Embryonic Lethal Abnormal Vision-like HuR-dependent mRNA Stability Regulates Post-transcriptional Expression of Cyclin-dependent Kinase Inhibitor p27Kip1

Gudrun Ziegeler,Jie Ming,Jana C Koseki,Sema Sevinc,Ting Chen,Suleyman Ergun,Xuebin Qin,Bertal H Aktas

doi:10.1074/jbc.m110.113365

Gudrun Ziegeler, Jie Ming + Show 6 more

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https://doi.org/10.1074/jbc.m110.113365

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Abstract

The cyclin-dependent kinase inhibitor p27(Kip1) plays a critical role in regulating entry into and exit from the cell cycle. Post-transcriptional regulation of p27(Kip1) expression is of significant interest. The embryonic lethal abnormal vision (ELAV)-like RNA-binding protein HuR is thought be important for the translation of p27(Kip1), however, different reports attributed diametrically opposite roles to HuR. We report here an alternative mechanism wherein HuR regulates stability of the p27(Kip1) mRNA. Specifically, human and mouse p27(Kip1) mRNAs interact with HuR protein through multiple U-rich elements in both 5' and 3' untranslated regions (UTR). These interactions, which occur in vitro and in vivo, stabilize p27(Kip1) mRNA and play a critical role in its accumulation. Deleting HuR binding sites or knocking down HuR expression destabilizes p27(Kip1) mRNA and reduces its accumulation. We also identified a CT repeat in the 5' UTR of full-length p27(Kip1) mRNA isoforms that interact with a approximately 41-kDa protein and represses p27(Kip1) expression. This CT-rich element and diffuse elements in the 3' UTR regulate post-transcriptional expression of p27(Kip1) at the level of translation. This is the first demonstration that HuR-dependent mRNA stability and HuR-independent mRNA translation plays a critical role in the regulation of post-transcriptional p27(Kip1) expression.

Highlights

Hufelandstrasse 55, D-45147 Essen, Germany. 3 To whom correspondence should be addressed: Laboratory for Translational Research, 1 Kendall Square, Bldg. 600, 3rd Floor, Cambridge, MA 02139
One group has reported that basal and cell cycle-dependent translation of p27Kip1 is stimulated by the embryonic lethal abnormal visual system-like RNA-binding protein HuR binding to the 5Ј untranslated regions (UTR) of p27Kip1 mRNA [27], whereas another reported that repression of internal ribosome entry site-dependent translation by HuR in proliferating but not quiescent cells is responsible for cell cycle-dependent expression of p27Kip1 [28]
Several U-rich elements in the 5Ј and 3Ј UTRs of p27Kip1 mRNA interact with HuR, whereas a CT repeat region in the 5Ј UTR interacts with a 41-kDa protein to regulate basal and cell cycle-dependent post-transcriptional expression of p27Kip1

Summary

Introduction

Hufelandstrasse 55, D-45147 Essen, Germany. 3 To whom correspondence should be addressed: Laboratory for Translational Research, 1 Kendall Square, Bldg. 600, 3rd Floor, Cambridge, MA 02139. Several studies suggest that p27Kip expression is regulated at the level of translation in the G1 phase of the cell cycle [22, 23]. An endonuclease binding site in the 5Ј UTR of p27Kip has been reported, suggesting that mRNA stability may play a role in regulating the post-transcriptional expression of p27Kip1 [30]. Several U-rich elements in the 5Ј and 3Ј UTRs of p27Kip mRNA interact with HuR, whereas a CT repeat region in the 5Ј UTR interacts with a 41-kDa protein to regulate basal and cell cycle-dependent post-transcriptional expression of p27Kip. Our data demonstrate that mRNA stability plays a critical role in the post-transcriptional regulation of p27Kip expression and that the 5Ј and 3Ј UTRs of p27Kip have distinct roles in the basal and cell cycle-dependent regulation of p27Kip expression

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