Localization of aminopeptidase N and dipeptidyl peptidase IV in pig striatum and in neuronal and glial cell cultures.
The subcellular distribution of the plasma membrane ectoenzymes, aminopeptidase N (aminopeptidase M) and dipeptidyl peptidase IV, has been examined by fractionating homogenates of porcine striata by a discontinuous Percoll gradient centrifugation procedure which distinguishes fractions containing pre- and post-synaptic elements. The two enzymes showed different distributions--dipeptidyl peptidase IV did not show a significant pre-synaptic location, whereas aminopeptidase N was present on both pre- and post-synaptic fractions. Immunofluorescent staining on mixed and neuron-enriched primary cultures of pig striatal tissue using affinity purified antibodies to the aminopeptidase and to the dipeptidyl peptidase revealed the ectoenzymes on distinct populations of cells. The astrocytic identity of the aminopeptidase N-staining cells was established by correlation with immunostaining for glial fibrillary acidic protein and for vimentin by confocal microscopy. Ultracryosections of striatum immunostained with gold-labelled immunoglobulins of differing diameters demonstrated aminopeptidase N on pericytes and confirmed its location on endothelial and astrocytic glial cells. Thus, several independent approaches indicated that aminopeptidase N, in addition to being present on endothelial and synaptic membranes, is found on astrocytes and pericytes in the perivascular neuropil, whereas dipeptidyl peptidase IV is less widely distributed on microvessels and appears not to have a synaptosomal location.
Barnes
K
K
Department of Biochemistry and Molecular Biology, University of Leeds, UK.
Kenny
A J
AJ
Turner
A J
AJ
D000626:Aminopeptidases / Q000032:analysis*; D000818:Animals; D000911:Antibodies, Monoclonal; D018826:CD13 Antigens; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D003342:Corpus Striatum / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D046508:Culture Techniques / Q000379:methods; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000032:analysis*; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D009457:Neuroglia / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000201:enzymology; D013552:Swine
D000911:Antibodies, Monoclonal; D005904:Glial Fibrillary Acidic Protein; D000626:Aminopeptidases; D018826:CD13 Antigens; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4