Abstract
The developmentally and tissue-specific expression of flavin-containing monooxygenase (FMO) enzymes has been previously characterized in a number of animal species, including humans, mice, rats, and rabbits. In this study, we used sensitive real-time reverse transcription-polymerase chain reaction methodology to systematically quantify the steady-state mRNA levels of FMO1, 2, 3, 4, and 5 in human tissues. We examined the developmental regulation of these enzymes in brain tissue. FMO1 was found to be down-regulated in human adult brain. The amount of other FMO mRNAs in human brains in different age groups was not significantly different. The study also provided a systematic quantitative comparison of the steady-state mRNA levels of FMO1 to 5 in several major human organs (i.e., liver, lung, kidney, small intestine, and brain). The nature of the quantitative analysis allowed a comprehensive comparison of each FMO mRNA in different tissues as well as among FMO isoforms in the same tissue. A comparison between fetal liver and adult liver showed that FMO1 was the only FMO that was down-regulated; all other FMOs had greater amounts of mRNA in adult liver. FMO5 was the most prominent FMO form detected in fetal liver. The FMO5 mRNA level was nearly as abundant as FMO3 in adult liver. Whereas other FMOs displayed a significant, dominant tissue-specific mRNA profile (i.e., FMO1 in kidney, FMO2 in lung, FMO3 and FMO5 in adult liver), FMO4 mRNA was observed more broadly at relatively comparable levels in liver, kidney, lung, and small intestine.
Footnotes
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The financial support of the National Institute of Health (Grant Number DK 59618) is gratefully acknowledged. Tissue for this project has been provided in part by the University of Miami Brain and Tissue Bank for Developmental Disorders, in contract to the National Institute for Child Health and Development (NICHD Contract NOI-HI-8-3284), and by the Brain and Tissue Bank for Developmental Disorders at the University of Maryland at Baltimore, in contract to the NICHD (Contract NOI-HD-8-3283).
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.105.006171.
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ABBREVIATIONS: FMO, flavin-containing monooxygenase; PCR, polymerase chain reaction; RT-PCR, reverse transcription-polymerase chain reaction; q-PCR, quantitative polymerase chain reaction; TBP, TATA-Box binding protein; HPRT, hypoxanthine phosphoribosyltransferase; ANOVA1, analysis of variance 1.
- Received June 22, 2005.
- Accepted September 22, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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