Cellular and Molecular Biology


Immunohistochemical localization of senescence marker protein-30 (SMP30) in the submandibular gland and ultrastructural changes of the granular duct cells in SMP30 knockout mice

K. Ishii1, T. Tsubaki1, K. Fujita2, A. Ishigami3, N. Maruyama3 and M. Akita4

1Department of Otolaryngology, Omiya Medical Center, Jichi Medical School, 2Department of Anatomy, Saitama Medical School, 3Organ Disorder and Aging Research Group, Tokyo Metropolitan Institute of Gerontology and 4Division of Morphological Science, Biomedical Research Center, Saitama Medical School

Offprint requests to: Masumi Akita, PhD, Prof. and Head, Division of Morphological Science, Biomedical Research Center, Saitama Medical School, 38 Moroyama, Saitama 350-0495, Japan. e-mail: makita@saitama-med.ac.jp

Summary. Senescence Marker Protein-30 (SMP30) is a calcium-regulating protein that decreases in an androgen-independent manner as aging occurs. An enzyme-labeled antibody technique has demonstrated that SMP30 localized to the ducts (granular, intercalated, and striated ducts) of mouse submandibular glands. Immunoelectronmicroscopy demonstrated that the granular duct cells were strongly positive for SMP30, but that pillar cells in the granular duct were negative for the protein. In SMP30-knockout (KO) mice, the granular ducts were smaller in diameter. Swelling of mitochondria in the granular duct cells was observed; however, this phenomenon was not observed in the pillar cells. After administration of alpha-isoproterenol, a beta-adrenergic stimulant, a large numbers of small secretory granules were present in the granular duct cells and an expansion of the rough endoplasmic reticulum in SMP30-wild type (WT) mice; in contrast, little change was observed in SMP30-KO mice. These results suggest that SMP30 may be closely related to a signal transduction pathway in the granular duct cells of submandibular glands. Histol Histopathol 20, 761-768 (2005)

Key words: SMP30, Submandibular gland, Granular duct, alpha-isoproterenol, Immunohistochemistry

DOI: 10.14670/HH-20.761