Figure 4. RIPK1 ablation causes keratinocyte necroptosis and skin inflammation.

a, Representative images of skin sections from the indicated mice stained with H&E or the indicated antibodies. Nuclei stained with 4′,6-diamidino-2-phenylindole (DAPI). Scale bars, 100 µm (H&E); 50 µm (immunostainings). b, Microscopic quantification of epidermal thickness and inflamed skin area in the indicated mice. Error bars represent mean values ± standard error of the mean (s.e.m.). c, qRT–PCR of cytokine and chemokine expression in total skin from the indicated mice. d, Quantification of CC3⁺ and CC3⁻ dying cells per high power field (hpf) in skin sections from the indicated mice. e, Immunoblot of primary keratinocytes stimulated with 20 ng ml⁻¹ recombinant murine TNF for the indicated time points. f, Quantification of cell viability in primary keratinocytes treated with 50 ng ml⁻¹ recombinant murine TNF in the presence or absence of z-VAD-FMK (zVAD; 20 µM) and necrostatin-1 (Nec; 30 µM). Mean values ± s.e.m. from biological triplicates (n = 3) are shown. g, Immunoblot of protein extracts from P4 epidermis, IECs or keratinocytes from mice of the indicated genotypes. h, Schematic model of the kinase-dependent (KD) and -independent (KI) functions of RIPK1 in apoptosis and necroptosis. Representative data of three independent experiments are shown in e, f. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.005; NS, not significant.