Kuusela P, Jacobsson A, Klingenspor M, Rehnmark S, Heldmaier G, Cannon B, Nedergaard J
The Wenner-Gren Institute, Stockholm University, Sweden.
Biochim Biophys Acta. 1997 Apr 21;1345(3):327-37. doi: 10.1016/s0005-2760(97)00008-8.
To examine the regulation of lipoprotein lipase (LPL) gene expression, LPL mRNA levels in the brown adipose tissue of intact mice and in mouse brown adipocyte cultures were examined. In intact mice, exposure to cold resulted in a rapid, transient, 5-fold increase in LPL mRNA level. Norepinephrine (NE) injection could fully mimic the effect of acute exposure to cold, and LPL mRNA and enzymatic activity were increased in parallel after NE injection. These results indicated positive adrenergic control of LPL gene expression in the brown adipose tissue of intact mice. In cultured mouse brown adipocytes, the level of spontaneously expressed LPL mRNA decreased in parallel with the progression of brown adipocyte differentiation. NE treatment of undifferentiated cells led to a decrease in LPL mRNA levels. In brown adipocytes that had reached a mature state, NE had a small negative or no effect on LPL mRNA levels, irrespective of whether the experiment was performed in the presence or absence of insulin or of newborn-calf serum. It was concluded that LPL gene expression in brown adipose tissue in intact mice is under adrenergic control but that this gene is not under positive adrenergic control in cultured brown adipocytes from mice, although these cells are otherwise adrenergically sensitive. The presence of additional factors may be necessary to confer adrenergic sensitivity to the LPL gene in the cultured brown adipocytes; alternatively, cells other than the mature brown adipocytes may confer the positive adrenergic sensitivity to the brown adipose tissue depots in situ.
为研究脂蛋白脂肪酶（LPL）基因表达的调控，检测了完整小鼠棕色脂肪组织及小鼠棕色脂肪细胞培养物中的LPL mRNA水平。在完整小鼠中，暴露于寒冷环境导致LPL mRNA水平迅速、短暂地增加5倍。注射去甲肾上腺素（NE）可完全模拟急性暴露于寒冷的效应，注射NE后LPL mRNA和酶活性平行增加。这些结果表明，完整小鼠棕色脂肪组织中LPL基因表达受肾上腺素能阳性调控。在培养的小鼠棕色脂肪细胞中，自发表达的LPL mRNA水平随棕色脂肪细胞分化进程而平行下降。用NE处理未分化细胞导致LPL mRNA水平降低。在已达到成熟状态的棕色脂肪细胞中，无论实验是在有无胰岛素或新生牛血清的情况下进行，NE对LPL mRNA水平的影响很小或无影响。得出的结论是，完整小鼠棕色脂肪组织中LPL基因表达受肾上腺素能控制，但在来自小鼠的培养棕色脂肪细胞中该基因不受肾上腺素能阳性调控，尽管这些细胞在其他方面对肾上腺素能敏感。可能需要其他因素的存在才能使培养的棕色脂肪细胞中的LPL基因对肾上腺素能敏感；或者，除成熟棕色脂肪细胞外的其他细胞可能赋予棕色脂肪组织原位对肾上腺素能的阳性敏感性。
