TY - JOUR
T1 - Src Family Kinase Links Insulin Signaling to Short Term Regulation of Na,K-ATPase in Nonpigmented Ciliary Epithelium
AU - Shahidullah, Mohammad
AU - Mandal, Amritlal
AU - Delamere, Nicholas A.
N1 - Funding Information:
The authors are grateful to the University of Arizona Meat Science laboratory, West Valley Processing Meat Processors (Buckeye, AZ) and Hatfield Quality Meat, Pennsylvania, for the supply of porcine eyes. The authors are thankful to Dr Chiu-Hsieh Hsu, Associate Professor, Department of Epidemiology and Biostatistics, University of Arizona, for assistance with statistical analysis of data. The corresponding author and the co-authors have no conflict of interest to declare. This research was supported by a grant from the National Institute of Health (Grant EY006915).
Publisher Copyright:
© 2016 Wiley Periodicals, Inc.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - Insulin has been shown to elicit changes of Na,K-ATPase activity in various tissues. Na,K-ATPase in the nonpigmented ciliary epithelium (NPE) plays a role in aqueous humor secretion and changes of Na,K-ATPase activity impact the driving force. Because we detect a change of NPE Na,K-ATPase activity in response to insulin, studies were carried out to examine the response mechanism. Ouabain-sensitive rubidium (Rb) uptake by cultured NPE cells, measured as a functional index of Na,K-ATPase-mediated inward potassium transport, was found to increase in cells exposed for 5 min to insulin. The maximally effective concentration was 100 nM. An intrinsic increase of Na,K-ATPase activity evident as a >2-fold increase in the rate of ouabain-sensitive ATP hydrolysis in homogenates obtained from cells exposed to 100 nM insulin for 5 min was also observed. Insulin-treated cells exhibited Akt, Src family kinase (SFK), ERK1/2, and p38 activation, all of which were prevented by a pI3 kinase inhibitor LY294002. The Rb uptake and Na,K-ATPase activity response to insulin both were abolished by PP2, an SFK inhibitor which also prevented p38 and ERK1/2 but not Akt activation. The Akt inhibitor MK-2206 did not change the Na,K-ATPase response to insulin. The findings suggest insulin activates pI3K-dependent Akt and SFK signaling pathways that are separate. ERK1/2 and p38 activation is secondary to and dependent on SFK activation. The increase of Na,K-ATPase activity is dependent on activation of the SFK pathway. The findings are consistent with previous studies that indicate a link between Na,K-ATPase activity and SFK signaling. J. Cell. Physiol. 232: 1489–1500, 2017.
AB - Insulin has been shown to elicit changes of Na,K-ATPase activity in various tissues. Na,K-ATPase in the nonpigmented ciliary epithelium (NPE) plays a role in aqueous humor secretion and changes of Na,K-ATPase activity impact the driving force. Because we detect a change of NPE Na,K-ATPase activity in response to insulin, studies were carried out to examine the response mechanism. Ouabain-sensitive rubidium (Rb) uptake by cultured NPE cells, measured as a functional index of Na,K-ATPase-mediated inward potassium transport, was found to increase in cells exposed for 5 min to insulin. The maximally effective concentration was 100 nM. An intrinsic increase of Na,K-ATPase activity evident as a >2-fold increase in the rate of ouabain-sensitive ATP hydrolysis in homogenates obtained from cells exposed to 100 nM insulin for 5 min was also observed. Insulin-treated cells exhibited Akt, Src family kinase (SFK), ERK1/2, and p38 activation, all of which were prevented by a pI3 kinase inhibitor LY294002. The Rb uptake and Na,K-ATPase activity response to insulin both were abolished by PP2, an SFK inhibitor which also prevented p38 and ERK1/2 but not Akt activation. The Akt inhibitor MK-2206 did not change the Na,K-ATPase response to insulin. The findings suggest insulin activates pI3K-dependent Akt and SFK signaling pathways that are separate. ERK1/2 and p38 activation is secondary to and dependent on SFK activation. The increase of Na,K-ATPase activity is dependent on activation of the SFK pathway. The findings are consistent with previous studies that indicate a link between Na,K-ATPase activity and SFK signaling. J. Cell. Physiol. 232: 1489–1500, 2017.
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U2 - 10.1002/jcp.25654
DO - 10.1002/jcp.25654
M3 - Article
C2 - 27748508
AN - SCOPUS:85000796991
VL - 232
SP - 1489
EP - 1500
JO - Journal of Cellular Physiology
JF - Journal of Cellular Physiology
SN - 0021-9541
IS - 6
ER -