PKM2 is a key factor to regulate neurogenesis and cognition by controlling lactate homeostasis

Adult hippocampal neurogenesis (AHN), the process of generating new neurons from adult neural stem/progenitor cells (NSPCs), is crucial for cognitive functions and is influenced by numerous factors, including metabolic processes. Pyruvate kinase M2 (PKM2), a key rate-limiting enzyme in glycolysis, catalyzes the production of pyruvate, which undergoes either oxidative phosphorylation or anaerobic oxidation. We observed that PKM2 is highly expressed in NSPCs, but its significance remains unclear for AHN and cognition. Using knockdown or knockout strategies, we discovered that PKM2 deficiency led to reduced AHN and impaired cognitive functions. Furthermore, we observed that knockout of PKM2 resulted in lower L-lactate levels, and supplementing L-lactate in PKM2 knockout mice improved AHN and cognitive functions. Mechanistically, L-lactate restored neurogenesis via monocarboxylate transporter 2 (MCT2), but not hydroxycarboxylic acid receptor 1. In summary, our findings demonstrate that PKM2 is essential for AHN, and lactate supplementation can restore neurogenesis in an MCT2-dependent manner.