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Caveolin and GLT‐1 gene expression is reciprocally regulated in primary astrocytes: Association of GLT‐1 with non‐caveolar lipid rafts
Author(s) -
Zschocke Jürgen,
Bayatti Nadhim,
Behl Christian
Publication year - 2004
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/glia.20116
Subject(s) - caveolae , biology , caveolin 1 , microbiology and biotechnology , caveolin , signal transduction , lipid raft , mef2 , scaffold protein , transcription factor , gene , genetics , enhancer
Caveolae represent membrane microdomains acting as integrators of cellular signaling and functional processes. Caveolins are involved in the biogenesis of caveolae and regulate the activity of caveolae‐associated proteins. Although caveolin proteins are found in the CNS, the regulation of caveolins in neural cells is poorly described. In the present study, we investigated different modes and mechanisms of caveolin gene regulation in primary rat astrocytes. We demonstrated that activation of cAMP‐dependent signaling pathways led to a marked reduction in protein levels of caveolin‐1/‐2 in cortical astrocytes. Application of transforming growth factor‐α (TGF‐α) also resulted in a decrease of caveolin‐1/‐2 expression. Decreased caveolin protein levels were mirrored by diminished caveolin gene transcription. The repressive effect of TGF‐α on caveolin‐1 expression was MAP kinase‐independent and partly mediated through the PI3‐kinase pathway. Further downstream, inhibition of histone deacetylases abrogated TGF‐α effects, suggesting that chromatin remodeling processes could contribute to caveolin‐1 repression. Intriguingly, alterations of caveolin gene expression in response to cAMP or TGF‐α coincided with reciprocal and brain‐region specific changes in glial glutamate transporter GLT‐1 expression. The reciprocal regulation of caveolin‐1 and GLT‐1 expression might be gated through a common PI3‐kinase dependent pathway triggered by TGF‐α. Finally, we showed that GLT‐1 is located in non‐caveolar lipid rafts of cortical astrocytes. In conclusion, this study highlights the occurrence of the reciprocal regulation of caveolin and GLT‐1 expression during processes such as astrocyte differentiation via common signaling pathways. We also provide strong evidence that GLT‐1 itself is concentrated in lipid rafts, inferring an important role for glial glutamate transporter function. © 2004 Wiley‐Liss, Inc.