RESEARCH ARTICLE Molecular Reproduction & Development 79:262–271 (2012) Glycolysis in Preimplantation Development is Partially Controlled by the Warburg Effect BETHANY K. REDEL, ALANA N. BROWN, LEE D. SPATE, KRISTIN M. WHITWORTH, JONATHAN A. GREEN, AND RANDALL S. PRATHER* Division of Animal Science, University of Missouri, Columbia, Missouri SUMMARY Glucose metabolism in preimplantation embryos has traditionally been viewed from a somatic cell viewpoint. Here, we show that gene expression in early embryos is similar to rapidly dividing cancer cells. In vitro-produced pig blastocysts were subjected to deep-sequencing, and were found to express two gene variants that have been ascribed importance to cancer cell metabolism (HK2 and the M2 variant of PKM2). Development was monitored and gene expression was quantified in additional embryos cultured in low or high O 2 (5% CO 2 , 5% O 2 , 90% N 2 vs. 5% CO 2 in air). Development to the blastocyst stage in the two atmospheres was similar, except low O 2 resulted in more total and inner cell mass nuclei than high O 2 . Of the 15 candidate genes selected that are involved in glucose metabolism, only TALDO1 and PDK1 were increased in the low O 2 environment. One paradigm that has been used to explain glycolysis under low oxygen tension is the Warburg Effect (WE). The WE predicts that expression of both HK2 and PKM2 M2 results in a slowing of glucose metabolism through the TCA cycle, thereby forcing the products of glycolysis to be metabolized through the pentose phosphate pathway and to lactic acid. This charging of the system is apparently so important to the early embryo that redundant mechan- isms are present, that is, a fetal form of PKM2 and high levels of PDK1. Here, we set the framework for using the WE to describe glucose metabolism and energy produc- tion during preimplantation development. Mol. Reprod. Dev. 79: 262–271, 2012. ß 2011 Wiley Periodicals, Inc. Received 3 October 2011; Accepted 9 December 2011 * Corresponding author: E125D ASRC 920 East Campus Dr. University of Missouri Columbia, MO 65211. E-mail: pratherr@missouri.edu Grant sponsor: Food for the 21st Century Bethany K. Redel and Alana N. Brown contributed equally to this work. Published online 15 December 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/mrd.22017 INTRODUCTION Metabolism of the early mammalian embryo presents many unique features that are different from a proliferating somatic cell. One major difference is that cleavage-stage embryos need not replicate the entire cell, just mainly the DNA and some plasma membrane. During cleavage from the 1-cell to the blastocyst stage, the cells get progressively smaller. Not until the blastocyst stage do the cells reach a ‘‘somatic’’ size, and subsequently need to replicate all the components within the cell prior to the next cell division. These rapid cell divisions require a unique metabolism that is similar to what is observed in both cancer cells and yeast Additional Supporting Information may be found in the online version of this article. Abbreviations: GV, germinal vesicle; high O 2 , 5% CO 2 in atmospheric oxygen; IVF, in vitro fertilization; ICM, inner cell mass; low O 2 , 5% O 2 , 5% CO 2 , 90% N2; PPP, pentose phosphate pathway; TCA, tricarboxylic acid; TE, trophectoderm; WE, Warburg Effect; Genes: GCK, glucokinase; GPT2, alanine aminotransferase; HK1, hexokinase; LDHA/B, lactate dehydrogenase A/B; PDH, pyruvate dehydrogenase kinase; PDK1, pyruvate dehydrogenase kinase; PGAM1, phosphoglycerate mutase 1; PKM2, pyruvate kinase; SLC2A1/2/3/5, solute carrier family 2 member 1/2/3/5; TALDO1, transaldolase 1; TKT, trans- ketolase; YWHAG, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, gamma polypeptide. ß 2011 WILEY PERIODICALS, INC.