High glucose-induced human cellular immune response is governed by miR-2909 RNomics

Possible role of miR-2909 RNomics in arsenic mediated pancreatic β-cell dysfunction

Chronic exposure of humans to inorganic arsenic as a potential risk for the incidence of diabetes has received wide attention. However, the biological mechanism through which arsenic plays a role in the development of diabetes is still being evaluated. One of the hallmark of diabetes is the β-cell dysfunction followed by the changes in the insulin secretion. Pancreatic duodenal homeobox 1 (PDX1) has been widely recognized to play crucial role in the β-cell development, survival and its regulation of insulin gene expression. Many of the arsenic mediated cellular affects have been shown to be regulated by miR-2909 in vitro. Our present study provides evidence to reveal that arsenic affects miR-2909 expression in the pancreatic β-cell and this novel miRNA regulates PDX1 transcriptional expression indirectly through genes coding for c-Jun, MafA, PI3K and directly at the translational level by targeting the PDX1 mRNA. We provide further evidence for this miR-2909 RNomics in pancreatic tissue obtained from NOD mice where the expression of miR-2909 was high compared to the control mice. Keeping in view the fact that arsenic is known to cause β-cell dysfunction and most of the cellular effects of arsenic have been shown to be mediated through miR-2909 RNomics, our study revealed that arsenic employs miR-2909 (at low doses) and c-Jun (at high doses) to down regulate PDX1 in order to cause β-cell dysfunction leading to diabetic state.

Tumorigenic PVT-1 gene locus is governed by miR-2909 RNomics

Genomic regulation and functional significance of PVT-1 gene locus, in the MYC-driven cancers, has remained enigmatic ever since its discovery. With the present study, an attempt is made to establish that cellular AATF genome encoded miR-2909 RNomics pathway involving crucial genes coding for KLF4, Deptor, mTORC1, STAT3, and p53 has the inherent capacity to ensure sustained co-amplification of PVT-1 gene locus together with c-Myc gene. Based upon these results, we propose that miR-2909 RNomics pathway may play a crucial role in the regulation of tumorigenic PVT-1 gene locus.

Human cellular mitochondrial remodelling is governed by miR-2909 RNomics

BACKGROUND

There exists a general recognition of the fact that mitochondrial remodelling as a result of aerobic glycolysis ensures human somatic cells to revert to a more primitive-form exhibiting stem-like phenotype. The present study is an attempt to demonstrate that miR-2909 RNomics within human peripheral blood mononuclear cells (PBMCs) has the inherent capacity to re-program these cells to exhibit mitochondrial remodelling paralleled by aerobic glycolysis together with intracellular lipid inclusions. Such re-programmed PBMCs also expressed genes having ability to sustain their de-differentiation state and survival.

MATERIAL AND METHODS

Human PBMCs were programed to ectopically express miR-2909. Expression levels of genes including glucose transporter-1 (Glut-1), hexokinase (HK), hypoxia inducia factor-1 (HIF-1α), c-Myc, p53,mechanistic target of rapamycin complex (mTORC1), polycombcomplex protein (Bmi-1), Notch,Nanog,Tie-2, Oct-4,CD59, p53, CD34, B-cell lymphoma-2 (Bcl2),sterol regulatory element-binding protein2 (SREBP2), peroxisome proliferator-activated receptor gamma (PPARγ) nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (Tfam), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) within miR-2909 expression vector transfected human PBMCs as well as PBMCs transfected with control vector containing scrambled sequence after 48h post-transfection using RT-qPCR and cellular ultrastructural features induced by miR-2909 ectopic expression were observed using transmission electron microscopy and morphometric analysis of an electron micrograph.

RESULTS

Ectopic expression of miR-2909 within human PBMCs resulted in their reprogramming into stem-like phenotype indicated by mitochondrial globular shaped coupled with cristae-poor morphology. Nuclear to cytoplasmic ratio (N/C), quantification of ATP levels, GSSG/GSH ratio, mitochondrial cytochrome c oxidase activity, secreted lactate concentrations, activity of antioxidant enzymes, levels of esterified cholesterol and triglycerides and flow-cytometric detection of apoptosis confirmed the compromised nature of mitochondrial function induced by ectopic miR-2909 expression in human PBMCs.

CONCLUSION

Based upon these results we propose that AATF gene-encoded miR-2909 may act as an epigenetic switch for cellular aerobic-glycolysis to ensure de-differentiation.

Cancer cells govern miR-2909 exosomal recruitment through its 3'-end post-transcriptional modification

It is widely believed that selective packaging of nucleic acids, especially microRNAs, into exosomes secreted by the cancer cells not only ensures their growth and survival but also helps in the escape from immune surveillance. Keeping in view the fact that human cellular miR-2909 has emerged to regulate genes involved in oncogenesis and immunity, the present study was addressed to reveal the nature of miR-2909 expression within cancer cells of different tissue origin and its incorporation into exosomes secreted by these cells. Post-transcriptional modification, especially 3'-end adenylation and uridylation of miR-2909, exerts opposing effects that may contribute to direct its sorting into exosomes secreted by cancer cells. Our study also revealed that selective partitioning of adenosine kinase, between cancer cells and their secreted exosomes, may be responsible for the nature of post-transcriptional modification of miR-2909 observed within these cells.