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Immunoelectron microscopic study of podoplanin localization in mouse salivary gland myoepithelium.

Hata M, Amano I, Tsuruga E, Kojima H, Sawa Y - Acta Histochem Cytochem (2010)

Bottom Line: In immunohistochemistry, the surfaces of both the mucous acini terminal portion and ducts were covered by a number of extensive myoepithelial cellular processes expressing podoplanin, and the immunostaining level with anti-podoplanin antibody to myoepithelial cells completely coincided with the immunostaining level with anti-α-SMA antibody.In immunoelectron microscopic study, a number of reaction products with anti-podoplanin antibody were found at the Golgi apparatus binding to the endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells, and were also found at the myoepithelial cell membrane.Podoplanin may be involved in maintaining the homeostasis of myoepithelial cells through its characteristic as a mucin-type transmembrane glycoprotein.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Growth & Development, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan.

ABSTRACT
We have recently reported that salivary gland cells express the lymphatic endothelial cell marker podoplanin. The present study was aimed to immunohistochemically investigate the expression of the myoepithelial cell marker α-smooth muscle actin (SMA) on podoplanin-positive cells in mouse parotid and sublingual glands, and to elucidate podoplanin localization in salivary gland myoepithelial cells by immunoelectron microscopic study. The distribution of myoepithelial cells expressing podoplanin and α-SMA was examined by immunofluorescent staining, and the localization of reaction products of anti-podoplanin antibody was investigated by pre-embedded immunoelectron microscopic method. In immunohistochemistry, the surfaces of both the mucous acini terminal portion and ducts were covered by a number of extensive myoepithelial cellular processes expressing podoplanin, and the immunostaining level with anti-podoplanin antibody to myoepithelial cells completely coincided with the immunostaining level with anti-α-SMA antibody. These findings suggest that podoplanin is a salivary gland myoepithelial cell antigen, and that the detection level directly reflects the myoepithelial cell distribution. In immunoelectron microscopic study, a number of reaction products with anti-podoplanin antibody were found at the Golgi apparatus binding to the endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells, and were also found at the myoepithelial cell membrane. These findings suggest that salivary gland myoepithelial cells constantly produce podoplanin and glycosylate at the Golgi apparatus, and transport them to the cell membrane. Podoplanin may be involved in maintaining the homeostasis of myoepithelial cells through its characteristic as a mucin-type transmembrane glycoprotein.

No MeSH data available.


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Immunoelectron microscopy for the membrane localization of podoplanin in salivary gland myoepithelial cells. (A) A strong density of immunostaining with anti-podoplanin is found at the cell membrane and in the cytoplasm of myoepithelial cells between sublingual gland acinar cells. Bar=10 µm. (B) A number of small DAB granules with strong density by immunostaining with anti-podoplanin are found at the myoepithelial cell membrane between sublingual gland acinar cells (arrowheads). Bar=2 µm.
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Figure 4: Immunoelectron microscopy for the membrane localization of podoplanin in salivary gland myoepithelial cells. (A) A strong density of immunostaining with anti-podoplanin is found at the cell membrane and in the cytoplasm of myoepithelial cells between sublingual gland acinar cells. Bar=10 µm. (B) A number of small DAB granules with strong density by immunostaining with anti-podoplanin are found at the myoepithelial cell membrane between sublingual gland acinar cells (arrowheads). Bar=2 µm.

Mentions: A number of reaction products with anti-podoplanin were found at the Golgi apparatus binding to endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells (Fig. 3). Furthermore, a number of reaction products with the anti-podoplanin were localized at the myoepithelial cell membrane between acinar cells (Fig. 4). The Golgi apparatus is composed of membrane-bound cisternae which have networks to the endoplasmic reticulum, and primarily functions to process proteins, package the macromolecules, and enable them to make their way to their destination [23]. The Golgi apparatus plays a role in the attachment of polysaccharides to a protein synthesized in the endoplasmic reticulum to form proteoglycans. Podoplanin is a mucin-type transmembrane glycoprotein negatively charged by extensive O-glycosylation and has a high content of sialic acid. Therefore, it is thought that podoplanin is continuously produced, glycosylated with polysaccharides in the Golgi apparatus, and transported to the cell membrane. Some reaction products with anti-podoplanin were observed at the basal side near the nuclei in the cytoplasm of the acinar cells in spite of the absence of reaction products with anti-podoplanin in the salivary gland acinar cells by fluorescence microscopy. Further studies on podoplanin localization in acinar cells by immunoelectron microscopy are required. It has been reported that podoplanin promotes plasma membrane extension and actin cytoskeleton rearrangement [15, 30, 33, 36], and that podoplanin is resistant to proteases because it is a negatively charged mucin-type protein [3]. Podoplanin may play a role in maintaining the shape of myoepithelial cell foot processes to protect acinar cells from the outside.


Immunoelectron microscopic study of podoplanin localization in mouse salivary gland myoepithelium.

Hata M, Amano I, Tsuruga E, Kojima H, Sawa Y - Acta Histochem Cytochem (2010)

Immunoelectron microscopy for the membrane localization of podoplanin in salivary gland myoepithelial cells. (A) A strong density of immunostaining with anti-podoplanin is found at the cell membrane and in the cytoplasm of myoepithelial cells between sublingual gland acinar cells. Bar=10 µm. (B) A number of small DAB granules with strong density by immunostaining with anti-podoplanin are found at the myoepithelial cell membrane between sublingual gland acinar cells (arrowheads). Bar=2 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: Immunoelectron microscopy for the membrane localization of podoplanin in salivary gland myoepithelial cells. (A) A strong density of immunostaining with anti-podoplanin is found at the cell membrane and in the cytoplasm of myoepithelial cells between sublingual gland acinar cells. Bar=10 µm. (B) A number of small DAB granules with strong density by immunostaining with anti-podoplanin are found at the myoepithelial cell membrane between sublingual gland acinar cells (arrowheads). Bar=2 µm.
Mentions: A number of reaction products with anti-podoplanin were found at the Golgi apparatus binding to endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells (Fig. 3). Furthermore, a number of reaction products with the anti-podoplanin were localized at the myoepithelial cell membrane between acinar cells (Fig. 4). The Golgi apparatus is composed of membrane-bound cisternae which have networks to the endoplasmic reticulum, and primarily functions to process proteins, package the macromolecules, and enable them to make their way to their destination [23]. The Golgi apparatus plays a role in the attachment of polysaccharides to a protein synthesized in the endoplasmic reticulum to form proteoglycans. Podoplanin is a mucin-type transmembrane glycoprotein negatively charged by extensive O-glycosylation and has a high content of sialic acid. Therefore, it is thought that podoplanin is continuously produced, glycosylated with polysaccharides in the Golgi apparatus, and transported to the cell membrane. Some reaction products with anti-podoplanin were observed at the basal side near the nuclei in the cytoplasm of the acinar cells in spite of the absence of reaction products with anti-podoplanin in the salivary gland acinar cells by fluorescence microscopy. Further studies on podoplanin localization in acinar cells by immunoelectron microscopy are required. It has been reported that podoplanin promotes plasma membrane extension and actin cytoskeleton rearrangement [15, 30, 33, 36], and that podoplanin is resistant to proteases because it is a negatively charged mucin-type protein [3]. Podoplanin may play a role in maintaining the shape of myoepithelial cell foot processes to protect acinar cells from the outside.

Bottom Line: In immunohistochemistry, the surfaces of both the mucous acini terminal portion and ducts were covered by a number of extensive myoepithelial cellular processes expressing podoplanin, and the immunostaining level with anti-podoplanin antibody to myoepithelial cells completely coincided with the immunostaining level with anti-α-SMA antibody.In immunoelectron microscopic study, a number of reaction products with anti-podoplanin antibody were found at the Golgi apparatus binding to the endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells, and were also found at the myoepithelial cell membrane.Podoplanin may be involved in maintaining the homeostasis of myoepithelial cells through its characteristic as a mucin-type transmembrane glycoprotein.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Growth & Development, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan.

ABSTRACT
We have recently reported that salivary gland cells express the lymphatic endothelial cell marker podoplanin. The present study was aimed to immunohistochemically investigate the expression of the myoepithelial cell marker α-smooth muscle actin (SMA) on podoplanin-positive cells in mouse parotid and sublingual glands, and to elucidate podoplanin localization in salivary gland myoepithelial cells by immunoelectron microscopic study. The distribution of myoepithelial cells expressing podoplanin and α-SMA was examined by immunofluorescent staining, and the localization of reaction products of anti-podoplanin antibody was investigated by pre-embedded immunoelectron microscopic method. In immunohistochemistry, the surfaces of both the mucous acini terminal portion and ducts were covered by a number of extensive myoepithelial cellular processes expressing podoplanin, and the immunostaining level with anti-podoplanin antibody to myoepithelial cells completely coincided with the immunostaining level with anti-α-SMA antibody. These findings suggest that podoplanin is a salivary gland myoepithelial cell antigen, and that the detection level directly reflects the myoepithelial cell distribution. In immunoelectron microscopic study, a number of reaction products with anti-podoplanin antibody were found at the Golgi apparatus binding to the endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells, and were also found at the myoepithelial cell membrane. These findings suggest that salivary gland myoepithelial cells constantly produce podoplanin and glycosylate at the Golgi apparatus, and transport them to the cell membrane. Podoplanin may be involved in maintaining the homeostasis of myoepithelial cells through its characteristic as a mucin-type transmembrane glycoprotein.

No MeSH data available.


Related in: MedlinePlus