Document Detail

Role of insulin in regulation of Na+-/K+-dependent ATPase activity and pump function in corneal endothelial cells.
MedLine Citation:
PMID:  20335606     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The Na(+)-/K(+)-dependent ATPase (Na,K-ATPase) expressed in the basolateral membrane of corneal endothelial cells plays an important role in the pump function of the corneal endothelium. The role of insulin in the regulation of Na,K-ATPase activity and pump function in corneal endothelial cells was investigated.
METHODS: Confluent monolayers of mouse corneal endothelial cells were exposed to insulin. ATPase activity was evaluated by spectrophotometric measurement of phosphate released from ATP with the use of ammonium molybdate; Na,K-ATPase activity was defined as the portion of total ATPase activity sensitive to ouabain. Pump function was measured with the use of a Ussing chamber; pump function attributable to Na,K-ATPase activity was defined as the portion of the total short-circuit current sensitive to ouabain. Western blot analysis and immunocytochemistry were performed to measure the expression of the Na,K-ATPase alpha(1)-subunit.
RESULTS: Insulin increased the Na,K-ATPase activity and pump function of cultured corneal endothelial cells. These effects were blocked by protein kinase C (PKC) inhibitors and protein phosphatases 1 and 2A inhibitor. Western blot analysis indicated that insulin decreased the ratio of the inactive Na,K-ATPase alpha(1)-subunit. Immunocytochemistry indicated that insulin increased the cell surface expression of the Na,K-ATPase alpha(1)-subunit.
CONCLUSIONS: These results suggest that insulin increases the Na,K-ATPase activity and pump function of cultured corneal endothelial cells. The effect of insulin is mediated by PKC and presumably results in the activation of PP1, 2A, or both, which are essential for activating Na,K-ATPase by alpha(1)-subunit dephosphorylation.
Shin Hatou; Masakazu Yamada; Yoko Akune; Hiroshi Mochizuki; Atsushi Shiraishi; Takeshi Joko; Teruo Nishida; Kazuo Tsubota
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-03-24
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  51     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-23     Completed Date:  2010-08-20     Revised Date:  2012-07-12    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3935-42     Citation Subset:  IM    
Division for Vision Research, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan.
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MeSH Terms
Basement Membrane / enzymology
Blotting, Western
Cell Line, Transformed
Cells, Cultured
Endothelium, Corneal / enzymology*
Insulin / physiology*
Membrane Transport Proteins / physiology*
Mice, Inbred C3H
Protein Kinase C / metabolism
Protein Phosphatase 1
Protein Phosphatase 2
Protein Subunits / metabolism
Sodium-Potassium-Exchanging ATPase / metabolism*
Reg. No./Substance:
0/Insulin; 0/Membrane Transport Proteins; 0/Protein Subunits; EC Kinase C; EC Phosphatase 1; EC Phosphatase 2; EC protein, mouse; EC ATPase

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