Lipoprotein lipase activity in cultured macrophage cell line J774(2) and its increase in variants deficient in adenylate cyclase and cyclic AMP-dependent protein kinase.
Lipoprotein lipase activity in cultured macrophage cell line J774(2) and its increase in variants deficient in adenylate cyclase and cyclic AMP-dependent protein kinase.
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培养的巨噬细胞系 J774(2) 中的脂蛋白脂肪酶活性及其在腺苷酸环化酶和环 AMP 依赖性蛋白激酶缺陷的变体中的增加。
DOI：
10.1016/0167-4889(83)90117-9
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Stein,Y
中科院分区：
文献类型：
--
作者：
Melmed,RN;Friedman,G;Chajek-Shaul,T;Stein,O;Stein,Y
比较了巨噬细胞J7742、ct2和j7h13株细胞系脂蛋白脂肪酶的合成和分泌情况。根据血清依赖性和1 M NaCl的抑制作用，测定酶活性为脂蛋白脂肪酶。3个品系的酶活性均随培养时间的延长而增加，在腺苷酸环化酶缺失的ct2品系中酶活性最高，而在环amp依赖性蛋白激酶缺失的j7h1_1品系中酶活性为中等。这三种细胞系在条件培养基中酶活性的半衰期均为30-40分钟，这表明观察到的不同水平的酶活性确实代表了细胞产生酶的不同水平。三种细胞系中约80%的脂蛋白脂肪酶活性存在于培养基中，50-70%的细胞活性可通过肝素暴露3分钟释放到培养基中。此外，用肝素孵育24小时后，三种细胞系的酶分泌均增强。利用二丁基cAMP、甲基异丁基黄嘌呤（IBMX）和霍乱毒素，研究了环AMP对脂蛋白脂肪酶活性的调节作用。这些药物显著降低了j7742细胞系的脂蛋白脂肪酶活性，但只有二丁基cAMP在ct2细胞系（腺苷酸环化酶缺陷）中有活性。在J7H1（蛋白激酶缺陷）系中，二丁基cAMP或IBMX在孵育的前4小时内没有反应。这些试剂的加入不影响细胞总蛋白的合成。目前的研究结果表明，在完整的细胞中，环AMP水平的变化与脂蛋白脂肪酶活性的变化有关。
Three macrophage cell lines, J7742, CT2and J7H1were compared with respect to synthesis and secretion of lipoprotein lipase. The enzyme activity measured was characterized as lipoprotein lipase on the basis of serum dependence and inhibition by 1 M NaCl. Enzyme activity in all three lines increased with time in culture and the highest activity was found in the medium of the CT2line which is adenylate cyclase deficient while that in the J7H1line, cyclic AMP-dependent protein kinase deficient, was intermediate. The half life of the enzyme activity in conditioned medium from all three lines was 30–40 min, suggesting that the different levels of activity observed do represent different levels of enzyme production by the cells. About 80% of the lipoprotein lipase activity from all three lines was present in the medium and 50–70% of cellular activity could be released into the medium by a 3-min exposure to heparin. In addition, 24 h incubation with heparin enhanced enzyme secretion in all three lines. To determine the role of cyclic AMP in the regulation of lipoprotein lipase activity use was made of dibutyryl cAMP, methyl isobutylxanthine (IBMX) and cholera toxin. These agents strikingly depressed lipoprotein lipase activity in the J7742line but only dibutyryl cAMP was active in the CT2line (adenylate cyclase deficient). In the J7H1(protein kinase deficient) line there was no response to dibutyryl cAMP or IBMX over the first 4 h of incubation. Addition of these agents did not affect total cell protein synthesis. The present findings indicate that in the intact cells changes in cyclic AMP levels are associated with a change in the activity of lipoprotein lipase.
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DOI：
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发表时间：
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DOI：
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发表时间：
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期刊：
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影响因子：
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DOI：
10.1016/0005-2760(80)90063-6
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期刊：
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影响因子：
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