Inducible overexpression of cingulin in stably transfected MDCK cells does not affect tight junction organization and gene expression

• Published in: Molecular membrane biology Vol. 25; no. 1; pp. 1 - 13
• Main Authors: Paschoud, Serge, Citi, Sandra
• Format: Journal Article
• Language: English
• Published: England Informa UK Ltd 2008; Taylor & Francis
• Subjects: Amino Acid Sequence; Animals; Cell Line; Cingulin; Dogs; Gene Expression Profiling; Gene Expression Regulation - physiology; MDCK; Membrane Proteins - biosynthesis; Membrane Proteins - genetics; microarray; Models, Biological; Molecular Sequence Data; occludin; Oligonucleotide Array Sequence Analysis; Protein Structure, Tertiary - physiology; RhoA; rhoA GTP-Binding Protein - genetics; rhoA GTP-Binding Protein - metabolism; tight junction; Tight Junctions - genetics; Tight Junctions - metabolism; ZO-1
• ISSN: 0968-7688; 1464-5203
• DOI: 10.1080/09687680701474009

Cingulin is a component of the cytoplasmic domain of vertebrate tight junctions (TJ). Mutation or down-regulation of cingulin in cultured cells results in changes in gene expression. Some of these changes are dependent on RhoA, whose activity is regulated by GEF-H1, which is inactivated by binding to cingulin at junctions. To gain further insights on the function of cingulin through dominant-negative effects, we cloned and sequenced canine cingulin, and developed stable MDCK cell lines where either full-length cingulin, or head or rod+tail domains were inducibly overexpressed. Surprisingly, analysis of these clones by immunoblotting, microarray, immunofluorescence, measurement of transepithelial resistance, and cell density showed that the overexpression of either full-length cingulin or its domains does not significantly affect TJ protein levels, gene expression, RhoA activity, cell density, doubling time, and the organization and function of TJ. These results suggest that compensatory mechanisms prevent dominant-negative effects in this model system, and that modulation of cellular functions by cingulin occurs within physiological protein levels.