Pin1 catalyzes conformational changes of Thr-187 in p27Kip1 and mediates its stability through a polyubiquitination process.
The cis-trans peptidylprolyl isomerase Pin1 plays a critical role in regulating a subset of phosphoproteins by catalyzing conformational changes on the phosphorylated Ser/Thr-Pro motifs. The phosphorylation-directed ubiquitination is one of the major mechanisms to regulate the abundance of p27(Kip1). In this study, we demonstrate that Pin1 catalyzes the cis-trans conformational changes of p27(Kip1) and further mediates its stability through the polyubiquitination mechanism. Our results show that the phosphorylated Thr-187-Pro motif in p27(Kip1) is a key Pin1-binding site. In addition, NMR analyses show that this phosphorylated Thr-187-Pro site undergoes conformational change catalyzed by Pin1. Moreover, in Pin1 knock-out mouse embryonic fibroblasts, p27(Kip1) has a shorter lifetime and displays a higher degree of polyubiquitination than in Pin1 wild-type mouse embryonic fibroblasts, suggesting that Pin1 plays a critical role in regulating p27(Kip1) degradation. Additionally, Pin1 dramatically reduces the interaction between p27(Kip1) and Cks1, possibly via isomerizing the cis-trans conformation of p27(Kip1). Our study thus reveals a novel regulatory mechanism for p27(Kip1) stability and sheds new light on the biological function of Pin1 as a general regulator of protein stability.
Zhou
Wei
W
Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
Yang
Qiaoyun
Q
Low
Choon Bing
CB
Karthik
Balakrishna Chandrababu
BC
Wang
Yu
Y
Ryo
Akihide
A
Yao
Shao Q
SQ
Yang
Daiwen
D
Liou
Yih-Cherng
YC
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D042846:CDC2-CDC28 Kinases / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D055550:Protein Stability; D013912:Threonine / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology*
C436291:CDKN1B protein, human; C093090:CKS1B protein, human; D002352:Carrier Proteins; C493961:Cdkn1b protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D050760:Cyclin-Dependent Kinase Inhibitor p27; D013912:Threonine; D042846:CDC2-CDC28 Kinases; C474110:Cks1 protein, mouse; D018844:Cyclin-Dependent Kinases; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse