Extended Data Fig. 10: The genetic activation of MKK3b prevents immobilization-induced atrophy.
a, Illustration of how electroporation was used to co-transfect the left and right tibialis anterior (TA) muscles of male and female C57BL6 mice with plasmid DNA encoding tdTomato and constitutively active (c.a.) MKK3b or LacZ as a control. Immediately following electroporation, the right hindlimb was subjected to immobilization while the left hindlimb was untouched and used for the control condition. b, At 7 days post electroporation, the TA muscles were collected and cross-sections were subjected to immunohistochemistry for laminin to identify the periphery of the transfected (tdTomato positive) and non-transfected (tdTomato negative) fibers, scale bars = 100 µm. The mean cross-sectional area (CSA) of the transfected and non-transfected fibers in each sample was determined from n = 58–130 transfected and non-transfected fibers per sample, and the resulting values for each sample were expressed relative to the mean value obtained in the sex-matched control group (that is, the tdTomato negative fibers from vehicle-treated muscles that were co-transfected with LacZ). Values in the graphs are presented as the group mean ± SEM, the number of samples per group is indicated at the bottom of the bars in the graphs (669–1269 fibers per group). The data were analyzed with two-way RM ANOVA. The P-value for each statistically significant pairwise comparison is annotated in the graphs with a * being used when P < 0.0001. Panel a created with BioRender.com.
