Elsevier

Biological Psychiatry

Volume 84, Issue 3, 1 August 2018, Pages 167-179
Biological Psychiatry

Priority Communication
Transcription Factor E2F3a in Nucleus Accumbens Affects Cocaine Action via Transcription and Alternative Splicing

https://doi.org/10.1016/j.biopsych.2017.11.027Get rights and content

Abstract

Background

Lasting changes in gene expression in brain reward regions, including nucleus accumbens (NAc), contribute to persistent functional changes in the addicted brain. We and others have demonstrated that altered expression of several candidate transcription factors in NAc regulates drug responses. A recent large-scale genome-wide study from our group predicted transcription factor E2F3 (E2F3) as a prominent upstream regulator of cocaine-induced changes in gene expression and alternative splicing.

Methods

We studied expression of two E2F3 isoforms—E2F3a and E2F3b—in mouse NAc after repeated cocaine administration and assayed the effects of overexpression or depletion of E2f3 isoforms in NAc on cocaine behavioral responses. We then performed RNA sequencing to investigate the effect of E2f3a overexpression in this region on gene expression and alternative splicing and performed quantitative chromatin immunoprecipitation at downstream targets in NAc following E2f3a overexpression or repeated cocaine exposure. Sample sizes varied between experiments and are noted in the text.

Results

We showed that E2f3a, but not E2f3b, overexpression or knockdown in mouse NAc regulates cocaine-induced locomotor and place conditioning behavior. Furthermore, we demonstrated that E2f3a overexpression substantially recapitulates genome-wide transcriptional profiles and alternative splicing induced by cocaine. We further validated direct binding of E2F3a at key target genes following cocaine exposure.

Conclusions

This study establishes E2F3a as a novel transcriptional regulator of cocaine action in NAc. The findings reveal a crucial role for E2F3a in the regulation of cocaine-elicited behavioral states. Moreover, the importance of this role is bolstered by the extensive recapitulation of cocaine’s transcriptional effects in NAc by overexpression of E2f3a.

Section snippets

Methods and Materials

See also Supplemental Methods and Materials in Supplement 1.

Repeated Cocaine Administration Increases E2f3a mRNA and E2F3a Nuclear Protein Levels in NAc

We probed isoform-specific expression of E2f3 mRNA in NAc following 7 days of 20 mg/kg cocaine (24 hours after final injection). We observed a cocaine-induced increase in E2f3a mRNA levels (main effect of treatment: F1,20 = 12.99, p = .0018, post hoc, E2f3a: p = .0207, E2f3b: p = .0512) (Figure 1D) and a nonsignificant trend for induction of E2f3b. We next investigated the effects of repeated cocaine administration on E2F3a and E2F3b protein levels and subcellular localization. We observed an

Discussion

Our findings provide direct evidence for the role of E2F3a as a key regulator of cocaine-elicited molecular actions via transcriptional regulation and splicing mechanisms. We identified E2f3 as a novel target of cocaine. Repeated cocaine exposure increased E2f3a mRNA expression in NAc and increased E2F3a protein levels in the nucleus. This positions E2F3a to bind DNA and regulate the observed changes in gene expression and RNA processing. The isoform-specific role of E2F3a was further confirmed

Acknowledgments and Disclosures

This work was supported by grants from the National Institute on Drug Abuse Grant Nos. R01DA007359 and P01DA008227 (to EJN).

Author contributions following CRediT Taxonomy are as follows: Conceptualization, HMC and EJN; Methodology, HMC and EJN; Software, IP and LS; Formal Analysis, HMC and IP; Investigation, HMC, EAH, RCB, CKL, CJP, DMW, and MEC; Resources, RLN; Writing—Original Draft, HMC; Writing—Review and Editing, HMC, EAH, CKL, CJP, DMW, RCB, and EJN; Supervision, LS, RCB, and EJN; Funding

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    EAH is currently affiliated with the Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; MEC is currently affiliated with the Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin; and RCB is currently affiliated with the Department of Psychology, McGill University, Montréal, Québec, Canada.

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