Oxytocin opposes effects of bacterial endotoxin on ER-stress signaling in Caco2BB gut cells

• Published in: Biochimica et biophysica acta Vol. 1860; no. 2; pp. 402 - 411
• Main Authors: Klein, Benjamin Y., Tamir, Hadassah, Hirschberg, David L., Ludwig, Robert J., Glickstein, Sara B., Myers, Michael M., Welch, Martha G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2016
• Subjects: Caco-2 Cells; Endoplasmic Reticulum Stress - drug effects; Enterocytes; Enterocytes - drug effects; Eukaryotic requiring enzyme 1a, A20; Heat-Shock Proteins - analysis; Humans; Inositol requiring enzyme 1a; Lipopolysaccharides - antagonists & inhibitors; NF-kappa B - antagonists & inhibitors; NF-kappa B - physiology; Oxytocin - pharmacology; Signal Transduction - drug effects; Unfolded Protein Response; X-box binding protein 1; eIF2a; XBP1; OT; X-box binding protein 1; IRE1a; Eukaryotic requiring enzyme 1a, A20; BiP; IKK; PERK; OTR; ER; FGM; LPS; Unfolded protein response; IκB; NF-κB; Enterocytes; PKR; UPR; Inositol requiring enzyme 1a; CHOP; TLR; GAPDH; A20
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2015.10.025

The neuropeptide neuromodulator and hormone oxytocin (OT) activates signaling pathways involved in mRNA translation in response to endoplasmic reticulum stress and reduces inflammation associated with experimental colitis in rats. The anti-inflammatory effects of OT may serve a vital role in the development, survival and function of newborn-type enterocytes during microbial gut colonization, which coincides with the milk suckling period when OT receptor expression peaks in the gut. Furthermore, mice deficient in the OT receptor have abnormal gut structure and function, underscoring OT's developmental importance. We tested the effect of OT upon lipopolysaccharide (LPS)-induced markers of the inflammatory response in Caco2BB gut cells in vitro using automated immunocapillary electrophoresis. We demonstrate that OT suppresses NF-κB signaling and presumably inflammatory transcriptional programs, which are unleashed by LPS through the modulation of IκB. We show that OT counteracts LPS-elicited silencing of the unfolded protein response, a pathway limiting endoplasmic reticulum stress by suppressing protein translation. OT selectively activates dsRNA-activated kinase (PKR), X-box binding protein 1 (XBP1), immunoglobulin binding protein (BiP), A20 (TNFα-induced protein 3) and inositol requiring enzyme 1a (IRE1a). OT inactivates eukaryotic translation initiation factor 2a (eIF2a) without significant activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK). Mild, preemptive stimulation of endoplasmic reticulum stress sensors by OT may precondition newborn enterocytes to resist apoptosis associated with inflammation and may support their differentiation and development by modulating cellular metabolism. OT may protect enterocytes and other cell types, such as neurons, from stress-related complications during postnatal development. •Oxytocin opposes the impact of LPS upon endoplasmic reticulum stress markers.•Oxytocin activates PKR and inactivates eIF2a, which mark translation inhibition.•OT modulates LPS-induced markers of inflammation in vitro.•The protein A20 may regulate the anti-inflammatory effects of oxytocin.•OT may precondition newborn enterocytes to resist apoptosis and support development.