Autoregulation of protein phosphatase type 2A expression.
Protein phosphatases are involved in many cellular processes. One of the most abundant of these enzymes, the serine/threonine-specific protein phosphatase type 2A (PP2A), is present in most eukaryotic cells and serves a variety of functions. However, the detailed study of its regulation and function has been hampered by the difficulty of manipulating its expression level in cell culture. By using a new mammalian expression vector to forcibly overexpress PP2A in the mouse fibroblast cell line NIH3T3, we now show that the catalytic subunit of PP2A is subject to a potent autoregulatory mechanism that adjusts PP2A protein to constant levels. This control is exerted at the translational level and does not involve regulation of transcription or RNA processing. Thus, our results demonstrate tight control of PP2A expression, and provide an explanation for the difficulty of increasing PP2A expression experimentally.
Department of Molecular Microbiology and Immunology, K. Norris Jr. Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90033, USA.
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Schönthal
D016475:3T3 Cells; D000818:Animals; D002384:Catalysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000201:enzymology; D006706:Homeostasis; D051379:Mice; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases