SSAT (Spermidine/spermine N1-acetyltransferase, also known as SAT1), the key enzyme in the catabolism of polyamines, is turned over rapidly and there is only a low amount present in the cell. In the present study, the regulation of SSAT by spermine analogues, the inducers of the enzyme, was studied in wild-type mouse fetal fibroblasts, expressing endogenous SSAT, and in the SSAT-deficient mouse fetal fibroblasts transiently expressing an SSAT–EGFP (enhanced green fluorescent protein) fusion gene. In both cell lines treatments with DENSpm (N1,N11-diethylnorspermine), CPENSpm (N1-ethyl-N11-[(cyclopropyl)-methy]-4,8-diazaundecane) and CHENSpm (N1-ethyl-N11-[(cycloheptyl)methy]-4,8-diazaundecane) led to high, moderate or low induction of SSAT activity respectively. The level of activity detected correlated with the presence of SSAT and SSAT–EGFP proteins, the latter localizing both in the cytoplasm and nucleus. RT–PCR (reverse transcription–PCR) results suggested that the analogue-affected regulation of SSAT–EGFP expression occurred, mainly, after transcription. In wild-type cells, DENSpm increased the amount of SSAT mRNA, and both DENSpm and CHENSpm affected splicing of the SSAT pre-mRNA. Depleted intracellular spermidine and spermine levels inversely correlated with detected SSAT activity. Interestingly, the analogues also reduced polyamine levels in the SSAT-deficient cells expressing the EGFP control. The results from the present study show that the distinct SSAT regulation by different analogues involves regulatory actions at multiple levels, and that the spermine analogues, in addition to inducing SSAT, lower intracellular polyamine pools by SSAT-independent mechanisms.
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Research Article|
July 29 2009
Spermine analogue-regulated expression of spermidine/spermine N1-acetyltransferase and its effects on depletion of intracellular polyamine pools in mouse fetal fibroblasts
Anne Uimari;
Anne Uimari
1
*Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, FI-70211 Kuopio, Finland
1Correspondence may be addressed to either of these authors (email anne.uimari@uku.fi or leena.alhonen@uku.fi).
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Tuomo A. Keinänen;
Tuomo A. Keinänen
*Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, FI-70211 Kuopio, Finland
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Anne Karppinen;
Anne Karppinen
*Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, FI-70211 Kuopio, Finland
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Patrick Woster;
Patrick Woster
†Department of Pharmaceutical Sciences, Wayne State University, 539 Shapero Hall, Detroit, MI 48202, U.S.A.
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Pekka Uimari;
Pekka Uimari
‡MTT, Biotechnology and Food Research, FI-31600 Jokioinen, Finland
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Juhani Jänne;
Juhani Jänne
*Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, FI-70211 Kuopio, Finland
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Leena Alhonen
Leena Alhonen
1
*Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, FI-70211 Kuopio, Finland
1Correspondence may be addressed to either of these authors (email anne.uimari@uku.fi or leena.alhonen@uku.fi).
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Publisher: Portland Press Ltd
Received:
March 11 2009
Revision Received:
May 26 2009
Accepted:
May 27 2009
Accepted Manuscript online:
May 27 2009
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biochem J (2009) 422 (1): 101–109.
Article history
Received:
March 11 2009
Revision Received:
May 26 2009
Accepted:
May 27 2009
Accepted Manuscript online:
May 27 2009
Citation
Anne Uimari, Tuomo A. Keinänen, Anne Karppinen, Patrick Woster, Pekka Uimari, Juhani Jänne, Leena Alhonen; Spermine analogue-regulated expression of spermidine/spermine N1-acetyltransferase and its effects on depletion of intracellular polyamine pools in mouse fetal fibroblasts. Biochem J 15 August 2009; 422 (1): 101–109. doi: https://doi.org/10.1042/BJ20090411
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