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Conversion of zonulae occludentes from tight to leaky strand type by introducing claudin-2 into Madin-Darby canine kidney I cells.

Furuse M, Furuse K, Sasaki H, Tsukita S - J. Cell Biol. (2001)

Bottom Line: Interestingly, the TER values of MDCK I clones stably expressing claudin-2 (dCL2-MDCK I) fell to the levels of MDCK II cells (>20-fold decrease).Similar results were obtained in mouse epithelial cells, Eph4.These findings indicated that the addition of claudin-2 markedly decreased the tightness of individual claudin-1/4-based TJ strands, leading to the speculation that the combination and mixing ratios of claudin species determine the barrier properties of individual TJ strands.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan.

ABSTRACT
There are two strains of MDCK cells, MDCK I and II. MDCK I cells show much higher transepithelial electric resistance (TER) than MDCK II cells, although they bear similar numbers of tight junction (TJ) strands. We examined the expression pattern of claudins, the major components of TJ strands, in these cells: claudin-1 and -4 were expressed both in MDCK I and II cells, whereas the expression of claudin-2 was restricted to MDCK II cells. The dog claudin-2 cDNA was then introduced into MDCK I cells to mimic the claudin expression pattern of MDCK II cells. Interestingly, the TER values of MDCK I clones stably expressing claudin-2 (dCL2-MDCK I) fell to the levels of MDCK II cells (>20-fold decrease). In contrast, when dog claudin-3 was introduced into MDCK I cells, no change was detected in their TER. Similar results were obtained in mouse epithelial cells, Eph4. Morphometric analyses identified no significant differences in the density of TJs or in the number of TJ strands between dCL2-MDCK I and control MDCK I cells. These findings indicated that the addition of claudin-2 markedly decreased the tightness of individual claudin-1/4-based TJ strands, leading to the speculation that the combination and mixing ratios of claudin species determine the barrier properties of individual TJ strands.

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Two models of paired TJ strands consisting of claudin-1, -2, and -4. (A) Homotypic adhesion of claudin-2 within paired strands constitutes aqueous pores with high conductance (*). (B) Heterotypic adhesion between claudin-1 and -2 constitutes aqueous pores with high conductance (*). See text for details.
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Figure 7: Two models of paired TJ strands consisting of claudin-1, -2, and -4. (A) Homotypic adhesion of claudin-2 within paired strands constitutes aqueous pores with high conductance (*). (B) Heterotypic adhesion between claudin-1 and -2 constitutes aqueous pores with high conductance (*). See text for details.

Mentions: Detailed electrophysiological analyses suggested the existence of aqueous pores within the paired TJ strands (Diamond 1977; Claude 1978; Reuss 1992; Gumbiner 1993). Stevenson et al. 1988 then discussed the possibility that MDCK I and II cells have very different channel characteristics caused by differences in the probability of the hypothetical aqueous pores in TJ strands being open and closed. Therefore, it is reasonable to speculate that claudin-2 is involved in the formation of aqueous pores with high conductance within the paired TJ strands in MDCK II cells. It is possible that claudin-2 forms such pores through its homotypic adhesion within paired claudin-1/4–based TJ strands (Fig. 7 A). However, as we discussed previously (Tsukita and Furuse 2000), it is also possible that the weak heterotypic adhesion of claudin-2 with claudin-1 (or -4) results in the formation of aqueous pores with high conductance within the paired TJ strands (Fig. 7 B). Claudin-2 does not adhere strongly with claudin-1 in a heterotypic manner in L fibroblast transfectants (Furuse et al. 1999), but a homopolymer of claudin-1 makes a paired strand with a heteropolymer consisting of claudin-1 and -2 in L fibroblast transfectants (our unpublished data; see Tsukita and Furuse 2000). Therefore, aqueous pores with a high probability of being in the open state would be formed between claudin-1 and -2 when they are apposed within paired TJ strands (Fig. 7 B). In this connection, it is interesting to point out that the overexpression of claudin-3 into MDCK I cells as well as that of claudin-1 into Eph4 cells did not affect the barrier functions of TJs (Fig. 4B and Fig. C). As claudin-1 can adhere with claudin-3 (and probably with claudin-4) in a heterotypic manner (Furuse et al. 1999), aqueous pores with high conductance would not be formed in claudin-1– or -3–overexpressed TJ strands. Furthermore, these findings excluded the possibility that the introduction of claudin-2 affected the TJ barrier function due to the unbalance between the total amounts of claudins and other TJ components such as ZO-1 (McCarthy et al. 2000).


Conversion of zonulae occludentes from tight to leaky strand type by introducing claudin-2 into Madin-Darby canine kidney I cells.

Furuse M, Furuse K, Sasaki H, Tsukita S - J. Cell Biol. (2001)

Two models of paired TJ strands consisting of claudin-1, -2, and -4. (A) Homotypic adhesion of claudin-2 within paired strands constitutes aqueous pores with high conductance (*). (B) Heterotypic adhesion between claudin-1 and -2 constitutes aqueous pores with high conductance (*). See text for details.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169456&req=5

Figure 7: Two models of paired TJ strands consisting of claudin-1, -2, and -4. (A) Homotypic adhesion of claudin-2 within paired strands constitutes aqueous pores with high conductance (*). (B) Heterotypic adhesion between claudin-1 and -2 constitutes aqueous pores with high conductance (*). See text for details.
Mentions: Detailed electrophysiological analyses suggested the existence of aqueous pores within the paired TJ strands (Diamond 1977; Claude 1978; Reuss 1992; Gumbiner 1993). Stevenson et al. 1988 then discussed the possibility that MDCK I and II cells have very different channel characteristics caused by differences in the probability of the hypothetical aqueous pores in TJ strands being open and closed. Therefore, it is reasonable to speculate that claudin-2 is involved in the formation of aqueous pores with high conductance within the paired TJ strands in MDCK II cells. It is possible that claudin-2 forms such pores through its homotypic adhesion within paired claudin-1/4–based TJ strands (Fig. 7 A). However, as we discussed previously (Tsukita and Furuse 2000), it is also possible that the weak heterotypic adhesion of claudin-2 with claudin-1 (or -4) results in the formation of aqueous pores with high conductance within the paired TJ strands (Fig. 7 B). Claudin-2 does not adhere strongly with claudin-1 in a heterotypic manner in L fibroblast transfectants (Furuse et al. 1999), but a homopolymer of claudin-1 makes a paired strand with a heteropolymer consisting of claudin-1 and -2 in L fibroblast transfectants (our unpublished data; see Tsukita and Furuse 2000). Therefore, aqueous pores with a high probability of being in the open state would be formed between claudin-1 and -2 when they are apposed within paired TJ strands (Fig. 7 B). In this connection, it is interesting to point out that the overexpression of claudin-3 into MDCK I cells as well as that of claudin-1 into Eph4 cells did not affect the barrier functions of TJs (Fig. 4B and Fig. C). As claudin-1 can adhere with claudin-3 (and probably with claudin-4) in a heterotypic manner (Furuse et al. 1999), aqueous pores with high conductance would not be formed in claudin-1– or -3–overexpressed TJ strands. Furthermore, these findings excluded the possibility that the introduction of claudin-2 affected the TJ barrier function due to the unbalance between the total amounts of claudins and other TJ components such as ZO-1 (McCarthy et al. 2000).

Bottom Line: Interestingly, the TER values of MDCK I clones stably expressing claudin-2 (dCL2-MDCK I) fell to the levels of MDCK II cells (>20-fold decrease).Similar results were obtained in mouse epithelial cells, Eph4.These findings indicated that the addition of claudin-2 markedly decreased the tightness of individual claudin-1/4-based TJ strands, leading to the speculation that the combination and mixing ratios of claudin species determine the barrier properties of individual TJ strands.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan.

ABSTRACT
There are two strains of MDCK cells, MDCK I and II. MDCK I cells show much higher transepithelial electric resistance (TER) than MDCK II cells, although they bear similar numbers of tight junction (TJ) strands. We examined the expression pattern of claudins, the major components of TJ strands, in these cells: claudin-1 and -4 were expressed both in MDCK I and II cells, whereas the expression of claudin-2 was restricted to MDCK II cells. The dog claudin-2 cDNA was then introduced into MDCK I cells to mimic the claudin expression pattern of MDCK II cells. Interestingly, the TER values of MDCK I clones stably expressing claudin-2 (dCL2-MDCK I) fell to the levels of MDCK II cells (>20-fold decrease). In contrast, when dog claudin-3 was introduced into MDCK I cells, no change was detected in their TER. Similar results were obtained in mouse epithelial cells, Eph4. Morphometric analyses identified no significant differences in the density of TJs or in the number of TJ strands between dCL2-MDCK I and control MDCK I cells. These findings indicated that the addition of claudin-2 markedly decreased the tightness of individual claudin-1/4-based TJ strands, leading to the speculation that the combination and mixing ratios of claudin species determine the barrier properties of individual TJ strands.

Show MeSH
Related in: MedlinePlus