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.

The Cardioprotective Effect of Brief Acidic Reperfusion after Ischemia in Perfused Rat Hearts is not Mimicked by Inhibition of the Na⁺/H⁺ Exchanger NHE1

“…However, both contracting and non-contracting versions of these cells exhibit a number of differences from adult cardiomyocytes that could compromise their usefulness for studies of PostC. These include major differences in mitochondrial dynamics and a greatly increased fractional dependence on glycolysis rather than oxidative phosphorylation, compared to adult cardiomyocytes [31][32][33]. To assess the usefulness of HL-1 as a model for cardioprotection by acidic reperfusion, we mimicked as closely as possible the protocol used in the Langendorff heart model while taking into account that compared to hearts exposed to no-flow ischemia, cultured HL-1 cardiomyocytes seem to require a substantially longer period of simulated ischemia to induce I/R damage [e.g.…”

“…Although other factors, such as the role of reduced hypercontracture in PostC protection in the intact heart [8] are likely to contribute, we speculate that the major reason for this discrepancy is the markedly different metabolism and mitochondrial function between HL-1 cells and adult cardiomyocytes [31][32][33]. Also a 15 min treatment with EIPA failed to protect the HL-1 cells from reperfusion damage.…”

“…However, while HL-1 cardiomyocytes bear many resemblances to adult cardiomyocytes [30], they also exhibit distinct differences from these cells with respect to e.g. mitochondrial organization and metabolism [31][32][33]. Also the contractile apparatus is not as organized as in the adult cardiomyocyte.…”

Antenatal Glucocorticoid Therapy Accelerates ATP Production With Creatine Kinase Increase in the Growth-Enhanced Fetal Rat Heart

“…11 The primers for CK-M were 5'-GTCCGTGGAAGCTCTCAACAG-3' (sense) and 5'-CA GAGGTGACACGGGCTTGT-3' (antisense). 21 The primers for Mi-CK were 5'-AGCAAGGATCCACGCTTTTCT-3' (sense) and 5'-TCTACCGATCCGATCTATGTT-3' (antisense). 21 The primers for GAPDH were 5'-CTGAGTATGT CGTGGAGTCTA-3' (sense) and 5'-CTGCTTCACCACCT TCTTGAT-3' (antisense).…”

“…21 The primers for Mi-CK were 5'-AGCAAGGATCCACGCTTTTCT-3' (sense) and 5'-TCTACCGATCCGATCTATGTT-3' (antisense). 21 The primers for GAPDH were 5'-CTGAGTATGT CGTGGAGTCTA-3' (sense) and 5'-CTGCTTCACCACCT TCTTGAT-3' (antisense). The threshold cycles (Ct) were calculated with Light Cycler software (Ver.…”