title: Joint participation of mitochondria and sarcoplasmic reticulum in the formation of tubular aggregates in gastrocnemius muscle of CK-/- mice.
abstract: Tubular aggregates are specific subcellular structures that appear in skeletal muscle fibres under different pathological conditions. The origin of the tubular aggregates is generally ascribed to proliferating membranes of sarcoplasmic reticulum. There are, however, histochemical indications for the presence of mitochondrial enzymes in tubular aggregates suggesting contribution of mitochondria to the genesis of tubular aggregates. In this study we used an immunocytochemical detection technique to assess participation of mitochondria and of sarcoplasmic reticulum in derivation of tubular aggregates. The fast skeletal muscle fibres (m. gastrocnemius) of mice bearing the double invalidation for both the mitochondrial and the cytosolic isoforms of creatine kinase (CK), an enzyme involved in energetics of muscle cells, were employed as a model muscle with tubular aggregates (Steeghs et al., Cell 89, 93-103, 1997). Immunogold labelling of the bc1 complex, a specific integral protein of the inner mitochondrial membrane, provided strong signals in both the mitochondria and tubular aggregates but not in other ultrastructural components of muscle fibres. A similar strong immunogold signal was obtained when labelling for SERCA1, a specific enzyme of the sarcoplasmic reticulum membrane, in regions of typical occurrence of the sarcoplasmic reticulum and in tubular aggregates. In double labelling experiments, we found simultaneous labelling of tubular aggregates with both the bc1 and SERCA1 antibodies. It is concluded, that in CK-/- mouse both the inner mitochondrial membrane and the membrane of the sarcoplasmic reticulum participate in the formation of tubular aggregates.
authors.affiliation: Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovak Republic.
authors.forename: Marta
authors.initials: M
authors.lastname: Novotová
authors.forename: Ivan
authors.initials: I
authors.lastname: Zahradník
authors.forename: Guy
authors.initials: G
authors.lastname: Brochier
authors.forename: Michaela
authors.initials: M
authors.lastname: Pavlovicová
authors.forename: Xavier
authors.initials: X
authors.lastname: Bigard
authors.forename: Renée
authors.initials: R
authors.lastname: Ventura-Clapier
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism / Q000648:ultrastructure; D003402:Creatine Kinase / Q000172:deficiency* / Q000235:genetics; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D008870:Microtubules / Q000201:enzymology* / Q000473:pathology / Q000648:ultrastructure; D008931:Mitochondria, Muscle / Q000201:enzymology* / Q000473:pathology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000473:pathology / Q000648:ultrastructure; D009135:Muscular Diseases / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D020736:Ribonucleoproteins, Small Cytoplasmic / Q000378:metabolism / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000473:pathology / Q000648:ultrastructure; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
chemical_list: C506944:Atp2a1 protein, mouse; C076675:Bc1 long-non-coding RNA, mouse; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D020736:Ribonucleoproteins, Small Cytoplasmic; D003402:Creatine Kinase; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases