Sex and estrogen affect the distribution of urocortin-1 immunoreactivity in brainstem autonomic nuclei of the rat

Urocortin-1 promotes colorectal cancer cell migration and proliferation and inhibits apoptosis via inhibition of the p53 signaling pathway

PURPOSE

To investigate the effect of urocortin-1 (UCN-1) on growth, migration, and apoptosis in colorectal cancer (CRC) in vivo and vitro and the mechanism by which UCN-1 modulates CRC cells in vitro.

METHODS

The correlation between UCN-1 and CRC was evaluated using The Cancer Genome Atlas (TCGA) database and a tissue microarray. The expression of UCN-1 in CRC cells was assessed using quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting. In vitro, the influence of UCN-1 on the proliferation, apoptosis, and migration of HT-29, HCT-116, and RKO cells was explored using the celigo cell counting assay or cell counting kit-8 (CCK8), flow cytometry, and wound healing or Transwell assays, respectively. In vivo, the effect of UCN-1 on CRC growth and progression was evaluated in nude mice. The downstream pathway underlying UCN-1-mediated regulation of CRC was determined using the phospho-kinase profiler array in RKO cells. Lentiviruses were used to knockdown or upregulate UCN-1 expression in cells.

RESULTS

Both the TCGA and tissue microarray results showed that UCN-1 was strongly expressed in the tissues of patients with CRC. Furthermore, the tissue microarray results showed that the expression of UCN-1 was higher in male than in female patients, and high expression of UCN-1 was associated with higher risk of lymphatic metastasis and later pathological stage. UCN-1 knockdown caused a reduction in CRC cell proliferation, migration, and colony formation, as well as an increase in apoptosis. In xenograft experiments, tumors generated from RKO cells with UCN-1 knockdown exhibited reduced volumes and weights. A reduction in the expression of Ki-67 in xenograft tumors indicated that UCN-1 knockdown curbed tumor growth. The human phospho-kinase array showed that the p53 signaling pathway participated in UCN-1-mediated CRC development. The suppression in migration and proliferation caused by UCN-1 knockdown was reversed by inhibitors of p53 signal pathway, while the increase in cell apoptosis was suppressed. On the other hand, overexpression of UCN-1 promoted proliferation and migration and inhibited apoptosis in CRC cells. Overexpression of p53 reversed the effect of UCN-1 overexpression on CRC development.

CONCLUSION

UCN-1 promotes migration and proliferation and inhibits apoptosis via inhibition of the p53 signaling pathway.

Liver vitronectin release into the bloodstream increases due to reduced vagal muscarinic signaling after cerebral stroke in female mice

Vitronectin (VTN) is a glycoprotein enriched in the blood and activates integrin receptors. VTN blood levels increase only in female mice 24 h after an ischemic stroke and exacerbate brain injury through IL-6-driven inflammation, but the VTN induction mechanism is unknown. Here, a 30 min middle cerebral artery occlusion (MCAO) in female mice induced VTN protein in the liver (normally the main source) in concert with plasma VTN. Male mice were excluded as VTN is not induced after stroke. MCAO also increased plasma VTN levels after de novo expression of VTN in the liver of VTN-/- female mice, using a hepatocyte-specific (SERPINA1) promoter. MCAO did not affect SERPINA1 or VTN mRNA in the liver, brain, or several peripheral organs, or platelet VTN, compared to sham mice. Thus, hepatocytes are the source of stroke-induced increases in plasma VTN, which is independent of transcription. The cholinergic innervation by the parasympathetic vagus nerve is a potential source of brain-liver signaling after stroke. Right-sided vagotomy at the cervical level led to increased plasma VTN levels, suggesting that VTN release is inhibited by vagal tone. Co-culture of hepatocytes with cholinergic neurons or treatment with acetylcholine, but not noradrenaline (sympathetic transmitter), suppressed VTN expression. Hepatocytes have muscarinic receptors and the M1/M3 agonist bethanechol decreased VTN mRNA and protein release in vitro via M1 receptors. Finally, systemic bethanechol treatment blocked stroke-induced plasma VTN. Thus, VTN translation and release are inhibited by muscarinic signaling from the vagus nerve and presents a novel target for lessening detrimental VTN expression.

Urocortin 1: A putative excitatory neurotransmitter in the enteric nervous system

BACKGROUND

Urocortin 1 (Ucn1), a stress-related peptide, is a member of the corticotropin-releasing factor (CRF) family and acts as a CRF1 receptor agonist. Ucn1 and CRF1 receptor immunoreactivity are present in the enteric nervous system (ENS), and Ucn1 elicits contraction of colonic muscle strips. Considering these findings, we have hypothesized that Ucn1 acts as an excitatory neurotransmitter in the ENS. The present study was conducted to determine whether exogenously applied Ucn1 causes contractions, whether it participates in neurally mediated contraction, and whether it is released from the ENS of the rat colon.

METHODS

Isometric tension of the rat colonic muscle strips (middle to distal colon) in a longitudinal direction was measured. The effects of Ucn1 on phasic contractions were examined in the absence and presence of antalarmin (CRF1 receptor antagonist), tetrodotoxin (TTX), and atropine. The effects of antalarmin on electrical field stimulation (EFS)-induced contractions were examined in the absence and presence of atropine. Ucn1 peptide in the bath solution was measured after EFS using an EIA kit.

KEY RESULTS

Ucn1 caused a significant and dose-dependent increase in phasic contractions. These effects were completely inhibited by antalarmin, TTX, and atropine. EFS-induced contractions were inhibited by antalarmin. Atropine markedly reduced EFS-induced contractions, and antalarmin did not decrease these contractions further. EFS elicited a significant increase in the concentration of Ucn1 in the bath solution, and this increase was completely inhibited by TTX.

CONCLUSIONS AND INFERENCES

These results suggest that Ucn1 acts as an excitatory neurotransmitter in the ENS enhancing the cholinergic neurotransmission.