Differential Interaction of the Cyclin-dependent Kinase (Cdk) Inhibitor p27Kip1 with Cyclin A-Cdk2 and Cyclin D2-Cdk4*
- From the Cell Biology Program and Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021
Abstract
Although p27Kip1 has been considered a general inhibitor of G1 and S phase cyclin-dependent kinases, we report that the interaction of p27 with two such kinases, cyclin A-Cdk2 and cyclin D-Cdk4, is different. In Mv1Lu cells containing a p27 inducible system, a 6-fold increase over the basal p27 level completely inhibited Cdk2 and cell cycle progression. In contrast, the same or a larger increase in p27 levels did not inhibit Cdk4 or its homologue Cdk6, despite extensive binding to these kinases. A p27-cyclin A-Cdk2 complex formed in vitro was essentially inactive, whereas a p27-cyclin D2-Cdk4 complex was active as a retinoblastoma kinase and served as a substrate for the Cdk-activating kinase Cak. High concentrations of p27 inhibited cyclin D2-Cdk4, apparently by conversion of active complexes into inactive ones by the binding of additional p27 molecules. In contrast to their differential interaction, cyclin A-Cdk2 and cyclin D2-Cdk4 were similarly inhibited by bound p21Cip1/Waf1. Roles of cyclin A-Cdk2 as a p27 target and cyclin D2-Cdk4 as a p27 reservoir may result from the differential ability of bound p27 to inhibit the kinase subunit in these complexes.
Footnotes
-
↵* This work was supported by a National Institutes of Health grant.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵‡ Leukemia Society of America fellow.
-
↵§ Investigator of the Howard Hughes Medical Institute. To whom correspondence should be addressed: Memorial Sloan-Kettering Cancer Center, Box 116, 1275 York Ave., New York, NY 10021. Tel.: 212-639-8975; Fax: 212-717-3298; E-mail:j-massague{at}ski.mskcc.org.
-
↵1 The abbreviations used are: Cdk, cyclin-dependent kinase; PAGE, polyacrylamide gel electrophoresis; GST, glutathione S-transferase; Cak, Cdk-activating kinase; Rb, retinoblastoma.
-
↵2 I. Reynisdóttir and J. Massagué, unpublished results.
-
↵3 S. W. Blain and J. Massagué, unpublished work.
-
- Received June 13, 1997.
- Revision received July 30, 1997.
