Possible role of calmodulin in the secretion of Entamoeba histolytica electron-dense granules containing collagenase.
Entamoeba histolytica cells secrete electron-dense granules (EDGs) that have collagenase activity. To study the possible involvement of calmodulin (CaM) on EDG secretion, the effect of several CaM antagonists (TFP, R24571, W-7, W-5, dibucaine and DL-propranolol) was tested on this cellular function. Except for W-5 and dibucaine, the rest of these compounds inhibited EDG secretion. Transmission electron microscopy of collagen-activated trophozoites showed numerous EDGs located in or near the surface membrane. In contrast, trophozoites incubated with TFP showed no EDGs. Protein kinase C inhibitors (H-7, ML-9) had no effect on EDG secretion, suggesting that CaM antagonists acted by selectively inhibiting CaM. These results suggest that a CaM-dependent process is involved in EDG secretion.
Muñoz
M de L
Mde L
Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, México.
Moreno
M A
MA
Pérez-Garcia
J N
JN
Tovar
G R
GR
Hernandez
V I
VI
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000276:immunology / Q000502:physiology*; D002458:Cell Fractionation; D003094:Collagen / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000737:chemistry; D004748:Entamoeba histolytica / Q000378:metabolism* / Q000472:pathogenicity / Q000648:ultrastructure; D004797:Enzyme-Linked Immunosorbent Assay; D003012:Microbial Collagenase / Q000378:metabolism*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D047428:Protein Kinase Inhibitors; D015290:Second Messenger Systems / Q000502:physiology
D002147:Calmodulin; D047428:Protein Kinase Inhibitors; D003094:Collagen; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D003012:Microbial Collagenase; D002118:Calcium