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SMAD4-Dependent Signaling Pathway Involves in the Pathogenesis of TGFBR2-Related CE-like Phenotype

Yen-Chiao Wang1,2,3, Olivia Betty Zolnik3, Chia-Yang Liu1,3

  • 1Edith Crawley Vision Research Center, Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.

Cells
|April 12, 2024
PubMed

Insights

The SMAD4 signaling pathway is crucial in corneal ectasia development. Disrupting SMAD4 in mice causes a corneal ectasia-like phenotype, similar to TGFBR2 pathway disturbances.

Area of Science:

  • Ophthalmology
  • Molecular Biology
  • Genetics

Background:

  • Disturbances in the Transforming Growth Factor beta (TGFB) signaling pathway, specifically via its Type-2 Receptor (TGFBR2), have been linked to a Corneal Ectasia (CE)-like phenotype.
  • Previous research suggests a potential role for TGFBR2 in CE pathogenesis.

Purpose of the Study:

  • To investigate the involvement of the SMAD4-dependent signaling pathway in the pathogenesis of TGFBR2-related Corneal Ectasia.
  • To determine if SMAD4 plays a role in the development of CE-like phenotypes.

Main Methods:

  • Conditional knockout of SMAD4 in mouse keratocytes using a novel triple transgenic mouse model (Kera-Smad4).
  • Administration of doxycycline (Dox) to induce SMAD4 knockout.
  • Analysis of corneal structure and phenotype using Optical Coherence Tomography (OCT), H&E staining, Masson's Trichrome staining, and immunostaining for K12 and PCNA.

Main Results:

  • Mice with SMAD4 knockout in keratocytes (Kera-Smad4) exhibited a Corneal Ectasia-like phenotype, characterized by thinner Central Corneal Thickness (CCT) and altered corneal radius and anterior chamber dimensions.
  • Histological analysis revealed decreased collagen formation in the corneal stroma of Kera-Smad4 mice, mirroring findings in Tgfbr2 models.
  • Immunostaining confirmed normal corneal epithelium (K12) but enhanced proliferation (PCNA) in Kera-Smad4 corneas, consistent with Tgfbr2 phenotypes.

Conclusions:

  • The SMAD4-dependent signaling pathway is implicated in the pathogenesis of Corneal Ectasia.
  • SMAD4 plays a critical role in maintaining corneal integrity and collagen production.
  • The findings suggest that SMAD4 is a key mediator in the TGFBR2-related CE-like phenotype.
Keywords:
Corneal EctasiaSMAD4TGFBkeratoconus

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