EMBO/soda-nel huggingface dataset:
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 2

Figure 2. Reduced Aβ content in the hippocampus of 5xFAD mice carrying inactive p75NTR variants

(A) Immunohistochemistry for p75NTR in hippocampal CA1 of 5 month old wild type, 5xFAD and p75NTR knock-out (KO) mice. Scale bar, 20μm.

(B) Western blot analysis of p75NTR expression in total lysates of hippocampus from 6 month old wild type (WT) and 5xFAD mice assessed using antibody GT15057 against p75NTR extracellular domain (Table S1). The lower panel shows reprobing for GAPDH to control for equal gel loading.

(C) Quantification of p75NTR expression in mouse hippocampus relative to GAPDH. Mean ± SEM; **, P<0.01; N=5 mice per group (one-way ANOVA followed by post hoc test).

(D) Immunostaining for Aβ plaques with 6E10 antibody in coronal sections through the hippocampus of 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A mice of the indicated ages. Scale bar, 400μm.

(E) Quantification of Aβ plaque burden in the hippocampus of 5xFAD mouse strains carrying different p75NTR variants as indicated. Histogram shows the percentage of hippocampal area occupied by Aβ plaques (mean ± SEM, N=5 mice per group). *, P<0.05 and **, P<0.01 vs 5XFAD. #, P<0.05 vs 5XFAD/KO (one-way ANOVA followed by post hoc test).

(F) Quantification of the number of Aβ plaques larger than 30um in diameter per um2 in coronal sections through the hippocampus of 9 month old 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A mice. Color codes are as in panel (E). Histogram shows mean ± SEM, N=4 mice per group; *, P<0.05 KO vs. knock-in genotypes.

(G-I) ELISA determinations of Aβ1-42 content in hippocampus of 5xFAD mouse strains carrying different p75NTR variants as indicated. Aβ monomers (G) refers to the soluble fraction after Tris-buffered saline extraction, Aβ oligomers (H) to the soluble fraction after RIPA buffer extraction of the Tris-buffered saline pellet, and Aβ fibrils (I) to the soluble fraction after formic acid treatment of the RIPA pellet. See Materials and Methods for details. Shown is mean ± SEM; squares denote individual animals. *, P<0.05 and **, P<0.01 vs 5XFAD. #, P<0.05 vs 5XFAD/KO (one-way ANOVA followed by post hoc test).
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 3

Figure 3. Reduced histopathology in the hippocampus of 5xFAD mice carrying inactive p75NTR variants

(A) Immunostaining for Glial fibrillary acidic protein (GFAP), a marker of astrocytes, and Aβ plaques in coronal sections through the hippocampus of 6 month old wild type, 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A mice. Scale bar, 300μm. Right hand panels show high magnification of the indicated areas. Scale bar, 50μm.

(B) Quantification of GFAP area in the hippocampus of wild type and 5xFAD mouse strains carrying different p75NTR variants as indicated. Histogram shows the percentage of hippocampal area occupied by GFAP immunostaining (mean ± SEM, N=5 mice per group). *, P<0.05 and **, P<0.01 vs 5XFAD. #, P<0.05 and ##, P<0.01 vs 5XFAD/KO (one-way ANOVA followed by post hoc test).

(C) Immunostaining for Ionized calcium binding adaptor molecule 1 (Iba1), a marker of microglial cells, and Aβ plaques in coronal sections through the hippocampus of 6 month old wild type, 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A. Scale bar, 300μm. Right hand panels show high magnification of the indicated areas. Scale bar, 10μm.

(D) Quantification of Iba1 area in the hippocampus of wild type and 5xFAD mouse strains carrying different p75NTR variants as indicated. Histogram shows the percentage of hippocampal area occupied by Iba1 immunostaining (mean ± SEM, N=5 mice per group). *, P<0.05 and **, P<0.01 vs 5XFAD. #, P<0.05 vs 5XFAD/KO. Other P values are indicated (one-way ANOVA followed by post hoc test).

(E) Immunostaining of reticulon 3 (RTN3), a marker of dystrophic neurites, and Aβ plaques in coronal sections through the hippocampus of 6 month old 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A mice. Scale bar, 40μm.

(F) Quantification of RTN3-positive dystrophic neurite area in the hippocampus of 5xFAD mouse strains carrying different p75NTR variants as indicated. Histogram shows the percentage of Aβ plaque area that overlapped with RTN3 immunostaining (mean ± SEM, N=5 mice per group). *, P<0.05 and **, P<0.01 vs 5XFAD. Other P values are indicated (one-way ANOVA followed by post hoc test).

(G) MitoSox staining, a mitochondrial superoxide indicator, and DAPI in coronal sections through the hippocampus of 6 month old wild type, 5xFAD, 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A mice. Scale bar, 60μm.

(H) Quantification of MitoSOX signal in the pyramidal cell layer of hippocampus of wild type and 5xFAD mouse strains carrying different p75NTR variants as indicated. Histogram shows MitoSox mean fluorescence intensity in arbitrary units (mean ± SEM, N=5 mice per group). **, P<0.01 and ***, P<0.001 vs 5XFAD. #, P<0.05 vs 5XFAD/KO. (one-way ANOVA followed by post hoc test).
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 4

Figure 4. Inactive p75NTR variants, but not the knock-out, fully rescue synaptic deficits and memory impairment of 5xFAD mice

(A) Percentage of change in field excitatory postsynaptic potential (fEPSP) recorded after theta-burst stimulation (TBS) in Schaffer collaterals of hippocampal slices from 6 month old wild type, 5xFAD and 5xFAD/p75NTR mutant mice, as indicated. Results are presented as mean % change normalized to t=0 ± SEM. N=6 (wild type), 5 (5xFAD), 9 (5xFAD/KO), 7 (5xFAD/ΔDD) and 8 (5xFAD/C259A) slices from 3 mice per genotype, respectively.

(B) Quantification of fEPSP (mean % change ± SEM) in the indicated genotypes at 3 time points. *, P<0.05; **, P<0.01 vs. 5xFAD (two-way ANOVA followed by post hoc test). N numbers as in (A).

(C) Behavior in the novel object recognition (NOR) test of 6 month old wild type, 5XFAD and 5XFAD/p75NTR mutant mice, as indicated. Histograms show mean recognition index ± SEM during training, and 30min, 24h and 14 days after training, corresponding to measures of short term, long term and remote memory, respectively. Bar color codes are as in panel (A). *, P<0.05 vs. 5xFAD (two-way ANOVA followed by post hoc test). N=12 (wild type, 5xFAD/ΔDD and 5xFAD/C259A), 10 (5xFAD) and 8 (5xFAD/KO) mice per genotype, respectively.

(D) Training latency in the Barnes maze test of 6 month old wild type, 5XFAD and 5XFAD/p75NTR mutant mice, as indicated. Histograms show mean latency in seconds to find the platform hole ± SEM in 4 consecutive training sessions. Bar color codes are as in panel (A). *, P<0.05 vs. 5xFAD; #, P<0.05 vs. wild type, 5xFAD/ΔDD or 5xFAD/C259A (two-way ANOVA followed by post hoc test). N=14 (wild type and 5xFAD/ΔDD), 10 (5xFAD, (5xFAD/KO and 5xFAD/C259A) mice per genotype, respectively.

(E) Percentage of time spent (mean ± SEM) in the target quadrant of the Barnes maze test 30min, 24h and 14 days after training. *, P<0.05 vs. 5xFAD; #, P<0.05 vs. wild type, 5xFAD/ΔDD or 5xFAD/C259A (two way ANOVA followed by post hoc test). N numbers as in (D).
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 5

Figure 5. Reduced amyloidogenic processing in hippocampal neurons carrying signaling-deficient p75NTR variants

(A) Western blot analysis of CTF beta (CTFβ) in hippocampal lysates of 9 month old 5xFAD mice carrying different p75NTR alleles detected using anti-APP-CTF antibody (A8717, Table S1). Arrows point to phospho-C99 and C99 CTFβ species as previously assigned by (Buxbaum et al., 1998) and (Kwart et al., 2019). Asterisk denotes different species of native and phosphorylated alpha and beta CTFs of lower molecular weights (based on Figs. 3F and 5A in (Kwart et al., 2019)). Lower panel shows reprobing for GAPDH.

(B) Quantification (mean ± SEM) of phospho-C99/C99 CTFβ species, normalized to GAPDH and expressed relative to levels in 5xFAD mice. *, P<0.05 5xFAD vs, 5xFAD/KO; ***, P<0.001 5xFAD vs. 5xFAD/ΔDD and 5xFAD/C259A; #, P<0.05 5xFAD/C259A vs. 5xFAD/KO; §, P=0.056 5xFAD/ΔDD vs. 5xFAD/KO. N=5 mice per group.

(C) Western blot analysis of soluble APP alpha (sAPPα) in the soluble Tris-buffered saline fraction (see Materials and Methods) of hippocampal homogenate made from 9 moth old 5xFAD mice carrying different p75NTR alleles detected using 6E10 antibody (Table S1). Lower panel shows reprobing for GAPDH.

(D) Quantification (mean ± SEM) normalized to GAPDH and expressed relative to levels in 5xFAD mice. *, P<0.05 5xFAD vs. 5xFAD/KO, 5xFAD/ΔDD and 5xFAD/C259A; #, P<0.05 5xFAD/C259A vs. 5xFAD/KO; §, P<0.05 5xFAD/ΔDD vs. 5xFAD/KO. N=9 mice per group.
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 6

Figure 6. Reduced APP internalization in hippocampal neurons carrying signaling-deficient p75NTR variants

(A) Internalization of triple mutant hAPP in wild type, p75NTR knock-out (KO), ΔDD and C259A hippocampal neurons (15min time point). Counterstaining for p75NTR and DAPI are also shown. Scale bar, 10μm.

(B) Kinetics of internalization of triple mutant hAPP in hippocampal neurons from wild type, p75NTR knock-out (KO), ΔDD and C259A mice. Shown is mean ± SEM of percentage internalization of total surface APP (set to 100%). N=3 independent experiments each performed in duplicate; *, P<0.05 knock-in vs. KO mutants; **, P<0.01, WT vs. all other genotypes (2-way ANOVA).

(C) Linear transformation of hAPP internalization kinetics shown in (B). IMAX denotes maximal internalization in %. T1/2 denotes time for half maximal internalization in minutes.

(D) Kinetics of internalization of p75NTR in wild type hippocampal neurons in the presence or absence of NGF. Shown is mean ± SEM of percentage internalization of total surface p75NTR (set to 100%). N=3 independent experiments each performed in duplicate; *, P<0.05 ± NGF (2-way ANOVA).

(E) Linear transformation of p75NTR internalization kinetics shown in (G). IMAX denotes maximal internalization in %. T1/2 denotes time for half maximal internalization in minutes.

(F) Internalization of endogenous p75NTR in wild type hippocampal neurons (30min time point). Counterstaining for MAP2 and DAPI are also shown. Scale bar, 10μm.

(G) Kinetics of internalization of p75NTR in hippocampal neurons from wild type, ΔDD and C259A mice. Show are mean ± SEM of percentage internalization of total surface p75NTR (set to 100%). N=3 independent experiments each performed in duplicate; *, P<0.05 knock-in mutants vs. WT (2-way ANOVA).

(H) Linear transformation of p75NTR internalization kinetics shown in (G). IMAX denotes maximal internalization in %. T1/2 denotes time for half maximal internalization in minutes.

(I) (A) Co-immunoprecipitation between p75NTR and β-adaptin in hippocampal extracts from 6 month wild type and p75NTR mutant mice as indicated. Results shown are representative from 2 independent experiments. Molecular weights are in kDa. IP: immunoprecipitation; IB: immunoblotting; WCL, whole cell lysate.
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 7

Figure 7. 5xFAD hAPP and p75NTR interact and co-internalize in hippocampal neurons

(A) Co-immunoprecipitation between hAPP and p75NTR in hippocampal extracts from 6 month 5xFAD and p75NTR mutant mice as indicated. Results shown are representative from 3 independent experiments. Molecular weights are indicated in kDa. IP: immunoprecipitation; IB: immunoblotting; WCL, whole cell lysate.

(B) Proximity ligation assay (PLA) between triple mutant hAPP and p75NTR in hippocampal neurons from wild type and C259A mice (first and second rows, respectively). The third row (no APP) shows control PLA reaction in neurons that did not receive hAPP lentivirus. The fourth row (KO) shows control PLA reaction in neurons from p75NTR knock-out mice infected with hAPP lentivirus. Counterstaining for MAP2 is also shown. Scale bar, 10μm.

(C) Quantification of total PLA signals in wild type and p75NTR mutant neurons in the presence or absence of hAPP lentivirus, as indicated. Values were normalized to levels in wild type neurons and are expressed as mean PLA puncta per cell ± SEM from at least 25 neurons in 3 independent experiments.

(D) Quantification of cell surface PLA signals in wild type and p75NTR mutant neurons in the presence or absence of triple mutanthAPP lentivirus, as indicated. Live neuron cultures were fed with anti-mouse p75NTR and anti-hAPP antibodies on ice, washed after staining, fixed, and developed with PLA reaction. Values were normalized to levels in wild type neurons and are expressed as mean PLA puncta per cell ± SEM from at least 25 neurons in 3 independent experiments.

(E) Internalization of hAPP/p75NTR PLA signals in hippocampal neurons of wild type and p75NTR mutant mice. Live neuron cultures were fed with anti-mouse p75NTR and anti-hAPP antibodies on ice, washed and plates placed at 37°C for different periods of time to allow internalization. Internalization was stopped by acid wash, followed by fixation and PLA reaction. Counterstaining for MAP2 and DAPI are also shown. Scale bar, 10μm.

(F) Kinetics of co-internalization of hAPP and p75NTR in hippocampal neurons from wild type, ΔDD and C259A mice. Show are mean ± SEM of percentage internalization of total surface PLA signal (set to 100%). N=3 independent experiments each performed in duplicate; **, P<0.01 knock-in mutants vs. WT (2-way ANOVA).

(G) Linear transformation of p75NTR internalization kinetics shown in (D).
Inactive variants of death receptor p75NTR reduce Alzheimer's neuropathology by interfering with APP internalization (2020)
Figure 8

Figure 8. Reduced 5xFAD hAPP trafficking to intracellular compartments containing BACE in neurons expressing ΔDD and C259A alleles

(A) Micrographs of triple mutant hAPP after 15min internalization (red), BACE1 immunocytochemistry (green) and their superimposition in wild type hippocampal neurons infected with 5xFAD hAPP lentivirus. DAPI and MAP2 staining are shown in the left column. Insets show higher (3.5x) magnification of the areas indicated in the main images. Scale bar, 5μm.

(B) Quantification of the proportion of BACE1 that co-localized with hAPP after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % BACE co-localized with hAPP. N=3 independent experiments, each performed in duplicate; **, P<0.01 vs. WT (one-way ANOVA followed by post hoc test).

(C) Quantification of the proportion of internalized hAPP that co-localized with BACE1 after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % internalized hAPP co-localized with BACE1. N=3 independent experiments, each performed in duplicate; *, P<0.05; **, P<0.01 vs. WT (one-way ANOVA followed by post hoc test).

(D) Micrographs of p75NTR after 15min internalization (red), Rab11 immunocytochemistry (green) and their superimposition in wild type hippocampal neurons. DAPI and MAP2 staining are shown in the left column. Insets show higher (3.5x) magnification of the areas indicated in the main merged images. Scale bar, 5μm.

(E) Quantification of the proportion of Rab11 that co-localized with p75NTR after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % Rab11 co-localized with p75NTR. n=4; *, P<0.05; **, P<0.01 vs. WT (one-way ANOVA followed by post hoc test).

(F) Quantification of the proportion of internalized p75NTR that co-localized with Rab11 after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % internalized p75NTR co-localized with Rab11. n=4; **, P<0.01 vs. WT (one-way ANOVA followed by post hoc test).

(G) Micrographs of triple mutant hAPP after 15min internalization (red), Rab11 immunocytochemistry (green) and their superimposition in wild type hippocampal neurons infected with 5xFAD hAPP lentivirus. DAPI and MAP2 staining are shown in the left column. Insets show higher (3.5x) magnification of the areas indicated in the main merged images. Scale bar, 5μm.

(H) Quantification of the proportion of Rab11 that co-localized with hAPP after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % Rab11 co-localized with hAPP. n=4; *, P<0.05 vs. WT (one-way ANOVA followed by post hoc test).

(I) Quantification of the proportion of internalized hAPP that co-localized with Rab11 after 6 and 15 min of internalization at 37°C. Results are expressed as mean ± SEM of % internalized hAPP co-localized with Rab11. n=4; *, P<0.05 vs. WT (one-way ANOVA followed by post hoc test).

Expanded View Figure Legends
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 1.

The p62 bodies in the cytoplasm of HeLa cells are ubiquitin-containing protein aggregates. (A) HeLa cells were fixed and stained for p62. The different patterns of p62 distribution were scored in >200 cells as cytoplasmic with small bodies, cytoplasmic with large and intense bodies, equal nuclear and cytoplasmic staining, and nuclear enriched. The percentage of cells in the respective groups is indicated. (B) Expression level of GFP-p62 in HeLa cells stably expressing GFP-p62 (S–GFP-p62) compared with the level of endogenous p62 in the parent HeLa cells. (C) Cells stably expressing GFP-p62 display a cytoplasmic punctuate localization of GFP-tagged p62 similar to endogenous p62. Video microscopy of live cells demonstrated that the small, faint bodies (thin arrows) displayed directed migration, whereas the majority of the larger, intense bodies (thick arrows) were nonmigratory (Videos 1 and 2, available at http://www.jcb.org/cgi/content/full/jcb.200507002/DC1). A still image from Video 1 is shown here. (D) Bodies containing either endogenous p62 or transiently or stably transfected GFP-p62 all contain polyubiquitin. HeLa cells were fixed and stained with p62 and polyubiquitin (clone FK1) mAbs directly coupled with AlexaFluor555 (red) and AlexaFluor488 (green), respectively. Cells expressing GFP-p62 were only stained for polyubiquitin (red). Bars, 20 μm.
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 2.

Both the PB1 and UBA domains are needed for p62 to form cytoplasmic bodies. (A) The indicated deletion constructs were fused COOH terminal to GFP and expressed in NIH3T3 fibroblasts. Asterisks indicate point mutations in the PB1 (D69A) and UBA (I431A) domains, respectively. (B) S–GFP-p62 cells were transiently transfected with the indicated myc-tagged p62 constructs, fixed, and stained for the myc tag. Bars, 20 μm.
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 3.

p62 bodies are found both as membrane-free protein aggregates and as membrane-confined autophagosomal and lysosomal structures. (A) Localization of bodies containing endogenous p62 or transiently expressed GFP-p62 relative to EEA1-positive early endosomes. Endogenous p62 were stained green using p62 antibodies directly labeled with AlexaFluor488, and EEA1 was stained red with EEA1 mAbs directly labeled with AlexaFluor555. Alternatively, transiently expressed GFP-p62 was expressed in HeLa cells, and EEA1 was stained red with EEA1 mAb (bottom). The boxed area is shown to the right at a higher magnification. (B) Colocalization of GFP-p62 and CD63 (stained red using a mAb) in HeLa cells stably expressing GFP-p62. (C) Immunoelectron micrograph of S–GFP-p62 stained with a GFP pAb (10-nm gold particle, arrows) and monoclonal CD63 (15-nm gold particle, arrowheads). (D) Rapid detergent extraction of GFP-p62 from LysoTracker-positive acidic organelles. HeLa cells transiently expressing GFP-p62 were labeled with LysoTracker for 60 min. The detergent extractions were imaged in a time series with 15-s time intervals after adding 1% Triton X-100. The boxed area is shown in the bottom two images at a higher magnification before and after detergent extraction. Bars (A, B, and D), 20 μm.
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 4.

p62 is found both in autophagosomes and in cytosolic aggregates/sequestosomes. (A) Immuno-EM of GFP-p62. S–GFP-p62 cells were labeled with rabbit anti-GFP (Abcam) followed by protein A–gold (15 nm). We observed labeling in membrane-free cytosolic structures and sequestosomes (arrows) as well as in endosomes (Endo). (B) Correlative immunofluorescence/EM of HeLa cells treated with 10 μM PSI for 5 h displaying typical sequestosomes. The insets show two magnifications of the sequestosome, which is labeled 1. (C) Representative image of a p62-containing autophagosome. HeLa cells transfected with GFP-p62 were immunogold labeled as in A. Note the cisternal-like membrane (arrowheads) surrounding the GFP-positive material. The arrow indicates a fused endosome.
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 5.

p62 bodies are degraded by autophagy. (A) Comparison of p62 degradation using pulse-chase labeling with 35S-methionine and immunoblotting after cycloheximide (CHX) treatment. HeLa cells were pulsed with 35S-methionine and incubated for the indicated times in nonradioactive medium. After immunopurification, the amount of radioactive p62 was determined by autoradiography, and the total amount of p62 was determined by an immunoblot of the same membrane. The p62 level in total cellular lysates after different times of 10 μg/ml cycloheximide treatment determined by immunoblotting (bottom). (B) The levels of p62 and LC3-II change with autophagic activity. HeLa or S–GFP-p62 cells were either left untreated or rapamycin (10 μg/ml) or bafilomycin A1 (Baf. A1; 10 μg/ml) was added for 18 h. Immunoblots were sequentially probed using LC3, p62, and actin antibodies. (C and D) The amount of p62 located to cytoplasmic bodies increases upon inhibition of autophagy. HeLa cells or S–GFP-p62 HeLa cells were left untreated or bafilomycin A1 was added for 18 h, the cells were fixed, and p62 was either stained red using a p62 mAb (C) or imaged directly (D). Nuclei were visualized using the Draq5 DNA stain. The settings for imaging were identical for the treated cells and the untreated control. (E) The majority of S–GFP-p62 cytoplasmic bodies are stained with antibodies recognizing transiently expressed LC3. S–GFP-p62 cells were transiently transfected with myc-LC3. Myc-LC3 was stained red using an anti-myc tag mAb. The boxed area indicates the part of the cell that is shown to the left at a higher magnification. Bars, 5 μm.
p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death. (2005)
Figure 6.

p62 is required for the formation of GFP-LC3–positive punctuated structures in HeLa cells. (A) HeLa cells transiently transfected with GFP-LC3 alone or cotransfected with siRNA against p62, HA-p62, or HA-p62 D69A were either left in normal medium or starved for amino acids for 1 h. The cells were fixed, and p62 was stained using a p62 mAb. More than 200 randomly selected cells for each condition were scored for the cytoplasmic pattern of GFP-LC3 as either diffuse or punctuate. The frequency of GFP-LC3–positive cells with punctuate localization are indicated to the right. (B) Endogenous p62 as well as coexpressed myc-tagged wild-type p62 or a UBA deletion mutant of p62 coimmunoprecipitated with GFP-LC3 from HeLa cell extracts. GFP or GFP-LC3 was immunoprecipitated from total cellular extracts after cotransfecting the indicated constructs. The cell cultures were either left untreated or starved for amino acids for 1 h as indicated. Copurified endogenous or ectopically expressed myc-tagged p62 constructs were detected using the p62 mAb. Bars, 20 μm.