Download Regulatory role of hsa-miR-939 on pro

Regulatory role of hsa-miR-939 on pro-inflammatory mechanisms
underlying chronic pain
Sujay Ramanathan1*, Marguerite K. McDonald1, Guillermo M. Alexander2, and Seena K. Ajit1
1
Department of Pharmacology and Physiology, 2 Department of Neurology, Drexel University, Philadelphia
19102
Abstract:
Introduction:
Complex regional pain syndrome (CRPS) is a chronic neuropathic pain disorder characterized by persistent
pain and inflammation. Previous investigation of circulating microRNAs in whole blood identified a
significant decrease in hsa-miR-939 in CRPS patients in comparison to control subjects. Concurrently,
interleukin- 6 (IL-6), vascular endothelial growth factor A (VEGFA), and tumor necrosis factor-alpha (TNFa)
proteins were upregulated in either all or a subset of CRPS patients stratified based on miRNA profile.
Circulating miRNAs exert paracrine tissue specific effects through exosomal transport involving specific
secretory and uptake mechanisms. Exosomes are secreted microvesicles transporting miRNAs, mRNAs, and
proteins through bodily fluids, facilitating intercellular communication.
Methods:
The role of miR-939 in regulating several proinflammatory genes including IL-6, VEGFA, nuclear factor
kappa B2 (NFκB2), and nitric oxide synthase 2 (NOS2A) was investigated through the overexpression of miR939 in vitro. The changes in inflammatory gene and protein expression were ascertained by qPCR and ELISA,
respectively, and NFκB2 function by fluorescence microscopy. Studies were also initiated to understand source
of circulating miR-939 and mechanisms of exosome release and uptake.
Results:
Transfection of miR-939 resulted in the reduction of IL-6 and NOS2A mRNAs, a decrease in protein levels of
IL-6, VEGFA, NOS2A, and an abrogation of NFκB activity. Collectively, our data suggests that
downregulation of miR-939 in CRPS patients may enhance target gene expression involved in inflammatory
pain signal transduction cascade. Preliminary studies also suggest the upregulation of miR-939 in the exosomal
fraction in CRPS patients in comparison to control individuals.
Conclusions:
We hypothesize that inflammation induces an increased miR-939 packaging into exosomes and concomitant
uptake of miR-939 enriched exosomes by recipient cells can decrease inflammatory gene expression within
the latter. We are using exosomes overexpressing miR-939 to investigate the potential role of exosomemediated miRNA transport to affect gene expression changes.
This study was supported by funds from NIH grant, NINDS 1R21NS082991-01 to Dr. Seena K. Ajit.