USP10 Promotes Fibronectin Recycling, Secretion, and Organization

Area of Science:

• Cell Biology
• Biochemistry
• Ophthalmology

Background:

• Integrins are crucial for myofibroblast function, including pathological adhesion and TGFβ activation.
• Upregulation of deubiquitinase USP10 protects αv integrins from degradation after corneal wounding, leading to cell-surface accumulation.
• Integrins bind and internalize extracellular matrix (ECM) components like fibronectin (FN).

Purpose of the Study:

• To investigate if increased integrin and matrix recycling contributes to extracellular fibronectin accumulation in primary human corneal fibroblasts (HCFs).

Main Methods:

• Primary HCFs were transfected with USP10 cDNA or control cDNA.
• Quantified internalized and recycled fibronectin using ELISA and live cell confocal microscopy.
• Assessed integrin and fibronectin recycling using streptavidin-488 labeling.
• Blocked α5β1 and αv integrins to determine their role in fibronectin recycling.

Main Results:

• USP10 overexpression significantly increased α5β1 and αv integrin recycling (1.9-fold and 1.7-fold, respectively).
• Concomitant increase in biotinylated fibronectin internalization (2.1-fold) and recycling (1.7-2.2-fold) was observed.
• Blocking α5β1 and αv integrins markedly reduced fibronectin recycling, confirming integrin dependence.
• Established that extracellular fibronectin comprises approximately 1/3 recycled and 2/3 endogenously secreted FN.

Conclusions:

• Reduced integrin degradation and subsequent increase in integrin/fibronectin recycling represent a novel mechanism for ECM accumulation in corneal scar tissue.
• This finding offers new insights into the pathogenesis of corneal scarring following injury.