Regulation of TonEBP transcriptional activator in MDCK cells following changes in ambient tonicity
1 Physiologisches Institut der Universität München, D-80336 Münich, Germany; and 2 Department of Medicine, Johns Hopkins University, Baltimore, Maryland 21205 In response to ambient hypertonicity, TonEBP (tonicity-responsive enhancer binding protein) stimulates certain genes including those encodi...
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Published in | American Journal of Physiology: Cell Physiology Vol. 283; no. 6; pp. C1604 - C1611 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
01.12.2002
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Subjects | |
Online Access | Get full text |
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Summary: | 1 Physiologisches Institut der Universität
München, D-80336 Münich, Germany; and
2 Department of Medicine, Johns Hopkins University,
Baltimore, Maryland 21205
In response to
ambient hypertonicity, TonEBP (tonicity-responsive enhancer binding
protein) stimulates certain genes including those encoding cytokines,
transporters for organic solutes, and a molecular chaperone. TonEBP is
regulated in a bidirectional manner, upregulated by an increase in
ambient tonicity while downregulated by a decrease. To investigate the
role of intracellular ionic strength in the activity of TonEBP, we
subjected Madin-Darby canine kidney cells to a variety of conditions.
Electron microprobe analysis was performed to measure intracellular
electrolytes. Under conditions in which changes in cell volume were
similar, TonEBP activity correlated with the intracellular ionic
strength regardless of the external tonicity. On the other hand,
inhibition of the Na + /K + -ATPase and high
external K + concentration led to a decreased activity of
TonEBP despite a marked increase in the intracellular ionic strength.
Because isotonic swelling is known to occur under these conditions,
these data suggest that dilution of the cytoplasmic constituents
inhibits the activity of TonEBP. We conclude that intracellular ionic
strength and water content are major factors that determine the
activity of TonEBP.
cell ionic strength; cell volume; organic osmolytes; heat shock
protein 70; Madin-Darby canine kidney cells |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0363-6143 1522-1563 |
DOI: | 10.1152/ajpcell.00216.2002 |