scholarly journals A novel intracellular compartment with unusual secretory properties in human neutrophils.

1991 ◽  
Vol 113 (4) ◽  
pp. 743-756 ◽  
Author(s):  
T Kobayashi ◽  
J M Robinson
Keyword(s):  
Alkaline Phosphatase ◽  
Cell Surface ◽  
Phosphatase Activity ◽  
Phorbol Ester ◽  
Alkaline Phosphatase Activity ◽  
Biochemical Analysis ◽  
Human Neutrophils ◽  
Tubular Structures ◽  
Intracellular Compartment ◽  
Specific Granules

Human neutrophils contain a novel intracellular compartment that is distinct from the previously characterized azurophil and specific granules. This compartment is distinguished by the presence of cytochemically detectable alkaline phosphatase activity. The alkaline phosphatase-containing compartments are short rod-shaped organelles that rapidly undergo a dramatic reorganization upon cell stimulation with either a chemoattractant or an active phorbol ester. Biochemical analysis shows that in unstimulated neutrophils the majority of the alkaline phosphatase activity is intracellular, but after stimulation essentially all of this activity becomes associated with the cell surface. The exocytotic pathway is unusual in that these small organelles fuse to form elongated tubular structures before their association with the plasmalemma.

Identification of intracellular sites of superoxide production in stimulated neutrophils

1998 ◽  
Vol 111 (1) ◽  
pp. 81-91 ◽  
Author(s):  
T. Kobayashi ◽  
J.M. Robinson ◽  
H. Seguchi
Keyword(s):  
Alkaline Phosphatase ◽  
Plasma Membrane ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Time Course ◽  
Superoxide Production ◽  
Human Neutrophils ◽  
Morphological Evidence ◽  
Marker Enzyme ◽  
Intracellular Compartments

In this study, we show that superoxide production is carried out within intracellular compartments of human neutrophils and not at the plasma membrane following stimulation with phorbol myristate acetate. Oxidant production was not observed in unstimulated cells. Stimulated cells exhibited superoxide production in two distinct types of intracellular organelles. Initially, activity was detected in slender rod-shaped granules and in spherical or elliptical granules. The oxidant-producing granules fused directly with the plasma membrane or fused to form larger intracellular vesicles which then became associated with the plasma membrane. Longer periods of stimulation with PMA resulted in a decrease in the number of vesicles containing oxidant reaction product only, and an increase in structures containing both the oxidant-reaction product and ferritin particles; the latter was used herein as a marker for endocytosis. Thus a complex pattern of intracellular vesicular trafficking occurs in stimulated neutrophils. Alkaline phosphatase activity, a marker enzyme for a type of intracellular neutrophil granule was co-localized in the oxidant reaction-positive intracellular compartments. The time course of up-regulation of alkaline phosphatase activity to the cell surface parallelled the release of superoxide from stimulated cells. Results from this study demonstrate for the first time cytochemical and morphological evidence that superoxide is released from stimulated neutrophils through exocytosis of an oxidant-producing intracellular granule.

scholarly journals Endothelial Cell Surface Alkaline Phosphatase Activity is Induced by IL-6 Released During Wound Repair

1997 ◽  
Vol 109 (4) ◽  
pp. 597-603 ◽  
Author(s):  
Richard L. Gallo ◽  
Robert A. Dorschner ◽  
Seiji Takashima ◽  
Michael Klagsbrun ◽  
Elof Eriksson ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Endothelial Cell ◽  
Cell Surface ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Wound Repair ◽  
Endothelial Cell Surface

scholarly journals Regulated internalization of caveolae.

1994 ◽  
Vol 127 (5) ◽  
pp. 1199-1215 ◽  
Author(s):  
R G Parton ◽  
B Joggerst ◽  
K Simons
Keyword(s):  
Alkaline Phosphatase ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Phosphatase Activity ◽  
Okadaic Acid ◽  
Alkaline Phosphatase Activity ◽  
Kinase Inhibitor ◽  
Cytochalasin D ◽  
Microtubule Organizing Center ◽  
Hypertonic Medium

Caveolae are specialized invaginations of the plasma membrane which have been proposed to play a role in diverse cellular processes such as endocytosis and signal transduction. We have developed an assay to determine the fraction of internal versus plasma membrane caveolae. The GPI-anchored protein, alkaline phosphatase, was clustered in caveolae after antibody-induced crosslinking at low temperature and then, after various treatments, the relative amount of alkaline phosphatase on the cell surface was determined. Using this assay we were able to show a time- and temperature-dependent decrease in cell-surface alkaline phosphatase activity which was dependent on antibody-induced clustering. The decrease in cell surface alkaline phosphatase activity was greatly accelerated by the phosphatase inhibitor, okadaic acid, but not by a protein kinase C activator. Internalization of clustered alkaline phosphatase in the presence or absence of okadaic acid was blocked by cytochalasin D and by the kinase inhibitor staurosporine. Electron microscopy confirmed that okadaic acid induced removal of caveolae from the cell surface. In the presence of hypertonic medium this was followed by the redistribution of groups of caveolae to the center of the cell close to the microtubule-organizing center. This process was reversible, blocked by cytochalasin D, and the centralization of the caveolar clusters was shown to be dependent on an intact microtubule network. Although the exact mechanism of internalization remains unknown, the results show that caveolae are dynamic structures which can be internalized into the cell. This process may be regulated by kinase activity and require an intact actin network.

Calcification of chick vertebral chondrocytes grown in agarose gels: a biochemical and ultrastructural study

1993 ◽  
Vol 104 (4) ◽  
pp. 1031-1038
Author(s):  
G.K. Hunter ◽  
D.P. Holmyard ◽  
K.P. Pritzker
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Biochemical Analysis ◽  
Glycerol Phosphate ◽  
Agarose Gels ◽  
Chondrocyte Cultures ◽  
Mineral Deposition ◽  
Rate Limiting ◽  
Maximal Production

Chick embryo vertebral chondrocytes (CHECOV cells) grown in agarose gels form spherical colonies containing cells of hypertrophic morphology and a metachromatically staining matrix. Biochemical analysis of these cultures resulted in the following findings. (i) Calcification of CHECOV cultures can be induced by addition of Pi (at least 1.9 mM) or beta-glycerol phosphate (BGP). (ii) Alkaline phosphatase activity reaches a maximal value at the time when mineral deposition is initiated. (iii) Added BGP is converted to Pi; maximal production of Pi occurs at the time of maximal alkaline phosphatase activity. (iv) BGP-supplemented cultures produce a degree of calcification that corresponds to the amount of BGP conversion to Pi. It can be concluded that Pi is rate-limiting for the calcification of chondrocyte cultures. BGP promotes calcification of these cultures by acting as a substrate for the alkaline phosphatase-mediated production of inorganic phosphate.

LEUCOCYTE METABOLISM IN PREGNANCY

1960 ◽  
Vol XXXV (IV) ◽  
pp. 575-584 ◽  
Author(s):  
C. Borel ◽  
J. Frei ◽  
A. Vannotti
Keyword(s):  
Alkaline Phosphatase ◽  
Oxygen Consumption ◽  
Pregnant Women ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Lactate Production ◽  
Glucose Consumption ◽  
In Pregnancy

ABSTRACT Enzymatic studies, on leucocytes of pregnant women, show an increase of the alkaline phosphatase activity and a decrease of the glucose consumption and lactate production, as well as of proteolysis. The oxygen consumption, with succinate as substrate, does not vary.

Sign in / Sign up

Export Citation Format

Share Document