TY - JOUR
T1 - Orientation and cellular distribution of membrane-bound catechol-O-methyltransferase in cortical neurons
T2 - Implications for drug development
AU - Chen, Jingshan
AU - Song, Jian
AU - Yuan, Peixiong
AU - Tian, Qingjun
AU - Ji, Yuanyuan
AU - Ren-Patterson, Renee
AU - Liu, Guangping
AU - Sei, Yoshitasu
AU - Weinberger, Daniel R.
PY - 2011/10/7
Y1 - 2011/10/7
N2 - Catechol-O-methyltransferase (COMT) is a key enzyme for inactivation and metabolism of catechols, including dopamine, norepinephrine, caffeine, and estrogens. It plays an important role in cognition, arousal, pain sensitivity, and stress reactivity in humans and in animal models. The human COMT gene is associated with a diverse spectrum of human behaviors and diseases from cognition and psychiatric disorders to chronic pain and cancer. There are two major forms of COMT proteins, membrane-bound (MB) COMT and soluble (S) COMT. MB-COMT is the main form in the brain. The cellular distribution of MB-COMT in cortical neurons remains unclear and the orientation of MB-COMT on the cellular membrane is controversial. In this study, we demonstrate that MB-COMT is located in the cell body and in axons and dendrites of rat cortical neurons. Analyses of MB-COMT orientation with computer simulation, flow cytometry and a cell surface enzyme assay reveal that the C-terminal catalytic domain of MB-COMT is in the extracellular space, which suggests that MB-COMT can inactivate synaptic and extrasynaptic dopamine on the surface of presynaptic and postsynaptic neurons. Finally, we show that the COMT inhibitor tolcapone induces cell death via the mechanism of apoptosis, and its cytotoxicity is dependent on dosage and correlated with COMT Val/Met genotypes in human lymphoblastoid cells. These results suggest thatMB-COMTspecific inhibitors can be developed and that tolcapone may be less hazardous at low doses and in specific genetic backgrounds.
AB - Catechol-O-methyltransferase (COMT) is a key enzyme for inactivation and metabolism of catechols, including dopamine, norepinephrine, caffeine, and estrogens. It plays an important role in cognition, arousal, pain sensitivity, and stress reactivity in humans and in animal models. The human COMT gene is associated with a diverse spectrum of human behaviors and diseases from cognition and psychiatric disorders to chronic pain and cancer. There are two major forms of COMT proteins, membrane-bound (MB) COMT and soluble (S) COMT. MB-COMT is the main form in the brain. The cellular distribution of MB-COMT in cortical neurons remains unclear and the orientation of MB-COMT on the cellular membrane is controversial. In this study, we demonstrate that MB-COMT is located in the cell body and in axons and dendrites of rat cortical neurons. Analyses of MB-COMT orientation with computer simulation, flow cytometry and a cell surface enzyme assay reveal that the C-terminal catalytic domain of MB-COMT is in the extracellular space, which suggests that MB-COMT can inactivate synaptic and extrasynaptic dopamine on the surface of presynaptic and postsynaptic neurons. Finally, we show that the COMT inhibitor tolcapone induces cell death via the mechanism of apoptosis, and its cytotoxicity is dependent on dosage and correlated with COMT Val/Met genotypes in human lymphoblastoid cells. These results suggest thatMB-COMTspecific inhibitors can be developed and that tolcapone may be less hazardous at low doses and in specific genetic backgrounds.
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U2 - 10.1074/jbc.M111.262790
DO - 10.1074/jbc.M111.262790
M3 - Article
C2 - 21846718
AN - SCOPUS:80053421300
SN - 0021-9258
VL - 286
SP - 34752
EP - 34760
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 40
ER -