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Protein phosphatase 2A (PP2A) regulates low density lipoprotein uptake through regulating sterol response element-binding protein-2 (SREBP-2) DNA binding
Journal article   Open access   Peer reviewed

Protein phosphatase 2A (PP2A) regulates low density lipoprotein uptake through regulating sterol response element-binding protein-2 (SREBP-2) DNA binding

Lyndi M Rice, Melissa Donigan, Muhua Yang, Weidong Liu, Devanshi Pandya, Biny K Joseph, Valerie Sodi, Tricia L Gearhart, Jenny Yip, Michael Bouchard, …
The Journal of biological chemistry, v 289(24), pp 17268-17279
13 Jun 2014
PMID: 24770487
url
https://doi.org/10.1074/jbc.M114.570390View
Published, Version of Record (VoR) Open

Abstract

Receptors, LDL - genetics Response Elements Humans Protein Phosphatase 2 - genetics Receptors, LDL - metabolism Hep G2 Cells Cholesterol, LDL - deficiency HEK293 Cells Protein Phosphatase 2 - metabolism Cholesterol, LDL - metabolism Protein Binding Active Transport, Cell Nucleus Sterol Regulatory Element Binding Protein 2 - metabolism
LDL-cholesterol (LDL-C) uptake by Ldlr is regulated at the transcriptional level by the cleavage-dependent activation of membrane-associated sterol response element-binding protein (SREBP-2). Activated SREBP-2 translocates to the nucleus, where it binds to an LDLR promoter sterol response element (SRE), increasing LDLR gene expression and LDL-C uptake. SREBP-2 cleavage and translocation steps are well established. Several SREBP-2 phosphorylation sites have been mapped and functionally characterized. The phosphatases dephosphorylating these sites remain elusive. The phosphatase(s) regulating SREBP-2 represents a novel pharmacological target for treating hypercholesterolemia. Here we show that protein phosphatase 2A (PP2A) promotes SREBP-2 LDLR promoter binding in response to cholesterol depletion. No binding to an LDLR SRE was observed in the presence of the HMG-CoA reductase inhibitor, lovastatin, when PP2A activity was inhibited by okadaic acid or depleted by siRNA methods. SREBP-2 cleavage and nuclear translocation were not affected by loss of PP2A. PP2A activity was required for SREBP-2 DNA binding. In response to cholesterol depletion, PP2A directly interacted with SREBP-2 and altered its phosphorylation state, causing an increase in SREBP-2 binding to an LDLR SRE site. Increased binding resulted in induced LDLR gene expression and increased LDL uptake. We conclude that PP2A activity regulates cholesterol homeostasis and LDL-C uptake.

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Web of Science research areas
Biochemistry & Molecular Biology
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