Regional differences in store-operated Ca2+ entry in the epithelium of the intact human lens

Jeremy D. Rhodes, Sarah L. Russell, Christopher D. Illingworth, George Duncan, I. Michael Wormstone

Research output: Journal PublicationArticlepeer-review

5 Citations (Scopus)


PURPOSE. An elevated level of Ca2+ is an important factor in cataract, yet precisely how Ca2+ enters the lens is unknown. Lens epithelial cells contain a range of G-protein-coupled receptors and receptor tyrosine kinases that induce increases in intracellular Ca2+. Receptor-associated Ca2+influx is, therefore, likely to be an important route for Ca2+ influx to the lens. The authors investigated stimulated and passive Ca2+influx in in situ human lens epithelium. METHODS. Ca2+ changes in equatorial (E) and central anterior (CA) epithelial cells were monitored with the use of a Ca2+indicator (Fluo4) and confocal microscopy. Gene expression was monitored by RT-PCR and immunoblotting. RESULTS. Adenosine triphosphate (ATP) induced Ca2+ responses that were smaller in CA than E. Ca2+ store depletion, using ATP (100 μM) or thapsigargin (1 μM), revealed greater relative store capacity and Ca2+influx in E. Ca2+influx was blocked by La2+ (0.5 μM) in both regions. Unstimulated Ca2+ influx was greater in E than CA. Greater expression of Orai1 and STIM1 was detected in E than in CA. CONCLUSIONS. Greater Ca2+store capacity and Ca2+ influx in E compared with CA reflects underlying differences in proliferation and differentiation between the regions. The relatively small resting Ca2+ influx in CA epithelium suggests that storeoperated Ca2+ entry (SOCE) is the main route of Ca2+influx in these cells. Greater resting influx and SOCE in E cells suggests that these are a major route for Ca2+ influx into the lens. Increased expression of Orai1 and STIM1 in E could account for the differences in Ca2+entry. Receptor activation will modulate Ca2+influx, and inappropriate activity may contribute to cortical cataract.

Original languageEnglish
Pages (from-to)4330-4336
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Issue number9
Publication statusPublished - 2009
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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