Dataset Information

AMPK-mediated phosphorylation of murine p27 at T197 promotes binding of 14-3-3 proteins and increases p27 stability.

ABSTRACT: The tuberous sclerosis complex 2 (Tsc2) gene product, tuberin, acts as a negative regulator of mTOR signaling, and loss of tuberin function leads to tumors of the brain, skin, kidney, heart, and lungs. Previous studies have shown that loss of tuberin function affects the stability and subcellular localization of the cyclin-dependent kinase inhibitor (CKI) p27, although the mechanism(s) by which tuberin modulates p27 stability has/have not been elucidated. Previous studies have also shown that AMP-activated protein kinase (AMPK), which functions in an energy-sensing pathway in the cell, becomes activated in the absence of tuberin. Here we show that in Tsc2-null tumors and cell lines, AMPK activation correlates with an increase in p27 levels, and inhibition of AMPK signaling decreases p27 levels in these cells. In addition, activation of AMPK led to phosphorylation of p27 at the conserved terminal threonine residue of murine p27 (T197) in both in vitro kinase assays and in cells. Phosphorylation of p27 at T197 led to increased interaction between p27 and 14-3-3 proteins and increased the protein stability of p27. Furthermore, activation of AMPK signaling promoted the interaction between p27 and 14-3-3 proteins and increased the stability of the p27 protein in a manner that was dependent on T197. These data identify a conserved mechanism for the regulation of p27 stability via phosphorylation at the terminal threonine (mT197/hT198) and binding of 14-3-3 proteins, which when AMPK is activated results in stabilization of the p27 protein.

SUBMITTER: Short JD

PROVIDER: S-EPMC3818129 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

AMPK-mediated phosphorylation of murine p27 at T197 promotes binding of 14-3-3 proteins and increases p27 stability.

Short John D JD Dere Ruhee R Houston Kevin D KD Cai Sheng-Li SL Kim Jinhee J Bergeron Judith M JM Shen Jianjun J Liang Jiyong J Bedford Mark T MT Mills Gordon B GB Walker Cheryl Lyn CL

Molecular carcinogenesis 20100501 5

The tuberous sclerosis complex 2 (Tsc2) gene product, tuberin, acts as a negative regulator of mTOR signaling, and loss of tuberin function leads to tumors of the brain, skin, kidney, heart, and lungs. Previous studies have shown that loss of tuberin function affects the stability and subcellular localization of the cyclin-dependent kinase inhibitor (CKI) p27, although the mechanism(s) by which tuberin modulates p27 stability has/have not been elucidated. Previous studies have also shown that AM ...[more]

PMID: 20146253

Similar Datasets

Project description:BackgroundPoly C Binding Protein 1 (PCBP1) is an RNA-binding protein that binds and regulates translational activity of subsets of cellular mRNAs. Depletion of PCBP1 is implicated in various carcinomas, but the underlying mechanism in tumorigenesis remains elusive.MethodsWe performed a transcriptome-wide screen to identify novel bounding mRNA of PCBP1. The bind regions between PCBP1 with target mRNA were investigated by using point mutation and luciferase assay. Cell proliferation, cell cycle, tumorigenesis and cell apoptosis were also evaluated in ovary and colon cancer cell lines. The mechanism that PCBP1 affects p27 was analyzed by mRNA stability and ribosome profiling assays. We analyzed PCBP1 and p27 expression in ovary, colon and renal tumor samples and adjacent non-tumor tissues using RT-PCR, Western Blotting and immunohistochemistry. The prognostic significance of PCBP1 and p27 also analyzed using online databases.ResultsWe identified cell cycle inhibitor p27Kip1 (p27) as a novel PCBP1-bound transcript. We then demonstrated that binding of PCBP1 to p27 3'UTR via its KH1 domain mainly stabilizes p27 mRNA, while enhances its translation to fuel p27 expression, prior to p27 protein degradation. The upregulated p27 consequently inhibits cell proliferation, cell cycle progression and tumorigenesis, whereas promotes cell apoptosis under paclitaxel treatment. Conversely, knockdown of PCBP1 in turn compromises p27 mRNA stability, leading to lower p27 level and tumorigenesis in vivo. Moreover, forced depletion of p27 counteracts the tumor suppressive ability of PCBP1 in the same PCBP1 over-expressing cells. Physiologically, we showed that decreases of both p27 mRNA and its protein expressions are well correlated to PCBP1 depletion in ovary, colon and renal tumor samples, independent of the p27 ubiquitin ligase Skp2 level. Correlation of PCBP1 with p27 is also found in the tamoxifen, doxorubincin and lapatinib resistant breast cancer cells of GEO database.ConclusionOur results thereby indicate that loss of PCBP1 expression firstly attenuates p27 expression at post-transcriptional level, and subsequently promotes carcinogenesis. PCBP1 could be used as a diagnostic marker to cancer patients.

Dataset Information

AMPK-mediated phosphorylation of murine p27 at T197 promotes binding of 14-3-3 proteins and increases p27 stability.

Publications

AMPK-mediated phosphorylation of murine p27 at T197 promotes binding of 14-3-3 proteins and increases p27 stability.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets