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The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium.
Invest Ophthalmol Vis Sci. 2005 Feb; 46(2):618-22.IO

Abstract

PURPOSE

Na,K-adenosine triphosphatase (ATPase) is essential for the regulation of cytoplasmic ion concentrations in lens cells. Earlier studies demonstrated that tyrosine phosphorylation by Lyn kinase, a Src-family member, inhibits Na,K-ATPase activity in porcine lens epithelium. In the present study, experiments were conducted to compare the ability of other Src-family kinases (Fyn, Src, and Lck) and Fes, a non-Src-family tyrosine kinase, to alter Na,K-ATPase activity.

METHODS

Membranes prepared from porcine lens epithelium were incubated with partially purified tyrosine kinases in buffer containing 1 mM adenosine triphosphate (ATP). ATP hydrolysis in the presence and absence of ouabain was used to measure Na,K-ATPase activity. Western blot analysis was used to examine phosphotyrosine-containing proteins and tyrosine kinase expression.

RESULTS

Fyn reduced Na,K-ATPase activity by approximately 30%. In contrast, Src caused a approximately 38% increase of Na,K-ATPase activity. Na,K-ATPase activity in membrane material treated with Lck or Fes was not significantly altered, even though Lck and Fes treatment induced robust tyrosine phosphorylation. Added exogenously, each tyrosine kinase induced a different pattern of membrane protein tyrosine phosphorylation. As judged by immunoprecipitation, Src, Fyn, Lyn, and Lck elicited tyrosine phosphorylation of the Na,K-ATPase alpha1 protein. Src, Fyn, Lyn, Lck, and Fes were each detectable in the epithelium by Western blot.

CONCLUSIONS

The results indicate considerable variation in the Na,K-ATPase activity response of lens epithelium to different tyrosine kinases. This could perhaps explain why inhibition of Na,K-ATPase activity is reported to be caused by tyrosine phosphorylation in some tissues, whereas stimulation of Na,K-ATPase activity is observed in other tissues.

Authors+Show Affiliations

Department of Biochemistry, University of Louisville, School of Medicine, KY 40292, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15671290

Citation

Bozulic, Larry D., et al. "The Influence of SRC-family Tyrosine Kinases On Na,K-ATPase Activity in Lens Epithelium." Investigative Ophthalmology & Visual Science, vol. 46, no. 2, 2005, pp. 618-22.
Bozulic LD, Dean WL, Delamere NA. The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium. Invest Ophthalmol Vis Sci. 2005;46(2):618-22.
Bozulic, L. D., Dean, W. L., & Delamere, N. A. (2005). The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium. Investigative Ophthalmology & Visual Science, 46(2), 618-22.
Bozulic LD, Dean WL, Delamere NA. The Influence of SRC-family Tyrosine Kinases On Na,K-ATPase Activity in Lens Epithelium. Invest Ophthalmol Vis Sci. 2005;46(2):618-22. PubMed PMID: 15671290.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium. AU - Bozulic,Larry D, AU - Dean,William L, AU - Delamere,Nicholas A, PY - 2005/1/27/pubmed PY - 2005/3/12/medline PY - 2005/1/27/entrez SP - 618 EP - 22 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 46 IS - 2 N2 - PURPOSE: Na,K-adenosine triphosphatase (ATPase) is essential for the regulation of cytoplasmic ion concentrations in lens cells. Earlier studies demonstrated that tyrosine phosphorylation by Lyn kinase, a Src-family member, inhibits Na,K-ATPase activity in porcine lens epithelium. In the present study, experiments were conducted to compare the ability of other Src-family kinases (Fyn, Src, and Lck) and Fes, a non-Src-family tyrosine kinase, to alter Na,K-ATPase activity. METHODS: Membranes prepared from porcine lens epithelium were incubated with partially purified tyrosine kinases in buffer containing 1 mM adenosine triphosphate (ATP). ATP hydrolysis in the presence and absence of ouabain was used to measure Na,K-ATPase activity. Western blot analysis was used to examine phosphotyrosine-containing proteins and tyrosine kinase expression. RESULTS: Fyn reduced Na,K-ATPase activity by approximately 30%. In contrast, Src caused a approximately 38% increase of Na,K-ATPase activity. Na,K-ATPase activity in membrane material treated with Lck or Fes was not significantly altered, even though Lck and Fes treatment induced robust tyrosine phosphorylation. Added exogenously, each tyrosine kinase induced a different pattern of membrane protein tyrosine phosphorylation. As judged by immunoprecipitation, Src, Fyn, Lyn, and Lck elicited tyrosine phosphorylation of the Na,K-ATPase alpha1 protein. Src, Fyn, Lyn, Lck, and Fes were each detectable in the epithelium by Western blot. CONCLUSIONS: The results indicate considerable variation in the Na,K-ATPase activity response of lens epithelium to different tyrosine kinases. This could perhaps explain why inhibition of Na,K-ATPase activity is reported to be caused by tyrosine phosphorylation in some tissues, whereas stimulation of Na,K-ATPase activity is observed in other tissues. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/15671290/The_influence_of_SRC_family_tyrosine_kinases_on_NaK_ATPase_activity_in_lens_epithelium_ L2 - https://iovs.arvojournals.org/article.aspx?doi=10.1167/iovs.04-0809 DB - PRIME DP - Unbound Medicine ER -