Fig. 5

Fig. 5

Fig. 5. Wnt/β-catenin signaling acts cell-autonomously in cardiomyocytes to promote cell cycle re-entry. (A) Illustration of the Cre responder construct hsp70l:LOXP-luc-myc-STOP-LOXP-mAxin1-p2a-nlsTomato, cryaa:AmCyan (abbreviated hs:L to Axin1-nT). (B) MF20 and Myc immunostaining to detect expression of myc-tagged luciferase in cryoinjured hs:L to Axin1-nT hearts, heat-shocked (h.s.) 3 times every 8 ​h from 6 dpi and harvested at 7 dpi 8 ​h after the last heat-shock. The yellow dotted lines represent the outline of the MF20⁺ cardiomyocyte area. n (hearts) ​= ​5. Scale bars, 100 ​μm. (C) Tomato, GFP and MF20 immunostaining of hearts from heat-shocked myl7:Cre, hs:L to Axin1-nT, myl7:H2B-GFP fish. White arrowheads point to DAPI⁺nT⁺GFP⁺ cardiomyocyte nuclei. Scale bars, 100 ​μm (overview), 10 ​μm (magnification). (D) Quantification of PCNA⁺GFP⁺/GFP⁺ borderzone cardiomyocytes of cryoinjured hearts from myl7:Cre, hs:L to Axin1-nT, myl7:H2B-GFP fish and myl7:Cre, myl7:H2B-GFP siblings, heat-shocked daily from 1 to 7 dpi. n (hearts) ​= ​16 (myl7:Cre, myl7:H2B-GFP), 10 (myl7:Cre, hs:L to Axin1-nT, myl7:H2B-GFP). Error bars represent CI 95%. Unpaired Welch's unequal variances t-test. (E) Tomato, GFP and PCNA immunostaining of 7 dpi hearts from myl7:Cre, hs:L to Axin1-nT, myl7:H2B-GFP fish, heat-shocked daily from 1 to 7 dpi. White arrowheads point to PCNA⁺nT^—GFP⁺ cardiomyocytes, yellow arrowheads point to PCNA^—nT⁺GFP⁺ cardiomyocytes. Scale bars, 100 ​μm (overview), 10 ​μm (magnification). (F) Quantification of PCNA⁺nT^—GFP⁺/nT^—GFP⁺ and PCNA⁺nT⁺GFP⁺/nT⁺GFP⁺ borderzone cardiomyocytes of cryoinjured hearts from myl7:Cre, hs:L to Axin1-nT, myl7:H2B-GFP fish, heat-shocked daily from 1 to 7 dpi. n (hearts) ​= ​7. Paired t-test.