PT  - JOURNAL ARTICLE
AU  - Apoorva Halikere
AU  - Dina Popova
AU  - Aula Hamod
AU  - Mavis R. Swerdel
AU  - Jannifer C. Moore
AU  - Jay A. Tischfield
AU  - Ronald P. Hart
AU  - Zhiping Pang
TI  - Addiction associated N40D mu-opioid receptor variant modulates synaptic function in human neurons
AID  - 10.1101/328898
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 328898
4099  - http://biorxiv.org/content/early/2018/05/23/328898.short
4100  - http://biorxiv.org/content/early/2018/05/23/328898.full
AB  - Background The OPRM1 A118G gene variant (N40D) encoding the μ-opioid receptor (MOR) has been associated with dependence on opiates and other abused drugs but its mechanism is unknown. With opioid abuse-related deaths rising at unprecedented rates, understanding these mechanisms may provide a path to therapy.Methods Seven human induced pluripotent stem (iPS) cell lines from homozygous N40D subjects (4 with N40 and 3 with D40 variants) were generated and human induced neuronal cells (iNs) were derived from these iPS cell lines. Morphological, gene expression as well as synaptic physiology analyses were conducted in human iN cells carrying N40D MOR variants; Two pairs of isogenic pluripotent stem cells carrying N40D were generated using CRISPR/Cas9 genome-editing and iN cells derived from them were analyzed.Results Inhibitory human neurons generated from subjects carrying N40D MOR gene variants show mature properties in morphological and functional analyses. Gene expression revealed that they express mature neuronal marker and MORs. Activation of MORs suppressed inhibitory synaptic transmission in human neurons carrying both N40 or D40 MOR variants but D40 show stronger effects. To mitigate the confounding effects of background genetic variation on neuronal function, the regulatory effects of MORs on synaptic transmission were validated in two sets of independently generated isogenic N40D iNs.Conclusions Activations of N40D MOR variants show different regulatory effects on synaptic transmission in inhibitory human neurons. This study identifies neurophysiological differences between human MOR variants that may predict altered opioid responsivity and/or dependence in this subset of individuals.