Role of mitochondria-cytoskeleton interactions in respiration regulation and mitochondrial organization in striated muscles

The aim of this work was to study the regulation of respiration and energy fluxes in permeabilized oxidative and glycolytic skeletal muscle fibers, focusing also on the role of cytoskeletal protein tubulin beta II isotype in mitochondrial metabolism and organization. By analyzing accessibility of mitochondrial ADP, using respirometry and pyruvate kinase-phosphoenolpyruvate trapping system for ADP, we show that the apparent affinity of respiration for ADP can be directly linked to the permeability of the mitochondrial outer membrane (MOM). Previous studies have shown that MOM permeability in cardiomyocytes can be regulated by VDAC interaction with cytoskeletal protein, beta II tubulin. We found that in oxidative soleus skeletal muscle the high apparent K-m for ADP is associated with low MOM permeability and high expression of non-polymerized beta II tubulin. Very low expression of non-polymerized form of beta II tubulin in glycolytic muscles is associated with high MOM permeability for adenine nucleotides (low apparent K-m for ADP). (C) 2013 Elsevier B.V. All rights reserved.