Regulation of Sarco/Endoplasmic Ca2+-ATPase Expression by Calcium in Human Lens Cells

Maintenance of cellular calcium levels is critical to cell function. Loss of calcium homeostasis might be a contributing factor to the development of cataract in the lens. In lens epithelium, calcium is involved in cell signaling and its precise regulation is vital. In this study, we investigated th...

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Bibliographic Details
Published in:Experimental eye research 2002-11, Vol.75 (5), p.583-590
Main Authors: Liu, L, Paterson, C.A, Borchman, D
Format: Article
Language:English
Subjects:
Biological and medical sciences
Blotting, Western
Ca2+-ATPase
calcium
Calcium - metabolism
Calcium-Transporting ATPases - metabolism
Cells, Cultured
Dactinomycin - pharmacology
Electrophoresis, Polyacrylamide Gel
Endoplasmic Reticulum - enzymology
Eye and associated structures. Visual pathways and centers. Vision
Fundamental and applied biological sciences. Psychology
Gene Expression - drug effects
Humans
lens
Lens Capsule, Crystalline - drug effects
Lens Capsule, Crystalline - metabolism
mRNA
protein expression
Reverse Transcriptase Polymerase Chain Reaction
RNA, Messenger - metabolism
SERCA
Thapsigargin - pharmacology
Vertebrates: nervous system and sense organs
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Summary:Maintenance of cellular calcium levels is critical to cell function. Loss of calcium homeostasis might be a contributing factor to the development of cataract in the lens. In lens epithelium, calcium is involved in cell signaling and its precise regulation is vital. In this study, we investigated the regulation of sarco/endoplasmic reticulum Ca2+-ATPase2b (SERCA2b) and SERCA3 isoform expression in cultured epithelial B-3 cells from human lenses. Both mRNA and membrane proteins samples were collected for semi quantitative RT-PCR using GAPDH as a control. Western blot analyses were performed on membrane samples. Thapsigargin, a SERCA isoform inhibitor which causes increased cytosolic levels elicited dose-and time-dependent up-regulation of SERCA3 at both mRNA and protein levels; SERCA2b expression was unaffected. Both EGTA and actinomycin partially inhibited the thapsigargin-induced SERCA3 up-regulation. These results indicate that the up-regulation of SERCA3 by thapsigargin is dependent on a calcium-mediated pathway that is likely to occur at the transcription level.
ISSN:0014-4835
1096-0007
DOI:10.1006/exer.2002.2049