The rate of folate receptor alpha (FRα) synthesis in folate depleted CHL cells is regulated by a translational mechanism sensitive to media folate levels, while stable overexpression of its mRNA is mediated by gene amplification and an increase in transcript half-life

• Published in: Journal of cellular biochemistry 2001-05, Vol.81 (2), p.205-219
• Main Authors: Zhu, Wei-Yong, Alliegro, Mary Anne, Melera, Peter W.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Blotting, Northern; Blotting, Southern; Blotting, Western; Carrier Proteins - biosynthesis; Cell Line; Cell Membrane - metabolism; Cloning, Molecular; Cricetinae; DNA, Complementary - metabolism; folate depletion; folate receptors; Folate Receptors, GPI-Anchored; Folic Acid - metabolism; gene amplification; Gene Expression Regulation; Gene Library; Glycosylation; Humans; Mice; Models, Genetic; Molecular Sequence Data; mRNA stability; Phosphatidylinositol Diacylglycerol-Lyase; Protein Biosynthesis; Receptors, Cell Surface; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Time Factors; transcription; Transcription, Genetic; translation; Type C Phospholipases - pharmacology
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/1097-4644(20010501)81:2<205::AID-JCB1036>3.0.CO;2-S

DC‐3F/FA3 cells (FA3) were obtained by selection of Chinese hamster lung fibroblasts for growth in folic acid free media, supplemented with 15 pM [6S]‐5‐formyltetrahydrofolic acid. These cells, as a result of low level gene amplification and RNA stabilization, were found to overexpress folate receptor alpha (FRα) mRNA by more than five hundred fold. The expression level of the receptor, a 43 kDa GPI‐linked plasma membrane glycoprotein, was found to be inversely related to changes in media folate concentrations while its steady state mRNA level remained unaffected. In low folate, the rate of receptor synthesis was found to increase by more than three fold, while its half‐life stabilized as compared to that observed in high folate media. Although DC‐3F cells were found to contain low amounts of FRα mRNA, receptor expression was undetectable, and changing media folate concentrations had no effect on the expression of either. Hence, while selection for growth in low folate leads to stable overexpression of FRα mRNA, receptor expression is regulated at the level of protein synthesis by a mechanism sensitive to media folate levels. J. Cell. Biochem. 81:205–219, 2001. © 2001 Wiley‐Liss, Inc.