title: The effect of long term calorie restriction on in vivo hepatic proteostatis: a novel combination of dynamic and quantitative proteomics.
abstract: Calorie restriction (CR) promotes longevity. A prevalent mechanistic hypothesis explaining this effect suggests that protein degradation, including mitochondrial autophagy, is increased with CR, removing damaged proteins and improving cellular fitness. At steady state, increased catabolism must be balanced by increasing mitochondrial biogenesis and protein synthesis, resulting in faster protein replacement rates. To test this hypothesis, we measured replacement kinetics and relative concentrations of hundreds of proteins in vivo in long-term CR and ad libitum-fed mice using metabolic (2)H(2)O-labeling combined with the Stable Isotope Labeling in Mammals protocol and LC-MS/MS analysis of mass isotopomer abundances in tryptic peptides. CR reduced absolute synthesis and breakdown rates of almost all measured hepatic proteins and prolonged the half-lives of most (≈ 80%), particularly mitochondrial proteins (but not ribosomal subunits). Proteins with related functions exhibited coordinated changes in relative concentration and replacement rates. In silico expression pathway interrogation allowed the testing of potential regulators of altered network dynamics (e.g. peroxisome proliferator-activated receptor gamma coactivator 1-alpha). In summary, our combination of dynamic and quantitative proteomics suggests that long-term CR reduces mitochondrial biogenesis and mitophagy. Our findings contradict the theory that CR increases mitochondrial protein turnover and provide compelling evidence that cellular fitness is accompanied by reduced global protein synthetic burden.
authors.affiliation: Kinemed Inc., Emeryville, CA 94608, USA. DrJohnCPrice@gmail.com
authors.forename: John C
authors.initials: JC
authors.lastname: Price
authors.forename: Cyrus F
authors.initials: CF
authors.lastname: Khambatta
authors.forename: Kelvin W
authors.initials: KW
authors.lastname: Li
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Bruss
authors.forename: Mahalakshmi
authors.initials: M
authors.lastname: Shankaran
authors.forename: Marcy
authors.initials: M
authors.lastname: Dalidd
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Floreani
authors.forename: Lindsay S
authors.initials: LS
authors.lastname: Roberts
authors.forename: Scott M
authors.initials: SM
authors.lastname: Turner
authors.forename: William E
authors.initials: WE
authors.lastname: Holmes
authors.forename: Marc K
authors.initials: MK
authors.lastname: Hellerstein
mesh_terms: D000818:Animals; D031204:Caloric Restriction; D049109:Cell Proliferation; D002853:Chromatography, Liquid; D017666:Deuterium Oxide; D004734:Energy Metabolism; D007553:Isotope Labeling; D008099:Liver / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D047495:PPAR gamma / Q000378:metabolism; D020543:Proteome / Q000032:analysis*
chemical_list: D024101:Mitochondrial Proteins; D047495:PPAR gamma; D020543:Proteome; D017666:Deuterium Oxide