RESUMO
Mitochondria-cytoskeleton interactions were analyzed in adult rat cardiomyocytes and in cancerous non-beating HL-1 cells of cardiac phenotype. We show that in adult cardiomyocytes ßII-tubulin is associated with mitochondrial outer membrane (MOM). ßI-tubulin demonstrates diffused intracellular distribution, ßIII-tubulin is colocalized with Z-lines and ßIV-tubulin forms microtubular network. HL-1 cells are characterized by the absence of ßII-tubulin, by the presence of bundles of filamentous ßIV-tubulin and diffusely distributed ßI- and ßIII-tubulins. Mitochondrial isoform of creatine kinase (MtCK), highly expressed in cardiomyocytes, is absent in HL-1 cells. Our results show that high apparent K(m) for exogenous ADP in regulation of respiration and high expression of MtCK both correlate with the expression of ßII-tubulin. The absence of ßII-tubulin isotype in isolated mitochondria and in HL-1 cells results in increased apparent affinity of oxidative phosphorylation for exogenous ADP. This observation is consistent with the assumption that the binding of ßII-tubulin to mitochondria limits ADP/ATP diffusion through voltage-dependent anion channel of MOM and thus shifts energy transfer via the phosphocreatine pathway. On the other hand, absence of both ßII-tubulin and MtCK in HL-1 cells can be associated with their more glycolysis-dependent energy metabolism which is typical for cancer cells (Warburg effect).
