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. 2017 Feb 8;26(8):1458–1464. doi: 10.1093/hmg/ddx048

Figure 1.

Figure 1

Ptrh2 null mice demonstrate progressive skeletal muscle pathology at P7. (A) Ptrh2 KO mice exhibit severe joint contractures at P7 compared to wild-type (WT) littermates. (B) The viability of ptrh2 KO mice (n = 25) is severely reduced compared with wild-type (n = 25). All Ptrh2 KO died at 7-10 days. (C) Quantitation of centrally-located nuclei in triceps, tibialis anterior and gastrocnemius skeletal muscle at P7 (n = 3 per genotype and muscle type; 1,000 myofibers/animal; *P < 0.01; **P < 0.001). (D) Quantitation of creatine kinase levels in WT and Ptrh2 KO gastrocnemius muscle at P7 (n = 4 per genotype, **P < 0.001). Creatine kinase detects severe muscle damage. (E) Myofibers ≤ 10 μm diameter were increased in Ptrh2 KO gastrocnemius muscle compared to WT (n = 8 per genotype; 1000 myofibers/animal, ***P < 0.0001) indicating a significant increase in small regenerating fibers. (F) Increased endomysial fibrosis in gastrocnemius muscle (arrows) as determined by Trichrome staining in Ptrh2 KO mice compared to WT (longitudinal sections; bar 50 μm.) (G) Quantitation of Trichrome staining demonstrated a significant increase of fibrosis in the Ptrh2 KO mice compared to aged matched littermate controls at P7. (n = 4 per genotype, *P < 0.01). (H,I)Ptrh2 KO mice had reduced sarcolemmal integrity as determined by the uptake of Evans blue dye (red stain; arrows) in gastrocnemius muscle compared to WT (n = 4 per genotype; 1,500 myofibers/animal; *P < 0.01). Myofibers were counterstained with Oregon Green-488-conjugated WGA (green; bar 50 μm). (I) Increased eMyHC expression in Ptrh2 KO mouse gastrocnemius muscle compared to age-matched WT littermates at P7 (n = 4 per genotype; ***P < 0.0001).