Figure 1
Pw1 is required for the establishment of muscle size and myofiber number. (A) Representative photomicrographs at lower (upper panel; scale bars = 200 μm) and higher magnification (lower panel; scale bars = 50 μm) of TA muscles cross-sections from 3 month Pw1+/+, Pw1+/p−, Pw1m−/+ and Pw1m−/p− mice stained with hematoxylin and eosin. (B) Histograms showing the muscle weight (left panel) and muscle/body weight ratio (right panel) of Tibialis Anterior (TA), Extensor Digitorum Longus (EDL), Quadriceps (QDC), Gastrocnemius (GAS), Soleus (SOL) muscles from 3 month Pw1+/+, Pw1+/p−, Pw1m−/+ and Pw1m−/p− mice (n = 10 for each genotype). Pw1+/p− and Pw1m−/p− muscles are smaller than Pw1+/+ and Pw1m−/+ muscles. Pw1m−/p− TA, QDC and GAS muscles are smaller than Pw1+/p− TA, QDC and GAS muscles. (C) Fiber size distribution in 3 month Pw1+/+ (dash), Pw1+/p− (red), Pw1m−/+ (grey) and Pw1m−/p− (green) TA. Values represent the mean number ± s.e.m. per 100 fibers (n = 5 for each genotype). Statistical analyses were performed using Student’s t-test. Pw1 depletion did not result in fibers area differences. (D) Histograms representing the fiber number in 3 month Pw1+/+, Pw1+/p−, Pw1m−/+ and Pw1m−/p− TA muscles sectioned through the midbelly region (n = 7 for each genotype). The number of fibers is decreased in Pw1+/p− and Pw1m−/p− TA muscles as compared to Pw1+/+ and Pw1m−/+ TA muscles. Pw1m−/p− TA muscles have reduced number of muscle fibers as compared to Pw1+/p−. (E) Left panel-Histograms showing total body weight of postnatal day 0 (P0) Pw1+/+, Pw1+/p−, Pw1m−/+, and Pw1m−/p− mice (n = 14 for each genotype). Pw1+/p− and Pw1m−/p− are smaller as compared to Pw1+/+ and Pw1m−/+ mice. Right panel-Histograms representing the fibers number in P0 Pw1+/+, Pw1+/p−, Pw1m−/+, and Pw1m−/p− mice TA muscles (n = 5 for each genotype). Pw1+/p− and Pw1m−/p− TA have less fiber as compared to Pw1+/+. Pw1m−/p− TA displays less number of fibers as compared to Pw1+/p− TA. Values are expressed as mean ± s.e.m. Statistical analyses were performed using one-way ANOVA and Tukey’s post-test for multiple comparison *P < 0.05, **P < 0.01 and ***P < 0.001 (n ≥ 4); n.s., not significant. In all the graphs Pw1+/+ (+/+), Pw1+/p− (+/p−), Pw1m−/+ (m−/+), and Pw1m−/p− (m−/p−).
