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Post‐translational dual regulation of cytochrome P450 aromatase at the catalytic and protein levels by phosphorylation/dephosphorylation
Author(s) -
Hayashi Takanori,
Harada Nobuhiro
Publication year - 2014
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13021
Subject(s) - dephosphorylation , aromatase , phosphorylation , chemistry , dual (grammatical number) , cytochrome p450 , microbiology and biotechnology , medicine , biochemistry , phosphatase , biology , enzyme , cancer , breast cancer , art , literature
The post‐translational regulation of aromatase has not been well characterized as compared with transcriptional regulation. Several studies of post‐translational regulation have focused on decreases in catalytic activity following phosphorylation. We report here dual post‐translational regulation of aromatase, at the catalytic activity and protein levels. Microsomal aromatase prepared from JEG ‐3 cells was rapidly inactivated and subsequently degraded in the presence of a cytosolic fraction with calcium, magnesium, and ATP . In a reconstituted system consisting of microsomal and cytosolic fractions, aromatase was protected from protein degradation by treatment with alkaline phosphatase, whereas degradation was enhanced by treatment with calcineurin inhibitors ( FK 506 and cyclosporin A). Furthermore, aromatase was protected from degradation by treatment with kinase inhibitors, especially the calcium/calmodulin kinase inhibitors KN 62 and KN 93. Similarly to the reconstituted system, aromatase in cultured JEG ‐3 cells was protected from degradation by KN 93, whereas FK 503 increased degradation in the presence of cycloheximide, although cellular aromatase m RNA levels were unchanged by these reagents. Knockdown of calcineurin and calcium/calmodulin kinase II (Ca MKII ) with small interfering RNA s resulted in a dose‐dependent increase in aromatase degradation and protection from degradation, respectively. The cytosol fraction‐dependent phosphorylation of microsomal aromatase was inhibited by calcineurin, KN 62, and KN 93, and promoted by Ca MKII and FK 506. These results indicate that aromatase is regulated acutely at the catalytic activity level and subsequently at the enzyme content level by Ca MKII /calcineurin‐dependent phosphorylation/dephosphorylation.