Polarized secretion of leukemia inhibitory factor


Background: The direction of cytokine secretion from polarized cells determines the cytokine's cellular targets. Leukemia inhibitory factor LIF) belongs to the interleukin-6 IL-6) family of cytokines and signals through LIFR/gp130. Three factors which may regulate the direction of LIF secretion were studied: the site of stimulation, signal peptides, and expression levels. Stimulation with IL-1 beta is known to promote IL-6 secretion from the stimulated membrane apical or basolateral) in the human intestinal epithelial cell line Caco-2. Since LIF is related to IL-6, LIF secretion was also tested in Caco-2 following IL-1 beta stimulation. Signal peptides may influence the trafficking of LIF. Two isoforms of murine LIF, LIF-M and LIF-D, encode different signal peptides which have been associated with different locations of the mature protein in fibroblasts. To determine the effect of the signal peptides on LIF secretion, secretion levels were compared in Madin-Darby canine kidney MDCK) clones which expressed murine LIF-M or LIF-D or human LIF under the control of an inducible promoter. Low and high levels of LIF expression were also compared since saturation of the apical or basolateral route would reveal specific transporters for LIF. Results: When Caco-2 was grown on permeable supports, LIF was secreted constitutively with around 40% secreted into the apical chamber. Stimulation with IL-1 beta increased LIF production. After treating the apical surface with IL-1 beta, the percentage secreted apically remained similar to the untreated, whereas, when the cells were stimulated at the basolateral surface only 20% was secreted apically. In MDCK cells, an endogenous LIF-like protein was detected entirely in the apical compartment. The two mLIF isoforms showed no difference in their secretion patterns in MDCK. Interestingly, about 70% of murine and human LIF was secreted apically from MDCK over a 400-fold range of expression levels within clones and a 200,000-fold range across clones. Conclusion: The site of stimulation affected the polarity of LIF secretion, while, signal peptides and expression levels did not. Exogenous LIF is transported in MDCK without readily saturated steps.

Publication DOI: https://doi.org/10.1186/1471-2121-9-53
Divisions: College of Health & Life Sciences > Aston Pharmacy School
College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences
College of Health & Life Sciences > Chronic and Communicable Conditions
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
Additional Information: © 2008 Hill and Vernallis; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords: Cell Biology
Publication ISSN: 1471-2121
Last Modified: 14 Mar 2024 08:09
Date Deposited: 19 Aug 2019 08:52
Full Text Link: http://www.biom ... /1471-2121/9/53
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2008-09-18
Authors: Hill, Eric J. (ORCID Profile 0000-0002-9419-1500)
Vernallis, Ann B.



Version: Published Version

License: Creative Commons Attribution

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