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Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands
11:31

Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands

Published on: May 30, 2017

The junctional proteins cingulin and paracingulin modulate the expression of tight junction protein genes through

Laurent Guillemot1, Domenica Spadaro, Sandra Citi

  • 1Department of Molecular Biology, University of Geneva, Geneva, Switzerland.

Plos One
|February 15, 2013
PubMed

Insights

Cingulin and paracingulin maintain expression of key tight junction proteins like claudin-2 by regulating the transcription factor GATA-4. Their absence unexpectedly decreases claudin-2 levels, revealing a complex regulatory mechanism in kidney cells.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Epithelial Biology

Background:

  • Cytoplasmic junctional proteins cingulin and paracingulin influence gene expression.
  • Depletion of cingulin or paracingulin in renal cells increases claudin-2 expression via Rho-dependent pathways.

Purpose of the Study:

  • Investigate the role of cingulin and paracingulin in regulating tight junction protein expression in MDCK cells.
  • Elucidate the mechanisms underlying the expression changes of claudin-2, ZO-3, and claudin-3 in double-knockdown cells.

Main Methods:

  • Generation and analysis of MDCK cell clones depleted of both cingulin and paracingulin (double-KD).
  • Assessment of claudin-2, ZO-3, and claudin-3 expression levels.
  • Measurement of RhoA activity.
  • Evaluation of transcription factor GATA-4 levels and function.
  • Rescue experiments involving GATA-4 overexpression and RhoA inhibition.

Main Results:

  • Depletion of both cingulin and paracingulin unexpectedly decreased claudin-2, ZO-3, and claudin-3 expression.
  • RhoA activity remained elevated in double-KD cells.
  • Decreased TJ protein expression correlated with reduced GATA-4 levels.
  • GATA-4 overexpression rescued TJ protein expression, while RhoA inhibition did not.

Conclusions:

  • GATA-4 is essential for the expression of claudin-2 and other tight junction proteins in MDCK cells.
  • Cingulin or paracingulin is required for maintaining GATA-4 expression.
  • Cingulin and paracingulin redundantly control TJ protein expression via distinct GATA-4 and RhoA pathways.

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