Glucocorticoid receptor in health and disease

Glucocorticoid hormones are essential for life, have a vital place in the treatment of inflammatory and autoimmune diseases and are increasingly implicated in the pathogenesis of a number of common disorders. Their action is mediated by an intracellular receptor protein, the glucocorticoid receptor (GR), functioning as a ligand-inducible transcription factor. Multiple synthetic glucocorticoids are used as potent antiinflammatory and immuno suppressive agents, but their therapeutic usefulness is limited by a wide range and severity of side-effects. One of the most important pharmaceutical goals has been to design steroidal and non-steroidal GR ligands with profound therapeutic efficacy and reduced unwanted effects. The therapeutic benefit of glucocorticoid agonists is frequently compromised by resistance to glucocorticoids, which may depend on: access of the hormones to target cells, steroid metabolism, expression level and isoform composition of the GR protein, mutations and polymorphisms in the GR gene and association of the receptor with chaperone proteins. The major breakthrough into the critical role of glucocorticoid signaling in the maintenance of homeostasis and pathogenesis of diseases, as well as into the molecular mechanisms underlying the therapeutic usefulness of antiinflammatory drugs acting through the GR is expected to result from the current progress in large-scale gene expression profiling technologies and computational biology.Glukokortikoidni hormoni su neophodni za održavanje homeostaze, imaju ključnu ulogu u terapiji inflamatornih i autoimunih poremećaja i učestvuju u pato - genezi mnogih bolesti. Ovi hormoni deluju posredstvom unutarćelijskog receptornog proteina, glukokortikoidnog receptora, koji funkcioniše kao inducibilan transkripcioni faktor aktiviran ligandom. Mnogi sintetski glukokortikoidi koriste se kao efikasni antiinflamatorni i imunosupresivni agensi, ali je njihov terapeutski učinak ograničen širokim spektrom i intenzitetom sporednih efekata. Jedan od najvažnijih ciljeva farmaceutske industrije jeste sinteza steroidnih i nesteroidnih liganada GR-a sa izraženom terapeutskom efikasnošću i redukovanim neželjenim efektima. Terapeutski učinak glukokortikoidnih agonista često je umanjen zbog rezistencije na glukokortikoide koja zavisi od: dostupnosti ciljnih ćelija hormonima, metabolizma steroida, nivoa ekspresije i izoformskog sastava GR, mutacija i polimorfizama u genu za receptor i interakcije receptora sa šaperonima. Očekuje se da veliki prodor u upoznavanju ključne uloge glukokortikoidnih hormona u održavanju homeostaze i patogenezi bolesti, kao i u rasvetljavanju molekularnih mehanizama terapeutskih efekata antiinflamatornih lekova koji deluju posredstvom GR rezultira iz napretka savremenih tehnologija za globalno izučavanje ekspresije gena i bioinformatike.Projekat ministarstva br. 14300

Cellular stress response: Defence against metal toxicity

All cells respond to various types of stress by increasing the transcription of specific genes that encode class of proteins termed stress proteins. This response is believed to represent a transient reprogramming of gene expression and biological activity, which serves to protect sensitive cellular components from damage, and assists in the rapid recovery after the stress is removed or ceases. The synthesis of stress proteins can be induced under a host of different stress conditions, including elevated level of metals. Although, understanding of the relationships between metals and their capacity to induce stress response is incomplete, these interactions are important to consider because they may reveal information regarding mechanisms of toxicity, cellular defense mechanisms against metal toxicity, and biochemical responses which can be exploited as biomarkers of exposure and toxicity of metals. This review is focused on two main classes of stress proteins, metallothioneins (MTs) and heat shock proteins (Hsps), which are usually induced in response to stress provoked by metals. It summarizes the results of studies on metals toxic effects and their ability to induce cellular stress response.Sve žive ćelije odgovaraju na različite tipove stresa povećavanjem transkripcije specifičnih gena koji kodiraju klasu proteina nazvanih stres proteini. Taj odgovor predstavlja prolazno reprogramiranje ekspresije gena i biološke aktivnosti, i služi da zaštiti osetljive ćelijske komponente od oštećenja, i pomogne u brzom oporavku posle uklanjanja ili prestanka delovanja stresa. Sinteza proteina stresa može biti indukovana pod delovanjem različitih stresogenih uslova, uključujući i povećani nivo metala. Pošto je razumevanje odnosa između metala i njihovog kapaciteta da indukuju odgovor na stres nedovoljno poznato, njihovo proučavanje je važno zato što može dati informacije o mehanizmima toksičnosti metala, ćelijskim odbrambenim mehanizmima i biohemijskim odgovorima koji se mogu koristiti kao biomarkeri izlaganja ili toksičnosti metala. Ovaj revijski članak je fokusiran na dve klase stres proteina, metalotioneina (MT) i proteina toplotnog stresa (Hsp), koje se najčešće indukuju u odgovoru na stres provociran metalima. Sumirani su rezultati istraživanja toksičnih efekata metala i njihove sposobnosti da indukuju ćelijski odgovor na stres

The influence of dexamethasone on Hsp70 level and association with glucocorticoid receptor in the liver of unstressed and heat-stressed rats

The aim of the present study was to examine the influence of dexamethasone on the levels of heat shock protein Hsp70 and glucocorticoid hormones receptor as well as on the interaction of these two proteins in the liver cytosol and nuclei of unstressed and rats exposed to whole body hyperthermic stress. The results, obtained by quantitative immunoblotting, have shown that dexamethasone provoked a reduction of Hsp70 basal level and an increase in its stress-induced level in the nuclei, supporting the idea that this hormone may be a factor included in the regulation of Hsp70 level both under normal and stress conditions. The cytosolic reduction and nuclear elevation of the glucocorticoid hormones receptor level by dexamethasone were also observed. Co-immunopurification of Hsp70 and glucocorticoid hormones receptor has revealed that the changes of cytosolic and nuclear levels of the two examined proteins resulted in the changes of their interaction within the respective cellular compartments. Thus, 41 °C heat stress was shown to cause at least two-fold elevation of Hsp70/GR ratio within the glucocorticoid hormones receptor heterocomplexes both in the presence and in the absence of dexamethasone. The results support the view that glucocorticoid hormones signaling pathway and heat shock system are interrelated.Cilj ovog rada bio je da se ispita uticaj deksametazona na koncentraciju proteina toplotnog stresa Hsp70 i glukokortikoidnog receptora (GR), kao i na interakciju ovih proteina, u citosolu i jedrima jetre nestresiranih pacova i pacova izloženih hipertermijskom stresu. Rezultati, dobijeni kvantitativnim imunoblotom, su pokazali da deksametazon dovodi do smanjenja bazalne i povećanja stresom indukovane koncentracije Hsp70 u jedrima, što ukazuje na mogućnost da je ovaj hormon jedan od faktora uključenih u regulaciju nivoa Hsp70 i u normalnim i u uslovima stresa. Zapaženo je i to da deksametazon uzrokuje smanjenje citosolne i povećanje jedarne koncentracije GR. Ko-imunopurifikacija Hsp70 i GR je pokazala da su promene u citosolnim i jedarnim koncentracijama ovih proteina praćene i promenama u njihovoj interakciji u odgovarajućim ćelijskim odeljcima. Tako, nađeno je da hipertermijski stres (41 °C) dovodi do najmanje dvostrukog povećanja odnosa Hsp70/GR u receptorskim heterokompleksima kako u prisustvu, tako i u odsustvu deksametazona. Rezultati podržavaju pretpostavku da su signalni putevi koje započinju glukokortikoidni hormoni i toplotni stres međusobno povezani

Glucocorticoid receptor in health and disease

Glucocorticoid hormones are essential for life, have a vital place in the treatment of inflammatory and autoimmune diseases and are increasingly implicated in the pathogenesis of a number of common disorders. Their action is mediated by an intracellular receptor protein, the glucocorticoid receptor (GR), functioning as a ligand-inducible transcription factor. Multiple synthetic glucocorticoids are used as potent antiinflammatory and immuno suppressive agents, but their therapeutic usefulness is limited by a wide range and severity of side-effects. One of the most important pharmaceutical goals has been to design steroidal and non-steroidal GR ligands with profound therapeutic efficacy and reduced unwanted effects. The therapeutic benefit of glucocorticoid agonists is frequently compromised by resistance to glucocorticoids, which may depend on: access of the hormones to target cells, steroid metabolism, expression level and isoform composition of the GR protein, mutations and polymorphisms in the GR gene and association of the receptor with chaperone proteins. The major breakthrough into the critical role of glucocorticoid signaling in the maintenance of homeostasis and pathogenesis of diseases, as well as into the molecular mechanisms underlying the therapeutic usefulness of antiinflammatory drugs acting through the GR is expected to result from the current progress in large-scale gene expression profiling technologies and computational biology.Glukokortikoidni hormoni su neophodni za održavanje homeostaze, imaju ključnu ulogu u terapiji inflamatornih i autoimunih poremećaja i učestvuju u pato - genezi mnogih bolesti. Ovi hormoni deluju posredstvom unutarćelijskog receptornog proteina, glukokortikoidnog receptora, koji funkcioniše kao inducibilan transkripcioni faktor aktiviran ligandom. Mnogi sintetski glukokortikoidi koriste se kao efikasni antiinflamatorni i imunosupresivni agensi, ali je njihov terapeutski učinak ograničen širokim spektrom i intenzitetom sporednih efekata. Jedan od najvažnijih ciljeva farmaceutske industrije jeste sinteza steroidnih i nesteroidnih liganada GR-a sa izraženom terapeutskom efikasnošću i redukovanim neželjenim efektima. Terapeutski učinak glukokortikoidnih agonista često je umanjen zbog rezistencije na glukokortikoide koja zavisi od: dostupnosti ciljnih ćelija hormonima, metabolizma steroida, nivoa ekspresije i izoformskog sastava GR, mutacija i polimorfizama u genu za receptor i interakcije receptora sa šaperonima. Očekuje se da veliki prodor u upoznavanju ključne uloge glukokortikoidnih hormona u održavanju homeostaze i patogenezi bolesti, kao i u rasvetljavanju molekularnih mehanizama terapeutskih efekata antiinflamatornih lekova koji deluju posredstvom GR rezultira iz napretka savremenih tehnologija za globalno izučavanje ekspresije gena i bioinformatike.Projekat ministarstva br. 14300

Rat liver tyrosine aminotransferase activity and induction by dexamethasone upon cadmium intoxication

This study was focused on Cd effects on basal and dexamethasone-induced tyrosine aminotransferase (TAT) activity in the rat liver cytosol. Cadmium (Cd), applied in the dose of 2 mg/kg b.w., stimulated both TAT activity and its induction by dexamethasone, inducing the most prominent alterations 24 h after administration. Doses lower than 2 mg Cd/kg b.w. were ineffective while the higher ones (3 and 4 mg Cd/kg b.w) led to the changes similar to those reached by 2 mg Cd/kg. The in vitro application of different Cd concentrations to the liver cytosol rendered the enzyme activity unchanged suggesting that the metal acted at the level of TAT gene transcription.Istraživanja su bila usmerena ka praćenju efekata Cd na osnovnu i deksametazonom indukovanu aktivnost tirozin aminotransferaze (TAT) u citosolu jetre pacova. Kadmijum (Cd) primenjen u dozi od 2 mg/kg telesne težine, stimulisao je i aktivnost TAT i indukciju enzima deksametazonom. Najizraženije promene su zapažene 24 h nakon injeciranja metala životinjama. Doze niže od 2mg/kg telesne težine nisu uticale na aktivnost enzima, dok su promene u prisustvu viših doza (3 i 4 mg Cd/kg telesne težine) bile približne onim zapaženim nakon tretiranja životinja sa 2 mg Cd/kg. Nepromenjena aktivnost enzima uočena nakon inkubiranja citosola jetre pacova sa različitim koncentracija Cd, sugerisala je da se uticaj metala ostvaruje na nivou transkripcije gena za tirozin aminotransferazu.nul

HSP70 level in the leaves of Phaseolus vulgaris intoxicated with cadmium.

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A possible role of metallothionein and heat shock proteins in glucocorticoid receptor protection against cadmium intoxication

The participation of metallothionein (Mt) and heat shock proteins (Hsps) in protection of glucocorticoid receptor (GR) binding capacity from a toxic metal cadmium (Cd), was investigated. Specific binding of a glucocorticoid to GR in the rat liver cytosol was studied after in vitro and in vivo Cd treatment. Reduction of the GR binding capacity observed after in vitro treatment was proportional to the applied metal concentrations. In animals administered different Cd doses, GR binding capacity was not reduced, except in those that received the highest dose, and a concomitant elevation of Mt, Hsp70 and Hsp90 levels was detected. The results led to the assumption that Cd-induced reduction of the GR binding capacity noticed in vitro, was prevented in intact animals by the elevated levels of Mt and Hsps.Ispitivano je učešće metalotioneina (Mt) i proteina toplotnog stresa (Hsp)y zapititi glukokortikoidnog receptora (GR) od toksičnog delovanja kadmijuma (Cd). Specifično vezivanje glukokortikoida za GRy citosolu jetre pacova praćeno je posle in vitro i in vivo tretmana kadmijumom. Zapaženo je da je u in vitro uslovima smanjenje sposobnosti GR da vezuje hormon proporcionalno primenjenoj koncentraciji metala. Kod životinja injeciranih različitim dozama Cd, kapacitet GR za vezivanje hormona je nepromenjen osim u prisustvu najveće doze, i istovremeno se uočava povećanje koncentracije Mt, Hsp70 i Hsp90. Dobijeni rezultati ukazuju da je smanjena sposobnost GR za vezivanje hormona zapažena nakon in vitro tretmana kadmijumom, kod životinja injeciranih kadmijumom sprečena povećanom indukcijom Mt i Hsp.Projekat ministarstva br. 03E0

Cellular stress response: Defence against metal toxicity

All cells respond to various types of stress by increasing the transcription of specific genes that encode class of proteins termed stress proteins. This response is believed to represent a transient reprogramming of gene expression and biological activity, which serves to protect sensitive cellular components from damage, and assists in the rapid recovery after the stress is removed or ceases. The synthesis of stress proteins can be induced under a host of different stress conditions, including elevated level of metals. Although, understanding of the relationships between metals and their capacity to induce stress response is incomplete, these interactions are important to consider because they may reveal information regarding mechanisms of toxicity, cellular defense mechanisms against metal toxicity, and biochemical responses which can be exploited as biomarkers of exposure and toxicity of metals. This review is focused on two main classes of stress proteins, metallothioneins (MTs) and heat shock proteins (Hsps), which are usually induced in response to stress provoked by metals. It summarizes the results of studies on metals toxic effects and their ability to induce cellular stress response.Sve žive ćelije odgovaraju na različite tipove stresa povećavanjem transkripcije specifičnih gena koji kodiraju klasu proteina nazvanih stres proteini. Taj odgovor predstavlja prolazno reprogramiranje ekspresije gena i biološke aktivnosti, i služi da zaštiti osetljive ćelijske komponente od oštećenja, i pomogne u brzom oporavku posle uklanjanja ili prestanka delovanja stresa. Sinteza proteina stresa može biti indukovana pod delovanjem različitih stresogenih uslova, uključujući i povećani nivo metala. Pošto je razumevanje odnosa između metala i njihovog kapaciteta da indukuju odgovor na stres nedovoljno poznato, njihovo proučavanje je važno zato što može dati informacije o mehanizmima toksičnosti metala, ćelijskim odbrambenim mehanizmima i biohemijskim odgovorima koji se mogu koristiti kao biomarkeri izlaganja ili toksičnosti metala. Ovaj revijski članak je fokusiran na dve klase stres proteina, metalotioneina (MT) i proteina toplotnog stresa (Hsp), koje se najčešće indukuju u odgovoru na stres provociran metalima. Sumirani su rezultati istraživanja toksičnih efekata metala i njihove sposobnosti da indukuju ćelijski odgovor na stres

Rat liver tyrosine aminotransferase activity and induction by dexamethasone upon cadmium intoxication

This study was focused on Cd effects on basal and dexamethasone-induced tyrosine aminotransferase (TAT) activity in the rat liver cytosol. Cadmium (Cd), applied in the dose of 2 mg/kg b.w., stimulated both TAT activity and its induction by dexamethasone, inducing the most prominent alterations 24 h after administration. Doses lower than 2 mg Cd/kg b.w. were ineffective while the higher ones (3 and 4 mg Cd/kg b.w) led to the changes similar to those reached by 2 mg Cd/kg. The in vitro application of different Cd concentrations to the liver cytosol rendered the enzyme activity unchanged suggesting that the metal acted at the level of TAT gene transcription.Istraživanja su bila usmerena ka praćenju efekata Cd na osnovnu i deksametazonom indukovanu aktivnost tirozin aminotransferaze (TAT) u citosolu jetre pacova. Kadmijum (Cd) primenjen u dozi od 2 mg/kg telesne težine, stimulisao je i aktivnost TAT i indukciju enzima deksametazonom. Najizraženije promene su zapažene 24 h nakon injeciranja metala životinjama. Doze niže od 2mg/kg telesne težine nisu uticale na aktivnost enzima, dok su promene u prisustvu viših doza (3 i 4 mg Cd/kg telesne težine) bile približne onim zapaženim nakon tretiranja životinja sa 2 mg Cd/kg. Nepromenjena aktivnost enzima uočena nakon inkubiranja citosola jetre pacova sa različitim koncentracija Cd, sugerisala je da se uticaj metala ostvaruje na nivou transkripcije gena za tirozin aminotransferazu.nul

Rat liver tyrosine aminotransferase activity and induction by dexamethasone upon cadmium intoxication

This study was focused on Cd effects on basal and dexamethasone-induced tyrosine aminotransferase (TAT) activity in the rat liver cytosol. Cadmium (Cd), applied in the dose of 2 mg/kg b.w., stimulated both TAT activity and its induction by dexamethasone, inducing the most prominent alterations 24 h after administration. Doses lower than 2 mg Cd/kg b.w. were ineffective while the higher ones (3 and 4 mg Cd/kg b.w) led to the changes similar to those reached by 2 mg Cd/kg. The in vitro application of different Cd concentrations to the liver cytosol rendered the enzyme activity unchanged suggesting that the metal acted at the level of TAT gene transcription