Dopamine transporters are dephosphorylated in striatal homogenates and in vitro by protein phosphatase 1

Foster, James D.; Pananusorn, Benchaporn; Cervinski, Mark A.; Holden, Heather E; Vaughan, Roxanne A.

doi:10.1016/s0169-328x(02)00645-9

Cited by 36 publications

(52 citation statements)

References 34 publications

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“…However, additional PKC phosphorylation sites outside the N-terminal domain might exist in DAT. Although one study indicated loss of PKC-stimulated phosphorylation after mutation of only Ser7 in the N-terminal domain of DAT , other studies have found residual basal and PKC-stimulated phosphorylation after mutation of the distal Ser cluster (Foster et al, 2003;Gorentla et al, 2009). Despite the fact that PKC stimulation markedly increases DAT N-terminal phosphorylation, this seems not to be involved in the PKC-mediated endocytosis of DAT, because truncation of the DAT N terminus almost abolished detectable phosphorylation without blunting PKCmediated down-regulation (Granas et al, 2003;Cervinski et al, 2005).…”

Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

“…Protein phosphatases generally play a pivotal role in regulation of SLC6 NTT phosphorylation, and tonic phosphatase activity has been suggested to maintain the transporters in a relatively dephosphorylated state. For DAT Vaughan et al, 1997;Foster et al, 2002Foster et al, , 2003, SERT (Ramamoorthy et al, 1998a), and NET (Jayanthi et al, 2004), transporter phosphorylation increases upon inhibition of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A). For DAT , SERT (Sakai et al, 1997;Ramamoorthy et al, 1998a), and NET (Jayanthi et al, 2004), inhibition of PP1/PP2A was shown to correlate with down-regulation of transport activity.…”

Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

“…Inhibitors of p38MAPK can also reduce the association of SERT with PP2A , which, combined with the observation that both the cGMP-and p38MAPK-mediated up-regulation in SERT catalytic activity is PP1/2A-dependent (Zhu et al, 2004a, indicates that PP2A is involved in a complex regulatory mechanism for SERT (for review, see Steiner et al, 2008). In vitro dephosphorylation studies of DAT have demonstrated that PP1 can dephosphorylate both PKC-stimulated metabolically phosphorylated rDAT and in vitro phosphorylated N-terminal of DAT (Foster et al, 2003;Gorentla et al, 2009). The phosphorylation level of GATs and GLYTs and their regulation by phosphatases has so far not been investigated in greater detail.…”

Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

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SLC6 Neurotransmitter Transporters: Structure, Function, and Regulation

et al. 2011

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Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

Section: Phosphorylation a Protein Kinase C-mediated Phosphorylationmentioning

confidence: 99%

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SLC6 Neurotransmitter Transporters: Structure, Function, and Regulation

et al. 2011

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“…In addition, DAT proteins can be rapidly regulated by G proteincoupled receptors and protein kinase/phosphatase-linked pathways, including those triggered by activation of protein kinase C (PKC), phosphatidylinositol 3-kinase, mitogen-activated protein kinase, calcium-calmodulin dependent protein kinase II, and PP1/PP2Ac (Carvelli et al, 2002;Foster et al, 2003;Morón et al, 2003;Vaughan, 2004;Bolan et al, 2007;Zapata et al, 2007). Phosphorylation of DAT proteins and DAT-associated proteins are involved in dynamic traffickingdependent and -independent regulation of DAT function (Foster et al, 2002(Foster et al, , 2003Vaughan, 2004). Recent studies examining the concomitant changes in DA transport and membrane DAT expression suggest that these events are correlated (Melikian, 2004).…”

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Dysregulation of Dopamine Transporter Trafficking and Function after Abstinence from Cocaine Self-Administration in Rats: Evidence for Differential Regulation in Caudate Putamen and Nucleus Accumbens

Samuvel

Jayanthi²,

Manohar³

et al. 2008

J Pharmacol Exp Ther

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The profound alterations produced by cocaine on dopamine (DA) neurotransmission raise the possibility that dopamine transporter (DAT)-expressing neurons may modify DA transport in response to repeated cocaine exposure to maintain the appropriate efficiency of DA clearance. In this study, we determined the changes in molecular mechanisms of DAT regulation in rats with a history of repeated cocaine self-administration followed by 3 weeks of abstinence. Using ex vivo caudate putamen (CPu) and nucleus accumbens (NAcc) synaptosomal preparations, we found that DA uptake was significantly higher in the CPu and NAcc of cocaine-experienced animals compared with yoked saline animals. Surface distribution, p-Ser phosphorylation, and protein phosphatase 2A catalytic subunit (PP2Ac) interaction of DAT were all altered in the CPu. Maximal velocity (V max ) values were elevated both in the CPu and NAcc of cocaine-experienced rats compared with saline controls. Although there was no change in the apparent affinity for DA in the CPu, increased DA affinity was evident in the NAcc. Consistent with elevated DAT activity in cocaine-experienced animals, a higher level of surface DAT, DAT-PP2Ac association, and decreased serine phosphorylation of DAT were observed in the CPu, but not in the NAcc. These results, for the first time, suggest that chronic cocaine self-administration followed by abstinence leads to persisting alterations in normal DAT trafficking and catalytic regulatory cascades in the CPu and NAcc in a brain region-specific manner.Drug abuse and dependence to psychostimulants (e.g., cocaine) and other drugs of abuse constitutes a major health problem worldwide, with profound social and financial costs. Although cocaine inhibits both the serotonin transporter (SERT) and norepinephrine transporter (NET), several lines of evidence have shown that cocaine produces its primary reinforcing effects by binding to the dopamine (DA) transporter (DAT) and blocking the reuptake of DA into presynaptic terminals, thereby potentiating DA neurotransmission in mesocorticolimbic reward pathways (Wise and Rompre, 1989;Robinson and Berridge, 1993;Koob et al., 1998;McFarland and Kalivas, 2001). The relevance of DAT in DA homeostasis and in the reinforcing effects of cocaine are supported by several studies on cocaine-induced behaviors, and on neurotransmitter synthesis, storage, release, and DA receptor expression resulting from removal of DAT genes in mutant mice, and changes described in human cocaine addicts (Fumagalli et al., 1998;Jones et al., 1998;Sora et al., 2001;Jayanthi and Ramamoorthy, 2005;Jayanthi et al., 2007). Thus, long-term changes in DAT levels, kinetics, or regulation would be expected to greatly influence spontaneous and drug-induced behaviors.The search for neuroadaptations in DAT expression has focused on studies in human cocaine-dependent users and a variety of animal models of cocaine addiction. Several strategies have been adapted to quantify DAT levels, including

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“…This suggests that changes in transporter activity cannot always be accounted for by changes in surface transporter level (Lin et al, 2003). PKC activation also results in transporter phosphorylation, suggesting an association between transporter phosphorylation and internalization (Ramamoorthy et al, 1998a;Foster et al, 2003;Lin et al, 2003;Vaughan, 2004). It has been shown recently that DAT exhibits normal PKC-mediated transporter kinetics and trafficking patterns even when PKC-mediated DAT phosphorylation is eliminated by mutation of predicted intracellular PKC sites on DAT (Granas et al, 2003), suggesting that PKCmediated DAT phosphorylation and down-regulation are two independent phenomena.…”

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confidence: 99%

Evidence for Biphasic Effects of Protein Kinase C on Serotonin Transporter Function, Endocytosis, and Phosphorylation

Jayanthi

Samuvel

Blakely³

et al. 2005

Mol Pharmacol

110

131

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The serotonin transporter (SERT) regulates 5-hydroxytryptamine (serotonin) (5-HT) neurotransmission and is a high-affinity target for antidepressants and psychostimulants. In the present study, we investigated the mechanisms that contribute to a previously unidentified biphasic regulation of endogenous SERTs expressed in the platelets. Treatment of rat platelets with ␤-phorbol 12-myristate 13-acetate (PMA) for 5 min or less resulted in a rapid inhibition of SERT involving changes in intrinsic activity of the transporter (increased K m and decreased V max ). ␤-PMA treatment for 30 min or more produced a sustained inhibition of SERT with a decrease only in the V max . Whereas inhibition of SERT activity was detected from 1 to 45 min after phorbol ester addition, the decrease in surface SERT required at least 30 min of phorbol ester incubation. Increased endocytosis of SERT accounted for the decrease in surface SERT at the later point. Protein kinase C (PKC)-mediated phosphorylation of SERT occurs on the plasma membrane during the initial phase of rapid transporter inhibition, and later, the phosphorylated SERT enters the intracellular pool. ␤-PMA-induced phosphorylation of SERT occurs initially on serine residues(s) and then on threonine residue(s). The initial serine phosphorylation corresponded to the first phase of rapid inhibition mediated by changes in intrinsic activity and/or silencing of SERT. The later phosphorylation on threonine residue(s) corresponded to the later phase of sustained inhibition mediated by an enhanced endocytosis of SERT. Together, these data reveal that in platelets, SERT function is regulated by PKC in a biphasic manner involving both trafficking-dependent and independent mechanisms and that these two events occur at distinct phases of transporter phosphorylation.5-Hydroxytryptamine (serotonin; 5-HT) controls many behavioral and physiological functions (Jacobs and Fornal, 1995). 5-HT uptake via the cocaine-and antidepressantsensitive serotonin transporter (SERT) is essential for serotonergic neurotransmission termination (Barker and Blakely, 1995). Altered SERT expression and two polymorphic regions in SERT promoter have been implicated in multiple forms of psychopathology, including depression, suicide, anxiety, aggression, schizophrenia, alcoholism, and drug addiction (Murphy et al., 2004). Although clearance of synaptic and extrasynaptic 5-HT seems to be the principal function of SERTs, certain cells, notably platelets, use SERTs to acquire 5-HT from the extracellular environment for subsequent release, involving in the processes of platelet activation (Cirillo et al., 1999). Platelets and 5-HT neurons share many common properties, including vesicular monoamine transporters, 5-HT release, biochemistry, identical SERT sequences, and 5-HT receptors (Owens and Nemeroff, 1994). In addition, alterations in platelet SERT have been observed in many psychiatric disorders and vascular diseases in which 5-HT has been implicated (Meltzer et al., 1981). Therefore, platelets have been w...

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Dopamine transporters are dephosphorylated in striatal homogenates and in vitro by protein phosphatase 1

Cited by 36 publications

References 34 publications

SLC6 Neurotransmitter Transporters: Structure, Function, and Regulation

SLC6 Neurotransmitter Transporters: Structure, Function, and Regulation

Dysregulation of Dopamine Transporter Trafficking and Function after Abstinence from Cocaine Self-Administration in Rats: Evidence for Differential Regulation in Caudate Putamen and Nucleus Accumbens

Evidence for Biphasic Effects of Protein Kinase C on Serotonin Transporter Function, Endocytosis, and Phosphorylation

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