Retinol Enhances Differentiation of the Gastric Parietal Cell Lineage in Developing Rabbits

Abstract

In the gastric glands, parietal cells are the targets for anti-ulcer drugs because they contain the proton pump or HK-ATPase responsible for acid secretion. Little is known about factors influencing developmental expression and activity of HK-ATPase. In this study, the parietal cell lineage was investigated in rabbits at post-natal days 0 (P0) to P60 by using morphological and biochemical methods. Immunohistochemical and ultrastructural studies show that the HK-ATPase-expressing cells that appear at P0 and P3 are pre-parietal cells. However, terminally differentiated, mature parietal cells make their appearance at P7. These data correlate with the activity of HK-ATPase, measured as K⁺-dependent hydrolysis of p-nitrophenyl phosphate. Three-day-retinol treatment of P3-P30 rabbits induced an increase in the (i) production of parietal cells, (ii) intensity of the HK-ATPase immunostaining per cell, (iii) activity of HK-ATPase and (iv) amount of HK-ATPase protein measured by Western blotting. In conclusion, retinol upregulates the development of HK-ATPase in rabbits, perhaps due to precocious acceleration of the differentiation program of parietal cell lineage.

Expression of retinoid receptors during rabbit lung development

“…The identification of the retinoid receptors in the rabbit species supports the molecular actions of RA previously described in rabbit trachea (Nervi et al, 1991;Inayama et al, 1996) and rabbit stomach development (Karam et al, 2004). The necessity to design the primers in highly conserved regions in order to clone the rabbit retinoid receptors probably contributed to the high degree of sequence homology with the other species.…”

Dysregulation of gastric H,K-ATPase by cigarette smoke extract

“…Gastric mucosal homogenates were prepared as previously described [20,24] . Part of the oxyntic mucosa of the stomach was scraped, minced and then homogenized on icecold hypotonic buffer (pH 6.7) containing 113 mmol/L mannitol, 37 mmol/L sucrose, 0.4 mmol/L EDTA, 5 mmol/L piperazine-N,N'-bis(2-ethanesulfonic acid)-tris (hydroxymethyl) aminomethane.…”

“…Portions of the homogenates or re-suspended pellets of control and smoke-treated mice were solubilized in buffer containing 1% SDS, 0.5 mol/L urea, 5% 2-mercaptoethanol, 0.25 mmol/L EDTA, 10% glycerol, 0.0025% bromophenol blue, and 30 mmol/L TrisHCl, pH 6.8 and run through 8% or 10% acrylamide [20] . Proteins were subsequently electro-transferred onto nitrocellulose membranes (Schleicher & Schuell Bioscience, Dassel, Germany) and probed with mouse monoclonal antibodies specific for the α-(97 kDa) or β-(60-80 kDa) subunits of H,K-ATPase (Medical & Biological Laboratories Co., Woburn, MA, USA) at a dilution of 1:2000.…”

“…To measure the intensity of H,K-ATPase immunolabeling of the cells, image analysis was performed on probed gastric mucosal tissue sections of some control (n = 4) and smoke-treated littermate mice (n = 4) using the Scion Imaging program as previously described [20] . Probed sections were examined at 40 × magnification with an Olympus microscope and photographed with a DP-70 digital camera with the option of fixed manual exposure to ensure equal exposure of control and smoketreated tissue sections.…”

“…They develop from epithelial progenitors which are anchored in the isthmus region [17][18][19] . During their development, parietal cells concomitantly synthesize the catalytic α-and regulatory β-subunits of H,K-ATPase [20] . Following their maturation in the isthmus, parietal cells bidirectionally migrate to become scattered throughout the glandular regions of the gastric epithelium.…”