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Claudin-11/OSP-based tight junctions of myelin sheaths in brain and Sertoli cells in testis.

Morita K, Sasaki H, Fujimoto K, Furuse M, Tsukita S - J. Cell Biol. (1999)

Bottom Line: We identified oligodendrocyte-specific protein (OSP) as claudin-11, a new claudin family member, due to its sequence similarity to claudins as well as its ability to form TJ strands in transfected fibroblasts.At the electron microscopic level, these linear structures were identified as the so-called interlamellar strands in myelin sheaths of oligodendrocytes.These findings indicated that the interlamellar strands of oligodendrocyte myelin sheaths can be regarded as a variant of TJ strands found in many other epithelial cells, and that these strands share a specific claudin species, claudin-11/OSP, with those in Sertoli cells to create and maintain the repeated compartments around axons by oligodendrocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606, Japan.

ABSTRACT
Members of the newly identified claudin gene family constitute tight junction (TJ) strands, which play a pivotal role in compartmentalization in multicellular organisms. We identified oligodendrocyte-specific protein (OSP) as claudin-11, a new claudin family member, due to its sequence similarity to claudins as well as its ability to form TJ strands in transfected fibroblasts. Claudin-11/OSP mRNA was expressed in the brain and testis. Immunofluorescence microscopy with anti-claudin-11/OSP polyclonal antibody (pAb) and anti-neurofilament mAb revealed that in the brain claudin-11/OSP-positive linear structures run in a gentle spiral around neurofilament-positive axons. At the electron microscopic level, these linear structures were identified as the so-called interlamellar strands in myelin sheaths of oligodendrocytes. In testis, well-developed TJ strands of Sertoli cells were specifically labeled with anti-claudin-11/OSP pAb both at immunofluorescence and electron microscopic levels. These findings indicated that the interlamellar strands of oligodendrocyte myelin sheaths can be regarded as a variant of TJ strands found in many other epithelial cells, and that these strands share a specific claudin species, claudin-11/OSP, with those in Sertoli cells to create and maintain the repeated compartments around axons by oligodendrocytes.

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L transfectants expressing FLAG-tagged OSP.  (a–d) Immunofluorescence (a)  and corresponding phase  contrast images (b) of stable  L transfectants expressing  FLAG-OSP. Cells were  stained with anti-FLAG mAb.  Expressed FLAG-OSP was  concentrated at cell–cell borders as planes (arrow) or on  thin cellular protrusions (arrowhead). At higher magnification (c and d), at cell–cell  contact planes, FLAG-OSP  was concentrated as networks  or as thick lines. (e) Freeze-fracture images of cell–cell  contact planes of stable L transfectants expressing FLAG-OSP. At low magnification,  large numbers of TJ strand/ groove-like structures were  observed. These strands  scarcely branched, and showed  a tendency to run parallel to  each other. Inset, higher magnification of strands on P-face  (top) and grooves on E-face  (bottom). Bars: (a and b) 10  μm; (c and d) 4 μm; (e) 500  nm; (inset) 100 nm.
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Figure 2: L transfectants expressing FLAG-tagged OSP. (a–d) Immunofluorescence (a) and corresponding phase contrast images (b) of stable L transfectants expressing FLAG-OSP. Cells were stained with anti-FLAG mAb. Expressed FLAG-OSP was concentrated at cell–cell borders as planes (arrow) or on thin cellular protrusions (arrowhead). At higher magnification (c and d), at cell–cell contact planes, FLAG-OSP was concentrated as networks or as thick lines. (e) Freeze-fracture images of cell–cell contact planes of stable L transfectants expressing FLAG-OSP. At low magnification, large numbers of TJ strand/ groove-like structures were observed. These strands scarcely branched, and showed a tendency to run parallel to each other. Inset, higher magnification of strands on P-face (top) and grooves on E-face (bottom). Bars: (a and b) 10 μm; (c and d) 4 μm; (e) 500 nm; (inset) 100 nm.

Mentions: Next, we introduced cDNA encoding OSP with a FLAG- sequence at its COOH terminus into cultured L fibroblasts which lacked TJs or the expression of claudins (Furuse et al., 1998b). Immunofluorescence microscopy of the stable transfectants with anti-FLAG mAb showed that expressed FLAG-OSP was concentrated at cell–cell borders as planes or on thin cellular protrusions (Fig. 2, a–d). This mAb gave no signal from parent L fibroblasts. Then, these stable L transfectants expressing FLAG-OSP were fixed with glutaraldehyde and examined by conventional freeze-fracture electron microscopy (Fig. 2 e). In these cells, TJ strand/groove-like structures were frequently observed to be arranged in a parallel manner, whereas in parent L cells these structures were not detected. These strands were associated with the P-face, and were mostly discontinuous with intervening spaces of various widths (Fig. 2 e, inset). On the E-face, complementary continuous grooves were identified, containing scattered particles (Fig. 2 e, inset). The OSP-induced strands did not bifurcate frequently and showed a tendency to run parallel to each other.


Claudin-11/OSP-based tight junctions of myelin sheaths in brain and Sertoli cells in testis.

Morita K, Sasaki H, Fujimoto K, Furuse M, Tsukita S - J. Cell Biol. (1999)

L transfectants expressing FLAG-tagged OSP.  (a–d) Immunofluorescence (a)  and corresponding phase  contrast images (b) of stable  L transfectants expressing  FLAG-OSP. Cells were  stained with anti-FLAG mAb.  Expressed FLAG-OSP was  concentrated at cell–cell borders as planes (arrow) or on  thin cellular protrusions (arrowhead). At higher magnification (c and d), at cell–cell  contact planes, FLAG-OSP  was concentrated as networks  or as thick lines. (e) Freeze-fracture images of cell–cell  contact planes of stable L transfectants expressing FLAG-OSP. At low magnification,  large numbers of TJ strand/ groove-like structures were  observed. These strands  scarcely branched, and showed  a tendency to run parallel to  each other. Inset, higher magnification of strands on P-face  (top) and grooves on E-face  (bottom). Bars: (a and b) 10  μm; (c and d) 4 μm; (e) 500  nm; (inset) 100 nm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2185072&req=5

Figure 2: L transfectants expressing FLAG-tagged OSP. (a–d) Immunofluorescence (a) and corresponding phase contrast images (b) of stable L transfectants expressing FLAG-OSP. Cells were stained with anti-FLAG mAb. Expressed FLAG-OSP was concentrated at cell–cell borders as planes (arrow) or on thin cellular protrusions (arrowhead). At higher magnification (c and d), at cell–cell contact planes, FLAG-OSP was concentrated as networks or as thick lines. (e) Freeze-fracture images of cell–cell contact planes of stable L transfectants expressing FLAG-OSP. At low magnification, large numbers of TJ strand/ groove-like structures were observed. These strands scarcely branched, and showed a tendency to run parallel to each other. Inset, higher magnification of strands on P-face (top) and grooves on E-face (bottom). Bars: (a and b) 10 μm; (c and d) 4 μm; (e) 500 nm; (inset) 100 nm.
Mentions: Next, we introduced cDNA encoding OSP with a FLAG- sequence at its COOH terminus into cultured L fibroblasts which lacked TJs or the expression of claudins (Furuse et al., 1998b). Immunofluorescence microscopy of the stable transfectants with anti-FLAG mAb showed that expressed FLAG-OSP was concentrated at cell–cell borders as planes or on thin cellular protrusions (Fig. 2, a–d). This mAb gave no signal from parent L fibroblasts. Then, these stable L transfectants expressing FLAG-OSP were fixed with glutaraldehyde and examined by conventional freeze-fracture electron microscopy (Fig. 2 e). In these cells, TJ strand/groove-like structures were frequently observed to be arranged in a parallel manner, whereas in parent L cells these structures were not detected. These strands were associated with the P-face, and were mostly discontinuous with intervening spaces of various widths (Fig. 2 e, inset). On the E-face, complementary continuous grooves were identified, containing scattered particles (Fig. 2 e, inset). The OSP-induced strands did not bifurcate frequently and showed a tendency to run parallel to each other.

Bottom Line: We identified oligodendrocyte-specific protein (OSP) as claudin-11, a new claudin family member, due to its sequence similarity to claudins as well as its ability to form TJ strands in transfected fibroblasts.At the electron microscopic level, these linear structures were identified as the so-called interlamellar strands in myelin sheaths of oligodendrocytes.These findings indicated that the interlamellar strands of oligodendrocyte myelin sheaths can be regarded as a variant of TJ strands found in many other epithelial cells, and that these strands share a specific claudin species, claudin-11/OSP, with those in Sertoli cells to create and maintain the repeated compartments around axons by oligodendrocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606, Japan.

ABSTRACT
Members of the newly identified claudin gene family constitute tight junction (TJ) strands, which play a pivotal role in compartmentalization in multicellular organisms. We identified oligodendrocyte-specific protein (OSP) as claudin-11, a new claudin family member, due to its sequence similarity to claudins as well as its ability to form TJ strands in transfected fibroblasts. Claudin-11/OSP mRNA was expressed in the brain and testis. Immunofluorescence microscopy with anti-claudin-11/OSP polyclonal antibody (pAb) and anti-neurofilament mAb revealed that in the brain claudin-11/OSP-positive linear structures run in a gentle spiral around neurofilament-positive axons. At the electron microscopic level, these linear structures were identified as the so-called interlamellar strands in myelin sheaths of oligodendrocytes. In testis, well-developed TJ strands of Sertoli cells were specifically labeled with anti-claudin-11/OSP pAb both at immunofluorescence and electron microscopic levels. These findings indicated that the interlamellar strands of oligodendrocyte myelin sheaths can be regarded as a variant of TJ strands found in many other epithelial cells, and that these strands share a specific claudin species, claudin-11/OSP, with those in Sertoli cells to create and maintain the repeated compartments around axons by oligodendrocytes.

Show MeSH
Related in: MedlinePlus