title: Distinct organization of energy metabolism in HL-1 cardiac cell line and cardiomyocytes.
abstract: Expression and function of creatine kinase (CK), adenylate kinase (AK) and hexokinase (HK) isoforms in relation to their roles in regulation of oxidative phosphorylation (OXPHOS) and intracellular energy transfer were assessed in beating (B) and non-beating (NB) cardiac HL-l cell lines and adult rat cardiomyocytes or myocardium. In both types of HL-1 cells, the AK2, CKB, HK1 and HK2 genes were expressed at higher levels than the CKM, CKMT2 and AK1 genes. Contrary to the saponin-permeabilized cardiomyocytes the OXPHOS was coupled to mitochondrial AK and HK but not to mitochondrial CK, and neither direct transfer of adenine nucleotides between CaMgATPases and mitochondria nor functional coupling between CK-MM and CaMgATPases was observed in permeabilized HL-1 cells. The HL-1 cells also exhibited deficient complex I of the respiratory chain. In conclusion, contrary to cardiomyocytes where mitochondria and CaMgATPases are organized into tight complexes which ensure effective energy transfer and feedback signaling between these structures via specialized pathways mediated by CK and AK isoforms and direct adenine nucleotide channeling, these complexes do not exist in HL-1 cells due to less organized energy metabolism.
authors.affiliation: Department of Pathophysiology, Centre of Molecular and Clinical Medicine, Faculty of Medicine, University of Tartu, Tartu, Estonia.
authors.forename: Margus
authors.initials: M
authors.lastname: Eimre
authors.forename: Kalju
authors.initials: K
authors.lastname: Paju
authors.forename: Sophie
authors.initials: S
authors.lastname: Pelloux
authors.forename: Nathalie
authors.initials: N
authors.lastname: Beraud
authors.forename: Mart
authors.initials: M
authors.lastname: Roosimaa
authors.forename: Lumme
authors.initials: L
authors.lastname: Kadaja
authors.forename: Marju
authors.initials: M
authors.lastname: Gruno
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Peet
authors.forename: Ehte
authors.initials: E
authors.lastname: Orlova
authors.forename: Reele
authors.initials: R
authors.lastname: Remmelkoor
authors.forename: Andres
authors.initials: A
authors.lastname: Piirsoo
authors.forename: Valdur
authors.initials: V
authors.lastname: Saks
authors.forename: Enn
authors.initials: E
authors.lastname: Seppet
mesh_terms: D000818:Animals; D002460:Cell Line; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008929:Mitochondria, Heart / Q000201:enzymology*; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000201:enzymology*; D010085:Oxidative Phosphorylation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007527:Isoenzymes; D009124:Muscle Proteins