Journal: iScience
Article Title: PTEN protein phosphatase activity regulates metastasis by targeting PKCδ
doi: 10.1016/j.isci.2025.112741
Figure Lengend Snippet: Identification of candidate substrates of PTEN protein phosphatase (A) The western blotting showed induced expression of various PTEN mutants and protein levels of p -AKT, AKT, p -FAK, and FAK in mouse melanoma B16F1 cells transfected with various PTEN mutant forms in tet-off inducible expressing vectors, which exogenous gene expression is controlled by the absence of doxycycline. C, empty vector; WT, PTEN wild type; ΔLP, PTEN phosphatase dead mutant (C124S); ΔL, PTEN lipid phosphatase deficient (G129E). The protein level of β-actin is the loading control. The expression of transfected various PTEN mutant forms was induced by taking off doxycycline for 24 h. +, with doxycycline; −, without doxycycline. The value of western blot band density was quantified by ImageJ analysis. After normalization with the value of β-actin, the fold change was presented to compare with no exogenous PTEN expression (+, with doxycycline). (B) Representative identification of different phosphoproteins in B16F1 cells with various PTEN mutants by Two-dimensional gel electrophoresis (2DE). The combination of two images from 2D gel electrophoresis of phosphoproteins purified from wildtype PTEN (green) and phosphatase dead mutant PTEN (magenta) B16F1 cells. Several phosphoprotein spots that were differentially represented are circled. The differentiated spots (phosphoproteins) were collected for mass spectrometry (MS) protein identification analysis. Using 2D gel electrophoresis and mass-spec technology, we identified 14 candidates, including AKT, IRS1, Add3, and PKCδ. The scale bar, 10 mM. (C) Western blot showed p-Add3, Add3, p -PKCδS643, p -PKCδT505, total PKCδ, and PTEN protein levels from B16F1 cells transfected with PTEN various mutant forms. C, empty vector; WT, PTEN wild type; ΔLP, PTEN phosphatase dead mutant; ΔL, PTEN lipid phosphatase deficient. The protein level of β-actin is the loading control. The value of western blot band density was quantified by ImageJ analysis. After normalization with the value of β-actin, the fold changes were presented to compare with control (C). The related protein levels were quantified with three repeated western blots (see ). (D) Western blot analysis of indicated proteins from A375sm transfectants harboring empty vector (C), PTEN wildtype (WT), and PTEN phosphatase dead mutant (ΔLP) and PTEN knockdown by shRNA. The value of western blot band density was quantified by ImageJ analysis. After normalization with the value of β-actin, the fold changes were presented to compare with control (C). The related protein levels were quantified with three repeated western blots (see ). (E) The schematic of CRISPR/Cas9 editing technology with a homology-directed repair (HDR) system for PTEN various mutant forms knock-in or knock-out specifically at PTEN exon 4 local. WT, wildtype PTEN; ΔL, PTEN lipid deficient mutant; ΔLP, PTEN phosphatase dead mutant; ΔP, PTEN protein deficient mutant. The human melanoma A375sm or A375p cells were cotransfected with the CRISPR/Cas9 expressed sgRNA for PTEN plasmid and a homology-directed repair (HDR) vector with various PTEN forms to insert the various PTEN forms into PTEN exon 4, or with a homology-directed repair (HDR) with RFP and puromycin genes into PTEN exon 4, therefore disrupted the PTEN gene. (F and G) PTEN protein phosphatase activity is required for dephosphorylating PKCδ. Western blots showed the indicated protein level from the melanoma cell lines A375sm (F) and A375p (G) with knocked-in PTEN wild type (WT), lipid phosphatase deficient mutant (ΔL), protein phosphatase deficient mutant (ΔP), PTEN phosphatase dead mutant (ΔLP), or total loss of PTEN (KO). The value of western blot band density was quantified by ImageJ analysis. After normalization with the value of β-actin, the fold changes were presented to compare with knocked-in PTEN wildtype (WT).
Article Snippet: anti- p -PKCδ T311 , Cell Signaling , Cat# 2055, RRID: AB_330876.
Techniques: Western Blot, Expressing, Transfection, Mutagenesis, Gene Expression, Plasmid Preparation, Control, Two-Dimensional Gel Electrophoresis, Electrophoresis, Purification, Mass Spectrometry, Knockdown, shRNA, CRISPR, Knock-In, Knock-Out, Activity Assay