N6-(Δ2-ISOpentenyl)adenosine—effects upon nucleic acid synthesis in lymphocytes in vitro and the development of immunologic hypersensitivity in vivo

Hacker, Bruce; Feldbush, Thomas L.

doi:10.1016/0006-2952(69)90055-0

Cited by 22 publications

(7 citation statements)

References 26 publications

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“…In mammalian systems, some of the cytokinin nucleosides exhibit immuno-suppressive activity [5] and inhibit the growth of leukemic cells [6,7]. Because of the key role that cytokinins play in plant growth and development, a full understanding of the molecular detail of cytokinin action is essential.…”

Section: Introductionmentioning

confidence: 99%

A stereochemical model for cytokinin activity

1989

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Section: Introductionmentioning

confidence: 99%

A stereochemical model for cytokinin activity

1989

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“…The Cytokinins occur in animal, plant, and bacterial tRNAs (9)(10)(11). In addition to their activity in plants, they have been reported to induce cytokinesis in animal cells (12)(13)(14). Formation of a naturally occurring cytokinin, N6-isopentenyladenosine in tobacco by A2-isopentenyl-tRNA transferase has been described (15).…”

Section: Resultsmentioning

confidence: 99%

Induction of Cytokinin-Independent Tobacco Tissues by Substituted Fluorenes

Bednar

Linsmaier-Bednar²

1971

Proc. Natl. Acad. Sci. U.S.A.

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Two morphactins and three aminofluorenes initiated the formation of compact tissue nodules in hormone-dependent tobacco callus cultures. These nodules, upon subculture, behaved like partially transformed plant tumors. They grew on cytokinin-free media, while control callus and nonnodule tissue still required an exogenous cytokinin source. The data indicate that substituted fluorenes, including carcinogenic aminofluorenes, can cause a neoplastic growth response in cultured tobacco tissues. Of particular interest in this study is the finding that a directed and heritable cellular change is induced in tobacco tissue in which a specific (the endogenous cytokinin) biosynthetic system is regularly and persistently activated.

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“…This effect parallels, at least in a superficial way, the inhibitory effects on cultured mammalian cells obtained both with cytokinins and anticytokinins (S. M. Hecht, and R. B. Frye, manuscript in preparation). In fact, compounds [4][5][6][7][8][9][10] are inhibitors of beef heart cyclic AMP phosphodiesterase (11) and compound 7 was shown to be a competitive inhibitor.…”

Section: Methodsmentioning

confidence: 99%

“…They have been reported, for example, to inhibit platelet aggregation (3) and the growth of several mammalian cell lines, including cancerous lines (4-6 and references in 5). N6-(3-Methyl-2-butenyl)adenosine (i6Ado) has been reported to be an immunosuppressive agent (7) and to induce hematological remissions in leukemia patients (8,9). Several cytokinins, including i6Ado, have also been shown to be capable of regulating the growth of phytohemagglutinin-transformed human lymphocytes (10 and references therein), presumably by involvement in cyclic AMP metabolism, and i6Ado was shown to act as a competitive inhibitor of beef heart cyclic AMP phosphodiesterase (11).…”

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confidence: 99%

Anticytokinin activity of substituted pyrrolo[2,3- d ]pyrimidines

Skoog

Schmitz²,

Hecht³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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Ten substituted pyrrolo[2,3-dpyrimidines were tested as cytokinins and anticytokinins in the tobacco bioassay. Eight new anticytokinins were identified and two were found to be highly active. The most potent species were 4-cyclohexylamino-and 4-cyclopentylamino-2-methylthiopyrrolo[2,3-djpyrimidine, of which 0.05 and 0.009 AM concentrations, respectively, were required to produce detectable inhibition of the growth of tobacco callus cultured on a medium containing 0.003 uM 6(3-methyl-2-butenylamino)purine. The inhibition of growth by moderate (<6.6 uM) concentrations of these compounds was reversible by equal or higher concentrations of 6-(3-methyl-2-butenylamino)purine, but not by indole-3-acetic acid or gibberellic acid. These substituted pyrrolo[2,3-djpyrimidines were also found to enhance bud formation at high cytokinin concentrations, suggesting that a cytokinin may act at more than one cellular site in exerting its growth-promoting and morphogenetic effects.Cytokinins are a class of hormones which promote cell division and participate in the regulation of growth and morphogenesis in plants (1). Although all plants are thought to require cytokinins for growth, intact plants generally grow without exogenous cytokinins, presumably because they make their own. In fact, several highly active cytokinins have been found to occur naturally as N6-substituted adenine derivatives at the purine, ribonucleoside, and ribonucleotide levels (1). Cytokinins are also present in the transfer RNA's of most forms of life, although their presence in tRNA has not been shown to be related to their regulation of growth (1, 2).Cytokinins have been found to influence the behavior of mammalian cells. They have been reported, for example, to inhibit platelet aggregation (3) and the growth of several mammalian cell lines, including cancerous lines (4-6 and references in 5). N6-(3-Methyl-2-butenyl)adenosine (i6Ado) has been reported to be an immunosuppressive agent (7) and to induce hematological remissions in leukemia patients (8,9). Several cytokinins, including i6Ado, have also been shown to be capable of regulating the growth of phytohemagglutinin-transformed human lymphocytes (10 and references therein), presumably by involvement in cyclic AMP metabolism, and i6Ado was shown to act as a competitive inhibitor of beef heart cyclic AMP phosphodiesterase (11).To facilitate the study of the mechanism of cytokinin action and provide potential chemotherapeutic agents, we designed and synthesized a class of structural analogs of cytokinins which behave as anticytokinins in plant bioassays (12,13). Proof that these "anticytokinins" act at the same cellular sites as the cytokinins is not presently accessible, since cytokinin-anticytokinin interaction is not monitored at the molecular level, but this interpretation has been proposed on the basis of the observed biological activities of the analogs in several assays and on the close structural relationship between cytokinins and anticytokinins (14). The successful preparation of a class...

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N6-(Δ2-ISOpentenyl)adenosine—effects upon nucleic acid synthesis in lymphocytes in vitro and the development of immunologic hypersensitivity in vivo

Cited by 22 publications

References 26 publications

A stereochemical model for cytokinin activity

A stereochemical model for cytokinin activity

Induction of Cytokinin-Independent Tobacco Tissues by Substituted Fluorenes

Anticytokinin activity of substituted pyrrolo[2,3- d ]pyrimidines

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