The role of microtubules (MTs) in steroid hormone-dependent human glucocorticoid receptor (hGR) activation/translocation is controversial. It was demonstrated recently that colchicine (COL) down-regulates hGR-driven genes in primary human hepatocytes by a mechanism involving inhibition of hGR translocation to the nucleus. To investigate whether inhibition of hGR translocation is the sole reason for its inactivation, we used human cervical carcinoma cells (HeLa) as a model. Herein we present evidence that perturbation of microtubules in HeLa cells leads to rapid time- and dose-dependent degradation of hGR protein. Degradation is proteasome mediated as revealed by its reversibility by proteasome inhibitor MG132. Moreover, degradation was observed for neither wt-hGR nor hGR mutants S226A and K419A in transiently transfected COS-1 cells. On the other hand, c-jun N-terminal kinase (JNK) seems not to be involved in the process because JNK inhibitor 1,9-Pyrazoloanthrone (SP600125) does not reverse hGR degradation. Similarly, another hGR functional antagonist, nuclear factor kappa beta (NFkappaB), did not play any role in the degradation process.

• MeSH
• anthraceny farmakologie   MeSH
• Cercopithecus aethiops MeSH
• COS buňky MeSH
• cytosol metabolismus   MeSH
• dexamethason farmakologie   MeSH
• HeLa buňky MeSH
• inhibitory cysteinových proteinas farmakologie   MeSH
• inhibitory enzymů farmakologie   MeSH
• intranukleární prostor metabolismus   MeSH
• JNK mitogenem aktivované proteinkinasy antagonisté a inhibitory   metabolismus   MeSH
• kolchicin farmakologie   MeSH
• leupeptiny farmakologie   MeSH
• lidé MeSH
• mikrotubuly účinky léků   metabolismus   fyziologie   MeSH
• mutace fyziologie   MeSH
• NF-kappa B metabolismus   MeSH
• nokodazol farmakologie   MeSH
• proteasomový endopeptidasový komplex účinky léků   metabolismus   MeSH
• receptory glukokortikoidů genetika   metabolismus   MeSH
• transfekce MeSH
• transport proteinů účinky léků   MeSH
• ubikvitin metabolismus   MeSH
• vinkristin farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anthraceny MeSH
• benzyloxycarbonylleucyl-leucyl-leucine aldehyde MeSH Prohlížeč
• dexamethason MeSH
• inhibitory cysteinových proteinas MeSH
• inhibitory enzymů MeSH
• JNK mitogenem aktivované proteinkinasy MeSH
• kolchicin MeSH
• leupeptiny MeSH
• NF-kappa B MeSH
• nokodazol MeSH
• proteasomový endopeptidasový komplex MeSH
• pyrazolanthrone MeSH Prohlížeč
• receptory glukokortikoidů MeSH
• ubikvitin MeSH
• vinkristin MeSH

The xenobiotic-mediated induction of three major human liver cytochrome P450 genes, CYP2B6, CYP2C9, and CYP3A4, is known to be regulated by the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR). CAR and PXR are regulated, at least in part, by the glucocorticoid receptor (GR) and the hypothesis of a signal transduction cascade GR-[CAR/PXR]-P450 has been proposed. This study was aimed at testing this hypothesis in primary human hepatocytes by using the tubulin network disrupting agent colchicine. Colchicine (COL) decreased both basal and rifampicin- and phenobarbital-inducible expression of CYP2B6, CYP2C8/9, and CYP3A4. A parallel down-regulation of mRNA expression of CAR, PXR, and tyrosine aminotransferase, a prototypic gene directly regulated by GR, was observed. COL affected neither the level of GR mRNA nor ligand binding to GR. To evaluate the effect of colchicine on GR-mediated gene transactivation, HeLa cells stably or transiently transfected with a GR-responsive element-dependent luciferase reporter gene were used. COL decreased the dexamethasone-induced luciferase expression in stably transfected cell line by 50%, whereas GR transactivation in transiently transfected cells was not affected by COL. In contrast, ligand-dependent GR translocation in the human embryonic kidney 293 cell line transiently transfected with GFP-GR was inhibited by COL. We conclude that alteration of the signal transduction mediated through the GR-[CAR/PXR]-P450 cascade by colchicine is responsible for the down-regulation of CYP2C9 and CYP3A4, implicating cytoskeleton as necessary for correct functioning of this cascade under physiological conditions.

• MeSH
• aromatické hydroxylasy biosyntéza   MeSH
• biologický transport účinky léků   MeSH
• COS buňky MeSH
• cytochrom P-450 CYP3A MeSH
• cytochrom P450 CYP2B6 MeSH
• cytochrom P450 CYP2C8 MeSH
• cytochrom P450 CYP2C9 MeSH
• down regulace účinky léků   MeSH
• enzymová indukce účinky léků   MeSH
• hepatocyty účinky léků   enzymologie   MeSH
• kolchicin farmakologie   MeSH
• kultivované buňky MeSH
• lidé MeSH
• messenger RNA biosyntéza   účinky léků   MeSH
• N-demethylasy biosyntéza   MeSH
• receptory glukokortikoidů účinky léků   metabolismus   MeSH
• regulace genové exprese enzymů účinky léků   MeSH
• systém (enzymů) cytochromů P-450 biosyntéza   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aromatické hydroxylasy MeSH
• CYP2B6 protein, human MeSH Prohlížeč
• CYP2C8 protein, human MeSH Prohlížeč
• CYP2C9 protein, human MeSH Prohlížeč
• CYP3A protein, human MeSH Prohlížeč
• CYP3A4 protein, human MeSH Prohlížeč
• cytochrom P-450 CYP3A MeSH
• cytochrom P450 CYP2B6 MeSH
• cytochrom P450 CYP2C8 MeSH
• cytochrom P450 CYP2C9 MeSH
• kolchicin MeSH
• messenger RNA MeSH
• N-demethylasy MeSH
• receptory glukokortikoidů MeSH
• systém (enzymů) cytochromů P-450 MeSH