Developmental and Androgenic Regulation of the Immunocytochemical Distribution of mK1, a True Tissue Kallikrein, in the Granular Convoluted Tubule of the Mouse Submandibular Gland

Abstract

S U M M A R YThe action of androgens on the immunocytochemical distribution of mK1, a true tissue kallikrein, was examined in the submandibular gland (SMG) of developing and adult mice by indirect enzyme-labeled and immunogold-labeled antibody methods for light and electron microscopy, respectively. In both sexes at 3 weeks of age, essentially all of the immature granular convoluted tubule (GCT) cells were uniformly immunostained. At 4 weeks of age (the onset of puberty), morphological differences between the two sexes appeared in the GCTs, in which some cells became immunonegative. Thereafter, the immunonegative GCT cells became more abundant in the SMG of males than of females and considerable intercellular variation in staining intensity for mK1 was seen, especially in males. A few slender GCT cells with strong immunoreactivity appeared in GCT segments only in males. Castration of males resulted in an increase in the number of immunopositive GCT cells, whereas administration of dihydrotestosterone (DHT) decreased the number of immunopositive GCT cells in the SMGs of both sexes. Slender GCT cells immunoreactive for mK1 were seen in females treated with DHT for 6 days. However, there were no immunostained slender GCT cells in female SMGs after injection of DHT for 2 weeks. Immunoelectron microscopy disclosed this type of cell in male SMGs, which closely resembles immature GCT cells of prepubertal mice, with a few small secretory granules uniformly labeled with gold particles, a sparse Golgi apparatus and RER, and basal infoldings. In mature male SMGs and in SMGs of DHT-treated females and castrated males, typical GCT cells had a well-developed Golgi apparatus and a net-like RER but few to no basal infoldings, whereas in the female gland equivalent cells had moderately developed RER and some basal infoldings. These results suggest that mK1 is one of the enzymes characteristically present in immature GCT cells and that its synthesis is inhibited in part by androgens, resulting in decreased numbers of immunopositive cells.

Morphologic changes in the granular convoluted tubule cells of the mouse submandibular gland following hypophysectomy and hormonal replacement

“…Very small secretory granules were usually mixed among large secretory granules in the above-described GCT cells that were increased in size by the hormone injections (Fig. 4a-c), as well as in the GCT cells of normal mice of both sexes (see our previous articles 8,9,11,12 ). However, small secretory granules were less abundant in the cells containing a few huge secretory granules in the group injected with all three hormones (Fig.…”

“…These morphological characteristics are almost the same as those of the developing GCT cells of perinatal (lactational) mice. [7][8][9]11,12 Our previous immunocytochemical studies suggested that all GCT cells of hypophysectomized mice and of perinatal mice are mK1-immunoreactive, whereas most of the GCT cells in mature male SMGs, and approximately one-third of GCT cells in mature female SMGs do not synthesize mK1. 9,11,12 mK1 is a member of the kallikrein gene family and has been identified as a true tissue kallikrein.…”

Role of thyroid hormone in the initiation of EGF (epidermal growth factor) expression in the sublingual gland of the postnatal mouse

“…Cells expressing EGF is less abundant in the GCTs of adult female SMGs (van Noorden et al, 1977;. GCT cells expressing a true tissue kallikrein, mK1, are less abundant in the SMGs of male than female mice (Kurabuchi et al, 1999(Kurabuchi et al, , 2002, and cellular mosaic expression of mK1 is also observed in the SLG of adult male mice (Kurabuchi et al, 2000). These findings suggest that GCT cells, all of which possess the same ultrastructural appearance, are not uniform in terms of producing the same secretory products.…”

Hormone-induced granular convoluted tubule-like cells in mouse parotid gland

“…All immature GCT cells expressed mK1, but the inhibition of mK1 was observed at 4 weeks of age, corresponding to the onset of puberty. Nearly all the SMG GCT cells in adult male mice expressed EGF, NGF and renin, while less than 1% of the population of GCT cells expressed mK1 (13). Therefore, mK1 appears to be a neonatal type of secretory product that is down-regulated by pituitary-dependent hormones ; this unusual characteristic differs from that of other GCT-specific secretory products.…”