Differential regulation of multiple brain-derived neurotrophic factor transcripts in the postnatal and adult rat hippocampus during development, and in response to kainate administration

Brain-derived neurotrophic factor (BDNF) is expressed at high levels in the hippocampus, where it has been implicated in physiological functions such as the modulation of synaptic strength as well as in the pathophysiology of epileptic seizures. BDNF expression is highly regulated and the BDNF gene can generate multiple transcript isoforms by alternate splicing of four 5' exons (exons I-IV) to one 3' exon (exon V). To gain insight into the regulation of different BDNF transcripts in specific hippocampal subfields during postnatal development, exon-specific riboprobes were used. Our data shows that BDNF exon I and exon II mRNAs are regulated in hippocampal subfields during postnatal development, in contrast to BDNF exon III and exon IV mRNA, which remain relatively stable through this period. Further, exons I and II show distinct temporal patterns of expression in the hippocampus: BDNF I mRNA peaks in adulthood in contrast to BDNF II mRNA which peaks at postnatal day 14 (P14). Finally, we have addressed whether kainate treatment in postnatal pups and adults regulates BDNF through the recruitment of the same, or distinct, BDNF promoters. Our data indicates that kainate-induced seizures induce strikingly different expression of distinct BDNF transcripts, both in magnitude as well as spatial patterns in the hippocampal subfields, of pups as compared to adults. These results suggest that kainate-mediated seizures differentially recruit BDNF promoters in the developing postnatal hippocampus in contrast to the adult hippocampus to achieve a hippocampal subfield specific regulation of exon-specific BDNF mRNAs

Supplementary Material for: Extracellular Uridine Triphosphate and Adenosine Triphosphate Attenuate Endothelial Inflammation through miR-22-Mediated ICAM-1 Inhibition

Adenosine and uridine triphosphate (ATP and UTP) can act as extracellular signalling molecules, playing important roles in vascular biology and disease. ATP and UTP acting via the P2Y₂-receptor have, for example, been shown to regulate endothelial dilatation, inflammation and angiogenesis. MicroRNAs (miRNAs), a class of regulatory, short, non-coding RNAs, have been shown to be important regulators of these biological processes. In this study, we used RNA deep-sequencing to explore changes in miRNA expression in the human microvascular endothelial cell line HMEC-1 upon UTP treatment. The expression of miR-22, which we have previously shown to target ICAM-1 mRNA in HMEC-1, increased significantly after stimulation. Up-regulation of miR-22 and down-regulation of cell surface ICAM-1 were confirmed with qRT-PCR and flow cytometry, respectively. siRNA-mediated knockdown of the P2Y₂-receptor abolished the effect of UTP on miR-22 transcription. Leukocyte adhesion was significantly inhibited in HMEC-1 following miR-22 overexpression and treatment with UTP/ATP. In conclusion, extracellular UTP and ATP can attenuate ICAM-1 expression and leukocyte adhesion in endothelial cells through miR-22