Ab59257

Cells were fixed with 4% paraformaldehyde (PFA) for 10 min at room temperature. Paraformaldehyde-fixed, paraffin-embedded tissue samples was cut into 4 μm slices and adhered to frosted glass slides. After washing with PBS and treating with PBS containing 0.1% Triton X-100 for 15 min, the sections and cells were permeabilized and blocked with 0.1% Tween-20 in PBS (PBST) containing 5% FBS for 90 min at room temperature. The cells were immunostained with anti-ACE2 (ab15348, 1:500, Abcam), anti-SP1 (T453) (ab59257, 1:500, Abcam), or anti-HNF4α antibodies (3113, 1:1 000, Cell Signaling Technology) overnight at 4 °C. The tissue sections were immunostained with anti-ACE2 (GB11267, 1:200, Servicebio, Wuhan, China) or anti-SARS-CoV-2-N antibodies (40143-MM05, 1:500, SinoBiological, Beijing, China) overnight at 4 °C. After washing three times with 0.1% Tween-20 in PBS (PBST), the cells were incubated with Alexa Fluor 594 anti-rabbit IgG (H+L) (A-21207, 1:200, ThermoFisher Scientific), Cy3 conjugated goat anti-mouse IgG (H+L) (GB21301, 1:300, Servicebio), or Alexa Fluor 488-conjugated goat anti-rabbit IgG (H+L) (GB25303, 1:500, Servicebio) at room temperature for 1 hr. After staining with primary antibodies, nuclei were counterstained with 4’,6-diamidino-2-phenylindole (DAPI). Images were acquired using a Zeiss Axioskop 2 plus fluorescence microscope (Carl Zeiss, Jena, Germany).

Sodium butyrate (NaBu), trichostatin A (TSA), cambinol (Cmb), and 5-aza-2′-deoxycytidine (AZA) were purchased from Sigma-Aldrich (#303410, #T8552, #C0494, and #A3656) and dissolved in phosphate-buffered saline (PBS) to final concentrations of 2 mM, 0.1 μM, 0.2 μM, and 15 mM in the fishes’ water, respectively. PBS alone was used as vehicle control. The pharmacological treatment lasted for 24 h from 7 to 8dpf. Acetyl-histone 4 and acetyl-lysine antibodies were obtained from Millipore (#06-866 and #05-515), anti-HDAC1 and anti-YY1 from ActiveMotif (#39531 and #61780), anti-Sp1 and anti-H4 from Abcam (ab59257 and ab16483), and McrBC enzyme from New England Biolabs (M0272).