Epithelial-mesenchymal status influences how cells deposit fibrillin microfibrils

Area of Science:

• Cell Biology
• Extracellular Matrix Biology
• Tissue Engineering

Background:

• Cellular phenotype, characterized by epithelial or mesenchymal markers, influences cell behavior and function.
• Extracellular matrix (ECM) deposition is crucial for tissue structure and integrity.
• The molecular mechanisms governing ECM assembly can vary depending on cell state.

Purpose of the Study:

• To investigate how epithelial-mesenchymal status affects extracellular matrix deposition.
• To identify the specific molecular components and pathways involved in fibrillin microfibril assembly in different cellular phenotypes.
• To understand the role of transforming growth factor beta (TGFβ) in modulating these processes.

Main Methods:

• Comparative analysis of extracellular matrix deposition in retinal pigmented epithelial (RPE) cells with distinct epithelial and mesenchymal markers.
• Assessment of the requirement for specific proteins (e.g., syndecan-4, fibronectin, β-catenin, zona occludens (ZO)-1, protein kinase C α (PKCα)) in microfibril assembly.
• Investigation of the role of integrins (α5β1, α8β1), actomyosin tension, and heparan sulfate biosynthesis.
• Utilizing TGFβ stimulation and cadherin interaction blocking to modulate cellular phenotype and ECM deposition.

Main Results:

• Epithelial RPE cells required syndecan-4, but not fibronectin or PKCα, for microfibril and perlecan assembly.
• Mesenchymal RPE cells required fibronectin and PKCα, but not syndecan-4, for microfibril assembly.
• Integrins α5β1 and/or α8β1, actomyosin tension, and heparan sulfate biosynthesis were common requirements for microfibril deposition.
• TGFβ altered gene expression and overcame syndecan-4 dependency in epithelial RPE cells; blocking cadherin interactions disrupted microfibril deposition.
• Renal podocytes, with a transitional phenotype, required both syndecan-4 and fibronectin for microfibril deposition.

Conclusions:

• Epithelial-mesenchymal status is a key determinant of extracellular matrix deposition pathways.
• Distinct molecular mechanisms govern fibrillin microfibril assembly in epithelial versus mesenchymal cells.
• Targeting these pathways could offer new strategies for tissue regeneration and disease treatment.