Erythrocyte transglutaminase-2 combats hypoxia and chronic kidney disease by promoting oxygen delivery and carnitine homeostasis

Cell Metab. 2022 Feb 1;34(2):299-316.e6. doi: 10.1016/j.cmet.2021.12.019.


Due to lack of nuclei and de novo protein synthesis, post-translational modification (PTM) is imperative for erythrocytes to regulate oxygen (O2) delivery and combat tissue hypoxia. Here, we report that erythrocyte transglutminase-2 (eTG2)-mediated PTM is essential to trigger O2 delivery by promoting bisphosphoglycerate mutase proteostasis and the Rapoport-Luebering glycolytic shunt for adaptation to hypoxia, in healthy humans ascending to high altitude and in two distinct murine models of hypoxia. In a pathological hypoxia model with chronic kidney disease (CKD), eTG2 is critical to combat renal hypoxia-induced reduction of Slc22a5 transcription and OCNT2 protein levels via HIF-1α-PPARα signaling to maintain carnitine homeostasis. Carnitine supplementation is an effective and safe therapeutic approach to counteract hypertension and progression of CKD by enhancing erythrocyte O2 delivery. Altogether, we reveal eTG2 as an erythrocyte protein stabilizer orchestrating O2 delivery and tissue adaptive metabolic reprogramming and identify carnitine-based therapy to mitigate hypoxia and CKD progression.

Keywords: HIF-1α; L-carnitine; PPARα; Slc22a5 (OCTN2)); bisphosphoglycerate mutase; chronic kidney disease; erythrocyte; hypoxia; proteostasis; transglutaminase 2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Carnitine* / metabolism
  • Erythrocytes / metabolism
  • Erythrocytes / pathology
  • Homeostasis
  • Humans
  • Hypoxia / metabolism
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Mice
  • Oxygen / metabolism
  • Renal Insufficiency, Chronic* / pathology
  • Solute Carrier Family 22 Member 5 / metabolism
  • Transglutaminases / metabolism


  • Hypoxia-Inducible Factor 1, alpha Subunit
  • SLC22A5 protein, human
  • Solute Carrier Family 22 Member 5
  • Transglutaminases
  • Carnitine
  • Oxygen