Related Experiment Video
Updated: Jun 24, 2026
Preparation and Culture of Rat Lens Epithelial Explants for Studying Terminal Differentiation
Published on: September 22, 2009
FGF-regulated BMP signaling is required for eyelid closure and to specify conjunctival epithelial cell fate
Jie Huang1, Lisa K Dattilo, Ramya Rajagopal
1Department of Ophthalmology and Visual Sciences, Washington University, St Louis, MO 63130, USA.
Abstract:
There are conflicting reports about whether BMP signaling is required for eyelid closure during fetal development. This question was addressed using mice deficient in BMP or TGFbeta signaling in prospective eyelid and conjunctival epithelial cells. Genes encoding two type I BMP receptors, the type II TGFbeta receptor, two BMP- or two TGFbeta-activated R-Smads or the co-Smad Smad4 were deleted from the ocular surface ectoderm using Cre recombinase. Only mice with deletion of components of the BMP pathway had an 'eyelid open at birth' phenotype. Mice lacking Fgf10 or Fgfr2 also have open eyelids at birth. To better understand the pathways that regulate BMP expression and function during eyelid development, we localized BMPs and BMP signaling intermediates in Fgfr2 and Smad4 conditional knockout (CKO) mice. We found that Fgfr2 was required for the expression of Bmp4, the normal distribution of Shh signaling and for preserving the differentiation of the conjunctival epithelium. FGF signaling also promoted the expression of the Wnt antagonist Sfrp1 and suppressed Wnt signaling in the prospective eyelid epithelial cells, independently of BMP function. Transcripts encoding Foxc1 and Foxc2, which were previously shown to be necessary for eyelid closure, were not detectable in Smad4(CKO) animals. c-Jun, another key regulator of eyelid closure, was present and phosphorylated in eyelid periderm cells at the time of fusion, but failed to translocate to the nucleus in the absence of BMP function. Smad4(CKO) mice also showed premature differentiation of the conjunctival epithelium, conjunctival hyperplasia and the acquisition of epidermal characteristics, including formation of an ectopic row of hair follicles in place of the Meibomian glands. A second row of eyelashes is a feature of human lymphedema-distichiasis syndrome, which is associated with mutations in FOXC2.
Insights
Bone morphogenetic protein (BMP) signaling is essential for proper eyelid closure in fetal development. Disrupting BMP pathways in mice leads to an
Area of Science:
- Developmental Biology
- Molecular Biology
- Ophthalmology
Background:
- Conflicting reports exist regarding the necessity of Bone Morphogenetic Protein (BMP) signaling for fetal eyelid closure.
- Understanding the molecular pathways regulating eyelid development is crucial for addressing congenital abnormalities.
- Previous studies highlight the roles of Fibroblast Growth Factor (FGF) and Wingless-related integration site (Wnt) signaling in development.
Purpose of the Study:
- To elucidate the role of BMP signaling in mouse eyelid closure during fetal development.
- To investigate the interplay between BMP, FGF, and Wnt signaling pathways in ocular surface development.
- To identify key regulatory genes and their functions in eyelid fusion.
Main Methods:
- Conditional knockout (CKO) mouse models were generated using Cre-lox technology to delete genes for BMP receptors, TGF-beta receptor, R-Smads, Smad4, Fgf10, and Fgfr2 in ocular surface ectoderm.
- Phenotypic analysis of resulting mice, including assessment of eyelid opening at birth.
- Localization of BMPs and signaling intermediates (Shh, Foxc1, Foxc2, c-Jun) in CKO mice.
- Analysis of conjunctival epithelium differentiation and associated epidermal characteristics.
Main Results:
- Deletion of BMP pathway components resulted in an 'eyelid open at birth' phenotype, confirming BMP's requirement for eyelid closure.
- FGF signaling (via Fgfr2) is necessary for Bmp4 expression, Shh distribution, and conjunctival epithelium differentiation.
- Loss of BMP signaling (Smad4 CKO) led to premature conjunctival differentiation, hyperplasia, epidermal changes, and absence of Foxc1/Foxc2 transcripts, impacting c-Jun function.
Conclusions:
- BMP signaling is indispensable for successful fetal eyelid closure in mice.
- FGF signaling acts upstream of BMP signaling, regulating its expression and influencing other developmental pathways like Shh and Wnt.
- Disruption of BMP signaling causes significant developmental defects in the ocular surface, including conjunctival abnormalities and altered expression of key transcription factors.
More Related Videos
05:15Isolation of Intact Eyeball to Obtain Integral Ocular Surface Tissue for Histological Examination and Immunohistochemistry
Published on: October 20, 2019
07:26Isolation of Whole Cell Protein Lysates from Mouse Facial Processes and Cultured Palatal Mesenchyme Cells for Phosphoprotein Analysis
Published on: April 1, 2022
Related Concept Videos
01:16TGF - β Signaling Pathway
01:51Determination
03:14Notch Signaling Pathway
The Notch gene came into the limelight in 1914 after the discovery that its mutation in Drosophila melanogaster leads to a serrated (or "notched") wing margin phenotype. It was not until 1985...
01:24Regulation of Angiogenesis and Blood Supply
01:16Cell Motility through Blebbing
Blebbing Through the Matrix
In multicellular...
02:33Hedgehog Signaling Pathway