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Wada R, Fujinuma S, Nakatsumi H, Matsumoto M, Nakayama KI. Phosphorylation of PBX2, a novel downstream target of mTORC1, is determined by GSK3 and PP1. J Biochem 2023; 173:129-138. [PMID: 36477205 DOI: 10.1093/jb/mvac094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/01/2022] [Accepted: 11/03/2022] [Indexed: 12/12/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a serine-threonine kinase that is activated by extracellular signals, such as nutrients and growth factors. It plays a key role in the control of various biological processes, such as protein synthesis and energy metabolism by mediating or regulating the phosphorylation of multiple target molecules, some of which remain to be identified. We have here reanalysed a large-scale phosphoproteomics data set for mTORC1 target molecules and identified pre-B cell leukemia transcription factor 2 (PBX2) as such a novel target that is dephosphorylated downstream of mTORC1. We confirmed that PBX2, but not other members of the PBX family, is dephosphorylated in an mTORC1 activity-dependent manner. Furthermore, pharmacological and gene knockdown experiments revealed that glycogen synthase kinase 3 (GSK3) and protein phosphatase 1 (PP1) are responsible for the phosphorylation and dephosphorylation of PBX2, respectively. Our results thus suggest that the balance between the antagonistic actions of GSK3 and PP1 determines the phosphorylation status of PBX2 and its regulation by mTORC1.
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Key Words
- glycogen synthase kinase 3 (GSK3)
Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; DMSO, dimethyl sulfoxide; ERK, extracellular signal–regulated kinase; FOXK1, forkhead box K1;
GSK3, glycogen synthase kinase 3; HA, hemagglutinin; LARP1, La-related protein 1; MEK, ERK kinase; mTORC1, mechanistic target of rapamycin complex 1; PBS, phosphate-buffered saline; PBX2, pre–B cell leukemia transcription factor 2; PI3K, phosphoinositide 3-kinase; PDK1, phosphoinositide-dependent protein kinase 1; PP1, protein phosphatase 1;
PP2A, protein phosphatase 2A; RAG, RAS-related GTP-binding protein; RHEB, Ras homolog enriched in Brain; shRNA, short hairpin RNA; siRNA, small interfering RNA; TBC1D7, TBC1 (TRE2-BUB2-CDC16) domain family member 7; TSC2, tuberous sclerosis complex 2; WT, wild-type
- mechanistic target of rapamycin complex 1 (mTORC1)
- phosphorylation
- pre–B cell leukemia transcription factor 2 (PBX2)
- protein phosphatase 1 (PP1)
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Affiliation(s)
- Reona Wada
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Shun Fujinuma
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Hirokazu Nakatsumi
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Masaki Matsumoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan.,Department of Omics and Systems Biology, Graduate School of Medical and Dental Sciences, Niigata University, 757 Ichibancho, Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
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