Regulatory Roles of Anoctamin-6 in Human Trabecular Meshwork Cells.

Area of Science:

• Ophthalmology
• Cell Physiology
• Ion Channel Biology

Background:

• Trabecular meshwork (TM) cell volume influences aqueous humor outflow resistance and intraocular pressure (IOP).
• Regulation of TM cell volume involves chloride ion (Cl-) release via swelling-activated channels (ICl,Swell), potentially modulated by calcium-activated anoctamins.
• The specific role of anoctamin Ano6 in TM cell volume regulation remains controversial.

Purpose of the Study:

• To investigate whether anoctamin activity, particularly Ano6, affects the volume regulation of primary TM cell cultures and cell lines.
• To clarify the role of Ano6 in chloride ion release and cell volume control within the trabecular meshwork.

Main Methods:

• Gene expression analysis using quantitative PCR, RT-PCR, and Western immunoblots.
• Electrophysiological recordings via whole-cell patch clamping to measure currents.
• Cell volume measurements using electronic cell sizing.

Main Results:

• TM cells predominantly express Ano6 compared to other anoctamin Ca2+-activated Cl- (CaCC) channels (Ano1, Ano2).
• Ionomycin-induced currents showed characteristics of CaCCs but with different reversal potentials than ICl,Swell.
• Inhibitors and Ano6 knockdown significantly reduced ionomycin-activated currents, ICl,Swell, and the regulatory volume response.

Conclusions:

• Ano6 regulates CaCCs involved in cation movement, ICl,Swell, and cell volume in TM cells.
• Targeting Ano6 presents a potential therapeutic strategy for modulating cell volume and outflow resistance in glaucoma.