Fig. 10

Brd4 regulates microgliosis and synaptic pruning in transgenic zebrafish expressing human 0N/4R-Tau and is expressed in human microglia.

a Schematic showing key functional domains of the human and zebrafish Brd4 orthologues. Amino acid homology is indicated for each domain. Truncated products formed by a splice site-targeting morpholino, or a stable germline 11-bp deletion in exon 4 of brd4 (pt435) are shown. b Western blot showing expression of Brd4 (above) and β-actin (below) in brains from WT and brd4^Pt435/Pt435 (abbreviated to brd4^−/−) zebrafish. c, d VMR light phase speed of [Ctrl], [Tau], and [Tau; brd4^+/−] zebrafish. c Example 1-min swim vectors (above); mean speed during the light phase of the VMR (below). Gray traces show mean frame-to-frame displacement scaled to show speed, colored markers and bars show 1-min binned group mean ± SE, similar to Fig. 5b. d Mean speed of individual zebrafish (n = 28–62 zebrafish/group), bars show group mean ± SE. ****p = 2.9 × 10⁻⁷, *p = 0.029, 1-way ANOVA with Šidák multiple comparisons test. e Acridine orange labeled spinal cord cells quantified as shown in Fig. 2a, d. Data points show individual zebrafish (n = 9–24 zebrafish/group), bars show group mean ± SE. ****p = 3.2 × 10⁻¹¹, 1-way ANOVA with Šidák multiple comparisons test. f Microglial density quantified as shown in Fig. 2h, i. Data points show individual zebrafish (n = 4–18 zebrafish/group), bars show mean ± SE. ****p < 0.0001, **p < 0.01, 1-way ANOVA with Šidák multiple comparisons test. g, h PSD95-immunoreactive synaptic puncta quantified in (g) optic tectum or (h) telencephalon. Data points show individual zebrafish (n = 13–22 zebrafish/group), bars show mean ± SE. ****p < 0.0001, 1-way ANOVA with Tukey multiple comparisons test. i Sections from control and PSP human substantia nigra labeled for Brd4 (green), Iba1 (microglia; red) and nuclei (DAPI, blue), and imaged by confocal microscopy. Inset panels show Brd4-immunoreactive microglial nuclei from the main panels at higher magnification. j The proportion of Iba1⁺ cells showing Brd4-immunoreactive nuclei in multiple sections of substantia nigra and globus pallidus from 4 control and 5 PSP cases. Data points show individual cases, bars show group mean ± SE, comparison by unpaired 2-tailed t-test. Numbers of [Brd4⁺, Iba1⁺]/[Iba1⁺] microglia analyzed in each group are indicated. Source data are provided as a Source Data file. Exact p-values for panels (f–h) shown in Supplementary Table 22.