Phosphate-activated glutaminase (GLS2), a p53-inducible regulator of glutamine metabolism and reactive oxygen species.
We identified a p53 target gene, phosphate-activated mitochondrial glutaminase (GLS2), a key enzyme in conversion of glutamine to glutamate, and thereby a regulator of glutathione (GSH) synthesis and energy production. GLS2 expression is induced in response to DNA damage or oxidative stress in a p53-dependent manner, and p53 associates with the GLS2 promoter. Elevated GLS2 facilitates glutamine metabolism and lowers intracellular reactive oxygen species (ROS) levels, resulting in an overall decrease in DNA oxidation as determined by measurement of 8-OH-dG content in both normal and stressed cells. Further, siRNA down-regulation of either GLS2 or p53 compromises the GSH-dependent antioxidant system and increases intracellular ROS levels. High ROS levels following GLS2 knockdown also coincide with stimulation of p53-induced cell death. We propose that GLS2 control of intracellular ROS levels and the apoptotic response facilitates the ability of p53 to protect cells from accumulation of genomic damage and allows cells to survive after mild and repairable genotoxic stress. Indeed, overexpression of GLS2 reduces the growth of tumor cells and colony formation. Further, compared with normal tissue, GLS2 expression is reduced in liver tumors. Thus, our results provide evidence for a unique metabolic role for p53, linking glutamine metabolism, energy, and ROS homeostasis, which may contribute to p53 tumor suppressor function.
Suzuki
Sawako
S
Department of Clinical Cell Biology and Division of Endocrinology and Metabolism, Chiba University Graduate School of Medicine, Chiba-shi, Chiba 260-8670, Japan.
Tanaka
Tomoaki
T
Poyurovsky
Masha V
MV
Nagano
Hidekazu
H
Mayama
Takafumi
T
Ohkubo
Shuichi
S
Lokshin
Maria
M
Hosokawa
Hiroyuki
H
Nakayama
Toshinori
T
Suzuki
Yutaka
Y
Sugano
Sumio
S
Sato
Eiichi
E
Nagao
Toshitaka
T
Yokote
Koutaro
K
Tatsuno
Ichiro
I
Prives
Carol
C
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D005972:Glutaminase / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D000975:Antioxidants; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D005973:Glutamine; D005972:Glutaminase; D005978:Glutathione