Role of osmoregulation in the actions of taurine |
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Authors: | S Schaffer K Takahashi J Azuma |
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Institution: | (1) Department of Pharmacology, School of Medicine, University of South Alabama, Mobile, Alabama, U.S.A., US;(2) Department of Clinical Evaluation of Medicines and Therapeutics, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan, JP |
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Abstract: | Summary. Taurine regulates an unusual number of biological phenomena, including heart rhythm, contractile function, blood pressure,
platelet aggregation, neuronal excitability, body temperature, learning, motor behavior, food consumption, eye sight, sperm
motility, cell proliferation and viability, energy metabolism and bile acid synthesis. Many of these actions are associated
with alterations in either ion transport or protein phosphorylation. Although the effects on ion transport have been attributed
to changes in membrane structure, they could be equally affected by a change in the activity of the affected transporters.
Three common ways of altering transporter activity is enhanced expression, changes in the phosphorylation status of the protein
and cytoskeletal changes. Interestingly, all three events are altered by osmotic stress. Since taurine is a key organic osmolyte
in most cells, the possibility that the effects of taurine on ion transport could be related to its osmoregulatory activity
was considered. This was accomplished by comparing the effects of taurine, cell swelling and cell shrinkage on the activities
of key ion channels and ion transporters. The review also compares the phosphorylation cascades initiated by osmotic stress
with some of the phosphorylation events triggered by taurine depletion or treatment. The data reveal that certain actions
of taurine are probably caused by the activation of osmotic-linked signaling pathways. Nonetheless, some of the actions of
taurine are unique and appear to be correlated with its membrane modulating and phosphorylation regulating activities.
Received January 25, 2000/Accepted January 31, 2000 |
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Keywords: | : Amino acids – Taurine – Osmotic stress – Signaling – Cell stretch – Ion transport – Phosphorylation |
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