Journal Article

Creatine maintains intestinal homeostasis and protects against colitis

Li, Xiaohong, McAlpine, William, Tang, Miao, Zhan, Xiaoming, Lu, Tianshi, Bu, Chun-Hui, Turer, Emre, Wang, Kuan-wen, Murray, Anne R., Wang, Tao, Zhan, Xiaowei, Beutler, Bruce

2017

Overview

Creatine, a nitrogenous organic acid, replenishes cytoplasmic ATP at the expense of mitochondrial ATP via the phosphocreatine shuttle. Creatine levels are maintained by diet and endogenous synthesis from arginine and glycine. Glycine amidinotransferase (GATM) catalyzes the rate-limiting step of creatine biosynthesis: the transfer of an amidino group from arginine to glycine to form ornithine and guanidinoacetate. We screened 36,530 third-generation germline mutant mice derived from N-ethyl-N-nitrosourea–mutagenized grandsires for intestinal homeostasis abnormalities after oral administration of dextran sodium sulfate (DSS). Among 27 colitis susceptibility phenotypes identified and mapped, one was strongly correlated with a missense mutation in Gatm in a recessive model of inheritance, and causation was confirmed by CRISPR/Cas9 gene targeting. Supplementation of homozygous Gatm mutants with exogenous creatine ameliorated the colitis phenotype. CRISPR/Cas9-targeted (Gatmc/c ) mice displayed a normal peripheral immune response and immune cell homeostasis. However, the intestinal epithelium of the Gatmc/c mice displayed increased cell death and decreased proliferation during DSS treatment. In addition, Gatmc/c colonocytes showed increased metabolic stress in response to DSS with higher levels of phospho-AMPK and lower levels of phosphorylation of mammalian target of rapamycin (phospho-mTOR). These findings establish an in vivo requirement for rapid replenishment of cytoplasmic ATP within colonic epithelial cells in the maintenance of the mucosal barrier after injury.

• Publisher: National Academy of Sciences
• Subject: Acids / Amidinotransferases - genetics / Amidinotransferases - metabolism / Animals / ATP / Biological Sciences / Biosynthesis / Colitis - genetics / Colitis - metabolism / Colitis - prevention & control / Colon - drug effects / Colon - metabolism / Creatine - metabolism / Creatine - pharmacology / CRISPR-Cas Systems / Epithelial Cells - drug effects / Epithelial Cells - metabolism / Female / Homeostasis / Homeostasis - drug effects / Immune response / Inflammatory bowel disease / Intestines - drug effects / Intestines - metabolism / Male / Mice, Inbred C57BL / Mutation / Mutation, Missense / Organic acids / Physiology / PNAS Plus / Protective Agents - metabolism / Protective Agents - pharmacology / Sodium sulfate / Stress response