Fig 2: Tyro3 is epistatic with Mertk for the retinal degeneration trait.(A) qPCR quantification of Tyro3 in C57BL/6, Mertk -/-V1, Mertk -/-V2, and Mertk -/-V3 retinal pigment epithelia (RPE) (mean ± SEM, n = 4–5 samples/genotype). **p<0.01, one-way ANOVA Dunnett’s test. (B) Representative and independent measurements of TYRO3 amounts in RPE. Western blot (WB) from C57BL/6, Mertk -/-V1, Mertk -/-V2, Mertk -/-V3, and Tyro3 -/-V1 mice RPE (mean ± SEM of n = 5 mice/ genotype). *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001, one-way ANOVA Dunnett’s test. (C) Schematic showing targeting of Tyro3 exons 7–18 with CRISPR/Cas9 in Mertk -/-V2 ES cells to generate the Mertk -/- V2 Tyro3 -/- V2 mouse line. Image not drawn to scale. (D, E) Representative and independent measurements of TYRO3 amounts in RPE. WB from C57BL/6, Mertk -/-V2 Tyro3 -/-V2, and Tyro3 -/-V1 mice RPE (mean ± SEM of n = 4 mice/ genotype). ****p<0.0001, one-way ANOVA Dunnett’s test. (F) Representative hematoxylin-eosin-stained transverse sections of the retina. Boxed section is shown as inset and indicates the areas quantified in (G). Scale bars = 200 mm (left panels) and 10 mm (insets). (G) Quantification of outer nuclear layer (ONL) thickness in the area indicated in (F) (mean ± SEM of 10 measurements/mouse, n = 3–6 mice/genotype). ****p<0.0001, one-way ANOVA Dunnett’s test. (H) Representative scotopic electroretinogram traces are shown at the highest luminance tested. (I) Quantification of a-wave amplitude and b-wave amplitude at highest luminance tested (mean ± SEM of n = 3–6 mice/genotype). *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001, one-way ANOVA Dunnett’s test. a-wave amplitude at increasing luminances. **p<0.01, ****p<0.0001, two-way ANOVA. Morphological and functional changes in the eye were assessed in 6-month-old C57BL/6, Mertk -/-V1, and Mertk -/-V2 Tyro3 -/-V2 mice. Source files for (A) qPCR quantification of Tyro3, (B, E) quantification of TYRO3 levels, (G) ONL thickness, (I) a-wave amplitude, b-wave amplitude, and a-wave amplitude at increasing luminances are available in Figure 4—source data 1. Supporting data for (C) is available in Figure 1—figure supplement 1D. GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL,-outer plexiform layer. Figure 4—source data 1.Independent datasets and unmodified images for results shown in Figure 4.

Fig 3: PTX upregulated Mertk by stimulating PPAR-γ nuclear translocation in vivo and in vitro. A Primary microglia were incubated with GW9662 (10 μM) for 1 h, followed with myelin debris (0.01 mg/ml) with or without PTX (25 μM) for 6 h. Quantitative RT-PCR analysis of Mertk mRNA in primary microglia (n = 3 repeats per group). B Representative immunoblots probed with antibodies against PPAR-γ, GADPH and H3 in nucleus and in cytoplasm of BV2 cells. C, Quantification of PPAR-γ levels normalized to H3 in nucleus (n = 3 repeats per group). D Immunofluorescent images of Iba-1 (green)/PPAR-γ (red)/DAPI (blue) colocalization in IC at Day 30 after BCAS. White scale bar: 20 μm, blue scale bar: 4 μm. E, Quantification of immunofluorescent intensity of PPAR-γ in DAPI area. The values were normalized to those of the control group (n = 4 mice per group). All data were presented as the mean ± SEM. *p < 0.05, **p < 0.01, “ns” means no significance (p > 0.05)

Fig 4: Reduced p-MerTK expression in human diabetic failing heart tissue.Immunohistochemistry image of human heart tissue showing no change in t-MERTK (A) and decrease in p-MerTK (B) in human diabetic failing heart tissue compared to normal human heart tissue.

Fig 5: ADORA3 antagonist upregulates Mertk expression and microglial phagocytosis by activation of cAMP/PKA/p‐CREB pathway. (A, B) Relative cAMP and PKA levels in the CC (n = 5). (C–F) Representative western blot images and quantitative analysis of CREB, p‐CREB, Mertk, and Axl expression in the CC (n = 5). (G, H) Immunofluorescence staining and quantitative analysis of Iba‐1+Mertk+ cells in the CC (n = 5). (I, J) Immunofluorescence staining and quantification of Iba‐1+Mertk+ cells in contact with damaged MBP in the STR (n = 5). Scale bar 50 μm, *p < 0.05, **p < 0.01, ***p < 0.001.