Figure 9: β-oxidation and Irg1l contribute to MMP production by epidermal cells that elevate mitochondrial uptake of fatty acids following wounding.

(a,b) Expression of mmp9 within wounded DMSO- and etomoxir-treated larvae, respectively, at 2 hpw (n=2 separate wounded cohorts). Remainder of wounded DMSO-treated larvae (2/18) displayed weak mmp9 expression. (c) Quantification of Lyz⁺ neutrophils within wounded DMSO- and etomoxir-treated Tg(lyz:EGFP) larvae at 0, 2, 4 and 6 hpw (mean±s.d.; n=2 separate wounded cohorts). (d–f) Live imaging MMP activity (using MMPSense 645 FAST reagent) within control MO-injected, MMP9-depleted and Irg1l-depleted wounded larvae, as detected at 4 hpw. Fluorescence intensity is displayed as a colormap, with warmer colours representing higher MMP activity. Arrows highlight pigment cell auto-fluorescence. Insets show bright field views of wounds. (g) Quantification of total fluorescence intensities of MMPSense within individual larvae as shown in d–f (mean±s.d.; n=2 separate wounded cohorts). White boxes in d–f highlight measured region. (h–k) Live imaging and quantification of MMP activity within DMSO-, GM6001- and etomoxir-treated wounded larvae, as detected and quantified in d–g (mean±s.d.; n=2 separate wounded cohorts). (l) Live imaging BODIPY FL C₁₆ and MitoTracker probe within epidermal cells at the wound border, as detected at 4 hpw. (m) Line fluorescence intensity measurements, for line shown in l, for BODIPY FL C₁₆ and MitoTracker probes demonstrating overlapping peak fluorescence intensities. (n,o) Live imaging mitochondrial uptake of BODIPY FL C₁₆ within epidermal cells in non-wounded (n) or wounded (o) larvae, at 4 hpw. BODIPY FL C₁₆ fluorescence intensity is displayed as a colormap. (p) Quantification of total fluorescence intensities of BODIPY FL C₁₆ within epidermal cells of individual larvae as shown in n and o (mean±s.d.; n=2 separate wounded cohorts). Measurements taken within regions highlighted with white box. White and black asterisks mark wound border. Numbers represent frequencies of larvae with displayed phenotypes. Scale bars, 20 μm in a; 50 μm and d; 5 μm in l. Statistical significance determined using a Student’s t-test. **P-value <0.01; ****P-value <0.0001.