Claudin-3 (CLDN3)

Claudin-3 is a transmembrane tight junction protein primarily responsible for forming and maintaining tight junctions in epithelial and endothelial cells[1][3][5][7]. Its structure includes four transmembrane domains, two extracellular loops, and PDZ-binding motifs that interact with other tight junction-associated proteins such as ZO-1, ZO-2, and MUPP1[3][6]. Claudin-3 regulates paracellular permeability, cell polarity, and tissue homeostasis. It is highly expressed in various tissues including gastrointestinal tract, liver, urinary tract, and choroid plexus[1][5][6]. Dysregulation of Claudin-3 has been linked to multiple diseases, most notably cancer (as it is often overexpressed and associated with invasion, metastasis, and loss of cell polarity[3]), gallstone formation (through its role in hepatic ion homeostasis[4]), and barrier dysfunctions (such as altered blood-brain or urothelial permeability)[3][6]. Claudin-3 is actively investigated as a therapeutic and diagnostic target in oncology because of its abnormal expression profile in various tumors; strategies include antibody-drug conjugates and peptide toxins aiming to selectively ablate Claudin-3-high tumor cells[3][1]. However, systemic targeting poses safety risks as Claudin-3 is important in normal tissue barrier integrity. The molecule is also used as a biomarker for tumor subtyping, patient selection, and monitoring barrier function in research and clinical diagnostics[3][6].

Other names

Claudin 3CLDN3Tight junction protein 3RVP-1

Barrier disruption (tumor ablation by targeting Claudin-3 overexpressing cells), Modulation of tight junction integrity and permeability