Involvement of gicerin in the extension of microvilli.
Gicerin is a cell adhesion molecule belonging to the immunoglobulin superfamily. To study the functional differences between l- and s-gicerin, we first examined the distribution of endogenous gicerin in B16 cells and found that l-gicerin was densely localized in microvilli. To clarify the relationship between gicerin and the microvilli, we established independent stable cell lines expressing l- and s-gicerin in L cells and found that l-gicerin localized to the microvilli. Scanning electron microscopic analysis revealed that the microvilli of l-gicerin-transfected cells were longer than those of s-gicerin and control transfectants. This suggested that l-gicerin might participate in the elongation of the microvilli. When cells were double-stained with antibodies to gicerin and moesin, a microvilli-specific protein, the staining of l-gicerin corresponded to that of moesin in the elongated microvilli. Moesin was coprecipitated with glutathione S-transferase-fusion proteins of the l-gicerin cytoplasmic domain but not with the s-gicerin cytoplasmic domain. To determine the region involved in the extension of microvilli, we generated transfectants of two truncated forms of l-gicerin cytoplasmic domain, and we found that only the transfectants of the longer mutant had the longer microvilli, while the shorter mutant exhibited short microvilli. These results suggested that l-gicerin-specific amino acid residues, especially amino acids 16-39, within the cytoplasmic domain of l-gicerin might be involved in the extension of microvilli.
Okumura
S
S
Department of Pharmacology, Osaka University School of Medicine, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Muraoka
O
O
Tsukamoto
Y
Y
Tanaka
H
H
Kohama
K
K
Miki
N
N
Taira
E
E
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D030161:Avian Proteins; D051929:CD146 Antigen; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000235:genetics*; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation / Q000235:genetics; D002465:Cell Movement / Q000235:genetics*; D003599:Cytoskeleton / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000502:physiology; D005822:Genetic Vectors; D008545:Melanoma; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000378:metabolism
D000199:Actins; D030161:Avian Proteins; D051929:CD146 Antigen; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; C497903:Mcam protein, mouse; D008840:Microfilament Proteins; D020033:Protein Isoforms; C071058:moesin