Effect of feeding behavior on circadian regulation of endothelin expression in mouse colon

Endothelin signaling in development

Since the discovery of endothelin 1 (EDN1) in 1988, the role of endothelin ligands and their receptors in the regulation of blood pressure in normal and disease states has been extensively studied. However, endothelin signaling also plays crucial roles in the development of neural crest cell-derived tissues. Mechanisms of endothelin action during neural crest cell maturation have been deciphered using a variety of in vivo and in vitro approaches, with these studies elucidating the basis of human syndromes involving developmental differences resulting from altered endothelin signaling. In this Review, we describe the endothelin pathway and its functions during the development of neural crest-derived tissues. We also summarize how dysregulated endothelin signaling causes developmental differences and how this knowledge may lead to potential treatments for individuals with gene variants in the endothelin pathway.

Interplay of the Circadian Clock and Endothelin System

The peptide hormone endothelin-1 and its receptors are linked to several disease states. Pharmacological inhibition of this pathway has proven beneficial in pulmonary hypertension, yet its potential in other disease states remains to be realized. This review considers an often understudied aspect of endothelin biology, circadian rhythm regulation and how understanding the intersection between endothelin signaling and the circadian clock may be leveraged to realize the potential of endothelin-based therapeutics.

EDN1-AS, A Novel Long Non-coding RNA Regulating Endothelin-1 in Human Proximal Tubule Cells

Endothelin-1 (ET-1) is a peptide hormone that functions as a vasoconstrictor in the vasculature, whereas in the collecting duct of the kidney it exerts blood pressure-lowering effects via natriuretic actions. Aberrant ET-1 signaling is associated with several pathological states including hypertension and chronic kidney disease. ET-1 expression is regulated largely through transcriptional control of the gene that encodes ET-1, EDN1. Here we report a long, non-coding RNA (lncRNA) that appears to be antisense to the EDN1 gene, called EDN1-AS. Because EDN1-AS represents a potential novel mechanism to regulate ET-1 expression, we examined the regulation of EDN1-AS expression and action. A putative glucocorticoid receptor response (GR) element upstream of the predicted EDN1-AS transcription start site was identified using the ENCODE database and the UCSC genome browser. Two homozygous deletion clones of the element were generated using CRISPR/Cas9. This deletion resulted in a significant increase in the expression of EDN1-AS, which was associated with increased secretion of ET-1 peptide from HK-2 cells (two-fold increase in KO cells vs. CNTL, n = 7, P < 0.05). Phenotypic characterization of these CRISPR clones revealed a difference in cell growth rates. Using a standard growth assay, we determined that the KO1 clone exhibited a three-fold increase in growth over 8 days compared to control cells (n = 4, P < 0.01) and the KO2 clone exhibited a two-fold increase (n = 4, P < 0.01). These results support a role for EDN1-AS as a novel regulatory mechanism of ET-1 expression and cellular proliferation.

Effects of Electroacupuncture on the Daily Rhythmicity of Intestinal Movement and Circadian Rhythmicity of Colonic Per2 Expression in Rats with Spinal Cord Injury

Background. Spinal cord injury (SCI) leads to bowel dysfunction. Electroacupuncture (EA) may improve bowel function. Objective. To assess EA on daily rhythmicity of intestinal movement and circadian rhythmicity of colonic Per2 expression in rats with SCI. Methods. Rats were randomized to the sham, SCI, and SCI+EA groups. EA was performed at bilateral Zusanli point (ST36) during daytime (11:00–11:30) for 14 days following SCI. Intestinal transit and daily rhythmicity of intestinal movement were assessed. Circadian rhythmicity of colonic Per2 expression was assessed by real-time RT-PCR. Results. EA shortened the stool efflux time and increased the dry fecal weight within 24 h in SCI rats. Daily rhythmicity of intestinal movements was unaffected by SCI. The expression of colonic Per2 peaked at 20:00 and the nadir was observed at 8:00 in the SCI and sham groups. In the SCI+EA group, colonic Per2 expression peaked at 12:00 and 20:00, and the nadir was observed at 8:00. Conclusion. SCI did not change the circadian rhythmicity of colonic Per2 expression in rats, and daily intestinal movement rhythmicity was retained. EA changed the daily rhythmicity of intestinal movement and the circadian rhythmicity of colonic Per2 expression in rats with SCI, increasing Per2 expression shortly after EA treatment.