In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 100, No. 4 ( 2003-02-18), p. 1592-1597
Kurzfassung:
The FHIT gene is inactivated early in the development of many human tumors, and Fhit-deficient mice have increased cancer incidence. Viral reexpression of Fhit kills Fhit-deficient cells by induction of apoptosis. Fhit, a member of branch 2 of the histidine-triad superfamily of nucleoside monophosphate hydrolases and transferases, is a diadenosine polyphosphate hydrolase, the active-site histidine of which is not required for tumor suppression. To provide a rigorous test of the hypothesis that Fhit function depends on forming a complex with substrates, we designed a series of alleles of Fhit intended to reduce substrate-binding and/or hydrolytic rates, characterized these mutants biochemically, and then performed quantitative cell-death assays on cancer cells virally infected with each allele. The allele series covered defects as great as 100,000-fold in k cat and increases as large as 30-fold in K M . Nonetheless, when mutant FHIT genes were expressed in two human cancer cell lines containing FHIT deletions, reductions in apoptotic activity correlated exclusively with K M . Mutants with 2- and 7-fold increases in K M significantly reduced apoptotic indices, whereas the mutant with a 30-fold increase in K M retained little cellular function. These data indicate that the proapoptotic function of Fhit is limited by substrate binding and is unrelated to substrate hydrolysis.
Materialart:
Online-Ressource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.0437915100
Sprache:
Englisch
Verlag:
Proceedings of the National Academy of Sciences
Publikationsdatum:
2003
ZDB Id:
209104-5
ZDB Id:
1461794-8
SSG:
11
SSG:
12
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