J Psychiatry Neurosci 2016;41(5):342-53
Armaz Aschrafi, PhD; Jan M. Verheijen, MSc; Peter M. Gordebeke, MSc; Nikkie F. Olde Loohuis, MSc; Kelly Menting, MSc; Amanda Jager, MSc; Miklos Palkovits, MD, PhD, DSc; Bram Geenen, MSc; Aron Kos, MSc; Gerard J.M. Martens, PhD; Jeffrey C. Glennon, PhD; Barry B. Kaplan, PhD; Balázs Gaszner, MD, PhD; Tamas Kozicz, MD, PhD
Background: Altered levels of urocortin 1 (Ucn1) in the centrally projecting Edinger–Westphal nucleus (EWcp) of depressed suicide attempters or completers mediate the brain’s response to stress, while the mechanism regulating Ucn1 expression is unknown. We tested the hypothesis that microRNAs (miRNAs), which are vital fine-tuners of gene expression during the brain’s response to stress, have the capacity to modulate Ucn1 expression.
Methods: Computational analysis revealed that the Ucn1 3′ untranslated region contained a conserved binding site for miR-326. We examined miR-326 and Ucn1 levels in the EWcp of depressed suicide completers. In addition, we evaluated miR-326 and Ucn1 levels in the serum and the EWcp of a chronic variable mild stress (CVMS) rat model of behavioural despair and after recovery from CVMS, respectively. Gain and loss of miR-326 function experiments examined the regulation of Ucn1 by this miRNA in cultured midbrain neurons.
Results: We found reduced miR-326 levels concomitant with elevated Ucn1 levels in the EWcp of depressed suicide completers as well as in the EWcp of CVMS rats. In CVMS rats fully recovered from stress, both serum and EWcp miR-326 levels rebounded to nonstressed levels. While downregulation of miR-326 levels in primary midbrain neurons enhanced Ucn1 expression levels, miR-326 overexpression selectively reduced the levels of this neuropeptide.
Limitations: This study lacked experiments showing that in vivo alteration of miR-326 levels alleviate depression-like behaviours. We show only correlative data for miR-325 and cocaine- and amphetamine-regulated transcript levels in the EWcp.
Conclusion: We identified miR-326 dysregulation in depressed suicide completers and characterized this miRNA as an upstream regulator of the Ucn1 neuropeptide expression in midbrain neurons.
Submitted May 3, 2015; Revised Sept. 21, 2015; Accepted Dec. 14, 2015; Early-released Apr. 5, 2016
Acknowledgements: The authors thank the individuals who provided technical assistance. This work was supported by a Donders Center for Neuroscience fellowship award of the Radboud University Nijmegen Medical Centre and a grant from FP7-Marie Curie International Reintegration to A. Aschrafi.
Affiliations: From the Department of Anatomy, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands (Aschrafi, Verheijen, Gordebeke, Menting, Geenan, Kozicz); the Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands (Loohuis, Jager, Kos, Glennon); the Department of Anatomy, Semmelweis University Budapest, Budapest, Hungary (Palkovits); the Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands (Martens); the Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland (Aschrafi, Kaplan); the Department of Anatomy, Pécs University, Medical Faculty, Pécs, Hungary (Gaszner); the Hayward Genetics Center, Department of Pediatrics, Tulane University, New Orleans, LA (Kozicz); and the Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, Antwerp, Belgium; Institute Born-Bunge, University of Antwerp, Antwerp, Belgium (Verheijen).
Competing interests: J. Glennon declares consulting fees from Boehringer Ingelheim outside the submitted work. No other competing interests declared.
Contributors: A. Aschrafi, M. Palkovits, B. Gaszner and T. Kozicz designed the study. All authors acquired the data, which A. Aschrafi, J. Verheijen, P. Gordebeke, G. Martens, B. Gaszner and T. Kozicz analyzed. A. Aschrafi, J. Glennon, B. Kaplan and T. Kozicz wrote the article, which all authors reviewed and approved for publication.
Correspondence to: A. Aschrafi, Department of Anatomy, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands; email@example.com