Fig. 5

Fig. 5. Cardiomyocytes remain lineage-restricted during adult heart regeneration. (A) Schematic of the hsp70l:LOXP-luc-myc-STOP-LOXP-dTomato, cryaa:YPet^ulm9 (hsp:L to T) transgene. (B–H) At 7 dpi, myc-tagged luciferase is not detectable in the ventricle of adult hsp70l:LOXP-luc-myc-STOP-LOXP-dTomato, cryaa:YPet^ulm9 (hsp:L to T) hearts without heat-shocks (B). After heat-shock, expression is found in myl7+ cardiomyocytes (C), Et(krt4:eGFP^sqet27)+ epicardial cells (D), fli1a:eGFP^y1Tg+endocardial cells (E), coro1a:eGFP^hkz04tTg+leukocytes (F), in wt1b:EGFP^li1Tg+epicardial cells, fibroblasts and macrophages (G), and in postnb:Citrine^cn6Tg+ activated fibroblasts (H). Boxed areas are shown in magnified view. Scale bars, 100 ​μm (overview), 10 ​μm (magnified view). (I) Experimental design for adult cardiomyocyte lineage tracing. (J) dTomato+ traced cells are randomly located throughout the ventricle, and express the cardiomyocyte marker myosin heavy chain (MHC). Scale bars, 100 ​μm (overview), 12.5 ​μm (magnified view). (K) No difference is detected in average percentages of dTomato+ traced cells expressing MHC between uninjured and regenerating hearts. Error bars, s.e.m. n (hearts) ​= ​4 (uninjured), 4 (7 dpi), 5 (30 dpi). n (traced cells) ​= ​942 (uninjured), 775 (7 dpi), 1134 (30 dpi). One-way ANOVA ​+ ​Holm-Sidak’s multiple comparisons test. Observed difference uninj. vs 7 dpi ​= ​0.3 (0.3% of traced cells in uninj.); smallest significant detectable difference ​= ​0.7 (0.7% of uninj.). Observed difference uninj. vs 30 dpi ​= ​0.6 (0.6% of traced cells in uninj.); smallest significant detectable difference ​= ​1.2 (1.2% of uninj.). Observed difference 7 dpi vs 30 dpi ​= ​0.2 (0.2% of traced cells in 7 dpi); smallest significant detectable difference ​= ​1.3 (1.4% of 7 dpi).