Journal of Lipid Research, Vol 38, 913-925, Copyright © 1997 by Lipid Research, Inc.

ARTICLES

Lipid-depleted diet perturbs membrane composition and intracellular transport in lactating mammary cells

M Ollivier-Bousquet, F Lavialle, P Guesnet, D Rainteau and G Durand
Laboratoire de Biologie Cellulaire et Moleculaire, INRA, Jouy-en-Josas, France.

When rats were fed a control or a lipid-depleted diet for five generations, reproduction was not disturbed but pup growth was affected. The membrane organization and the secretory activity of mammary epithelial cells from these lactating rats were investigated. This diet induced a large decrease in the level of polyunsaturated fatty acids of membrane phospholipids (26.6% versus 44.0%). The level of 20:4 (n-6) was strongly decreased, mainly in phosphatidylethanolamine. Annexin VI, which interacts preferentially with this phospholipid, accumulated at the periphery of the cell and was largely associated to the hydrophobic region of the bilayer as compared to control membranes. Casein synthesis and casein secretion measured in incubated explants, after pulse-chase metabolic labeling, were both reduced by about 60% in lipid-deprived cells. The secretory ratio (radioactive secreted caseins in %) was not modified, suggesting that the mechanism of basal secretion was not mainly affected. On the contrary, the secretagogue effect of prolactin disappeared. The intracellular transport of the hormone was considerably slowed down by the diet and prolactin did not reach the lumen of the acini after 1 h of chase, in contrast to what occurred in control cells. Addition of 20:4 (n-6), in vitro, to mammary fragments from lipid-deprived rats restored the localization of annexin VI, increased synthesis and secretion of caseins as well as intracellular transport of PRI. Together, these data underline the importance of the level of 20:4 (n- 6) in membrane phospholipids for exocytic and endocytic transport in lactating mammary epithelial cells.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Lessard, N. Gagnon, D. L. Godson, and H. V. Petit Influence of Parturition and Diets Enriched in n-3 or n-6 Polyunsaturated Fatty Acids on Immune Response of Dairy Cows During the Transition Period J Dairy Sci, July 1, 2004; 87(7): 2197 - 2210. [Abstract] [Full Text] [PDF]

				M Lkhider, B Petridou, A Aubourg, and M Ollivier-Bousquet Prolactin signalling to milk protein secretion but not to gene expression depends on the integrity of the Golgi region J. Cell Sci., January 5, 2001; 114(10): 1883 - 1891. [Abstract] [PDF]