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Induction of type III‐deiodinase activity in astroglial cells by retinoids
Author(s) -
Esfandiari Ali,
Gagelin Claire,
Gavaret JeanMichel,
Pavelka Stanislav,
Len AnaMaria,
Pierre Michel,
Courtin FrançOise
Publication year - 1994
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.440110306
Subject(s) - deiodinase , endocrinology , medicine , hormone , biology , retinoic acid , triiodothyronine , retinoid , fibroblast , incubation , cell culture , dio2 , biochemistry , in vitro , genetics
Thyroid hormones and retinoic acid (RA) are important modulators of growth, development, and differentiation. Type III deiodinase (D‐III), which catalyzes thyroid hormones degradation in the brain and in cultured astroglial cells, is induced in astroglial cells by multiple pathways, including cAMP, 12.0‐tetradecanoylphorbol‐13‐acetate (TPA), fibroblast growth factors, and thyroid hormones themselves. In the present study, the effects of retinoids on D‐III activity were examined in astroglial cells cultures in a chemically defined medium devoid of hormones and growth factors. Incubation of astroglial cells with 5 μM all‐ trans ‐RA caused up to 200‐fold increase in D‐III activity, which reached a plateau after 48 h. The retinoid‐induced increase in D‐III activity was concentration dependent (0.5 μM all‐ trans ‐RA and 9‐ cis ‐RA producing half‐maximal effect). Retinol was effective at physiological concentrations (1 and μM). The 48 h effects of 5 μM all‐ trans ‐RA and 10 nM thyroid hormones on D‐III activity were at least additive. Addition of 2 nM acidic fibroblast growth factor or 1 mM 8‐bromo‐cAMP for the last 8 h of a 48 h incubation with 5 μM all‐ trans ‐RA did not alter the induction by all‐ trans ‐RA, whereas 0.1 μM TPA in the same conditions produced an additive effect with all‐ trans ‐RA. All‐ trans ‐RA (5 μM) had little or no effect on type II deiodinase, the enzyme which catalyzes the activation of thyroxine to 3,5,3′‐triiodothyronine. The potent action of retinoids on the enzyme responsible for thyroid hormones degradation in the brain may protect the brain from the effects of 3,5,3′‐triiodothyronine in regions influenced by retinoids. © 1994 Wiley‐Liss, Inc.