Characterization of a mitochondria associated phosphocreatine phosphatase in thermogenic adipocytes

ABSTRACT: Adaptive thermogenesis has attracted much attention because of its ability to raise systemic energy expenditure and counter obesity and diabetes. Recent data have indicated that thermogenic fat cells utilize creatine to stimulate futile substrate cycling, dissipating chemical energy as heat. This model was based on the super-stoichiometric relationship between creatine added to mitochondria and O2 consumed, and this project aims at providing direct evidence for the molecular basis of this futile creatine cycling activity. In this project, we found that thermogenic fat cells contain robust phosphocreatine hydrolase (PCr’ase) activity, attributable to tissue-nonspecific alkaline phosphatase (TNAP), which was identified by the quantitative mass spectrometric analysis of a purified mitochondrial protein fraction containing the PCr’ase activity. TNAP hydrolyzes phosphocreatine to initiate a futile cycle of creatine dephosphorylation and phosphorylation; it is localized to mitochondria of thermogenic fat cells, where the futile creatine cycling occurs. Furthermore, we demonstrated in this project the essential role of TNAP in activating the futile creatine cycling and increasing whole body energy expenditure using genetic and pharmacological approaches. We also found that the genetic depletion of TNAP in murine adipose tissue causes rapid-onset obesity, with no change in movement or feeding behavior of the animals. Using quantitative mass spectrometry, we showed that genetic depletion of TNAP causes an upregulation of UCP1, as well as other proteins involved in oxidative metabolism, to compensate for a dampened thermogenesis. In summary, the data we acquired in this project illustrate the critical role of TNAP as a phosphocreatine phosphatase in the futile creatine cycling and adipose thermogenesis.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Adipose Tissue, Subcutaneous Abdominal Adipose Tissue

DISEASE(S): Type 2 Diabetes Mellitus

SUBMITTER: mark Jedrychowski  

LAB HEAD: Bruce Spiegelman

PROVIDER: PXD025032 | Pride | 2022-02-17

REPOSITORIES: Pride