TY - JOUR
T1 - Induction of tight junctions in human connexin 32 (hCx32)-transfected mouse hepatocytes
T2 - Connexin 32 interacts with occludin
AU - Kojima, Takashi
AU - Sawada, Norimasa
AU - Chiba, Hideki
AU - Kokai, Yasuo
AU - Yamamoto, Masao
AU - Urban, Marcia
AU - Lee, Gang Hong
AU - Hertzberg, Elliot L.
AU - Mochizuki, Yohichi
AU - Spray, David C.
N1 - Funding Information:
We thank Ms. H. Duffy and Ms. M. Mia for technical support and Ms. F. Andrade for secretarial support. This work was supported in part by NIH Grant DK41918, Grants-in-Aid from the Ministry of Education, Culture, Sports, and Science, and the Ministry of Welfare of Japan.
PY - 1999/12/9
Y1 - 1999/12/9
N2 - Small gap junction plaques are associated with tight junction strands in some cell types including hepatocytes and it is thought that they may be closely related to tight junctions and the establishment of cell polarity. In order to examine roles of gap junctions in regulating expression and structure of tight junctions, we transfected human Cx32 cDNA into immortalized mouse hepatocytes (CHST8 cells) which lack endogenous Cx32 and Cx26. Immunocytochemistry revealed that endogenous integral tight junction protein occludin was strongly localized and was colocalized with Cx32 at cell borders in transfectants, whereas neither was detected in parental cells. In Northern blots, mRNAs encoding occludin and the other integral tight junction proteins, claudin-1 and -2, were induced in the transfectants compared to parental cells. In Western blots, occludin protein was increased in the transfectants compared to parental cells, and binding of occludin to Cx32 protein was demonstrated by immunoprecipitation. In freeze fracture of the transfectants, tight junction strands were more numerous and complex compared to parental cells, and small gap junction plaques appeared within induced tight junction strands. Nevertheless, no change in barrier function of tight junctions was observed. These results indicate that in hepatocytes, gap junction, and tight junction expression are closely coordinated, and that Cx32 may play a role in regulating occludin expression.
AB - Small gap junction plaques are associated with tight junction strands in some cell types including hepatocytes and it is thought that they may be closely related to tight junctions and the establishment of cell polarity. In order to examine roles of gap junctions in regulating expression and structure of tight junctions, we transfected human Cx32 cDNA into immortalized mouse hepatocytes (CHST8 cells) which lack endogenous Cx32 and Cx26. Immunocytochemistry revealed that endogenous integral tight junction protein occludin was strongly localized and was colocalized with Cx32 at cell borders in transfectants, whereas neither was detected in parental cells. In Northern blots, mRNAs encoding occludin and the other integral tight junction proteins, claudin-1 and -2, were induced in the transfectants compared to parental cells. In Western blots, occludin protein was increased in the transfectants compared to parental cells, and binding of occludin to Cx32 protein was demonstrated by immunoprecipitation. In freeze fracture of the transfectants, tight junction strands were more numerous and complex compared to parental cells, and small gap junction plaques appeared within induced tight junction strands. Nevertheless, no change in barrier function of tight junctions was observed. These results indicate that in hepatocytes, gap junction, and tight junction expression are closely coordinated, and that Cx32 may play a role in regulating occludin expression.
KW - CHST8 cells
KW - Claudin-1 and -2
KW - Gap junction
KW - ZO-1
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U2 - 10.1006/bbrc.1999.1778
DO - 10.1006/bbrc.1999.1778
M3 - Article
C2 - 10581193
AN - SCOPUS:18744431114
SN - 0006-291X
VL - 266
SP - 222
EP - 229
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -