CLDN7

CLDN7 Full Name

claudin 7

CLDN7 Introduction

CLDN7, officially known as Claudin 7, is a member of the claudin superfamily, which comprises over 20 integral membrane proteins essential for the formation of tight junctions (TJs) in epithelial and endothelial tissues. Unlike some claudins that are primarily barrier-sealers, CLDN7 exhibits a hybrid functional profile, participating in both paracellular sealing and selective ion permeation depending on its binding partners. Structurally, it features four transmembrane domains, two extracellular loops, and a short cytoplasmic C-terminal tail containing a PDZ-binding motif. This motif is critical for anchoring the protein to intracellular scaffolding molecules such as ZO-1 and ZO-2, thereby integrating CLDN7 into the broader cytoskeletal network that maintains tissue cohesion and polarity.CLDN7 is widely but not ubiquitously expressed, with highest abundance in the kidney, lung, gastrointestinal tract, and sweat glands. Notably, its expression is developmentally regulated; in fetal tissues, CLDN7 levels are often lower compared to adult counterparts, suggesting a role in maturing epithelial barrier function. In the kidney, CLDN7 is predominantly localized to the distal convoluted tubule and collecting duct, where it contributes to cation selectivity. In the epidermis, it is uniquely concentrated in the granular layer, implicating its involvement in stratum corneum barrier formation. This restricted yet strategic distribution highlights that CLDN7 is not merely a housekeeping junctional protein but a tissue-specific modulator of epithelial physiology.

Figure1. Claudin-7 deficiency induces metabolic reprogramming of neutrophils in the colorectal cancer microenvironment.(Liang X, Yuan D, Zhao S, et al. 2025)

Molecular Interactions and Heteromeric Complexes
A defining feature of CLDN7 is its propensity to form heteromeric cis-interactions with other claudin family members, particularly CLDN1, CLDN3, and CLDN4. These pairings are not random; they dictate the charge selectivity and pore size of the paracellular pathway. For example, co-expression of CLDN7 with CLDN4 in renal epithelia enhances Na⁺ selectivity, whereas its interaction with CLDN1 in intestinal cells promotes tighter barrier properties against small solutes. Additionally, CLDN7 can trans-interact with claudins on adjacent cells to form intercellular strands. The PDZ-binding domain at its C-terminus also mediates recruitment of signaling molecules like EPB41L5 (erythrocyte membrane protein band 4.1-like 5), linking junctional complexes to Rho GTPase pathways, thereby influencing cell migration and proliferation beyond simple adhesion.

Physiological Roles Beyond Barrier Function
While CLDN7 is traditionally viewed through the lens of tight junction integrity, emerging evidence assigns it broader physiological tasks. In renal proximal tubules, it participates in magnesium homeostasis by modulating the paracellular flux of divalent cations. In the pulmonary alveolar epithelium, CLDN7 expression correlates with surfactant production and fluid clearance, suggesting a role in respiratory distress responses. Furthermore, CLDN7 has been detected in exosomes and at basolateral membranes under certain conditions, indicating that its localization is not strictly apical-junctional. This plasticity implies that CLDN7 may act as a sensor of extracellular stimuli, such as osmotic stress or inflammatory cytokines, dynamically altering junctional permeability to protect epithelial monolayers from acute injury.

Alternate Names for CLDN7

CLDN7; claudin 7; CLDN-7; CEPTRL2; CPETRL2; Hs.84359; claudin-1; claudin-7; clostridium perfringens enterotoxin receptor-like 2;

• 1.Liang X, Yuan D, Zhao S, et al. Claudin-7 deficiency induces metabolic reprogramming of neutrophils in the colorectal cancer microenvironment. Cell Death & Disease, 2025, 16(1): 728.