Journal: Journal of Biological Chemistry

Article Title: Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other

doi: 10.1074/jbc.m115.647180

Figure Lengend Snippet: FIGURE 1. Exogenous PCSK9 can induce degradation of the LDLR in the absence of APLP2. HepG2 (A) and Huh7 (B) cells were transfected with a control non-target siRNA (Ctrl) or 3 different siRNAs targeting APLP2. Cells wereincubatedovernightwithserum-freeconditionedmedialackingorcon- taining 1 g/ml of PCSK9-V5. HepG2 and Huh7 cell lysates were then sub- jected to Western blotting using LDLR, APLP2, and -actin antibodies. LDLR and APLP2 signals were normalized to that of -actin. C, the input HEK293 conditioned medium was analyzed using mAb-V5 to detect PCSK9-V5. D, duplicate samples of Huh7 cells matching those in panel B were analyzed by FACS to assess the cell surface LDLR levels. Values were normalized to that of the first lane (control non-target siRNA in the absence of PCSK9). Error bars represent S.E. *, p 0.05 (Student’s t test). The data shown here are represen- tative of two to three independent experiments.

Article Snippet: Mouse APLP2 was detected using a rabbit polyclonal antibody kindly provided by Dr. G. Thinakaran (University of Chicago), whereas human APLP2 was detected with either mAb-V5 or a rabbit polyclonal antibody (Novus Biologicals).

Techniques: Transfection, Control, Western Blot

Journal: Journal of Biological Chemistry

Article Title: Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other

doi: 10.1074/jbc.m115.647180

Figure Lengend Snippet: FIGURE 4. Sortilin and APLP2 are novel cellular targets of PCSK9. A, overexpressed PCSK9 induces sortilin and APLP2 degradation in HEK293 cells. Triplicate Western blot analyses revealing that both sortilin-Myc and APLP2-V5 expression levels in HEK293 cells were reduced by 90 and 40%, respectively, upon transfection with a PCSK9 plasmid, as compared with a control empty pIRES vector (V). Quantification of sortilin and APLP2 band intensities were normalized against those of -actin. B, HEK293 cells transfected with a cDNA coding for an empty vector control (pIRES; V) or individually with human sortilin or APLP2 tagged at the C terminus with a Myc or V5 epitope, respectively, or together in the absence or presence of a cDNA coding for untagged PCSK9. The following day the cells were washed and then pulsed for 4 h with [35S]Met Cys in the presence or absence of 5 mM NH4Cl. The cells were then extracted and their lysates immunoprecipitated (IP) with a mAb-V5 or mAb-Myc or a polyclonal antibody for PCSK9. The precipitates were separated on an 8% SDS-PAGE. The dried gel was then autoradiographed. Notice the co-precipitation of sortilin and APLP2 in the presence of NH4Cl. These data are representative of at least three independent experiments.

Article Snippet: Mouse APLP2 was detected using a rabbit polyclonal antibody kindly provided by Dr. G. Thinakaran (University of Chicago), whereas human APLP2 was detected with either mAb-V5 or a rabbit polyclonal antibody (Novus Biologicals).

Techniques: Western Blot, Expressing, Transfection, Plasmid Preparation, Control, Immunoprecipitation, SDS Page

Journal: Journal of Biological Chemistry

Article Title: Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other

doi: 10.1074/jbc.m115.647180

Figure Lengend Snippet: FIGURE 5. Sortilin, APLP2, and soluble APLP2 are degraded by both PCSK9 and ER-localized PCSK9-KDEL isoforms. HEK293 cells were transfected with indicated DNA amounts of vectors encoding a control protein 7B2, sortilin (no tag), APLP2-V5, soluble APLP2-V5 (sAPLP2-V5), PCSK9-V5, or PCSK9-V5-KDEL, as indicated. After 48 h, lysates and media were analyzed by Western blotting for the indicated proteins. The data show that overexpressed PCSK9 or PCSK9-KDEL induces degradation of sortilin (A), APLP2 (B), and sAPLP2 (C) in HEK293 cells. Quantification of sortilin and APLP2 band intensities were normalized against those of -actin or GAPDH. These data are representative of two independent experiments.

Article Snippet: Mouse APLP2 was detected using a rabbit polyclonal antibody kindly provided by Dr. G. Thinakaran (University of Chicago), whereas human APLP2 was detected with either mAb-V5 or a rabbit polyclonal antibody (Novus Biologicals).

Techniques: Transfection, Control, Western Blot

Journal: Journal of Biological Chemistry

Article Title: Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other

doi: 10.1074/jbc.m115.647180

Figure Lengend Snippet: FIGURE 6. Co-expression of sortilin, APLP2, or both with PCSK9 has no major effect on LDLR degradation. Huh7 cells were transfected with a total of 3 g using 1 g of each vector encoding for either a control protein 7B2 (), sortilin (), APLP2 (), or PCSK9 (), as indicated. After 48 h, lysates were analyzed by Western blotting for expression of the LDLR, sortilin-Myc, APLP2- V5, intracellular pro- and mature-PCSK9-V5, and -actin. Media were ana- lyzed for secreted endogenous and overexpressed PCSK9-V5 using a rabbit polyclonal human PCSK9 antibody. Quantification of LDLR expression was normalized against that of -actin. These data are representative of at least 3 different experiments showing similar results.

Article Snippet: Mouse APLP2 was detected using a rabbit polyclonal antibody kindly provided by Dr. G. Thinakaran (University of Chicago), whereas human APLP2 was detected with either mAb-V5 or a rabbit polyclonal antibody (Novus Biologicals).

Techniques: Expressing, Transfection, Plasmid Preparation, Control, Western Blot

Journal: Journal of Biological Chemistry

Article Title: Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other

doi: 10.1074/jbc.m115.647180

Figure Lengend Snippet: FIGURE 7. Sortilin binds APLP2. A, schematic diagram of sortilin and APLP2 fused to the G. princeps luciferase half-domains, Gluc-1 and Gluc-2, respectively. B, heat map generated by G. princeps luciferase complementation assay showing the interaction profile of 36 protein pairs. Normalized luminescence ratio ranging from strong to null interactions is displayed on a light blue to black scale. C, validation of sortilin-Myc and APLP2-V5 interaction was confirmed by co-expression in HEK293 cells and immunoprecipitation with mAb-Myc followed by Western blotting (WB) using a mAb-Myc or mAb-V5.

Article Snippet: Mouse APLP2 was detected using a rabbit polyclonal antibody kindly provided by Dr. G. Thinakaran (University of Chicago), whereas human APLP2 was detected with either mAb-V5 or a rabbit polyclonal antibody (Novus Biologicals).

Techniques: Luciferase, Generated, Biomarker Discovery, Expressing, Immunoprecipitation, Western Blot