Related Experiment Video

Updated: Jun 9, 2026

Modeling Cataract Surgery in Mice
05:19

Modeling Cataract Surgery in Mice

Published on: December 1, 2023

Inactivation of Smad4 leads to impaired ocular development and cataract formation

Ying Liu1, Kirio Kawai, Shabnam Khashabi

  • 1Department of Ophthalmology and Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. yingliu@doheny.org

Biochemical and Biophysical Research Communications
|August 26, 2010
PubMed
Abstract

Insights

Smad4 is crucial for eye development. Its inactivation caused severe defects in the lens, cornea, eyelids, and retina, highlighting its essential role in visual system formation.

Area of Science:

  • Developmental Biology
  • Ophthalmology
  • Molecular Biology

Background:

  • Transforming Growth Factor-beta (TGFβ) superfamily signaling is vital for embryonic development and maintaining tissue homeostasis.
  • Smad4 acts as a central intracellular mediator in TGFβ signaling pathways, forming complexes with other Smad proteins to regulate gene transcription.
  • The specific roles of Smad4 in different compartments of the developing visual system remain incompletely understood.

Purpose of the Study:

  • To investigate the functional significance of Smad4 in the development and maintenance of various ocular structures.
  • To elucidate the consequences of Smad4 inactivation on the lens, cornea, eyelids, and retina.

Main Methods:

  • Conditional inactivation of the Smad4 gene in ocular tissues using a Pax6 promoter-driven Cre transgenic system.
  • Analysis of morphological and cellular changes through standard histological and molecular techniques.

Main Results:

  • Smad4 inactivation in the lens resulted in microphthalmia, cataract formation, and abnormal adhesion between the retina, lens, iris, and cornea.
  • Disruption of Smad4 in eyelid ectoderm and cornea led to impaired eyelid fusion and defects in corneal epithelium and stroma development.

Conclusions:

  • Smad4 is indispensable for the proper development and ongoing maintenance of the lens.
  • Smad4 plays a critical role in the normal morphogenesis of the cornea, eyelids, and retina.

Related Concept Videos

TGF - β Signaling Pathway01:16

TGF - β Signaling Pathway

The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
X-Inactivation01:58

X-Inactivation

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.
Hedgehog Signaling Pathway02:33

Hedgehog Signaling Pathway

The Hedgehog gene (Hh) was first discovered due to its control of the growth of disorganized, hair-like bristles phenotype in Drosophila, much like hedgehog spines. Hh plays a crucial role in the development of organs and the maintenance of homeostasis in both invertebrates and vertebrates. However, while Drosophila has only one Hh protein, mammals have multiple functional Hedgehog proteins - Sonic (Shh), Desert (Dhh), and Indian Hedgehog (Ihh). All of these homologous proteins have adapted to...
The Retinoblastoma Gene01:20

The Retinoblastoma Gene

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
Photoreceptors and Visual Pathways01:22

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...