Protein kinase C (PKC) is known to be involved in the regulation of exocytosis in different cell lines and tissues. Experiments were designed to determine whether the Harderian gland of CD-1 mouse produces PKC isoenzymes and whether the expression of the isoforms changes during pregnancy. The presence of the isoenzymes was assessed by immunoblotting experiments using extract of total Harderian gland and polyclonal antisera specific for nine different PKC isoforms. Antisera giving a positive staining on Western blots were subsequently used for immunohistochemical investigation using a secondary antibody conjugated to alkaline phosphatase. Immunoblotting experiments revealed that the Harderian gland from female mouse expresses PKC isoforms-α,-ε,-ζ and-η. These isoforms were also detected in the Harderian gland from 13-day pregnant mouse; however, striking quantitative changes were seen concerning the α- and ε-isoforms. The 80-kDa native form of PKC-α almost doubled in the pregnant mouse in comparison with normal female mouse whereas the amount of 50-kDa catalytic domain did not change. Protein kinase C-ε appeared as a 92- to 93-kDa form and a 67-kDa form. While the 92- to 93-kDa protein was expressed to a similar extent in both types of mouse, the 67-kDa form was more abundant inthe Harderian gland from normal female mouse. These data were corroborated by immunohistochemical experiments and showing a diffuse and granular staining of the adenomeres. These observations demonstrate for the first time (to our knowledge) that the mouse Harderian gland produces several PKC isoenzymes that could be involved in the regulation of exocytosis and/or other functions. Moreover, the expression of the α- and ε-isoforms could be regulated by sexual hormones, as suggested by the differential abundance of these two proteins in the gland of pregnant mouse compared with normal female mouse.
ASJC Scopus subject areas
- Cell Biology