title: Direct regulation of diurnal Drd3 expression and cocaine reward by NPAS2.
abstract: BACKGROUND
  Circadian gene disruptions are associated with the development of psychiatric disorders, including addiction. However, the mechanisms by which circadian genes regulate reward remain poorly understood.
  
  
  METHODS
  We used mice with a mutation in Npas2 and adeno-associated virus-short hairpin RNA mediated knockdown of Npas2 and Clock in the nucleus accumbens (NAc). We performed conditioned place preference assays. We utilized cell sorting quantitative real-time polymerase chain reaction, and chromatin immunoprecipitation followed by deep sequencing.
  
  
  RESULTS
  Npas2 mutants exhibit decreased sensitivity to cocaine reward, which is recapitulated with a knockdown of neuronal PAS domain protein 2 (NPAS2) specifically in the NAc, demonstrating the importance of NPAS2 in this region. Interestingly, reducing circadian locomotor output cycles kaput (CLOCK) (a homologue of NPAS2) in the NAc had no effect, suggesting an important distinction in NPAS2 and CLOCK function. Furthermore, we found that NPAS2 expression is restricted to Drd1 expressing neurons while CLOCK is ubiquitous. Moreover, NPAS2 and CLOCK have distinct temporal patterns of DNA binding, and we identified novel and unique binding sites for each protein. We identified the Drd3 dopamine receptor as a direct transcriptional target of NPAS2 and found that NPAS2 knockdown in the NAc disrupts its diurnal rhythm in expression. Chronic cocaine treatment likewise disrupts the normal rhythm in Npas2 and Drd3 expression in the NAc, which may underlie behavioral plasticity in response to cocaine.
  
  
  CONCLUSIONS
  Together, these findings identify an important role for the circadian protein, NPAS2, in the NAc in the regulation of dopamine receptor expression and drug reward.
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219.
authors.forename: Angela R
authors.initials: AR
authors.lastname: Ozburn
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Falcon
authors.affiliation: Bioinformatics Analysis Core, Clinical and Translational Science Institute at the University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Alan
authors.initials: A
authors.lastname: Twaddle
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: Alexandria L
authors.initials: AL
authors.lastname: Nugent
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219.
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Gillman
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: Sade M
authors.initials: SM
authors.lastname: Spencer
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: Rachel N
authors.initials: RN
authors.lastname: Arey
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: Shibani
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Bioinformatics Analysis Core, Clinical and Translational Science Institute at the University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: James
authors.initials: J
authors.lastname: Lyons-Weiler
authors.affiliation: Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390-9070.
authors.forename: David W
authors.initials: DW
authors.lastname: Self
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219.
authors.forename: Colleen A
authors.initials: CA
authors.lastname: McClung
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D056926:CLOCK Proteins / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D003042:Cocaine / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000502:physiology; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D050637:Receptors, Dopamine D3 / Q000378:metabolism*; D012201:Reward; D013028:Space Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D003042:Cocaine; D018765:Dopamine Uptake Inhibitors; D009419:Nerve Tissue Proteins; D017447:Receptors, Dopamine D1; D050637:Receptors, Dopamine D3; C493594:Drd3 protein, mouse; C491259:Npas2 protein, mouse; C538944:Clock protein, mouse
keywords: Circadian; Clock; Cocaine; Drd3; Npas2; Reward