Genetic Elements Regulating Human Placental Lactogen Expression
Human placental lactogen (hPL), also known aschorionic somatomammotropin (hCS), is specifically expressed in placental syncytiotrophoblast cells (1, 2). The levels of hPL increase during pregnancy such that by the third trimester this hormone accounts for 10% of the placental protein and greater than 5% of the mRNA (3, 4) and is the most abundant peptide hormone produced in primates (5). However, the biological role of hPL is still not clearly understood. It is believed to play a role in regulating maternal metabolism (reviewed in 6); however, the lack of biological defects in pregnancies lacking hPL (reviewed in 7) suggests that its function may be redundant or only required in particular circumstances; for example, maternal nutritional states. Nevertheless, the high amount of hPL mRNA during pregnancy and its tissue-specific expression suggest that it is a highly regulated system of gene expression.
KeywordsEnhancer Activity Growth Hormone Gene Human Placental Lactogen Placental Protein SV40 Enhancer
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