Specific interaction between lens MIP/Aquaporin-0 and two members of the gamma-crystallin family

• Published in: Molecular vision 2005-01, Vol.11, p.76-87
• Main Authors: Fan, Jianguo, Fariss, Robert N, Purkiss, Andrew G, Slingsby, Christine, Sandilands, Aileen, Quinlan, Roy, Wistow, Graeme, Chepelinsky, Ana B
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Aquaporins; Cell Line; Epithelial Cells - metabolism; Eye Proteins - metabolism; gamma-Crystallins - metabolism; Gene Expression; Genetic Vectors; Green Fluorescent Proteins - metabolism; Kidney - cytology; Kidney - metabolism; Luminescent Proteins - metabolism; Membrane Glycoproteins - metabolism; Microscopy, Confocal; Molecular Sequence Data; Plasmids; Protein Binding; Proto-Oncogene Proteins c-myc - metabolism; Rabbits; Red Fluorescent Protein; Transfection
• ISSN: 1090-0535

Major Intrinsic Protein (MIP)/Aquaporin 0 is required for lens transparency and is specifically expressed in lens fiber cell membranes. We have demonstrated previously that in the rat lens MIP interacts specifically with gammaE-crystallin, resulting in its recruitment to the plasma membrane. Our goal was to examine the interaction or lack of interaction between MIP and all members of the gamma-crystallin family and to provide evidence for a physiological role these interactions may play in gamma-crystallin or MIP function. Full length MIP was expressed as untagged, enhanced green fluorescent protein (EGFP) tagged, or myc tagged proteins. Members of the gamma-crystallin family were expressed as red fluorescent protein (HcRed) tagged proteins in the rabbit kidney epithelial cell line RK13. Co-localization of tagged proteins was analyzed by confocal fluorescence microscopy. Confocal fluorescence microscopy demonstrated that gammaE- and gammaF-crystallin co-localize specifically with full length MIP in mammalian cells while other gamma-crystallins, including gammaA-, gammaB-, gammaC-, gammaD-, and gammaS-crystallin do not. As a result of this interaction, either gammaE- or gammaF-crystallin was recruited to the plasma membrane from the cytoplasm. MIP does not interact with the Elo mutant of gammaE-crystallin, which has been linked to a dominant cataract phenotype in mice. These experiments demonstrate that MIP interacts selectively with gammaE- and gammaF-crystallin, and not with other gamma-crystallins. This raises the possibility of MIP playing a structural role in the organization of gamma-crystallins in rodent lens fibers and/or that gammaE- and gammaF-crystallin may have a specific role in MIP function in the rodent lens.