (3) and did not occur in non-differenciated K-562 cells. Furthermore, the inhibitory effect of cell growth by ribose was suggested mainly due to the suppression of DNA synthesis through the interference in HMP shunt pathway. The uptake of ribose also caused intracellular alteration of purine metabolites in this cell line. Taken together, these results strongly suggested the important role of ribose that may regulate the interaction between sugar and purine metabolism.
On the other hand, the poor capacity of reabsorption of ribose was revealed in both intestine and renal tubule. The result may then account in part for the almost null level of plasma ribose despite of the existence in urine. We also confirmed the uptake and catabolism of ribose occurred in restricted organs and were not very active. These traits have an advantage to use ribose as marker of the disarrangement of purine metabolism. The abnormal level of urinary ribose had been already reported in some patients of hereditary diseases. However, the measurement of ribose in body fluid requires high sensitive and reliable tech-nique because of its very low level. We had started the basic study of ribose assay system including the gene technology, and some noteworthy methods are discussed in this report.