Fig. 9

Cytoskeletal elements vinculin and myosin heavy chain (I, IIA, IIB) are altered in fast- and slow-twitch muscles. Cytoskeletal protein vinculin was increased in A gastrocnemius, E tibialis anterior, and I soleus muscles in 12-month-old transgenic and 9-month-old knock-in mouse models of SBMA. In tibialis anterior, both transgenic (p < 0.05) and knock-in mice (p < 0.01) showed significant increases in vinculin. Vinculin increase only reached statistical significance in knock-in mice in soleus (p < 0.05) and gastrocnemius (p < 0.01). B Gastrocnemius muscle showed a significant decrease in MHC I in both transgenic (p < 0.05) and knock-in mice (p < 0.05). C MHC IIA was unaltered in gastrocnemius of transgenic and knock-in mice. D Knock-in mice showed a significant decrease in MHC IIB levels (p < 0.05) in gastrocnemius, which did not occur in transgenic mice. F Tibialis anterior showed a significant decrease in MHC I in both transgenic (p < 0.01) and knock-in (p < 0.05) mice. G Tibialis anterior showed undetectable levels of MHCIIA. Knock-in soleus lysate used as positive control. H Tibialis anterior showed a significant decrease in MHC IIB in both transgenic (p < 0.01) and knock-in (p < 0.0001) mice. J Soleus muscle showed a significant increase in MHC I in both transgenic (p < 0.05) and knock-in mice (p < 0.05). K Soleus muscle also showed an increase in MHC IIA in both transgenic (p < 0.05) and knock-in (p < 0.05) mice. L As expected, soleus did not express MHC IIB in non-transgenic, transgenic, or knock-in mice. NTg gastrocnemius lysate used as positive control. Student’s t-test was used to evaluate statistical significance. NTg Non-transgenic; Tg Transgenic; WT Wild-type; KI, Knock-in; MHC I Myosin heavy chain type 1; MHC II Myosin heavy chain type 2A; MHC IIB Myosin heavy chain type 2B; *p < 0.05; **p < 0.01, ****p < 0.0001