Document Type

Article

Publication Date

2009

Publication Title

JOURNAL OF BIOLOGICAL CHEMISTRY

Volume

284

Issue

5

First Page

2617

Last Page

2627

DOI

10.1074/jbc.M804847200

Abstract

Spy1A is a cyclin-like protein required for progression through the G(1)/S phase of the cell cycle. Elevated Spy1A protein levels have been implicated in tumorigenesis and are attributed to overriding the DNA damage response and enhancing cell proliferation. Understanding how Spy1A is produced and degraded is essential in resolving how it contributes to normal and abnormal growth processes. Herein, we demonstrate that Spy1A is degraded in a cell cycle-dependent manner during mitosis via the ubiquitin-proteasome system. We have resolved the E3 ligase and essential phosphorylation sites mediating Spy1A degradation. Furthermore, we have determined that non-degradable forms of Spy1A do not trigger cell cycle arrest but, rather, contribute to uncontrolled cell growth. Further investigation into the regulation of Spy1A may reveal novel strategies for understanding the etiology and progression of specific growth disorders.

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