Pyruvate Kinase Isoform Expression Alters Nucleotide Synthesis to Impact Cell Proliferation

Metabolic regulation influences cell proliferation. The influence of pyruvate kinase isoforms on tumor cells has been extensively studied, but whether PKM2 is required for normal cell proliferation is unknown. We examine how PKM2 deletion affects proliferation and metabolism in nontransformed, nonimmortalized PKM2-expressing primary cells. We find that deletion of PKM2 in primary cells results in PKM1 expression and proliferation arrest. PKM1 expression, rather than PKM2 loss, is responsible for this effect, and proliferation arrest cannot be explained by cell differentiation, senescence, death, changes in gene expression, or prevention of cell growth. Instead, PKM1 expression impairs nucleotide production and the ability to synthesize DNA and progress through the cell cycle. Nucleotide biosynthesis is limiting, as proliferation arrest is characterized by severe thymidine depletion, and supplying exogenous thymine rescues both nucleotide levels and cell proliferation. Thus, PKM1 expression promotes a metabolic state that is unable to support DNA synthesis. [Display omitted] •PKM1 expression following PKM2 loss results in proliferation arrest of primary cells•PKM2 deletion with PKM1 expression does not alter global gene expression•A change in pyruvate kinase isoform expression affects nucleotide synthesis•PKM1 expression limits the availability of deoxynucleotides for DNA synthesis Lunt et al. show that deletion of PKM2 in primary cells leads to PKM1 expression and proliferation arrest in primary cells. This change in pyruvate kinase isoform expression leads to decreased nucleotide synthesis, limiting the availability of deoxynucleotide precursors required for DNA synthesis and cell proliferation.