CLDN3
CLDN3: A Critical Gene in Maintaining Epithelial Barrier Integrity
Description
CLDN3 (claudin-3) is a transmembrane protein that plays a vital role in forming tight junctions between epithelial cells. Tight junctions are specialized structures that seal the gaps between adjacent cells, creating a barrier that prevents the leakage of fluids and molecules across the epithelium. CLDN3 is one of the major claudin proteins expressed in the epithelial cells of various organs, including the intestines, kidneys, and lungs.
Structure and Function
CLDN3 is a tetraspan transmembrane protein with four transmembrane domains and two extracellular loops. Its extracellular domains interact with CLDN3 molecules on neighboring cells, forming the primary strands of tight junctions. These strands are further stabilized by additional proteins, such as occludin and junctional adhesion molecules (JAMs).
Together, tight junctions formed by CLDN3 and other proteins create a selectively permeable barrier that controls the movement of ions, water, and small molecules across the epithelium. This barrier is essential for maintaining tissue homeostasis, ion balance, and preventing the entry of harmful substances into the body.
Associated Diseases
Mutations or alterations in CLDN3 expression have been linked to several diseases, including:
- Inflammatory bowel disease (IBD): CLDN3 deficiency or dysfunction disrupts the intestinal epithelial barrier, leading to increased intestinal permeability and inflammation.
- Nephrotic syndrome: Mutations in CLDN3 can cause a rare form of nephrotic syndrome called steroid-resistant nephrotic syndrome (SRNS).
- Lung diseases: Reduced CLDN3 expression has been associated with chronic obstructive pulmonary disease (COPD) and asthma.
- Cancer: CLDN3 downregulation or loss of function has been observed in several types of cancer, including breast cancer, colorectal cancer, and lung cancer.
Did you Know ?
According to the National Institutes of Health (NIH), mutations in CLDN3 account for approximately 10% of cases of steroid-resistant nephrotic syndrome in children.
