Activity of complex III of the mitochondrial electron transport chain is essential for early heart muscle cell differentiation.
During development of the heart, mitochondria proliferate within cardiomyocytes. It is unclear whether this is a response to the increasing energy demand or whether it is part of the developmental program. To investigate the role of the electron transport chain (ETC) in this process, we used transgenic murine embryonic stem (ES) cells in which the green fluorescent protein gene is under control of the alpha-myosin heavy chain promoter (alpha-MHC), allowing easy monitoring of cardiomyocyte differentiation. Spontaneous contraction of these cells within embryoid bodies (EBs) was not affected by inhibition of the ETC, suggesting that early heart cell function is sufficiently supported by anaerobic ATP production. However, heart cell development was completely blocked when adding antimycin A, an inhibitor of ETC complex III, before initiation of differentiation, whereas KCN did not block differentiation, strongly suggesting that specifically complex III function rather than mitochondrial ATP production is necessary for early heart cell development. When the underlying mechanism was examined, we noticed that antimycin A but not KCN lead to inhibition of spontaneous intracellular Ca++ oscillations, whereas both substances decreased mitochondrial membrane potential, as expected. We postulate that mitochondrial complex III activity is necessary for these Ca++ oscillations, which in turn are a prerequisite for cardiomyocyte differentiation.
Spitkovsky
Dimitry
D
Institute of Vegetative Physiology, Center of Physiology and Pathophysiology, The University of Köln, Germany.
Sasse
Philipp
P
Kolossov
Eugen
E
Böttinger
Cornelia
C
Fleischmann
Bernd K
BK
Hescheler
Jürgen
J
Wiesner
Rudolf J
RJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D004579:Electron Transport / Q000502:physiology*; D014450:Electron Transport Complex III / Q000502:physiology*; D005318:Fetal Heart / Q000166:cytology*; D017930:Genes, Reporter; D005865:Gestational Age; D008564:Membrane Potentials; D051379:Mice; D008822:Mice, Transgenic; D008929:Mitochondria, Heart / Q000502:physiology*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000502:physiology* / Q000648:ultrastructure; D018995:Myosin Heavy Chains / Q000235:genetics; D011190:Potassium Cyanide / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D024723:Ventricular Myosins / Q000235:genetics
D012333:RNA, Messenger; D014157:Transcription Factors; D000968:Antimycin A; D000255:Adenosine Triphosphate; D024723:Ventricular Myosins; D018995:Myosin Heavy Chains; D014450:Electron Transport Complex III; D011190:Potassium Cyanide