Monocarboxylates, such as lactate and pyruvate, are precursors for biosynthetic pathways, including those for glucose, lipids, and amino acids via the tricarboxylic acid (TCA) cycle and adjacent metabolic networks. The transportation of monocarboxylates across the cellular membrane is performed primarily by monocarboxylate transporters (MCTs), the membrane localization and stabilization of which are facilitated by the transmembrane protein basigin (BSG). Here, we demonstrate that the MCT/BSG axis sits at a crucial intersection of cellular metabolism. Abolishment of MCT1 in the plasma membrane was achieved by Bsg depletion, which led to gluconeogenesis impairment via preventing the influx of lactate and pyruvate into the cell, consequently suppressing the TCA cycle. This net anaplerosis suppression was compensated in part by the increased utilization of glycogenic amino acids (e.g., alanine and glutamine) into the TCA cycle and by activated ketogenesis through fatty acid β-oxidation. Complementary to these observations, hyperglycemia and hepatic steatosis induced by a high-fat diet were ameliorated in Bsg-deficient mice. Furthermore, Bsg deficiency significantly improved insulin resistance induced by a high-fat diet. Taken together, the plasma membrane–selective modulation of lactate and pyruvate transport through BSG inhibition could potentiate metabolic flexibility to treat metabolic diseases.
Akihiro Ryuge, Tomoki Kosugi, Kayaho Maeda, Ryoichi Banno, Yang Gou, Kei Zaitsu, Takanori Ito, Yuka Sato, Akiyoshi Hirayama, Shoma Tsubota, Takashi Honda, Kazuki Nakajima, Tomoya Ozaki, Kunio Kondoh, Kazuo Takahashi, Noritoshi Kato, Takuji Ishimoto, Tomoyoshi Soga, Takahiko Nakagawa, Teruhiko Koike, Hiroshi Arima, Yukio Yuzawa, Yasuhiko Minokoshi, Shoichi Maruyama, Kenji Kadomatsu