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Calcium‐Independent, Tyrosine Phosphorylation‐Dependent Effects of Serum on the Morphology of Cultured Neurohypophysial Astrocytes
Author(s) -
Ramsell K. D.,
Cobbett P.
Publication year - 2000
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.2000.00545.x
Subject(s) - medicine , endocrinology , calcium , morphology (biology) , phosphorylation , tyrosine , tyrosine phosphorylation , chemistry , biology , microbiology and biotechnology , zoology , biochemistry
Activation of adenylate cyclase induces cultured neurohypophysial astrocytes (pituicytes) to change from a protoplasmic, nonstellate form to a stellate form. Stellation is inhibited and reversed (destellation) by serum. The objective of the present studies was to examine the roles of Ca 2+ and tyrosine phosphorylation in mediating these morphological changes. The effects of forskolin (to induce stellation) and serum (to inhibit and reverse stellation) were not affected by replacement of Ca 2+ with Co 2+ in the medium or by treatment of cultures with thapsigargin. However, genistein, a specific inhibitor of tyrosine kinase(s), significantly reduced the effect of serum on forskolin‐induced stellation. Also, dephostatin, a specific inhibitor of tyrosine phosphatase, inhibited forskolin‐induced stellation. In contrast, genistein did not have a dramatic effect on serum‐induced destellation. The data demonstrate that morphological changes exhibited by cultured pituicytes are independent of Ca 2+ but may be modulated by the activity of tyrosine kinase(s) and phosphatase(s).