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Plasticity of Na,K‐ATPase isoform expression in cultures of flat astrocytes: Species differences in gene expression
Author(s) -
Peng Liang,
Arystarkhova Elena,
Sweadner Kathleen J.
Publication year - 1998
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199811)24:3<257::aid-glia1>3.0.co;2-#
Subject(s) - biology , astrocyte , gene isoform , protein subunit , neuroglia , cerebellum , glutamate receptor , gene expression , microbiology and biotechnology , biochemistry , central nervous system , gene , receptor , neuroscience
The Na,K‐ATPase plays an active role in glial physiology, contributing to K + uptake as well as to the Na + gradients used by other membrane carriers. There are multiple isoforms of Na,K‐ATPase α and β subunits, and different combinations result in different affinities for Na + and K + . Isoform choice should thus influence K + and Na + homeostasis in astrocytes. Prior studies of astrocyte Na,K‐ATPase subunit composition have produced apparently conflicting results, suggesting plasticity of gene expression. Purified flat astrocytes from the cerebral cortex and cerebellum of both mouse and rat were systematically investigated here. Using antibodies specific for the α1, α2, α3, β1, β2, and β3 subunits, isoform level was assessed with Western blots, and cellular distribution was visualized with immunofluorescence. Although α1 was always expressed, differences were observed in the expression of α2 and β2, subunits that can be expressed in astrocytes in vivo and in coculture with neurons. In addition, abundant α subunit was expressed in rat astrocytes and in mouse cerebellar astrocytes without an equivalent level of any of the known β isoforms, suggesting that an additional β subunit important for glia is yet to be discovered. Conditions that have been shown to increase Na,K‐ATPase activity in astrocyte cultures, such as dibutyryl cAMP, high extracellular K + , and glutamate, did not specifically induce missing subunits, suggesting that cellular interactions are required to alter the ion transporter phenotype. GLIA 24:257–271, 1998. © 1998 Wiley‐Liss, Inc.