Related Experiment Video
Updated: Jun 22, 2026
11:17
Sensing of Barrier Tissue Disruption with an Organic Electrochemical Transistor
Published on: February 10, 2014
Tricellulin forms a barrier to macromolecules in tricellular tight junctions without affecting ion permeability
Susanne M Krug1, Salah Amasheh, Jan F Richter
1Institute of Clinical Physiology, Charité, Freie Universität, Berlin, Germany.
Molecular Biology of the Cell
|June 19, 2009
Summary
Tricellulin protein enhances cell barrier function. At higher expression, it acts as a barrier for macromolecules in tricellular tight junctions and all solutes in bicellular tight junctions.
Area of Science:
- Cell biology
- Biophysics
Background:
- Tricellulin is a protein found in tight junctions, specifically at the meeting points of three cells (tricellular tight junctions, tTJs) and two cells (bicellular tight junctions, bTJs).
- Understanding the distinct roles of tricellulin in tTJs versus bTJs is crucial for elucidating its contribution to epithelial barrier integrity.
Purpose of the Study:
- To investigate the specific barrier functions of tricellulin in both tTJs and bTJs.
- To determine how varying expression levels of tricellulin impact cellular permeability and tight junction ultrastructure.
Main Methods:
- TRIC-a (tricellulin) was expressed in MDCK II cells, either globally or restricted to tTJs.
- Measurements included paracellular electrical resistance and permeability assays for ions and macromolecules.
- Tight junction ultrastructure was analyzed using electron microscopy.
Main Results:
- Global tricellulin expression increased electrical resistance and reduced permeability to ions and larger solutes, improving bicellular tight junction (bTJ) integrity.
- In tTJs, tricellulin minimized macromolecule permeability without affecting ion permeability, while ultrastructure remained unchanged.
- The tTJ central tube's properties explain this selective barrier function.
Conclusions:
- At low expression, the tTJ central tube allows macromolecule passage.
- Higher tricellulin expression establishes a barrier in tTJs effective for macromolecules and in bTJs for all solute sizes.
- Tricellulin plays distinct, dose-dependent roles in regulating permeability at bTJs and tTJs.
Related Concept Videos
01:29Tight Junctions
Tight junctions are molecular seals between cells that prevent the leaking of fluids, ions, and other small solutes across cavities and compartments in multicellular organisms. They are mainly composed of claudin and occludin transmembrane proteins, and other proteins such as tricellulin and JAM (junctional adhesion molecule). All these proteins are 4-pass transmembrane proteins, except JAM, which is a single-pass transmembrane protein belonging to the immunoglobulin superfamily. The...
01:14Overview of Cell-Cell Junctions
The complex three-dimensional arrangement of cells in any multicellular organism is defined and maintained by interactions of cells with each other and the extracellular matrix. Cell-cell junctions are specialized structures where the multi-protein complexes on one cell interact with the multi-protein complexes on another cell. These cell junctions are classified into three main types based on their function — occluding, anchoring, and gap junctions.
Occluding or Tight Junctions
Tight...
Occluding or Tight Junctions
Tight...
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...
01:24Adherens Junctions
Strong contact points between adjacent cells anchor them to each other, forming tissues. Such anchoring junctions are of two types – adherens junctions and desmosomes. Adherens junctions are abundant in tissues such as epithelium and endothelium, forming a continuous zone of adhesion called the adhesion belt. In other tissues, such as heart muscle, they appear as clusters, linking the cells to produce coordinated heart muscle contraction.
Adherens Junctions are Dynamic
The endothelial cells...
Adherens Junctions are Dynamic
The endothelial cells...
01:26Tension Response at Adherens Junctions
The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin homology) domains...
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin homology) domains...
00:59Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...