CLDN7

CLDN7 is a tight junction component that maintains intestinal epithelial barrier integrity, with its loss disrupting paracellular permeability and predisposing to inflammation and tumorigenesis (PMID:34026335). Conditional intestinal knockout compromises tight junction integrity, raises intercellular permeability, and promotes susceptibility to experimental colitis and colitis-associated carcinogenesis with activation of Wnt/β-catenin signaling (PMID:34026335); barrier loss also reshapes gut microbiota composition, and this dysbiosis is itself a driver of the resulting inflammation, as antibiotic depletion attenuates and microbiota transfer restores colitis severity in knockout mice (PMID:39004000). CLDN7 transcription is reinforced epigenetically through ACSS2-mediated histone H4K12 crotonylation at the CLDN7 locus, a pathway augmented by crotonate that fortifies the barrier (PMID:40650658). In cancer contexts CLDN7 instead behaves oncogenically: it is a direct target of the tumor-suppressive miR-1193 in cervical cancer (PMID:32547067), its overexpression drives proliferation, invasion, and epithelial-mesenchymal transition in gastric cancer (PMID:29788731), and in cisplatin-resistant ovarian cancer cells it promotes autophagy/mitophagy, migration, invasion, and chemoresistance (PMID:42057112).

1. 2021 High

   Established that intestinal CLDN7 is required for tight junction barrier integrity and that its loss links barrier failure to inflammation and Wnt-driven carcinogenesis.

   Evidence Inducible intestinal conditional knockout mice with AOM/DSS colitis/CAC, FITC-dextran permeability, and β-catenin/TCF/LEF immunostaining

   PMID:34026335

   Open questions at the time

   • Does not resolve whether Wnt activation is a direct consequence of CLDN7 loss or secondary to barrier breach
   • No structural or claudin-channel mechanism for the permeability defect
2. 2024 Medium

   Placed CLDN7 upstream of microbiota-mediated inflammation, showing that barrier loss-induced dysbiosis is causally required for the inflammatory phenotype.

   Evidence Conditional KO mice with antibiotic depletion, co-housing microbiota transfer, 16S sequencing, and inflammatory/AMP qRT-PCR

   PMID:39004000

   Open questions at the time

   • Specific bacterial taxa and inflammatory signaling axis not defined
   • Co-housing only partially restores inflammation, leaving microbiota-independent contributions unquantified
3. 2025 Medium

   Identified an upstream epigenetic mechanism controlling CLDN7 expression via histone crotonylation, connecting a metabolic acyl-CoA pathway to barrier maintenance.

   Evidence Genetic/pharmacological ACSS2 inhibition, H4K12cr chromatin measurement at CLDN7 locus, crotonate rescue, and colitis model

   PMID:40650658

   Open questions at the time

   • Whether H4K12cr acts directly versus through intermediary factors not resolved
   • Single lab; no independent confirmation of the ACSS2-CLDN7 axis
4. 2018 Medium

   Revealed a context-dependent oncogenic role, with CLDN7 overexpression driving proliferation, invasion, and EMT in gastric cancer.

   Evidence Gain- and loss-of-function in gastric cancer cell lines with proliferation, invasion, and EMT marker assays

   PMID:29788731

   Open questions at the time

   • Molecular mechanism linking CLDN7 to EMT not defined
   • Cell-line only; no in vivo validation
5. 2020 Medium

   Defined a post-transcriptional control point, establishing CLDN7 as a direct miR-1193 target mediating tumor-suppressive effects in cervical cancer.

   Evidence 3'UTR luciferase reporter, qRT-PCR/Western, proliferation/migration/invasion assays, and CLDN7 rescue in miR-1193-overexpressing cells

   PMID:32547067

   Open questions at the time

   • Does not explain how CLDN7 mechanistically drives the malignant phenotype downstream
   • Single lab; cell-line only
6. 2026 Medium

   Connected CLDN7 to chemoresistance, showing it promotes cisplatin resistance through regulation of autophagy/mitophagy in ovarian cancer.

   Evidence siRNA knockdown in SKOV3/DDP cells, LC3/MitoTracker immunofluorescence, mitophagy marker Western blot, cisplatin sensitivity assays, and xenografts

   PMID:42057112

   Open questions at the time

   • Molecular link between CLDN7 and the mitophagy machinery not identified
   • Whether this reflects a tight-junction-dependent or independent function is unknown

• How CLDN7 switches between barrier-protective (tumor-suppressive) and oncogenic functions across tissue contexts remains unresolved.
• No unifying mechanism reconciling intestinal barrier protection with pro-invasive cancer roles
• Direct claudin junction partners and channel properties not characterized in this corpus