STIMULATION OF PHOSPHATIDYLCHOLINE BIOSYNTHESIS IN MOUSE MLE-12 TYPE-II CELLS BY CONDITIONED MEDIUM FROM CORTISOL-TREATED RAT FETAL LUNG FIBROBLASTS

被引:12
作者
MACDONALD, JIS
POSSMAYER, F
机构
[1] UNIV WESTERN ONTARIO,DEPT OBSTET & GYNAECOL,LONDON,ON N6A 5A5,CANADA
[2] UNIV WESTERN ONTARIO,DEPT BIOCHEM,LONDON,ON N6A 5A5,CANADA
[3] UNIV WESTERN ONTARIO,MRC,FETAL & NEONATAL HLTH GRP,LONDON,ON N6A 5A5,CANADA
关键词
D O I
10.1042/bj3120425
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Treatment of murine adult MLE-12 type-II and fetal-rat type-II cells with fetal-rat-fibroblast-conditioned medium (FFCM) resulted in a 2-fold stimulation of [C-14]choline incorporation into phosphatidylcholine. Soluble CTP:phosphocholine cytidylyl-transferase (CT) activity was increased approx. 3-fold in FFCM-treated fetal-rat type-II cells but was not changed in MLE-12 cells. Neither choline kinase nor cholinephosphotransferase activities were affected by treatment of MLE-12 cells with FFCM. Long-term labelling of MLE-12 cells with [C-14]choline, followed by a 14-18 h chase with FFCM, resulted in a 2.5-fold decrease in [C-14]phosphocholine levels relative to controls, suggesting that CT was being activated. In contrast, oleate treatment increased CT activity in the particulate fraction in both cells. Western blots indicate that soluble CT undergoes dephosphorylation in response to FFCM, but no translocation to the particulate fraction was noted. Treatment with oleate stimulated a marked translocation. Tryptic phosphopeptide maps from FFCM-treated cells revealed only minor alterations in the phosphorylation pattern. It is concluded that FFCM and oleate activate CT through different mechanisms. The results are consistent with FFCM activating CT in MLE-12 as well as fetal type-II cells. However, the reason why this activation cannot be detected in vitro is not known.
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页码:425 / 431
页数:7
相关论文
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