The retina and retinal pigment epithelium differ in nitrogen metabolism and are metabolically connected
Rong Xu, Brianna Ritz, Yekai Wang, Jiancheng Huang, Chen Zhao, Kaizheng Gong, Xinnong Liu, Jianhai Du
Abstract
synthesis of glutamate, glutamine, and aspartate, whereas RPE uses multiple transaminases to utilize and synthesize amino acids. Retina consumes more leucine than RPE, but little leucine is catabolized. The synthesis of serine and glycine is active in RPE but limited in the retina. RPE, but not the retina, uses alanine as mitochondrial substrates through mitochondrial pyruvate carrier. However, when the mitochondrial pyruvate carrier is inhibited, alanine may directly enter the retinal mitochondria but not those of RPE. In conclusion, our results demonstrate that the retina and RPE differ in nitrogen metabolism and highlight that the RPE supports retinal metabolism through active amino acid metabolism.