title: Possible role of cytoskeleton in intracellular arrangement and regulation of mitochondria.
abstract: The origin of significant differences between the apparent affinities of heart mitochondrial respiration for exogenous ADP in isolated mitochondria in vitro and in permeabilized cardiomyocytes or skinned fibres in situ is critically analysed. All experimental data demonstrate the importance of structural factors of intracellular arrangement of mitochondria into functional complexes with myofibrils and sarcoplasmic reticulum in oxidative muscle cells and the control of outer mitochondrial membrane permeability. It has been shown that the high apparent K(m) for exogenous ADP (250-350 mM) in permeabilized cells and in ghost cells (without myosin) and fibres (diameter 15-20 mm) is independent of intrinsic MgATPase activity. However, the K(m) may be decreased significantly by a selective proteolytic treatment, which also destroys the regular arrangement of mitochondria between sarcomeres and increases the accessibility of endogenous ADP to the exogenous pyruvate kinase-phosphoenolpyruvate system. The confocal microscopy was used to study the changes in intracellular distribution of mitochondria and localization of cytoskeletal proteins, such as desmin, tubulin and plectin in permeabilized cardiac cells during short proteolytic treatment. The results show the rapid collapse of microtubular and plectin networks but not of desmin localization under these conditions. These results point to the participation of cytoskeletal proteins in the intracellular organization and control of mitochondrial function in the cells in vivo, where mitochondria are incorporated into functional complexes with sarcomeres and sarcoplasmic reticulum.
authors.affiliation: Laboratory of Fundamental and Applied Bioenergetics, INSERM E0221, Joseph Fourier University, Grenoble, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Appaix
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Kuznetsov
authors.forename: Yves
authors.initials: Y
authors.lastname: Usson
authors.forename: Laurence
authors.initials: L
authors.lastname: Kay
authors.forename: Tatiana
authors.initials: T
authors.lastname: Andrienko
authors.forename: Jose
authors.initials: J
authors.lastname: Olivares
authors.forename: Tuuli
authors.initials: T
authors.lastname: Kaambre
authors.forename: Peeter
authors.initials: P
authors.lastname: Sikk
authors.forename: Raimund
authors.initials: R
authors.lastname: Margreiter
authors.forename: Valdur
authors.initials: V
authors.lastname: Saks
mesh_terms: D000244:Adenosine Diphosphate / Q000502:physiology; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D006321:Heart / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000502:physiology* / Q000648:ultrastructure; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology; D009206:Myocardium / Q000166:cytology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000244:Adenosine Diphosphate; D017301:Ca(2+) Mg(2+)-ATPase; D010100:Oxygen