We are just beginning to understand how any tissue, not just lens, regulates Na,K-ATPase activity. Work in our laboratory causes us to think lens Na,K- ATPase activity can be fine tuned by a mechanism dependent on tyrosine phosphorylation. This may underlie the spatial distribution of Na,K-ATPase activity. It also may enable the lens to increase the activity of dormant Na,K- ATPase in the anterior epithelium or in some regions of the fibers. The mechanism leading to a change of Na,K-ATPase activity involves Src tyrosine kinases and can be set in motion by agonists like ATP or endothelin-1 that are released from the lens itself. Some agonists cause an increase of Na,K-ATPase activity while others cause inhibition even though tyrosine phosphorylation is involved in both responses. In this proposal we present a plan to test the hypothesis that the signaling pathways leading to Na,K-ATPase activation and inhibition involve different Src kinases that associate with Na,K-ATPase. In seeking to understand the interaction between Src tyrosine kinases and Na,K- ATPase we propose studies to figure out how Src-family kinase activation and Na,K-ATPase activity modulation fit in the context of other signaling events such as the transient cytoplasmic calcium rise.
The specific aims are: (1) Test the hypothesis that different members of the Src kinase family are involved in stimulatory and inhibitory Na,K-ATPase activity responses. (2) Determine where Src kinase activation fits in the sequence of signaling events that leads to altered Na,K-ATPase activity following receptor activation. (3) Study how Src-Na,K- ATPase interactions affect lens function. By studying lens Na,K-ATPase we hope to obtain information that will help us plan experiments in the future to explain why lens sodium-potassium homeostasis fails in human cortical cataract. PUBLIC HEALTH RELEVEANCE. Lens cells utilize Na, K-ATPase to maintain a stable cytoplasmic ion composition. Regulation of Na,K-ATPase activity is important because lenses become opaque when the ion composition is abnormal. Work in our laboratory causes us to think the lens has an elegant system for fine tuning Na,K-ATPase activity. We want to know more about how the mechanism works and how it affects lens function. Pilot studies tell us the mechanism involves Src tyrosine kinases. Here we propose studies to understand the interaction between Src kinases and Na,K-ATPase.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY009532-20
Application #
8220966
Study Section
Anterior Eye Disease Study Section (AED)
Program Officer
Araj, Houmam H
Project Start
1993-01-01
Project End
2013-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
20
Fiscal Year
2012
Total Cost
$322,898
Indirect Cost
$109,058
Name
University of Arizona
Department
Physiology
Type
Schools of Medicine
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Mandal, Amritlal; Shahidullah, Mohammad; Delamere, Nicholas A (2018) TRPV1-dependent ERK1/2 activation in porcine lens epithelium. Exp Eye Res 172:128-136
Delamere, Nicholas A; Mandal, Amritlal; Shahidullah, Mohammad (2016) The Significance of TRPV4 Channels and Hemichannels in the Lens and Ciliary Epithelium. J Ocul Pharmacol Ther 32:504-508
Gao, Junyuan; Sun, Xiurong; White, Thomas W et al. (2015) Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens. Biophys J 109:1830-9
Shahidullah, M; Mandal, A; Delamere, N A (2015) Damage to lens fiber cells causes TRPV4-dependent Src family kinase activation in the epithelium. Exp Eye Res 140:85-93
Mandal, Amritlal; Shahidullah, Mohammad; Delamere, Nicholas A (2015) Calcium entry via connexin hemichannels in lens epithelium. Exp Eye Res 132:52-8
Beckel, Jonathan M; Argall, Arthur J; Lim, Jason C et al. (2014) Mechanosensitive release of adenosine 5'-triphosphate through pannexin channels and mechanosensitive upregulation of pannexin channels in optic nerve head astrocytes: a mechanism for purinergic involvement in chronic strain. Glia 62:1486-501
Sanderson, Julie; Dartt, Darlene A; Trinkaus-Randall, Vickery et al. (2014) Purines in the eye: recent evidence for the physiological and pathological role of purines in the RPE, retinal neurons, astrocytes, Müller cells, lens, trabecular meshwork, cornea and lacrimal gland. Exp Eye Res 127:270-9
Shahidullah, Mohammad; Mandal, Amritlal; Delamere, Nicholas A (2012) TRPV4 in porcine lens epithelium regulates hemichannel-mediated ATP release and Na-K-ATPase activity. Am J Physiol Cell Physiol 302:C1751-61
Shahidullah, M; Mandal, A; Beimgraben, C et al. (2012) Hyposmotic stress causes ATP release and stimulates Na,K-ATPase activity in porcine lens. J Cell Physiol 227:1428-37
Mandal, A; Shahidullah, M; Beimgraben, C et al. (2011) The effect of endothelin-1 on Src-family tyrosine kinases and Na,K-ATPase activity in porcine lens epithelium. J Cell Physiol 226:2555-61

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