Heteromeric gap junction channels in rat hepatocytes in which the expression of connexin26 is induced.
More than one isotype of the gap junction channel-forming protein subunit, known as connexin, are synthesized in most mammalian cells. Using a modified primary cell culture of rat hepatocytes, in which both connexin32 and connexin26 were expressed in a comparable degree, the molecular composition of connexin subtypes in a gap junction channel (i.e., homomeric or heteromeric) was studied. A fluorescent dye Lucifer Yellow-coupling among hepatocytes was blocked in the presence of 20 microM beta-glycyrrhetinic acid, and antagonist for the gap junction channel. Similarly, either one of the antibodies raised against connexin32 or connexin26 completely inhibited dye-coupling activity among hepatocytes. In addition, we studied the dye-coupling properties at different extracellular pHs in two primary rat hepatocytes: one in which connexin26 was induced, and the other which expresses connexin32 as a major gap junction channel protein. The dye-coupling among the connexin26-induced hepatocytes was more sensitive to lowering pHs than among the normal hepatocytes, in which less than 5% of gap junction protein is connexin26. Taken together, data obtained in our study strongly suggest that the connexins (32 & 26) are assembled to form heteromeric, rather than homomeric, gap junction channels in the connexin226-induced rat hepatocytes.
Lee
M J
MJ
Institute of Biotechnology, Yeungam University, Kyongsan, Korea.
Rhee
S K
SK
D000287:Administration, Topical; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D000072259:Connexin 26; D017630:Connexins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D019281:Dimerization; D005456:Fluorescent Dyes; D017629:Gap Junctions / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D005786:Gene Expression Regulation; D006034:Glycyrrhetinic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007546:Isoquinolines; D008099:Liver / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D000097002:Gap Junction beta-1 Protein
D000893:Anti-Inflammatory Agents; D000906:Antibodies; D000072259:Connexin 26; D017630:Connexins; D005456:Fluorescent Dyes; D006034:Glycyrrhetinic Acid; D007546:Isoquinolines; D000097002:Gap Junction beta-1 Protein; C017475:lucifer yellow