Relationship between phosphatidic acid level and regulation of protein transit in colonic epithelial cell line HT29-cl19A.
Colonic epithelial HT29-cl19A cells are polarized and secrete proteins among which alpha(1)-antitrypsin represents about 95%. Secretion occurs via a constitutive pathway, so that the rates of secretion directly reflect the rates of protein transit. In this paper we have demonstrated that: 1) in resting cells phospholipase D (PLD) is implicated in the control of apical protein transit; 2) phorbol esters stimulate apical protein transit (stimulation factor 2.2), which is correlated with a PLD-catalyzed production of phosphatidic acid (PA) (2.45-fold increase); 3) the stimulation of cholinergic receptors by carbachol results in an increase (stimulation factor 1.45) of apical protein transit which is independent of protein kinase C and PLD activities, but related to PA formation (1.7-fold increase) via phospholipase(s) C and diacylglycerol kinase activation; 4) an elevation of the cAMP level enhances apical protein transit by a PA-independent mechanism; 5) a trans-Golgi network or post-trans-Golgi network step of the transit is the target for the regulatory events. In conclusion, we have shown that PA can be produced by two independent signaling pathways; whatever the pathway followed, a close relationship between the amount of PA and the level of secretion was observed.
Auger
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R
Laboratoire de Biochimie des Transports Cellulaires, CNRS, Unité Mixte de Recherche 8619, Bâtiment 432, Université Paris XI, 91 405 Orsay Cedex, France.
Robin
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Camier
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Vial
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Rossignol
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B
Tenu
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JP
Raymond
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D002217:Carbachol / Q000494:pharmacology; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D019852:Diacylglycerol Kinase / Q000378:metabolism; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D007700:Kinetics; D010712:Phosphatidic Acids / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D020536:Enzyme Activators; D010712:Phosphatidic Acids; D000515:alpha 1-Antitrypsin; D002217:Carbachol; D019852:Diacylglycerol Kinase; D010738:Type C Phospholipases; D010739:Phospholipase D