Cyclin D1 controls development of cerebellar granule cell progenitors through phosphorylation and stabilization of ATOH1 (2021)
Figure 5

Figure 5 Prox1 suppresses CCND1 with HDAC activity

A. Immunostaining of P5 cerebellum with indicated antibodies.

B-D. Overexpression analysis of PROX1. (B, C) Prox1 expression plasmids were introduced to mouse P5 EGL and immunostaining for CCND1 (magenta) was performed the following day. Nuclei of electroporated cells were detected with GFP (green). Images of Control (B), PROX1 overexpression (C). Arrow heads indicates the CCND1 positive cells. White lines are representing as pial surfaces. (D) The proportion of CCND1-positive cells among the electroporated cells. Bars and error bars are representing as Mean ± SEM. Student T-test between Control (N=3) and PROX1 overexpression (N=3). **p < 0.01. Number of cells 382, 147 and 88 cells from N=3 mice (control), 187, 108 and 94 cells from N=3 mice (Prox1 OE).

E-G. Prox1 acute KO analysis. (E, F) Expression plasmids of Cre recombinase were introduced to P5 EGL of Prox1fl/fl mice and immunostaining for CCND1 (magenta) was performed at P8. Nuclei of electroporated cells were labeled with GFP (green). Images of H2B-GFP electroporation (E, Control), Cre electroporation (F, Cre). Arrows indicate the cells of interest where GFP signals are co-localized with CCND1. (G) The proportions of CCND1+ cells among the electroporated cells. Bars and error bars are representing as Mean ± SEM. Student T-test between Control (N=3) and Cre (N=3). **p < 0.01. Number of cells: 238, 129 and 529 cells from N=3 mice (Control), 169, 210 and 216 cells from N=3 mice (Cre).

H-K. Rescue experiment of Prox1 with Ccnd1 and Cdk4-expressing plasmids. (H-J) Prox1 expressing plasmids were introduced with Ccnd1 and Cdk4 expression plasmids (Prox1+4D) to P5 EGL together with H2B-GFP plasmid. Immunostaining for ATOH1 (magenta) was performed the following day. Nuclei of electroporated cells were detected by GFP (green). Arrows indicate the cells of interest where GFP signals are co-localized with ATOH1. (K) Proportions of ATOH1+ cells (AT+GCPs) among the electroporated cells. The Tukey-Kramer test was performed on Control (N=6), Prox1 (N=3) and Prox1+4D (N=4) mice. **p < 0.01, *p <0.05, N.S.: Not Significant. Bars and error bars are representing as Mean ± SEM. Control value is the same as Fig 2G,K. Number of cells: 54, 72 and 59 cells from N=3 mice (Prox1), 26, 53, 68 and 53 cells from N=4 mice (Prox1+4D).

L. ChIP assay in P7 mouse cerebellum with anti-Prox1 or goat IgG as a negative control. Primer set used in this experiment was designed to amplify Ccnd1 promoter region.

M-R. Administration of Valproic acid (VPA) to electroporated mice. (M) Expression plasmids of Prox1 were introduced to P5 EGL and VPA or Saline was administered intraperitoneally 2 days after electroporation. Immunostaining for CCND1 (magenta) was performed the day following the last VPA treatment. Nuclei of electroporated cells were detected with GFP (green). Arrows indicate the cells of interest where GFP signals are co-localized with CCND1. (N-Q) Images of H2B-GFP with Saline (N), PROX1 with Saline (O), H2B-GFP with VPA (P), and PROX1 with VPA (Q). (R) The relative proportions of CCND1+ cells among the electroporated cells (normalized to the Control). Tukey-Kramer test among Control+saline (N=4), PROX1+saline (N=3), Control +VPA (N=3) and PROX1 +VPA (N=3). Bars and error bars are representing as Mean ± SEM. **p < 0.01, *p <0.05, N.S.: Not Significant. Number of cells: 120, 488, 934 and 211 from N=4 mice (Control+saline), 630, 356 and 545 from N=3 mice (Control+VPA), 363, 127 and 219 from N=3 mice (Prox1+saline), 110, 116 and 202 from N=3 mice (Prox1+VPA).

Data information: Scale bars: 20µm (A-C H-J, N-Q), 50µm (E,F)