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The unique acyl chain specificity of biliary phosphatidylcholines in mice is independent of their biosynthetic origin in the liver
Author(s) -
Agellon Luis B.,
Walkey Christopher J.,
Vance Dennis E.,
Kuipers Folkert,
Verkade Henkjan J.
Publication year - 1999
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510300305
Subject(s) - phosphatidylcholine , choline , phosphatidylethanolamine , phosphocholine , biochemistry , gallbladder , chemistry , biology , phospholipid , medicine , membrane
The liver synthesizes phosphatidylcholine (PC) de novo from choline via the CDP‐choline pathway, and from phosphatidylethanolamine (PE) via the phosphatidylethanolamine N ‐methyltransferase (PEMT) pathway. Significant amounts of PC, which are highly specific in their acyl chain composition, are secreted into bile by the liver. To determine whether either of the 2 PC biosynthetic routes is sufficient to provide physiological PC concentrations in bile, or is responsible for the unique acyl chain composition of bile PC, we analyzed gallbladder bile composition in mice that synthesized PC either via the PEMT pathway (induced by feeding a choline‐deficient diet) or the CDP‐choline pathway (based on genetic PEMT‐deficiency). The PC concentration in gallbladder bile of mice that synthesize PC mainly via the CDP‐choline pathway was comparable with control mice that synthesize PC via both pathways, whereas it was reduced by ≈40% in mice that synthesize PC via the PEMT pathway. The acyl chain composition of bile PC was similar irrespective of the active PC biosynthetic pathway in the liver. These data demonstrate that the CDP‐choline pathway alone, but not the PEMT pathway alone, can account for physiological concentrations of PC in gallbladder bile. Moreover, the specificity of biliary PC fatty acyl composition is determined independently from the synthetic origin of PC.