Comparative analysis of expression and secretion of placental leptin in mammals.
Comparative analysis of expression and secretion of placental leptin in mammals.
复制标题
DOI：
10.1152/ajpregu.00776.2002
复制
发表时间：
2003-08
期刊：
影响因子：
--
通讯作者：
J. Zhao;T. Kunz;Nancy L. Tumba;L. Schulz;Chris Li;M. Reeves;E. Widmaier
中科院分区：
文献类型：
--
作者：
J. Zhao;T. Kunz;Nancy L. Tumba;L. Schulz;Chris Li;M. Reeves;E. Widmaier
血浆瘦素水平升高似乎是怀孕哺乳动物的普遍特征。然而，瘦素水平升高的机制可能是物种特有的，一些物种上调脂肪瘦素的产生，另一些物种在胎盘中表达瘦素。研究了胎盘瘦素在两个最丰富的哺乳动物目--啮齿目和翼手目的代表性物种以及培养的人类绒毛膜癌细胞(BeWo)中的表达。Leptin mRNA在小棕蝠(Myotis Lucifugus，小棕蝠)、青花菜(Eptesicus fuscus，大棕蝠)和褐家鼠(Rattus norveicus，实验鼠)的BeWo细胞和胎盘中均有表达，但在普通实验小鼠的胎盘中不表达。CAMP刺激BeWo细胞分泌瘦素，并刺激细胞内瘦素mRNA的表达。除了脂肪和胎盘组织外，在心脏、脾和肝脏中也能检测到瘦素的转录本，但在肺、脑和肾脏中检测不到。在青霉中也观察到了肝脏的表达，但在小鼠或大鼠中没有，而且似乎不是肝脏脂肪沉积的结果。从卢氏分枝杆菌胎盘组织中克隆了瘦素基因，并对其进行了序列分析，该基因与其他哺乳动物的瘦素基因同源性高达95%。结论：1)胎盘瘦素的表达和分泌是物种特有的特征，2)胎盘瘦素的产生是孕期母体瘦素水平升高的三个主要机制之一，其他的机制是脂肪瘦素的产生和循环瘦素结合蛋白的产生上调，3)妊娠食虫蝙蝠肝脏瘦素的表达可能是这些物种在妊娠和哺乳期间皮下脂肪含量极低所导致的一种适应。
Increased plasma level of leptin appears to be a ubiquitous feature of pregnant mammals. The mechanisms by which leptin levels are increased may be species specific, however, with some species upregulating adipose leptin production and others expressing leptin in the placenta. Placental leptin expression was examined in representative species of the two most abundant mammalian orders, Rodentia and Chiroptera, and in cultured human choriocarcinoma (BeWo) cells. Leptin mRNA was expressed in BeWo cells and in placentas of Myotis lucifugus (little brown bat), Eptesicus fuscus (big brown bat), and Rattus norvegicus (laboratory rat), but not the common laboratory mouse Mus musculus. cAMP stimulated secretion of leptin from BeWo cells and also stimulated leptin mRNA expression in the cells. In addition to adipose and placental tissue, leptin transcript in M. lucifugus was detectable in heart, spleen, and liver, but not in lung, brain, and kidney. Hepatic expression was also observed in E. fuscus, but not in mice or rats, and did not appear to result from hepatic fat deposition. Leptin cDNA was cloned and sequenced from M. lucifugus placenta and shared up to 95% homology with other mammalian leptin cDNAs. It is concluded that 1) placental leptin expression and secretion are species-specific traits, 2) placental leptin production represents one of three major mechanisms for achieving high circulating maternal leptin levels during pregnancy, the others being upregulation of adipose leptin production and production of circulating leptin-binding proteins, and 3) hepatic leptin expression in pregnant insectivorous bats may be an adaptation resulting from the presence of extremely low amounts of subcutaneous fat during pregnancy and lactation in these species.