Glycolytic network restructuring integral to the energetics of embryonic stem cell cardiac differentiation

Abstract

Decoding of the bioenergetic signature underlying embryonic stem cell cardiac differentiation has revealed a mandatory transformation of the metabolic infrastructure with prominent mitochondrial network expansion, and a distinctive switch from glycolysis to oxidative phosphorylation. Here, we demonstrate that despite reduction in total glycolytic capacity, stem cell cardiogenesis engages a significant transcriptome, proteome, as well as enzymatic and topological rearrangement in the proximal, medial, and distal modules of the glycolytic pathway. Glycolytic restructuring was manifested by a shift in hexokinase (Hk) isoforms from Hk-2 to cardiac Hk-1, with intracellular and intermyofibrillar localization mapping mitochondrial network arrangement. Moreover, upregulation of cardiac specific enolase 3, phosphofructokinase, phosphoglucomutase and a marked increase in glyceraldehyde 3-phosphate dehydrogenase (GAPDH) phosphotransfer activity, along with apparent post-translational modifications of GAPDH and phosphoglycerate kinase, were all distinctive for derived cardiomyocytes compared to the embryonic stem cell source. Lactate dehydrogenase (LDH) isoforms evolved towards LDH-2 and LDH-3, containing higher proportions of heart-specific subunits, and pyruvate dehydrogenase isoforms rearranged between E1α and E1β, transitions favorable for substrate oxidation in mitochondria. Concomitantly, transcript levels of fetal pyruvate kinase isoform M2, aldolase 3 and transketolase, which shunt the glycolytic with pentose phosphate pathways, were reduced. Collectively, changes in glycolytic pathway modules indicate active redeployment which would facilitate connectivity of the expanding mitochondrial network with ATP utilization sites. Thus, the delineated developmental dynamics of the glycolytic phosphotransfer network is integral to the remodeling of cellular energetic infrastructure underlying stem cell cardiogenesis. Keywordsbioenergetics; cardiogenesis; embryonic stem cells; proteomics; transcriptome Robust developmental transitions in the bioenergetic system highlights embryonic stem (ES) cell differentiation into the energy-demanding cardiac phenotype, characterized by a switch *Correspondence at Mayo Clinic, 200 First Street SW, Stabile 5, Rochester, MN 55905, USA. dzeja.petras@mayo.edu; terzic.andre@mayo.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript from glycolytic to oxidative energy metabolism with expansion and maturation of the mitochondrial network [1][2][3]. Extensive...

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