1. KIF4 Motor Regulates Activity-Dependent Neuronal Survival by Suppressing PARP-1 Enzymatic Activity 
Ryosuke Midorikawa, Yosuke Takei, Nobutaka Hirokawa 
Cell 
Volume 125, Issue 2, Pages (April 2006)
DOI: /j.cell
Copyright © 2006 Elsevier Inc. Terms and Conditions

2. Figure 1 KIF4 Binds to PARP-1 with Its Tail Domain
(A) Screening of KIF4 binding protein. (a) Structural view of full length KIF4 and GST-KIF4 tail fusion proteins. Putative NLS (nuclear localization signal, amino acids no. 794–799; Lee et al., 2001) is depicted. (b) GST pull-down. P110 in 1.0 M NaCl-eluents are visualized by Coomassie brilliant blue (arrow). Each lane corresponds to sequential elution (three times in 1.0 M NaCl buffer and three times in 2.0 M NaCl buffer, respectively). (c) Negative control using only GST.
(B) Immunoprecipitation of ES cell lysates (a) and fibroblast cell lysates (b) show that KIF4 and PARP-1 form a complex. Immunoblotting of lysates is also presented in (a). IgG was used for negative control experiments in (b).
(C) In vitro binding assay. About a half of the PARP-1 is collected by the GST-KIF4 tail beads. Various amounts of PARP-1 were loaded in the left four lanes for a comparison. The presence of DNA did not affect the results.
(D) DNA pull-down using DNA-cellulose. PARP-1 binds to DNA but GST-KIF4 tail does not. FT: flow through.
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

3. Figure 2 Regulation of PARP-1 Enzymatic Activity by KIF4
(A) Effect of KIF4 tail on PARP-1 automodification. 32P-NAD-labeled PARP-1 represents the automodification of PARP-1, which is inhibited by the addition of GST-KIF4 tail (upper panel). Activated calf-thymus DNA (Scovassi et al., 1984) was added to each sample. Immunoblotting using anti-PARP-1 and anti-GST antibodies is shown in the middle and lower panels.
(B) Overexpression of deletion mutants. (a) Structure of GFP-fusion proteins. (b) Fluorescent images of transfected cells. Bar = 10 μm. (c) Immunolabeling of transfected cells with anti-poly (ADP-ribose) (PAR) antibody after PARP-1 activation by DNA damage. Bar = 10 μm. (d) Measurement of fluorescence intensities using anti-PAR antibody. A total of 300 transfected cells in three independent experiments were examined. Mean ± SEM is presented (∗∗∗p < 0.001; t test). (e) Biochemical measurement of PARP-1 activity of lysates of transfected cells. The transfection efficiency of each vector was adjusted to about 35%. Each value was calculated from three independent experiments. Mean ± SD is presented (∗p < 0.05; t test).
(C) PARP-1 activity of kif4+/Y and kif4−/Y ES cells before and after PARP-1 activation by H2O2-induced DNA damage. Three independent kif4−/Y ES cell clones were analyzed. Data were collected from five experiments. Mean ± SEM is presented (∗p < 0.05; t test).
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

4. Figure 3 Neuronal Cell Death after Removal of Trophic Factors
(A) Phase contrast images and MAP2 immunolabeling of neurons at 1 and 6 days after removal of trophic factors. Bars = 20 μm.
(B) Percentage of apoptotic cells. Two days after deprivation of trophic factors with various stimuli as denoted at the bottom of the graph, the numbers of cells with condensed chromatin (shown in the upper panels; bars = 5 μm) per 1000 cells were counted. Three independent kif4−/Y clones were analyzed. Values (mean ± SD) were calculated from three experiments.
(C and D) PARP-1 activity of kif4+/Y and kif4−/Y neurons.
(C) PARP-1 activity of cell lysates collected 1 day after deprivation of trophic factors. After treatment with 50 mM KCl for 5min, the PARP-1 activity of kif4+/Y cell lysates significantly increases (∗p < 0.05; t test). In contrast, the PARP-1 activity of kif4−/Y neurons was significantly higher than that of kif4+/Y before stimulation (∗p < 0.05; t test), and is unchanged by KCl treatment. Addition of 3-AB suppresses PARP-1 activity. Mean ± SD is presented. Data were accumulated from five independent experiments.
(D) Immunolabeling of MAP2-positive cells with anti-PAR antibody before and after treatment with 50 mM KCl for 5 min. Fluorescence intensities of poly (ADP-ribose) labeling are higher in kif4−/Y cells than in kif4+/Y cells before treatment with KCl (arrowheads). Bars = 10 μm.
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

5. Figure 4 Knockdown by RNAi (A–D) Knockdown of PARP-1.
(A) Immunostaining of CGCs at 2.5 days after the transfection of siRNAs is denoted in the panels. Control in (a) means a condition without siRNA. The percentages of PARP-1-positive cells are denoted at the bottom of the panels. Values (mean ± SD) were calculated from three experiments. The differences between (a) and (b) and between (b) and (c) are statistically significant (p < 0.001; t test). Bars = 20 μm.
(B) Immunoblotting of lysates. Values denoted at the bottom are the relative intensity of PARP-1 immunoreactivity calculated from three independent experiments. (∗p < 0.05; t test).
(C) DAPI-staining of CGCs transfected with siRNAs. At day 2 after transfection, trophic factors were removed and cells kept in the conditions denoted at the bottom of panels for 4 days. Apoptotic cells are indicated by arrowheads. Bars = 20 μm.
(D) Percentage of apoptotic cells. Values (mean ± SD) were calculated from three independent experiments. (∗∗p < 0.01; t test).
(E–J) Knockdown of KIF4.
(E) Immunoblotting of lysates. Values denoted at the bottom are the relative intensity of KIF4 immunoreactivity calculated from three independent experiments. (∗p < 0.05; t test).
(F) Immunolabeling by anti-PAR antibody for CGCs transfected with siRNA denoted at the top of each panel and subjected to various stimuli for 10 min denoted at the bottom. Control means without siRNA. White line circles indicate nuclei. Bars = 20 μm.
(G) CMFDA labeling and phase-contrast images of CGCs transfected with siRNAs targeted for KIF4. At 1 day after transfection, survival assay was started and cells were kept under the various conditions denoted at the bottom of the panels for 7 days. Bars = 20 μm.
(H) Statistical analysis of PAR-positive cells in nuclei after various stimuli denoted at the bottom of panel. Nuclear positive cells per 200 cells were counted for each experiment. Mean ± SD calculated from three experiments is presented. (∗∗p < 0.01; t test).
(I and J) Percentages of living cells cultured under the various conditions for 7 days are denoted at the bottom of the panels. Values (mean ± SD) were calculated from three independent experiments. (∗p < 0.05 and ∗∗p < 0.01; t test).
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

6. Figure 5
KIF4 Is Dissociated from PARP-1 and Moves to Neurites after Membrane Depolarization
(A) Before and after incubation with 25 mM KCl for 15 min, both kif4+/Y and kif4−/Y neurons were labeled with 5 μM Rhod2-AM, a calcium-sensitive fluorescent dye. White line circles show the area of nuclei. Bars = 10 μm.
(B) Effect of VSCC blocker nicardipine (Nic) on KCl-dependent survival of MAP2-positive cells. (a) Survival of MAP2-positive cells. (b) Percentages of apoptotic cells (mean ± SD) were calculated from three experiments using DAPI staining (∗p < 0.05; t test).
(C–E) Activity-dependent dissociation of KIF4 from PARP-1.
(C) Effect of the automodification of PARP-1 on its binding to KIF4. Activated calf-thymus DNA (Scovassi et al., 1984) was added to each sample. (a) PARP inhibitors (DPQ and DHIQ) inhibit the 32-P-NAD-labeling of PARP-1 (upper panel). Immunoblotting using anti-PARP-1 antibody (lower panel). (b) Binding of PARP-1 with GST-KIF4 tail. Automodified PARP-1 does not bind to KIF4 tail.
(D) (a) Interaction between KIF4 and PARP-1 in depolarized neurons. After depolarization in the presence or absence of BAPTA-AM, lysates were collected and immunoprecipitation performed using anti-PARP-1 antibody. (b) The KIF4/PARP-1 ratio of the intensity of the immunoblots (mean ± SD; ∗p < 0.05; t test).
(E) Increased automodification of PARP-1 in depolarized neurons. 32-P-NAD-labeled PARP-1 is immunoprecipitated.
(F) Immunolabeling of neurons with KIF4 (a–d) and PARP-1 (e and f) antibodies before and after depolarization. (a) Cells before depolarization. (b) Cells treated with 50 mM KCl. Immunoreactivity of KIF4 in neurites is indicated by arrowheads. (c) Cells treated with 50 mM KCl + 6 μM BAPTA-AM (a calcium chelator). (d) Cells treated with 50 mM KCl + 50 μM DHIQ. In (c) and (d), redistribution of KIF4 was inhibited. (e and f) Immunolabeling of neurons before (e) and after (f) depolarization using anti-PARP-1 antibody.
(G) (a and b) Nocodazol (Noc)-treated cells were incubated with 50 mM KCl for 25 min and immunolabeled by anti-KIF4 antibody. Nocodazol treatment decreases KIF4 immunoreactivity in neurites (arrowheads in [b]). CMFDA labeling in (a) and (b) demonstrates that nocodazol treatment did not affect cell viabilities. (c and d) Effect of nocodazol. Neurons treated with 2.5 μM nocodazol for 1 hr show an intermittent disruption of microtubules in neurites (d, arrowheads).
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

7. Figure 6
CaMKII Mediates Depolarization-Dependent PARP-1 Activation and Dissociation of the KIF4/PARP-1 Complex
(A–C) Electrical stimulation applied to CGCs.
(A) Calcium imaging using fluo-4 AM for CGCs before and after stimulation is denoted at the top of each panel. Bars = 10 μm.
(B) Immunolabeling by anti-PAR antibody after subjecting to the stimuli denoted at the top of each panel. Bars = 10 μm. Values mean percentages of nuclear positive cells per 200 cells. Mean ± SD calculated from three experiments is presented. (a and b: ∗∗p < 0.01; b and c: ∗∗p < 0.01; t test).
(C) Cellular localization of KIF4 after field stimulation. KIF4 was immunolabeled after subjecting to the various stimuli denoted at the top of each panel. The elevated immunoreactivity of KIF4 in neurites is indicated by arrowheads. Values mean percentages (mean ± SD) of cells with illuminated neurites per 200 cells calculated from three experiments. (a and b: ∗∗p < 0.01; b and c: ∗∗p < 0.01; t test). Bars = 10 μm.
(D) CaMKII-dependent phosphorylation of PARP-1 in CGCs. (a) Labeling of PARP-1 with [32P]-orthophosphate before and after depolarization (upper panel). The phosphorylation of PARP-1 was blocked by KN-62. Bottom panel shows immunoblotting of immunoprecipitates using anti-PARP-1 antibody. (b) Automodification of PARP-1. Cells were subjected to the various stimuli denoted at the top of the panel, and lysates were immunoprecipitated using anti-PAR antibody and immunoblotted with anti-PARP-1 antibody. (c) KIF4 is dissociated from PARP-1 after KCl treatment. KN-62 blocks this dissociation.
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions

8. Figure 7
Overexpression of Headless KIF4 Promotes Neuronal Cell Death in Developing Brain
(A–F) In utero electroporation of KIF4 expression vectors.
(A) Construction of the expression vectors. Headless or tailless kif4 genes were inserted in the downstream of the CAG promoter for bicistronic coexpression with GFP. MCS: multicloning sites.
(B) A typical view of GFP expression in cerebrum transfected with the headless kif4 construct. Coronal section of whole brain at 3 days after electroporation (postnatal day 1) is shown. Bars = 100 μm.
(C) Coexpression of GFP with KIF4. KIF4 is illuminated by immunolabeling with anti-KIF4 polyclonal antibody. Bars = 10 μm.
(D) GFP-positive cells in brain sections transfected with headless kif4 (a and b) or tailless kif4 (c and d). Sections photographed at 3 (a and c) and 8 (b and d) days after electroporation are shown. Bars = 10 μm.
(E) Statistical analysis. An area of about 3.8 mm2 of each section was examined and the mean number (mean ± SD) of GFP-positive cells per 0.21 mm2 (corresponding to a visual field of 20× objective) are shown. To calculate each point on the graph, 18 sections obtained from two independent electroporation were examined. ∗∗∗p < 0.001; t test.
(F) Cellular morphology of GFP-positive neurons. GFP signal (left panels), DNA labeling (middle panel), and merged (right panel) of sections transfected with headless (a) and tailless (b) kif4 genes. Arrowheads show nucleus with condensed chromatin. Values at the bottom of the middle panels mean percentages (mean ± SD) of GFP-positive cells with condensed chromatin. Forty cells observed in 18 sections (obtained from two electroporations) were used to calculate each value. The difference between the values was statistically significant, ∗∗p < 0.01; t test). Bars = 10 μm.
(G) Schematic model of the involvement of KIF4 in the regulation of the survival of developing neurons. (1) KIF4 binds to PARP-1 and inhibits PARP-1 activity. (2) After membrane depolarization, elevated Ca2+ activates CaMKII, which phosphorylates PARP-1. (3) PARP-1 is automodificated (Homburg et al., 2000). (4) KIF4 is dissociated from poly ADP-ribosylated PARP-1 and moves into neurites. Upregulated PARP-1 activity promotes expression of genes and modifies nuclear proteins to support cell survival.
Cell  , DOI: ( /j.cell )
Copyright © 2006 Elsevier Inc. Terms and Conditions