Temporal changes in NCAM immunoreactivity during taste cell differentiation and cell lineage relationships in taste buds.
Neural cell adhesion molecule (NCAM) is a type III cell marker in the taste buds. In order to clarify the cell type of Mash1-expressing cells in taste buds, expression of NCAM was examined in Mash1-expressing taste cells of adult mice in comparison with gustducin- and T1r3-expressing cells, using a combination of NCAM immunohistochemistry and in situ hybridization. About 98% of Mash1-expressing cells were NCAM immunopositive (IP), suggesting that Mash1-expressing cells should be categorized as type III cells. Unexpectedly, small subsets of gustducin- and T1r3-expressing cells were also found to be NCAM-IP, contradicting previous immunohistochemical studies in rats, in which gustducin-IP cells were observed specifically in type II cells, which do not have NCAM immunoreactivity. Examinations of developing taste buds showed temporal changes in the ratio of NCAM-IP cells in gustducin- and T1r3-expressing cells; the ratio of NCAM-IP cells in these gene-expressing cells were approximately 90% at 0.5 days after birth and decreased markedly during development. In contrast, the majority of Mash1-expressing cells showed constant NCAM immunoreactivity throughout development. In addition, BrdU-labeling experiments showed that the differentiation of Mash1-expressing cells precedes those of gustducin- and T1r3-expressing cells in taste buds of adult mice. These results suggest that T1r3- and gustducin-expressing cells are NCAM-IP at the beginning of cell differentiation, and that NCAM immunoreactivity in gustducin- and T1r3-expressing cells might remain from the previous developmental stage expressing Mash1.
Miura
Hirohito
H
National Food Research Institute, 2-1-12 Kannondai, Ibaraki 305-8642, Japan. hmiura@affrc.go.jp
Kato
Hiromi
H
Kusakabe
Yuko
Y
Ninomiya
Yuzo
Y
Hino
Akihiro
A
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000502:physiology*; D019070:Cell Lineage / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D019006:Neural Cell Adhesion Molecules / Q000096:biosynthesis*; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D043562:Receptors, G-Protein-Coupled; D013650:Taste Buds / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis; D015293:Transducin / Q000096:biosynthesis
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D019006:Neural Cell Adhesion Molecules; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; D015293:Transducin; C499317:Ascl1 protein, mouse; C431926:taste receptors, type 1; C075192:gustducin