Oxidative Stress in gata1⁺ Erythroid Cells

(A) BLASTP identity analysis of key proteins involved in the oxidative stress response between Danio rerio and Homo sapiens.

(B) Representative flow cytometry histograms showing CellRox emission in 72 hpf embryos after 48 hr of 1-naphthol exposure (concentrations shown as μg per 5 mL).

(C) Quantification of CellRox probe signal MFI relative to unstressed embryos. n = 20 individual animals per condition showing one of five independent experiments.

(D) Live imaging of a gata1:DsRed transgenic zebrafish at 72 hpf indicating DsRed-positive primitive erythroid cells.

(E) Representative flow cytometry of single-cell suspensions prepared from wild-type and gata1:DsRed zebrafish at 72 hpf.

(F and G) Pro-oxidant exposure induces ROS in Gata1⁺ erythroid precursors. Animals were exposed to 20 μg/5 mL 1-naphthol followed by flow cytometry of Gata1⁺ erythroid cells by gating on DsRed-positive cells (or all cells for total-body ROS) and measuring CellRox probe MFI to determine ROS. n = 20–25 individual animals per condition showing one of four independent experiments.

(H) NAC combined with 1-naphthol reduces ROS in Gata1⁺ erythroid cells. All pro-oxidant exposure times were from 24 to 72 hpf.

All data are shown as the mean ± SD, with the p value from a Student t test. See also Figure S1.

Gata1⁺ Erythroid Cells Contribute a Significant Proportion of ROS to Total-Body ROS

(A) Gata1⁺ primitive erythroid cells contribute to total ROS. Cells from stressed gata1:DsRed zebrafish were gated initially for the total cell population, then evaluated by cumulative distribution function of CellROX green ROS probe signal. The 20^th to 80^th percentiles of ROS signal were gated, and the makeup of each percentile in terms of the gata1:DsRed fraction of all cells was determined. n = 20–25 individual animals per condition showing one of three independent experiments.

(B) Makeup of each percentile of ROS probe signal in terms of % gata1:DsRed contribution showing that the highest ROS signal originates mostly from Gata1⁺ erythroid cells. One-way ANOVA indicates p value < 0.0001 for overall effect and p < 0.001 in two-way comparisons between all groups.

(C) o-Dianisidine-stained vlad tepes zebrafish at 72 hpf showing a lack of erythrocytes. Scale bars represent 500 μm.

(D) Vlad tepes zebrafish have reduced total-body ROS. Vlad tepes and phenotypically normal clutch mates were treated with 20 μg/5 mL 1-naphthol followed by flow cytometry of total-body ROS indicated by CellRox ROS probe (n = 17–22 individual animals per condition in one of two experiments). All pro-oxidant exposure times were from 24 to 72 hpf.

All data are shown as the mean ± SD, with the p value from a Student t test, unless otherwise noted.

Oxidative Stress Induces tp53, which Can Modulate ROS Levels

(A) Zebrafish show increased 8-oxo-dG after pro-oxidant exposure (1-naphthol at 20 μg/5 mL). n = 5–6 per condition, one of two independent experiments.

(B) Representative image of a TUNEL assay from zebrafish after pro-oxidant exposure (20 μg/5 mL). Boxed region indicates the CHT. Scale bar represents 500 μm.

(C) Number of TUNEL-positive cells present in the CHT. n = 14–16 individual animals per condition in one of two independent experiments. ^∗p < 0.0001.

(D) Heatmap of RNA-seq data from untreated and 1-naphthol-treated zebrafish. Unsupervised clustering was performed on genes with log₂ expression >2-fold difference.

(E) Distribution of genes with log₂ expression >2-fold difference between control and 1-naphthol-treated zebrafish. n = 5 control animals and n = 6 naphthol-treated animals.

(F) IPA results of the significant Upstream Regulators having greater expression in 1-naphthol-treated zebrafish.

(G) RT-PCR of tp53 in zebrafish after pro-oxidant exposure (n = 20 individual animals per group, technical duplicates, pooled from four independent experiments). ^∗p < 0.05, ^∗∗p < 0.01.

(H) Tp53 inactivation using pifithrin (PFT) during pro-oxidant exposure (1-naphthol at 30 μg/5 mL) at 1 μM final concentration increases ROS in Gata1⁺-expressing erythrocytes. ROS measured using the CellRox ROS probe relative to untreated group. n = 20–25 individual animals per condition showing one of three independent experiments. See also Figure S2G.

(I) Elevated ROS in tp53^M214K zebrafish Gata1⁺-expressing erythroid cells after pro-oxidant challenge. n = 20–25 individual animals per condition showing one of three independent experiments.

(J) Erythroid progenitors in TP53^R270H/+murine whole bone marrow have increased ROS generation after short-term oxidative challenge. After exposure to 1 mM acrolein, nucleated CD71⁺ cells were gated by flow cytometry (see Figure S2H for gating) and ROS measured using CellROX green probe. ROS is given relative to the untreated group. Shown are data pooled from two independent experiments. All zebrafish pro-oxidant exposure times were from 24 to 72 hpf. n = 10–20 individual animals per condition pooled from two independent experiments.

All data are shown as the mean ± SD, with the p value from a Student t test.

Genetic Inactivation of tp53 Leads to Elevated ROS, Cell Death, and Increased Mitochondrial Basal OCR

(A) Relative erythroid cell death indicated by propidium iodide staining cells after 1-naphthol exposure (20 μg/5 mL) and quantified by flow cytometry. n = 20–21 individual animals per group pooled from two independent experiments.

(B) Pro-oxidant exposure (0–30 μg/5 mL) leads to increased death and edema in tp53^M214K/M214K zebrafish (mutants denoted as tp53^m/m). Embryos were scored at 96 hpf (after 72 hr of pro-oxidant exposure). n ≥ 100/individual animals per group, p value from chi-square analysis. Data pooled from three independent experiments.

(C) Severe hemolytic edema in tp53^M214K/M214K zebrafish exposed to 1-napthol (20 μg/5 mL). Hemoglobin staining was performed using o-dianisidine.

(D) Heatmap of RNA-seq data from untreated and 1-naphthol-treated tp53^M214K/M214K zebrafish (treated from 24 to 72 hpf). Unsupervised clustering was performed on genes with log₂ expression >2-fold difference. n = 5 individual animals in each group.

(E) GO term analysis using the PANTHER database and software for GO enrichment analysis for biological process indicates genes involved in metabolism are highly upregulated in tp53^M214K/M214K after pro-oxidant challenge.

(F) Live image displaying erythroid precursors from gata1:DsRed × mito:GFP zebrafish at 72 hpf. Imaging performed with a Leica TCS SPE Spectral Confocal system. Scale bar represents 25 μm.

(G) Mitochondrial content of gata1:DsRed × mito:GFP and gata1:DsRed × mito:GFP × tp53^M214K zebrafish. Single-cell suspensions at 72 hpf were made and mitochondrial content determined by flow cytometry measuring GFP MFI. n = 18–20 individual animals per group in two independent experiments.

(H) Lack of OXPHOS reserve in tp53^M214/M214KK zebrafish. Mitochondrial OCR was measured using the Seahorse biochemical analyzer. Yellow bars indicate the amount of reserve OXPHOS, which is the difference between maximal OCR and basal OCR. Shown are the mean and SEM. n = 12–15 individual animals per group in two independent experiments. See also Figure S3D.

(I) Basal OCR is higher in tp53^M214K/M214K zebrafish. Shown are the means and SD. n = 12–15 per group showing one of two independent experiments.

(J) Quantification of OXPHOS reserve indicates tp53^M214K/M214K zebrafish have no reserve. Shown are the means and SD. n = 12–15 per group showing one of two independent experiments. All pro-oxidant exposure times were from 24 to 72 hpf, except (C) and (I and J), which were from 24 to 96 hpf and from 24 to 120 hpf, respectively.

(K) Pro-oxidant exposure (20 μg/5 mL) combined with oligomycin exposure leads to decreased death and edema in tp53^M214K/M214K zebrafish. Embryos scored at 96 hpf after 72 hr of drug exposure. n ≥ 100/individual animals per group, p value from chi-square analysis. Data pooled from three independent experiments.