Figure 3.

Rapid increase in collagen expression and collagen I-expressing cell abundance during mechanical overload. A: quantification of time course microarray analysis of various collagen isoform transcripts following mechanical overload (GEO: GSE47098) (1, 76). Note the peak for the most abundant collagen transcripts (Col Ia1, Col Ia2, Col XIIa1, and Col IIIa1) at 7 days post-mechanical overload in a murine model. B: cells expressing collagen I, the most abundant collagen isoform in skeletal muscle, were identified using a mouse line expressing green fluorescent protein (GFP) under the control of the collagen-α1(I) promoter (77). Four-month-old mice were subjected to sham surgery (Control), or 4 or 7 days of mechanical overload via synergist ablation surgery. A portion of the plantaris was fixed prior to staining with phalloidin. Fibers and adherent collagen I-GFP+ cells were visualized at ×40 magnification using a Nikon A1R Inverted Confocal Microscope.