EMBO/soda-nel huggingface dataset:
Coordinated regulation of autophagy by p38α MAPK through mAtg9 and p38IP (2009)
Figure 5

The role of p38IP in p38α‐dependent inhibition of autophagy. (A) 293/GFP–LC3 cells were pre‐treated with 10 μM anisomycin for 30 min before incubation in either full medium or EBSS. Cell lysates were analysed by SDS–PAGE for GFP–LC3 lipidation using an anti‐LC3 antibody. The membrane was also probed with anti‐β tubulin. The GFP–LC3 lipidation was quantified as the amount of GFP–LC3II/GFP–LC3I (data are represented as mean±s.e.m. of triplicates, P=0.0091, Student's t‐test). (B) HEK293A cells labelled with [14C]valine, as described in Material and Methods section, were pretreated with 10 μM anisomycin for 30 min before incubation in either full medium, EBSS, or EBSS with leupeptin for 2 h. Cells were then analysed for long‐lived protein degradation (data are represented as mean±s.e.m. of triplicates, representative of two experiments, EBSS untreated versus anisomycin treated (P=0.0363); EBSS untreated versus leupeptin treated (P=0.0001), Student's t‐test). (C) HEK293 cells were transfected with control siRNA or siRNA for p38IP. After 24‐h incubation, control or p38IP‐depleted cells were pre‐treated with anisomycin, followed by a 2‐h incubation with full medium, full medium with leupeptin, EBSS, or EBSS with leupeptin. Cell lysates were analysed with anti‐p38α or anti‐LC3 antibodies. LC3II/LC3I levels were quantified and presented normalized to control, untreated cells incubated in EBSS. Data are representative of two experiments. (D) HEK293A cells transiently transfected with HA‐p38IP and RFP‐mAtg9 were treated with anisomycin for 30 min and mAtg9 was immunoprecipitated. 5% of the lysates or the immunoprecipitates were probed with anti‐HA and anti‐mAtg9 antibodies (data is representative of 3 experiments, *P=0.0332).
Coordinated regulation of autophagy by p38α MAPK through mAtg9 and p38IP (2009)
Figure 6

Overexpression of p38α inhibits autophagy and competes with mAtg9 for binding to HA–p38IP. (A) HEK293A cells were transfected with RFP–mAtg9 and Flag–p38 (lanes 2 and 7), RFP–mAtg9, Flag–p38 and HA–p38IP (lanes 3 and 8), or RFP–mAtg9 and HA–p38IP (lanes 4 and 9). RFP–mAtg9 was immunoprecipitated with an anti‐mAtg9 antibody, the co‐immunoprecipitated HA–p38IP was detected with an anti‐HA antibody, and co‐immunoprecipitated Flag–p38 was detected with an anti‐Flag antibody. RFP–mAtg9 was detected with an anti‐Atg9 antibody. (B) HEK293A cells were transfected with RFP–Atg9 and HA–p38IP (lanes 1 and 5), RFP–mAtg9, Flag–p38, and HA–p38IP (lanes 2 and 6), or Flag–p38 and HA–p38IP (lanes 3 and 7). HA–p38IP was immunoprecipitated with an anti‐HA antibody, the co‐immunoprecipitated RFP–Atg9 was detected with an anti‐Atg9 antibody, and co‐immunoprecipitated Flag–p38 was detected with an anti‐p38α antibody. HA–p38IP was detected with an anti‐HA antibody. (C) HEK293A cells were transfected with Flag–p38α for 24 h. Cells were incubated in either full medium, EBSS, or EBSS plus leupeptin for 2 h, lysed, and analysed for endogenous LC3 lipidation using an anti‐LC3 antibody, and immunoblotted with anti‐Flag antibody. LC3 lipidation was quantified as the amount of LC3II/LC3I (data are represented as mean±s.e.m. of triplicates, n=2 experiments, EBSS control versus EBSS with Flag‐p38α, ***P=0.0026).
Coordinated regulation of autophagy by p38α MAPK through mAtg9 and p38IP (2009)
Figure 7

p38α requires p38IP for inhibition of autophagy. (A) 293/GFP–LC3 cells were transfected with control or p38α siRNA. At 72 h after transfection, cells were incubated in either full medium, EBSS, or EBSS with leupeptin for 2 h, then fixed and visualized by confocal microscopy. Bars=5 μm (data are represented as mean±s.e.m. n=60 cells, EBSS control versus p38α siRNA (***P=0.0001); EBSS with leupeptin control versus p38α siRNA (***P=0.0001), Student's t‐test). (B) HEK293A cells were transfected with control or p38α siRNA. At 72 h after transfection, cells were incubated in either full medium, EBSS, or EBSS containing leupeptin for 2 h. Cells lysates were analysed for LC3 lipidation using an anti‐LC3 antibody. The membrane was also probed with anti‐actin and anti‐p38α antibodies. LC3 lipidation was quantified as the amount of LC3II/LC3I (data are represented as mean ±s.e.m. n=5, full medium control versus p38α siRNA (**P=0.0056); EBSS control versus p38α siRNA (**P=0.048); EBSS with Leu control versus p38α siRNA (**P=0.04), Student's t‐test). (C) HEK293A cells were transfected with control or p38α siRNA. At 72 h after transfection, cells were incubated in either full medium or EBSS for 2 h, then fixed and immunostained to detect endogenous mAtg9 localization. The percentage of cells with dispersed mAtg9 was quantified as in Figure 2E (data are represented as mean±s.e.m. n=200 cells, full medium control versus p38α siRNA (**P=0.0027); EBSS control versus p38α siRNA (*P=0.0459); Student's t‐test). Bars=5 μm (D) HEK293A cells were transfected with siRNA for p38α, homogenized and subjected to centrifugation, and the resulting post‐nuclear supernatant (PNS) was fractionated by centrifugation at 100 000 g into membrane pellet and cytosol as in Figure 2A. Equal protein amounts were resolved by SDS–PAGE and immunoblotted with anti‐MPR, anti‐HA, and anti‐p38α antibodies. Data are representative of four experiments. (E) HEK293A cells were transfected with control, p38α siRNA or both p38α siRNA, and p38IP siRNA. At 72 h after transfection, cells were incubated in either full medium, full medium with leupeptin, EBSS, or EBSS with leupeptin for 2 h. Cells lysates were analysed for LC3 lipidation using an anti‐LC3 antibody. The membrane was also probed with anti‐p38α. LC3 lipidation was quantified as the amount of LC3II/LC3I. Data are representative of two experiments.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 1

HDAC6 KO MEF cells are defective in aggregate clearance but not in autophagosome induction or targeting. (A) Filter‐trap analysis of MG132‐induced, SDS‐insoluble ubiquitinated aggregates generated in wild‐type (WT), HDAC6 KO, and KO MEFs reconstituted with different HDAC6 constructs as indicated. The signal intensity from the ubiquitin immunoblot (bottom panel) was quantified and presented as the average of the means from three independent experiments along with the standard deviation (top). Note the significant accumulation of ubiquitin‐positive aggregates in HDAC6 KO MEFs and KO MEFs stably expressing HDAC6‐CD and ΔBUZ mutants. WT, HDAC6 KO, and HDAC6 KO MEFs stably expressing human HDAC6 (hHDAC6 WT), HDAC6 CD (catalytically inactive mutant), or HDAC6 ΔBUZ (ubiquitin‐binding‐deficient mutant) were analysed for the level of HDAC6 using an anti‐human HDAC6 antibody. Mouse endogenous HDAC6 (mHDAC6) and actin levels were determined by each corresponding antibody. (B) WT and HDAC6 KO MEFs were treated with MG132 and subjected to Western blot analysis for LC3, actin, and HDAC6. (C) Cells were treated with MG132 as described under Materials and methods and immunostained with antibodies to ubiquitin (green) and LC3 (red). Arrows indicate ubiquitin‐positive aggregates that colocalize with LC3‐positive autophagosomes. Scale bar, 10 μm. (D) WT and ATG5 KO MEFs are treated with 2.5 μM MG132 for 1 day and incubated with normal growth media for 18 h. MEFs are immunostained with anti‐LC3 (red) and anti‐ubiquitin antibody (green).
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 2

HDAC6 is required for efficient lysosome–autophagosome fusion. (A) Wild‐type and HDAC6 KO MEFs were transfected with pcDNA, pcDNA‐HDAC6WT, HDAC6CD, or HDAC6ΔBuz, along with mCherry‐GFP‐LC3 as indicated. Yellow signals indicate non‐acidic autophagosomes and red signals indicate acidic autophagolysosomes. Scale bar, 10 μm. (B) The total number of yellow vesicles was quantified from three independent experiments (>12 cells each) and presented as the percentage of total mCherry‐GFP‐LC3 dots (red plus yellow) along with the standard deviation. (C) In vitro fusion assays. Autophagosomes (APGs) and lysosomes (Lys) purified from wild type and HDAC6−/− MEFs were subjected to heterotypic and homotypic in vitro fusion assays (representative fields are shown in Supplementary Figure S3). Values are means+s.e. of the percentages of fusion from three independent experiments (more than 10 images per each experiment). (D) EM images of wild‐type and HDAC6 KO MEFs in normal growth conditions. Yellow arrows, autophagosomes; red arrows, autophagolysosomes; green arrowheads, multilamellar bodies. (E) Quantification of autophagosomes and autophagolysosomes. The error bar represents the standard error.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 3

HDAC6 is not required for starvation‐induced autophagy. (A) Autophagosome–lysosome fusion is analysed in wild‐type and HDAC6 KO MEFs with or without starvation (6 h) using mCherry‐GFP‐LC3 as described in Figure 2A. (B) Wild‐type and HDAC6 KO MEFs were cultured in Hank's solution for 3 h followed by immunoblotting with an antibody for LC3, HDAC6, and GAPDH. (C) Long‐lived protein degradation in wild‐type and HDAC6 KO MEF cells. The degradation of [14C]‐valine labelled long‐lived protein was measured in the presence or absence of 3‐methyl adenine (3MA, inhibits the formation of autophagic vacuoles). The average of percentage degradation from three independent experiments is presented. The error bar represents the standard deviation.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 4

Actin remodelling is required for autophagosome–lysosome fusion under basal conditions. (A) Wild‐type and HDAC6 KO MEFs were treated with MG132 and immunostained with antibodies to Lamp‐1 (a lysosome marker, red) and ubiquitin (green) as indicated. F‐actin was detected by phalloidin (blue). The arrows indicate ubiquitin‐positive aggregates that are surrounded by F‐actin and Lamp‐1. (B, C) Wild‐type and HDAC6 KO MEFs were transfected with mCherry‐GFP‐LC3, followed by treatment with LatA (100 nM) or nocodazole (250 nM) for 6 h and analysed as described in Figure 3A. (D) Autophagosomes (APGs) and lysosomes (Lys) isolated from fed mouse hepatocytes were treated or not with latrunculin (LatA) as indicated, extensively washed to remove traces of the inhibitor, and then labelled with the antibody and subjected to in vitro fusion assay in the presence or absence of purified actin. The number of total fusion events/total number of vesicles for each condition was as follows: 176/880; 233/1110; 84/930; and 180/950. The differences with untreated samples were significant at **P0.01. (E) Autophagosomes (APGs) and lysosomes (Lys) isolated from fed or starved mouse hepatocytes were treated or not with latrunculin (LatA) as labelled and subjected to in vitro fusion assay. The differences with untreated samples were significant at *P0.05. The number of total fusion events/total number of vesicles for each condition was as follows: 169/1250; 87/972; 190/1120; and 175/1165. (F) Autophagosomes (APGs) and lysosomes (Lys) isolated from HDAC6 KO MEFs were treated or not with latrunculin (LatA) as indicated and subjected to in vitro fusion assay.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 5

Autophagosomes are required for actin remodelling at protein aggregates. (A) Biochemical characterization of autophagic compartments isolated from HDAC6 KO cells. Different subcellular fractions (75 μg protein) isolated from the wild type (WT) were subjected to SDS–PAGE and immunoblotting for the indicated proteins. Hom, homogenate; APG, autophagosomes; APL, autophagolysosomes; Lys, lysosomes. (B) Autophagosomes (APGs) and lysosomes (Lys) isolated from fed cells were treated or not with latrunculin (LatA) as labelled and subjected to in vitro fusion assay. The differences with untreated samples were significant at **P0.01. (C) WT and ATG5 KO MEFs were treated with MG132 and immunostained with antibodies to ubiquitin (green) as indicated. F‐actin was detected by phalloidin (red). The arrows indicated ubiquitin‐positive protein aggregates.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 6

Cortactin is recruited to protein aggregates and required for efficient autophagosome–lysosome fusion in homeostatic autophagy. (A) Wild‐type and HDAC6 KO MEFs were treated with MG132 and immunostained with antibodies against cortactin (red), ubiquitin (green), and phalloidin for F‐actin (blue) as indicated. The arrows indicated ubiquitin‐positive aggregates that were colocalized with F‐actin and cortactin. (B) Wild‐type MEFs were transfected with control or cortactin siRNA, treated with MG132, and stained with antibodies for Lap‐1 (red, to label lysosome), or ubiquitin (green) and phalloidin for actin (blue). Note that F‐actin staining at protein aggregates was lost, but lysosomes remained concentrated in cortactin knockdown cells (arrow). (C) Wild‐type MEFs were transfected with control or cortactin siRNA, treated MG132 2.5 μM for 18 h, and subjected to filter‐trap assay using a ubiquitin antibody. The knockdown level of endogenous cortactin was confirmed by immunoblotting using an antibody against cortactin and GAPDH in the right panel. (D) U2OS cells were transfected with control siRNA and cortactin siRNA. Autophagosome–lysosome fusion was analysed with or without starvation (6 h) using the mCherry‐GFP‐LC3 reporter as described in Figure 3A. (E) The mCherry‐GFP‐LC3 plasmid was cotransfected with wild type, 9KQ (acetylation‐mimic), or 9KR (deacetylation‐mimic) cortactin‐expressing plasmids into wild‐type MEFs. Autophagosome–lysosome fusion was analysed as described in Figure 3A.
HDAC6 controls autophagosome maturation essential for ubiquitin‐selective quality‐control autophagy (2009)
Figure 7

HDAC6 KO mouse and knockdown fly developed spontaneous neurodegeneration and protein aggregate accumulation. (A) HDAC6 KO mice accumulate ubiquitin‐positive protein aggregates in the brain. The hippocampus and cerebral cortex regions from 6‐month‐old wild‐type and HDAC6 KO littermates were subjected to immunostaining with a ubiquitin antibody and counterstained with hematoxylin. The red arrows indicate ubiquitin‐positive neuritic aggregates and black arrows indicate cytoplasmic aggregates. These ubiquitin‐positive structures were rarely observed in control littermates. Scale bar, 50 μm (B) Apoptotic cell death in the cortex and hippocampus region of HDAC6 KO mice as determined by TUNEL staining. Apoptotic cells were only observed in HDAC6 KO mice. Scale bar, 100 μm. (C) HDAC6 depletion in the Drosophila eye leads to ubiquitin‐positive pathology. Immunostaining for ubiquitin (green) in frontal eye sections of 1‐day‐old (d1) and 30‐day‐old (d30) fly eyes. The eyes of HDAC6‐depleted flies (GMR:GAL4/UAS‐HDAC6RNAi) developed ubiquitin‐ positive cytoplasmic inclusions that become more prominent at day 30 (d30). Blue, DAPI. (D) Depletion of HDAC6 in the Drosophila eye leads to age‐dependent degeneration. Light micrographs (left) and corresponding Richardson‐stained frontal eye sections (right) of 1‐day‐old and 30‐day‐old fly eyes. The eyes of control flies (GMR:GAL4/+) and HDAC6‐depleted flies (GMR:GAL4/UAS‐HDAC6RNAi) show normal highly organized ommatidial array at day 1; 30‐day‐old control animals also show no defects, but 30‐day‐old HDAC6‐depleted flies show degeneration with disorganization of the ommatidial array and loss of normal eye architecture ( × 40 and × 80).
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 1

SENP3 is associated with PELP1, TEX10 and WDR18. (A, B) Flag‐SENP3 or HA‐PELP1 was expressed in HeLa cells as indicated. Proteins were captured on Flag‐ or HA‐beads and immunoblotted using antibodies directed against endogenous PELP1 or SENP3 as indicated. (C) Endogenous PELP1 was immunoprecipitated from HeLa cells with a rabbit polyclonal antibody and immunocomplexes were probed for the presence of SENP3 by western blotting with an anti‐SENP3 antibody. (D–F) Flag‐ or HA‐tagged proteins were expressed in HeLa cells, captured on Flag‐ or HA‐beads and subjected to immunoblotting as indicated. In all experiments, the inputs represent 2.5% of the total cell lysate.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 2

WDR18 and TEX10 co‐immunoprecipitate with PELP1. (A, B) Flag‐PELP1 and HA‐WDR18 were expressed in HeLa cells as indicated. HA‐WDR18 was captured on HA‐beads and the bound material was probed by immunoblotting for the presence of ectopically expressed Flag‐tagged PELP1 or endogenous PELP1 as indicated. (C) Endogenous PELP1 was immunoprecipitated from HeLa cells with a rabbit polyclonal antibody and immunocomplexes were probed for the presence of endogenous WDR18 by western blotting with an anti‐WDR18 antibody. (D) Flag‐TEX10 was expressed with HA‐PELP1 in HeLa cells, captured on Flag‐beads and proteins were immunoblotted as indicated. (E) HA‐TEX10 was expressed, captured on HA‐beads and associated proteins were probed for the presence of endogenous WDR18 using immunoblotting. The inputs represent 2.5% of the total cell lysate. (F) Scheme of mutual interactions between PELP1, TEX10, WDR18 and SENP3.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 3

PELP1 localizes to the granular region of the nucleolus. (A–C) Immunofluorescence staining of endogenous PELP1, SENP3, UBF1 and NPM1 in HeLa cells. Nuclei were visualized using DAPI staining.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 4

PELP1, TEX10, WDR18 and MDN1 are involved in ribosome biogenesis. (A) Diagram summarizing the main steps of rRNA processing. (B) HeLa cells were transfected with siRNA duplexes targeting PELP1, TEX10, WDR18, MDN1 or a control siRNA as indicated. Downregulation of the respective proteins was analysed by western blotting as indicated (WB, three lower panels). At 72 h after transfection, cells were pulse labelled with 32P‐orthophosphate for 1 h and chased for 2.5 h. RNA was separated on a denaturing agarose gel and detected by ethidium bromide (EtBr) staining and autoradiography after drying of the gel. (C) The signal intensities of the 28S and 32S rRNA forms were quantified by phosphoimager analysis and the ratio of 28S:32S rRNA was calculated. Values represent the average of four (two for siMDN1) independent experiments. Error bars indicate s.d. (D) PELP1 is associated with ITS2‐containing RNA species. Endogenous PELP1 was immunoprecipitated from HeLa cells. In total, 10% of the immunoprecipitated material was analysed by western blotting (lower panel). The remaining material was used for RNA isolation and cDNA synthesis. The cDNA was used as template for PCR amplification using primers within the ITS2/28S region or GAPDH as a control. Input corresponds to 10% of the cell lysate. Vertical line in the upper panel indicates removal of irrelevant adjacent lanes. (E) Pre‐ribosomal particles were separated by sucrose gradient centrifugation of nuclear extracts. Proteins were recovered from the fractions by TCA precipitation and further analysed by SDS–PAGE and western blotting using antibodies as indicated. Vertical lines solely indicate loading onto two separate gels. (F) Nucleolar export of pre‐60S particles is strongly compromised in cells depleted of PELP1, TEX10, WDR18, MDN1 or SENP3. HeLa cells expressing YFP‐RpL27 from a tetracycline‐inducible promoter were transfected with the indicated siRNAs. After 24 h, expression of YFP‐RpL27 was induced and 72 h later the localization of RpL27 was monitored. Pictures were taken using identical exposure times.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 5

PELP1 is modified by SUMO in a SENP3‐controlled process. (A) HA‐PELP1 was expressed alone or in combination with SUMO1 or SUMO2 in the presence or absence of SV5‐tagged SENP3 in HeLa cells. Expression of the respective proteins was verified by western blotting. Detection of β‐tubulin served as loading control. (B) SUMO modification of endogenous PELP1 was monitored by anti‐PELP1 immunoblotting in HeLa cells transfected with siRNAs as indicated. Depletion of the respective proteins was verified by western blotting. (C) HeLa cells were transfected with siRNAs and plasmids as indicated. His‐SUMO conjugates were recovered on Ni‐NTA beads and subjected to western blotting using anti‐PELP1 antibodies. (D) HA‐PELP1 or HA‐PELP1K826R was expressed in the presence of SUMO1 or SUMO2 in HeLa cells. Expression of the respective proteins was analysed by western blotting. Detection of β‐tubulin served as loading control. (E, F) Flag‐p14ARF and SUMO were expressed in HeLa cells and SUMO modification of ectopically expressed HA‐PELP1 or endogenous PELP1 was monitored by immunoblotting with anti‐HA or anti‐PELP1 antibodies as indicated. Arrowheads indicate SUMO–PELP1 conjugates.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 6

Nucleolar partitioning of PELP1 is controlled by the SUMO system. (A) Flag‐SUMO2 was expressed in HeLa cells by transient transfection. Flag‐SUMO2‐expressing cells were visualized by indirect immunofluorescence. The localization of endogenous PELP1 was monitored in Flag‐SUMO2‐positive cells (green arrowheads) or untransfected cells (white arrowheads) using anti‐PELP1 antibody. (B–D) HeLa cells were transfected with siRNAs as indicated. After fixation and permeabilization, the localization of PELP1, LAS1L, TEX10 or PES1 was monitored by indirect immunofluorescence using the corresponding antibodies. (E) HeLa cells were depleted of endogenous PELP1 and reconstituted with siRNA resistant constructs expressing either wild‐type HA‐tagged PELP1 or a Flag‐tagged PELP1–SUMO2 fusion protein. The localization of the respective proteins was monitored by indirect immunofluorescence using either anti‐HA‐ or anti‐Flag‐antibodies. (F) The localization of LAS1L or SENP3 was analysed in cells expressing Flag‐PELP1–SUMO2. Indirect immunofluorescence was done using anti‐LAS1L or anti‐SENP3 antibodies. Nuclei were counterstained with DAPI.
The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex (2011)
Figure 7

LAS1L is modified by SUMO in a SENP3‐controlled manner. (A) LAS1L was generated by in vitro transcription/translation and incubated with recombinant E1 and E2 enzymes and SUMO1 or SUMO2, respectively, in the presence of ATP. In the control reaction (lane 1) SUMO was not added. (B) HeLa cells were transfected with siRNAs and plasmids as indicated. Expression of the respective proteins was verified by western blotting. Detection of β‐tubulin served as loading control. (C) HeLa cells were transfected with siRNAs and plasmids as indicated. His‐SUMO2 conjugates were captured on magnetic Ni‐NTA beads and subjected to western blotting using anti‐LAS1L antibodies. Vertical lines indicate removal of irrelevant neighbouring lanes from the initial gel (see Supplementary Figure 14).