Phosphoproteomics reveals that the hVPS34 regulated SGK3 kinase specifically phosphorylates endosomal proteins including Syntaxin-7, Syntaxin-12, RFIP4 and WDR44
Phosphoproteomics reveals that the hVPS34 regulated SGK3 kinase specifically phosphorylates endosomal proteins including Syntaxin-7, Syntaxin-12, RFIP4 and WDR44
Abstract The serum- and glucocorticoid-regulated kinase (SGK) isoforms contribute resistance to cancer therapies targeting the PI3K pathway. SGKs are homologous to Akt and these kinases display overlapping specificity and phosphorylate several substrates at the same residues, such as TSC2 to promote tumor growth by switching on the mTORC1 pathway. The SGK3 isoform is upregulated in breast cancer cells treated with PI3K or Akt inhibitors and recruited and activated at endosomes, through its phox homology domain binding to PtdIns(3)P. We undertook genetic and pharmacological phosphoproteomic screens to uncover novel SGK3 substrates. We identified 40 potential novel SGK3 substrates, including 4 endosomal proteins STX7 (Ser126) and STX12 (Ser139), RFIP4 (Ser527) and WDR44 (Ser346) that were efficiently phosphorylated in vitro by SGK3 at the sites identified in vivo, but poorly by Akt. We demonstrate that these substrates are poorly phosphorylated by Akt as they possess an n+1 residue from the phosphorylation site that is unfavorable for Akt phosphorylation. Phos-tag analysis revealed that stimulation of HEK293 cells with IGF1 to activate SGK3, promoted phosphorylation of a significant fraction of endogenous STX7 and STX12, in a manner that was blocked by knock-out of SGK3 or treatment with 14H inhibitor. SGK3 phosphorylation of STX12 enhanced interaction with the VAMP4/VTI1A/STX6 containing SNARE complex and promoted plasma membrane localization. Our data reveal novel substrates for SGK3 and suggest a mechanism by which STX7 and STX12 SNARE complexes are regulated by SGK3. They reveal new biomarkers for monitoring SGK3 pathway activity.
Peltier Julien、Trost Matthias、Alessi Dario R.、Nirujogi Raja S、Malik Nazma、Karapetsas Athanasios、Gourlay Robert、Wightman Melanie、Macartney Thomas、Prescott Alan R
Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee||Department of Bioanalysis, Immunogenicity & Biomarkers, GlaxoSmithKline R&DMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee||Faculty of Medical Sciences, Institute for Cell and Molecular BiosciencesMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee||Salk Institute for Biological StudiesMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeMedical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeDundee Imaging Facility, School of Life Sciences, University of Dundee
基础医学生物科学研究方法、生物科学研究技术生物化学
Peltier Julien,Trost Matthias,Alessi Dario R.,Nirujogi Raja S,Malik Nazma,Karapetsas Athanasios,Gourlay Robert,Wightman Melanie,Macartney Thomas,Prescott Alan R.Phosphoproteomics reveals that the hVPS34 regulated SGK3 kinase specifically phosphorylates endosomal proteins including Syntaxin-7, Syntaxin-12, RFIP4 and WDR44[EB/OL].(2025-03-28)[2025-04-24].https://www.biorxiv.org/content/10.1101/741652.点此复制
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