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Influence of protein histidine phosphatase overexpression and down-regulation on human umbilical-vein endothelial cell viability

Authors

  • Anna Seeger,

    1. Westfaelische WilhelmsUniversitaet Muenster, Institut fuer Pharmazeutische und Medizinische Chemie, Hittorfstr. 5862, D48149 Muenster, Germany
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  • Karsten Rose,

    1. Westfaelische WilhelmsUniversitaet Muenster, Institut fuer Pharmazeutische und Medizinische Chemie, Hittorfstr. 5862, D48149 Muenster, Germany
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  • Nien Tze Ma,

    1. Westfaelische WilhelmsUniversitaet Muenster, Institut fuer Pharmazeutische und Medizinische Chemie, Hittorfstr. 5862, D48149 Muenster, Germany
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  • Elisabeth Kremmer,

    1. Helmholtz Zentrum Muenchen, Institut fuer Molekulare Immunologie, Marchioninistr. 25, D81377 Muenchen, Germany
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  • Susanne Klumpp,

    Corresponding author
    1. Westfaelische WilhelmsUniversitaet Muenster, Institut fuer Pharmazeutische und Medizinische Chemie, Hittorfstr. 5862, D48149 Muenster, Germany
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  • Josef Krieglstein

    Corresponding author
    1. Westfaelische WilhelmsUniversitaet Muenster, Institut fuer Pharmazeutische und Medizinische Chemie, Hittorfstr. 5862, D48149 Muenster, Germany
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Deceased.

To whom correspondence should be addressed (email krieglst@uni-muenster.de).

Abstract

PHP (protein histidine phosphatase) is expressed by mammalian tissues, particularly in blood vessel walls. We investigated whether PHP plays a significant role in endothelial cells. By Western blot and immunofluorescence analysis PHP was found in HUVEC (human umbilical-vein endothelial cells). Overexpression of PHP by the use of a plasmid vector, pIRES2-AcGFP1-PHP, induced apoptosis in HUVEC. To exclude the possibility that increased cellular protein alone unspecifically caused cell damage, the inactive H53A mutant of PHP was also overexpressed as a control; it did not lead to apoptosis. Down-regulation of PHP by the RNAi (RNA interference) technique did not affect cell viability. In conclusion, HUVEC are damaged by overexpression, but not down-regulation, of PHP, suggesting a pronounced impact of the enzyme on the cells when its activity is increased.

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