Endogenous expression of Notch pathway molecules in human trabecular meshwork cells

Area of Science:

• Ocular biology
• Cellular mechanobiology
• Glaucoma research

Background:

• Trabecular meshwork (TM) cells respond to physical forces via mechanotransduction.
• Previous studies explored TGF-β, Wnt, and YAP/TAZ pathways in TM cells under mechanical stress.
• The role of Notch signaling in TM cell mechanotransduction remained uninvestigated.

Purpose of the Study:

• To investigate the role of Notch signaling in trabecular meshwork cells.
• To compare endogenous Notch pathway molecule expression in glaucomatous (GTM) vs. non-glaucomatous (NTM) TM cells.
• To assess Notch signaling in response to mechanical cues like substrate stiffness and cyclical strain.

Main Methods:

• Utilized primary GTM and NTM cells, including those from high (HF) and low (LF) flow regions.
• Exposed cells to tissue culture plastic, cyclical strain (6h, 24h), or hydrogels of varying rigidity (3 kPa, 80 kPa).
• Quantified Notch pathway gene expression via qRT-PCR and measured phagocytosis as a function of stiffness and Dexamethasone treatment.

Main Results:

• Notch pathway genes were overexpressed in GTM cells compared to NTM cells on plastic substrates.
• Cyclical strain altered the expression of a subset of Notch pathway genes.
• Notch expression and phagocytic ability decreased with increasing substrate stiffness, with highest levels on soft substrates.

Conclusions:

• Notch expression in TM cells is intrinsically different between GTM and NTM and is modulated by substrate stiffness and strain.
• Substrate stiffness significantly impacts Notch expression and phagocytic function, with implications for glaucoma.
• The Notch pathway's role in TM cell homeostasis and disease warrants further mechanistic investigation.