Abstract
AbstractS . boulardii is a probiotic yeast widely prescribed in a lyophilized form that determines in human and rat small intestine several effects including endoluminal secretion of enzymes and of polyamines, stimulation of microvillous enzymes, of sIgA ,increased production of the receptor for polymeric immunoglobulins by crypt cells, and enhanced D-glucose uptake.Aim: The objective of this study was to determine the pathway(s) by which these effects generated by the yeast are transduced into the cell. Methods: Litters of 6 growing Wistar rats each (30 days post partum) were treated with S .boulardii (50[micro]g per g body wt) or with saline during 72 hours. For each animal, the cytosol was prepared from the whole mucosa after the fat cake was discarded. Several known intestinal substrates were immunoprecipitated and immunoblotted using specific antibodies recognizing the non-, mono- or diphosphorylated forms of these substrates. The signals were detected using ECL and were measured by optodensitometry. Results: treatement with S.boulardii enhanced markedly the RAS-GAP-RAF-ERK1,2 pathway with participation of GRB2, SHC, SOS, and CRKII. Unit p85a of Pi-3 kinase ,tested in its phosporylated form, was also enhanced by the probiotic compared to control samples. In rats treated with an inhibitor of RAF-1 and of ERK 1,2 (PD098059) the expression of mucosal disaccharidases was inhibited by about 50%. Conclusion: The probiotic S. boulardii generates in vivo mitogen and metabolic signals which are transduced into intestinal cells downstream from the apical membrane to the nuclei, using recruitment substrates and serine, threonine, or tyrosine kinases .
Highlights
Wistar rats each ( 30 days post partum ) were treated with S.boulardii (50μg per g body wt) or with saline during 72 hours
There is so far no information regarding the mechanism(s) by which the probiotic S. boulardii generates mitogenic and metabolic effects that are transduced from the apical epithelial membrane downstream to the nucleus
Our study shows that intestinal mucosal samples from intact rats as well as from rats-treated with S. boulardii, express several signaling substrates, recruited proteins, serine, threonine and tyrosine kinases that transduce mitogenic and metabolic signals from the epithelial membrane to the nucleus
Summary
Wistar rats each ( 30 days post partum ) were treated with S.boulardii (50μg per g body wt) or with saline during 72 hours. Saccharomyces boulardii (S. boulardii ) is a biotherapeutic agent , effective in acute and chronic enterocolopathies [ 1-6 ], Lyophilized preparations of S. boulardii ( Biocodex, Gentilly, France ) when administered orally to humans or rats, exert trophic intestinal effects including increases in the specific and total activities of microvillous enzymes such as sucrase [7], aminopeptidase [8], trehalase [ 9 ],enhanced secretion of s-IgA in jejunal and ileal fluid [10] increased production of the receptor for polymeric immunoglobulins by crypt cells [10] and a marked stimulation of the sodium-dependent Dglucose uptake by brush border membrane vesicles with a corresponding increase in the sodium D glucose co-transporter 1 (SGLT-1) [11]. The objectives of the present study were to determine wheter the trophic effects generated by S. boulardii could be regulated in rat intestinal mucosal extracts by known signalling substrates and phosphorylated kinases
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