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. 2013 Jul 25;123(8):3564–3576. doi: 10.1172/JCI67521

Figure 4. Upregulation of tendon gene expression following injury.

Figure 4

(A) Longitudinal sections parallel to the axis of Achilles tendons were made in adult mice to create a mouse model for tendon injury. (B) We observed increased LacZ expression (reflecting Egr1 expression) in Achilles tendons 1 week after tendon injury in Egr1+/– mice. m, muscle. (C) qRT-PCR analyses of tendon-associated gene expression in injured tendons versus noninjured tendons 1 week after injury. The following tendon markers were analyzed: the tendon-associated transcription factors, Scx and Mkx; the tendon-associated collagens, Col1a1, Col1a2, Col3a1, Col5a1, Col6a1, Col12a1, and Col14a1; and the tendon-associated molecules, Tnmd, Tnc, Dcn, Bgn, Fn1, Fbn1, and Eln. mRNA levels of noninjured tendons were normalized to 1. Error bars represent SEM. *P < 0.05; **P < 0.01; ***P < 0.001, paired Student’s t tests. (D–I) Adjacent transverse sections of noninjured (D and E) and injured (F–I) Achilles tendons were hybridized with Egr1 (D, F, and H) or Col1a1 (E, G, and I) probes (blue labeling). Three weeks after injury, Egr1 and Col1a1 expression was upregulated in injured tendons at the site of injury compared with control (noninjured) tendons. Scale bars: 1 mm (A and B); 200 μm (D–G); 50 μm (H and I).