MicroRNA 101b Is Downregulated in the Prefrontal Cortex of a Genetic Model of Depression and Targets the Glutamate Transporter SLC1A1 (EAAT3)in Vitro

Abstract

Background:MicroRNAs (miRNAs) are small regulatory molecules that cause translational repression by base pairing with target mRNAs. Cumulative evidence suggests that changes in miRNA expression may in part underlie the pathophysiology and treatment of neuropsychiatric disorders, including major depressive disorder (MDD).Methods:A miRNA expression assay that can simultaneously detect 423 rat miRNAs (miRBase v.17) was used to profile the prefrontal cortex (PFC) of a genetic rat model of MDD (the Flinders Sensitive Line [FSL]) and the controls, the Flinders Resistant Line (FRL). Gene expression data from the PFC of FSL/FRL animals (GEO accession no. GSE20388) were used to guide mRNA target selection. Luciferase reporter assays were used to verify miRNA targets in vitro.Results:We identified 23 miRNAs that were downregulated in the PFC of the FSL model compared with controls. Interestingly, one of the identified miRNAs (miR-101b) is highly conserved between rat and human and was recently found to be downregulated in the PFC of depressed suicide subjects. Using a combination of in silico and in vitro analyses, we found that miR-101b targets the neuronal glutamate transporter SLC1A1 (also known as EAAC1 or EAAT3). Accordingly, both mRNA and protein levels of SLC1A1 were found to be upregulated in the PFC of the FSL model.Conclusions:Besides providing a list of novel miRNAs associated with depression-like states, this preclinical study replicated the human association of miR-101 with depression. In addition, since one of the targets of miR-101b appears to be a glutamate transporter, our preclinical data support the hypothesis of a glutamatergic dysregulation being implicated in the etiology of depression.

The Role of Neural Plasticity in Depression: From Hippocampus to Prefrontal Cortex

“…Energy and glutathione metabolic pathways in the prefrontal cortex were shown to be significant biological pathways in depressive rats [ 58 ]. Many studies have indicated that changes in glutamate metabolism were associated with depression [ 59 – 67 ]. In a stress-induced depressive mouse model, the prefrontal cortex in depression showed a significant reduction of glutamate in the GABAergic pathway, which may contribute to depression [ 62 ].…”

“…In addition, a novel miRNA (miR-101b) was found to be downregulated in depression and could decrease mRNA and protein levels of glutamate transporter SLC1A1 in the prefrontal cortex [ 59 ]. In addition, in the medial prefrontal cortices of chronic unpredictable mild stress-induced depressive mice, there was a downregulation of mRNAs encoding proteins for the GABAergic synapses, dopaminergic synapses, synaptic vesicle cycle, and neuronal growth and an upregulation of miRNAs of regulating these mRNAs [ 70 ].…”

Mitochondria: A Connecting Link in the Major Depressive Disorder Jigsaw

“…Among the various miRNAs, miR-146a-5p, miR-146b-5p, miR425-3p and miR-24-3p have been suggested to play an important role in treatment response [68]. In a genetic rat model of depression, miR-101b, which targets glutamate transporter, has been found to be downregulated [69]. In astrocytoma cells, miR-101 has been shown to reverse the methylation of promoter of PR domain containing 16 (PRDM16) leading to disruption of mitochondrial function, reduced ATP synthesis and initiation of mitochondria-dependent apoptosis [70].…”

Circadian Regulation of Glutamate Transporters

“…Moreover, it has been demonstrated that miRNA-124 and miRNA-181a positively regulate GLT1 ( 82 , 83 ), while miRNA-107 inhibits GLT1 expression ( 84 ). Specifically, EAAC1 rhythm is negatively controlled by miRNA-96-5p ( 71 ), miRNA-26a-5p ( 85 ) and miRNA-101b ( 86 ). This former miRNA also negatively regulates to EAAC1 protein ( 86 ).…”

“…Specifically, EAAC1 rhythm is negatively controlled by miRNA-96-5p ( 71 ), miRNA-26a-5p ( 85 ) and miRNA-101b ( 86 ). This former miRNA also negatively regulates to EAAC1 protein ( 86 ). However, no evidence shows that miRNAs can target EAAT4 and EAAT5.…”