Role of aquaporin-1 in trabecular meshwork cell homeostasis during mechanical strain

N. W. Baetz, E. A. Hoffman, A. J. Yool, W. D. Stamer

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Aquaporin-1 (AQP1) channels are expressed by trabecular meshwork (TM) and Schlemm's canal cells of the conventional outflow pathway where fluid movement is predominantly paracellular, suggesting a non-canonical role for AQP1. We hypothesized that AQP1 functions to protect TM cells during periods of mechanical strain. To test this idea, primary cultures of confluent human TM cells on Bioflex membranes were exposed to static and cyclic stretch for 8 and 24 h using the Flexcell system. AQP1 expression in TM cells was assessed by SDS-PAGE and Western blot using anti-AQP1 IgGs. AQP1 protein bands were analyzed using densitometry and normalized to β-actin expression. Cell damage was monitored by measuring lactate dehydrogenase (LDH) and histone deacetylase appearance in conditioned media. Recombinant expression of AQP1 in TM cell cultures was facilitated by transduction with adenovirus. Results show that AQP1 expression significantly increased 2-fold with 10% static stretch and 3.5-fold with 20% static stretch at 8 h (n = 4, p < 0.05) and 24 h (n = 6, p < 0.05). While histone deacetylase levels were unaffected by treatments, release of LDH from TM cells was the most profound at the 20% static stretch level (n = 4, p < 0.05). Significantly, cells were refractory to the 20% static stretch level when AQP1 expression was increased to near tissue levels. Analysis of LDH release with respect to AQP1 expression revealed an inverse linear relationship (r2 = 0.7780). Taken together, AQP1 in human TM appears to serve a protective role by facilitating improved cell viability during conditions of mechanical strain.

Original languageEnglish (US)
Pages (from-to)95-100
Number of pages6
JournalExperimental eye research
Volume89
Issue number1
DOIs
StatePublished - Jun 15 2009
Externally publishedYes

Keywords

  • cell viability
  • cell volume
  • glaucoma
  • schlemm's canal

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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