TY - JOUR
T1 - Proline modulates the intracellular redox environment and protects mammalian cells against oxidative stress
AU - Krishnan, Navasona
AU - Dickman, Martin B.
AU - Becker, Donald F.
N1 - Funding Information:
This work is a contribution of the University of Nebraska Agricultural Research Division, supported in part by funds provided through the Hatch Act. Additional support was provided by NIH Pilot Grant 5P-20-RR017675-03 and NIH Grant P20 RR-017675-02 from the National Center for Research Resources. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. We thank Dr. Andy Hu (University of New Mexico School of Medicine) for the generous gift of the P5CS gene, Daniell Shea for assistance with the flow cytometry experiments, and Dr. Ashraf Raza in the Metabolomics Core Facility in the Redox Biology Center.
PY - 2008/2/15
Y1 - 2008/2/15
N2 - The potential of proline to suppress reactive oxygen species (ROS) and apoptosis in mammalian cells was tested by manipulating intracellular proline levels exogenously and endogenously by overexpression of proline metabolic enzymes. Proline was observed to protect cells against H2O2, tert-butyl hydroperoxide, and a carcinogenic oxidative stress inducer but was not effective against superoxide generators such as menadione. Oxidative stress protection by proline requires the secondary amine of the pyrrolidine ring and involves preservation of the glutathione redox environment. Overexpression of proline dehydrogenase (PRODH), a mitochondrial flavoenzyme that oxidizes proline, resulted in 6-fold lower intracellular proline content and decreased cell survival relative to control cells. Cells overexpressing PRODH were rescued by pipecolate, an analog that mimics the antioxidant properties of proline, and by tetrahydro-2-furoic acid, a specific inhibitor of PRODH. In contrast, overexpression of the proline biosynthetic enzymes Δ1-pyrroline-5-carboxylate (P5C) synthetase (P5CS) and P5C reductase (P5CR) resulted in 2-fold higher proline content, significantly lower ROS levels, and increased cell survival relative to control cells. In different mammalian cell lines exposed to physiological H2O2 levels, increased endogenous P5CS and P5CR expression was observed, indicating that upregulation of proline biosynthesis is an oxidative stress response.
AB - The potential of proline to suppress reactive oxygen species (ROS) and apoptosis in mammalian cells was tested by manipulating intracellular proline levels exogenously and endogenously by overexpression of proline metabolic enzymes. Proline was observed to protect cells against H2O2, tert-butyl hydroperoxide, and a carcinogenic oxidative stress inducer but was not effective against superoxide generators such as menadione. Oxidative stress protection by proline requires the secondary amine of the pyrrolidine ring and involves preservation of the glutathione redox environment. Overexpression of proline dehydrogenase (PRODH), a mitochondrial flavoenzyme that oxidizes proline, resulted in 6-fold lower intracellular proline content and decreased cell survival relative to control cells. Cells overexpressing PRODH were rescued by pipecolate, an analog that mimics the antioxidant properties of proline, and by tetrahydro-2-furoic acid, a specific inhibitor of PRODH. In contrast, overexpression of the proline biosynthetic enzymes Δ1-pyrroline-5-carboxylate (P5C) synthetase (P5CS) and P5C reductase (P5CR) resulted in 2-fold higher proline content, significantly lower ROS levels, and increased cell survival relative to control cells. In different mammalian cell lines exposed to physiological H2O2 levels, increased endogenous P5CS and P5CR expression was observed, indicating that upregulation of proline biosynthesis is an oxidative stress response.
KW - Oxidative stress protection
KW - Proline
KW - Proline biosynthesis
KW - Proline oxidation
KW - Reactive oxygen species (ROS)
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U2 - 10.1016/j.freeradbiomed.2007.10.054
DO - 10.1016/j.freeradbiomed.2007.10.054
M3 - Article
C2 - 18036351
AN - SCOPUS:38649109148
VL - 44
SP - 671
EP - 681
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
IS - 4
ER -