Different intracellular locations for prostaglandin endoperoxide H synthase-1 and -2.
The subcellular locations of prostaglandin endoperoxide synthase-1 and -2 (PGHS-1 and -2) were determined by quantitative confocal fluorescence imaging microscopy in murine 3T3 cells and human and bovine endothelial cells using immunocytofluorescence with isozyme-specific antibodies. In all of the cell types examined, PGHS-1 immunoreactivity was found equally distributed in the endoplasmic reticulum (ER) and nuclear envelope (NE). PGHS-2 immunoreactivity was also present in the ER and NE. However, PGHS-2 staining was twice as concentrated in the NE as in the ER. A histofluorescence staining method was developed to localize cyclooxygenase/peroxidase activity. In quiescent 3T3 cells, which express only PGHS-1, histofluorescent staining was most concentrated in the perinuclear cytoplasmic region. In contrast, histochemical staining for PGHS-2 activity was about equally intense in the nucleus and in the cytoplasm, a pattern of activity staining distinct from that observed with PGHS-1. Our results indicate that there are significant differences in the subcellular locations of PGHS-1 and PGHS-2. It appears that PGHS-1 functions predominantly in the ER whereas PGHS-2 may function in the ER and the NE. We speculate that PGHS-1 and PGHS-2 acting in the ER and PGHS-2 functioning in the NE represent independent prostanoid biosynthetic systems.
Morita
I
I
Department of Biochemistry, Michigan State University, East Lansing 48824, USA.
Schindler
M
M
Regier
M K
MK
Otto
J C
JC
Hori
T
T
DeWitt
D L
DL
Smith
W L
WL
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002451:Cell Compartmentation; D004721:Endoplasmic Reticulum / Q000201:enzymology; D004730:Endothelium, Vascular / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000201:enzymology; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*
D007527:Isoenzymes; D010455:Peptides; D011451:Prostaglandin-Endoperoxide Synthases