Species differences in functions of dopamine transporter: paucity of MPP+ uptake and cocaine binding in bovine dopamine transporter

doi:10.1016/0304-3940(96)12913-X

Neuroscience Letters

Volume 214, Issues 2–3, 23 August 1996, Pages 199-201

https://doi.org/10.1016/0304-3940(96)12913-X Get rights and content

Abstract

Expression of cloned cDNA for human, rat and bovine dopamine transporter (DAT) in COS cells allows the comparison of the functional differences among the respective dopamine transporters. Human DAT showed the highest activities for dopamine uptake, MPP⁺ uptake and cocaine binding, indicating that humans are more vulnerable to 1-methyl-4-phenylpyridinium (MPP⁺) toxicity and cocaine addiction. However, bovine DAT showed poor MPP⁺ uptake and cocaine binding, even though its dopamine uptake ability was quite avid. Here, we conclude that the paucity of MPP⁺ uptake and cocaine binding is a unique characteristic in bovine DAT.

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Cited by (19)

Human Self-Domestication and the Extended Evolutionary Synthesis of Addiction: How Humans Evolved a Unique Vulnerability
2019, Neuroscience
Citation Excerpt :
The ligand recognition site of the kappa opioid receptor subtypes differ among mammalian species as found in a study comparing ligand selectivity patterns between humans, rats and guinea pigs (Rothman et al., 1992). Human dopamine transporter (DAT) shows the highest activities for dopamine uptake, uptake of neurotoxin 1-methyl-4-phenylpyridinium (MPP+) and cocaine binding when compared to bovine and rat (Lee et al., 1996). Lee et al. (1996) concluded that humans are, therefore, more vulnerable to MPP+ toxicity and cocaine addiction.
Humans are more vulnerable to addiction in comparison to all other mammals, including nonhuman primates, yet there is a lack of research addressing this. This paper reviews the field of comparative addiction neuroscience, highlighting the significant inter-species variation in the mesocortical dopaminergic and other neuromodulatory systems involved in addiction. Artificial selection gives rise to significant changes in neuroanatomy, neurophysiology and behaviour as shown in certain rodent strains and other domesticated animals. These changes occur over a few generations, relatively short periods of time in evolutionary terms, and demonstrate how dynamic these neuromodulatory systems are in response to the environment. During the course of human evolution, traits crucial to our survival, expansion and domination (traits such as the ability to innovate, adapt to different environments and thrive in a civilization) have been positively selected for, yet also predispose humans to addiction. This is evident in our unique neurochemistry and receptor-drug activation potencies. Examples of these are provided as possible targets for precision medicine.
Genetic Polymorphism and Susceptibility to Pesticides
2010, Hayes' Handbook of Pesticide Toxicology
This chapter appraises the gene–environment interactions that refer to phenotypic effects resulting from interactions between genes and the environment. Such interactions are often viewed in the context of disease, specifically how one's risk for an environmentally induced disease or condition is influenced by his/her genetic makeup. At the intersection of gene–environment interactions are biotransformation enzymes. The most well-known site of biotransformation is the liver, where biotransformation enzymes are found in abundance. Biotransformation enzymes act on endogenous compounds, such as steroid hormones, as well as exogenous compounds, including pesticides and other man-made chemicals, often serving to make them more polar and more suitable for excretion. Sometimes, however, biotransformation may generate more reactive products, which may be more toxic than their parent compounds. The Human Genome Project has generated an unprecedented opportunity, as well as the necessary tools and technologies, to explore how individual genetic variability can influence the chances of developing a pesticide-related disease. Technologies are now in hand to measure hundreds of thousands of specific genetic variants in an individual, although it remains costly to apply such extensive analyses to the thousands of samples needed for a statistically robust study. Future studies aimed at elucidating genetic risk factors for pesticide-related diseases should consider multiple potential genetic variants, rather than one or a handful of candidate genes and detailed consideration of pesticide exposures, including consideration of early life exposures, and specific pesticides.
Genetic Polymorphism and Susceptibility to Pesticides
2010, Hayes' Handbook of Pesticide Toxicology, Third Edition: Volume 1
This chapter appraises the gene–environment interactions that refer to phenotypic effects resulting from interactions between genes and the environment. Such interactions are often viewed in the context of disease, specifically how one's risk for an environmentally induced disease or condition is influenced by his/her genetic makeup. At the intersection of gene–environment interactions are biotransformation enzymes. The most well-known site of biotransformation is the liver, where biotransformation enzymes are found in abundance. Biotransformation enzymes act on endogenous compounds, such as steroid hormones, as well as exogenous compounds, including pesticides and other man-made chemicals, often serving to make them more polar and more suitable for excretion. Sometimes, however, biotransformation may generate more reactive products, which may be more toxic than their parent compounds. The Human Genome Project has generated an unprecedented opportunity, as well as the necessary tools and technologies, to explore how individual genetic variability can influence the chances of developing a pesticide-related disease. Technologies are now in hand to measure hundreds of thousands of specific genetic variants in an individual, although it remains costly to apply such extensive analyses to the thousands of samples needed for a statistically robust study. Future studies aimed at elucidating genetic risk factors for pesticide-related diseases should consider multiple potential genetic variants, rather than one or a handful of candidate genes and detailed consideration of pesticide exposures, including consideration of early life exposures, and specific pesticides.
Role of dopamine transporter (DAT) in dopamine transport across the nasal mucosa
2006, Life Sciences
Dopamine is a catecholamine neurotransmitter necessary for motor functions. Its deficiency has been observed in several neurological disorders, but replacement of endogenous dopamine via oral or parenteral delivery is limited by poor absorption, rapid metabolism and the inability of dopamine to cross the blood-brain barrier. The intranasal administration of dopamine, however, has resulted in improved central nervous system (CNS) bioavailability compared to that obtained following intravenous delivery. Portions of the nasal mucosa are innervated by olfactory neurons expressing dopamine transporter (DAT) which is responsible for the uptake of dopamine within the central nervous system. The objective of these studies was to study the role of DAT in dopamine transport across the bovine olfactory and nasal respiratory mucosa. Western blotting studies demonstrated the expression of DAT and immunohistochemistry revealed its epithelial and submucosal localization within the nasal mucosa. Bidirectional transport studies over a 0.1–1 mM dopamine concentration range were carried out in the mucosal–submucosal and submucosal–mucosal directions to quantify DAT activity, and additional transport studies investigating the ability of GBR 12909, a DAT inhibitor, to decrease dopamine transport were conducted. Dopamine transport in the mucosal–submucosal direction was saturable and was decreased in the presence of GBR 12909. These studies demonstrate the activity of DAT in the nasal mucosa and provide evidence that DAT-mediated dopamine uptake plays a role in the absorption and distribution of dopamine following intranasal administration.
Cloning of dopamine, norepinephrine and serotonin transporters from monkey brain: Relevance to cocaine sensitivity
2001, Molecular Brain Research
We used RT–PCR to clone monoamine transporters from Macaca mulatta, Macaca fasicularis and Saimiri sciureus (dopamine transporter; DAT) and Macaca mulatta (norepinephrine transporter; NET and serotonin transporter; SERT). Monkey DAT, NET and SERT proteins were >98% homologous to human and, when expressed in HEK-293 cells, displayed drug affinities and uptake kinetics that were highly correlated with monkey brain or human monoamine transporters. In contrast to reports of other species, we discovered double (leucine for phenylalanine 143 and arginine for glutamine 509; Variant I) and single (proline for leucine 355; Variant II) amino acid variants of DAT. Variant I displayed dopamine transport kinetics and binding affinities for various DAT blockers (including cocaine) versus [³H] CFT (WIN 35, 428) that were identical to wild-type DAT (n=7 drugs; r²=0.991). However, we detected a six-fold difference in the affinity of cocaine versus [³H] cocaine between Variant I (IC₅₀: 488±102 nM, SEM, n=3) and wild-type DAT (IC₅₀: 79±8.2 nM, n=3, P<0.05). Variant II was localized intracellularly in HEK-293 cells, as detected by confocal microscopy, and had very low levels of binding and dopamine transport. Also discovered was a novel exon 5 splice variant of NET that displayed very low levels of transport and did not bind cocaine. With NetPhos analysis, we detected a number of highly conserved putative phosphorylation sites on extracellular as well as intracellular loops of the DAT, NET, and SERT, which may be functional for internalized transporters. The homology and functional similarity of human and monkey monoamine transporters further support the value of primates in investigating the role of monoamine transporters in substance abuse mechanisms, neuropsychiatric disorders and development of diagnostic and therapeutic agents.
Structure and function of the dopamine transporter
2000, European Journal of Pharmacology
Citation Excerpt :
It has been noted that changes in binding affinity of a cocaine analog (Kd) do not always parallel changes in its potency to inhibit dopamine uptake (Ki). For example, in mutant human dopamine transporter in which the C-terminus is truncated or substituted, both cocaine and CFT inhibit dopamine uptake with a Ki similar to that in wild-type, while their binding affinities are at least four to fivefolds lower than those in wild-type (Lee et al., 1996a,b). Likewise, CFT potently inhibits dopamine uptake by COS-dopamine transporter in which the carrier appears prematurely truncated after transmembrane domain 6, even though no specific [3H]CFT binding is observed in those cells (Sugamori et al., 1999).
The dopamine transporter mediates uptake of dopamine into neurons and is a major target for various pharmacologically active drugs and environmental toxins. Since its cloning, much information has been obtained regarding its structure and function. Binding domains for dopamine and various blocking drugs including cocaine are likely formed by interactions with multiple amino acid residues, some of which are separate in the primary structure but lie close together in the still unknown tertiary structure. Chimera and site-directed mutagenesis studies suggest the involvement of both overlapping and separate domains in the interaction with substrates and blockers, whereas recent findings with sulfhydryl reagents selectively targeting cysteine residues support a role for conformational changes in the binding of blockers such as cocaine. The dopamine transporter can also operate in reverse, i.e. in an efflux mode, and recent mutagenesis experiments show different structural requirements for inward and outward transport. Strong evidence for dopamine transporter domains selectively influencing binding of dopamine or cocaine analogs has not yet emerged, although the development of a cocaine antagonist at the level of the transporter remains a possibility.

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Species differences in functions of dopamine transporter: paucity of MPP+ uptake and cocaine binding in bovine dopamine transporter

Abstract

Prog. Neurobiol.

Trends Neurosci.

Trends Pharmacol. Sci.

Role of transmitter uptake mechanisms in synaptic neurotransmission

Br. J. Pharmacol.

Cloning and expression of a cocaine-sensitive dopamine transporter complementary DNA

Science

Parkinsonism-inducing neurotoxin MPP+: uptake and toxicity in nonneuronal COS cells expressing dopamine transporter cDNA

Ann. Neurol.

Species differences in functions of dopamine transporter: paucity of MPP⁺ uptake and cocaine binding in bovine dopamine transporter

Parkinsonism-inducing neurotoxin MPP⁺: uptake and toxicity in nonneuronal COS cells expressing dopamine transporter cDNA