title: Immunocytochemical localization of prohormone convertases PC1 and PC2 in the mouse thyroid gland and respiratory tract.
abstract: We examined immunocytochemical localization of the prohormone convertases, PC1 and PC2, in the thyroid gland and respiratory tract of the adult mouse using the indirect enzyme- and immunogold-labeled antibody methods for light and electron microscopy, respectively. In the thyroid gland, PC1- and/or PC2-immunoreactive cells were cuboidal, scattered in the follicular epithelium and in the interfollicular spaces. When serial sections were immunostained with anti-calcitonin, anti-PC1, anti-calcitonin-gene-related-peptide (CGRP), and anti-PC2 sera, respectively, localization of both PC1 and PC2 was restricted to the calcitonin/CGRP-producing parafollicular cells. In the respiratory tract, only PC1 immunoreactivity was observed in the basal granulated neuroendocrine cells, which were scattered in the tracheal epithelium. Consecutive sections immunostained with anti-PC1 and anti-CGRP sera showed that a subpopulation of these PC1-immunoreactive cells contained CGRP. Double immunogold electron microscopy of the thyroid parafollicular cells revealed that calcitonin- and/or CGRP-immunopositive secretory granules were also labeled with both PC1 and PC2. These findings suggest that procalcitonin is proteolytically cleaved by PC2 alone or by PC2 together with PC1, and that the proCGRP is cleaved by PC1.
authors.affiliation: Department of Histology, School of Dentistry, The Nippon Dental University, Tokyo, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kurabuchi
authors.forename: Shigeyasu
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D002116:Calcitonin / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D045664:Proprotein Convertase 1; D045706:Proprotein Convertase 2; D043484:Proprotein Convertases; D012137:Respiratory System / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D013381:Subtilisins / Q000378:metabolism*; D013961:Thyroid Gland / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002116:Calcitonin; D043484:Proprotein Convertases; D013381:Subtilisins; C473656:Pcsk1 protein, mouse; D045664:Proprotein Convertase 1; D045706:Proprotein Convertase 2; D016282:Aspartic Acid Endopeptidases; D015740:Calcitonin Gene-Related Peptide