PAS proteiny jako stresové senzory vývojové regulátory J. Vondráček I Per-Arnt-Sim -nadrodina proteinů PAS environmentálni senzory, které zprostředkovávají transkripční odpověď na různé typy stimulů: cirkadiánní rytmy - vnímání světelných podnětů; vnímání hladiny kyslíku; *S sensing of toxicants; *S vývojové regulace - deregulovány v nádorových onemocněních; Tyto proteiny umožňují adaptaci na rychlé změny v prostředí. PAS proteiny jsou součástí širší rodiny basic-helix-loop helix (bHLH) proteinů: Existují 3 hlavní podskupiny bHLH proteinů: (a) pouze s bHLH doménou; nebo ty, kde bHLH doména navazuje na druhou dimerizační doménu: (b) doménu leucinových zipů (Zip) nebo (c) PAS doménu. Bask helix-loop-helix PAS L Leu-X-X- Leu-Leu Nuclear hurmone receptor-interaction domain P300 and CBP interaction domain PAS proteiny (rodina transkripčních faktorů): Dioxin,'Liver development ahr bHLH n n" AR NT I l25l AHRR II I I PAS Variable 14 13 100 aa Hypoxia signalin g hifio/mofi EPA61/MQP2/ HIF2«L HIF3a II35I I 23 11 : Ibsl I 23 I 12 I 21 13 Neurogenesis ARNT2 SIM1/SIM2 SIM2/SIM1 IE 16 21 23 13 10 11 Circadian MOP3/BMAL1/Cycle NPA62/MQP4 Clock Pa-1,2ľid3 MQP9 I 1411 I IS" TL J5_ 12 22 16 I 14 I 26 18 15 I Orphans HPAS1/MOP5 H PAS3/MOP6 j j I Coactivators 5RC-1 TIF2 RAC3 23 23 13 http://mcardle.oncology.wisc.edu/bradfield/ PAS doména PAS oblast obsahuje 2 sousedící opakování -130 aminokyselin, PAS A and PAS B. Tato doména je velmi starý signalizační prostředek, který zůstává zachován v průběhu evoluce. Byla identifikována v proteinech živočichů, bakterií, hub, kvasinek a rostlin: řada bakterií obsahuje PAS-like proteiny, které detekují světlo a kyslík (Dos, Aer, FixL, PYP); podobné proteiny vnímají světlo u rostlin (fytochromy PhyA-PhyE, NPH1; faktor interagující s fytochromem -PIF3). Struktura a funkce domén Ah R a ARNT: Dimerizace Ligand/HSP90/X AP2 binding AhR protein NLS bHLH PAS N B NLS Dimerizace TAD Arnt protein Variabilní konec TAD 100 aa Annu Rev Pharmacol Toxicol. 2000;40:519-61. AhR • transkripční faktor aktivovaný Ugandy; prostřed ková vá toxicitu řady environmentálních polutantů; reguluje metabolizaci xenobiotik a podílí se na bioaktivaci promutagenů. Jak byl objeven AhR? různá citlivost inbredních myších kmenů na indukci aktivity enzymů (CYP1A) v jaterních mikrozómech po expozici TCDD a 3-methylcholanthrenu - 60. léta; • autozomálně dominantní typ dědičnosti; • izolace unikátního proteinu; klonování genu -90. léta B r Br N, 2-azido-3-[,J5l]-7,8-dibromo-dibenzo-p-dioxin 200 kDa ISkDa 89 kDa 52 kl)a PAS domain bHT.H A B Q-rich ligand and hsp90 binding AhR:Arnt:DRE complex formation Josephy and Mannervik, Molecular Toxicology 2nd ed. Arthropods Nematoda Priapula Ecdysozoa Evoluce a AhR: Mollusca Annelida Platylielminthes Brachiopoda Echinodermata Hemichordata Lopholrochozoa AHR1 AHR2 AHRR Totrapods Fundutus AHR2 zabraSsh AHR2 human AHR mouse AHR FundutusAHRI zebmtish ahri mouse AHRR human AHRR Fundutue AHRR Drosopttlia AHR C. elegans AHR Invertebrate phyla Chem. Biol. Interact (2002) 141:131 Evoluce a AhR: Organism: Name: Ligand-binding: Physiological function: Nematodes: Caenorhabditis elegans AHR-1 No Neuronal development; Behavioral effects. Insects: brosophila melanogaster Spineless (Ss) No Development; Regulation of homeobox genes and dendrite Vertebrates: AhR (AhRl, AhR2) t Yes J ^ox^ development; Neuronal differentiation? Orcadian rhytms? Toxické AhR Ugandy nfľlassicflľ?AhR IJgands and CľVPI A1 Inducers Cl -či Cl Cl II II 'O' Cl Cl ci^^^0^^^\Ci '—' 1—v cr v o v ^-ci 3^4Jf.4.r5-Peatachloroblpbeavt 2J.7.8-TetraehtQrodIbenzafuraii Benzoť^pvmie Annu. Rev. Pharmacol. Toxicol. 43:309 Polycyklické aromatické uhlovodíky (PAHs) vážný regionální problém v ČR -doprava; průmyslová výroba; 250 200 £P 150 S 100 - 50 - ■ PASU ■ PANU □ oxidované PAU □ alkylované PAU ■ ostatní PAU ■ 16 US EPA PAU B Třeboň Praha Poruba Bartovice Karviná 160 140 -120 -100 80 - 60 40 - 20 ■ PASU ■ PANU □ oxidované PAU □ alkylované PAU ■ ostatní PAU □ 16 US EPA PAU B B B Třeboň Praha Poruba Bartovice Karviná 2,3,7,8-tetrachlórdibenzo-p-dioxin li i jedna z nejtoxičtějších látek vznikajících činností člověka; modelový zástupce této skupiny, definující jejich toxicitu; Dioxiny a kontaminace potravin Langlebiges Gift Ein Dioxin-Skandal erschüttert Deutschland: Hühner, Puten und Schweine haben auf deutschen Bauernhöfen vergiftetes Futter gefressen. Ein Futtermittelhersteller hatte technische Fette aus der Diesel-Produktion für Tiernahrung genutzt. Über Eier oder Fleisch nehmen Menschen die Dioxine auf, wo sie sich in Leber und Gewebe einlagern. Dioxiny a lidské zdraví: I Cl V červenci 1976 došlo k malé chemické továrně zhruba 15 km severně od Milána k explozi a zamoření okolí 2,3,7,8-tetrachlorodibenzo-p-dioxinem (TCDD) Cl Cl NaOH Cl Cl OH high temp. Cl-V^5^ Cl Cl Cl t L Vietnam - Agent Orange Spolana Neratovice - pracovní expozice Endogenní a přírodní Ugandy AhR??? Annu. Rev. Pharmacol. Toxicol. 43:309 Jiné přírodní Ugandy AhR??? Annu. Rev. Pharmacol. Toxicol. 43:309 Toxické účinky dioxinů: Epithelial hyperplasia Tumor promotion Induction of drug-metabolizing enzymes Altered ER signaling Porphyria Deregulated lipid metabolism Decreased serum thyroxine Wasting Metabolism of arachidonic acid to biologically active products Persistent thyroid hormone receptor activation EGF receptor down-regulation Lipid peroxidation Immunosuppression Inhibition of gluconeogenesis Teratogenesis/eiribryotoxicity Utilization of brown adipose tissue Vitamin A depletion Cardiac dysfunction Figure I Biological responses to TCDD. A wide variety of cellular processes have been shown to be affected by TCDD. Schmidt & Bradfield, Annu. Rev. Cell Dev. Biol. 12:55 Aktivace Ah R: Aktivace AhR: LIGAND »2 ^ lig.-rr! OO rtsp90 ■ Imrmunophilin j^J 26S proleasome O UbtquilLn Fig. 1. Model of AI IR-mediated signal transduction pathway, (J) Ligand enters cell. (2) Ligand binds to AHR-hsp90-immunophilin complex causing conformational change and exposing the NLS domain. (3) A11R complex is actively imported into the nucleus via NLS and nuclear import receptors. (4a) If receptor complex is in a misfolded conformation, it ma\ be proteolytically degraded. i.4.i AHR dissociates from hspLX) and immunophilin exposing Mill PAS domain and NLS. (5) AHR dirnerizes with ARN I-blocking NLS sequence. {(■>) AMR ARNI complex binds to XRE regions in DNA. (7) AIIR ARNI complex dissociates from DNA and ARN I exposing NES. (Sa) AHR is ubiquinated in the nucleus and degraded or (8) AMR is exported from nucleus via CRM-I export receptor. (9) AMR is ubiquinated in cytoplasm and (10) targeted to 26S proteasome for degradation. Note that the pathway is linear and also note the degradation of the AMR terminal step regardless of whether it occurs within the nucleus or cytoplasm. NI.S. nuclear localization signal: CRM-I. chromosome region maintenance protein 1; 26S. 26S proteasome. Chemico-Biological Interactions 141 (2002)41-61 Aktivace AhR: Geny regulované AhR obsahují v promotorové nebo enhancerové oblasti tzv. xenobiotic response elements (XRE) / dioxin responsive elements (DRE): • enzymy I. fáze biotransformace - CYP1A1, CYP1A2, CYP 1B1; • enzymy II. fáze biotransformace - UDP-glucuronosyltransferase, GST-Ya, NADP(H):oxidoreductase; • regulátory buněčného cyklu, apoptózy, diferenciace, senescence - Bax?, p27KiP\ JunD, TGF-fi • AhRR. AhR deficientní myši • růstová retardace; • narušení vývoje jater a imunitního systému; • hromadění retinoidů v játrech; • abnormální vaskularizace ledvin a jater; • řada efektů v imunitním systému a hematopoéze; • odolné vůči karcinogenním účinkům BaP a teratogenitě TCDD; Jaterní defekty: +/+ -t- Flg. 1. 4fi -/- mice have smaller hepatocytesthan wild-type mice. Livers of 1-year-old mice were fixed in formalin, and 6-fiin sections were examined afterstainingwith hematoxylin/eosin. (A and B) Thin sections from wild-type (A) and age-matched Ah knockout IB) mice are shown, and results of mor-phometric analyses follow. (O There is a significant decrease in the total area of the hepatocytes of Ah -/- mice, {D and F) Whereas the cytoplasmic area of Ah -/- hepatocytes is significantly decreased (D), the nuclear areas of Ah +/+ and Ah -/- hepatocytes are not different (E). Mean and standard errors generated from comparison of six 1-year-old male Ah +/+ and six age- and sex-matched ,4 b -/- miceareshown; asterisks indicate significance (P < 0,05), +/+ Arnt fxneo/fxneo Ahr cannula D r^ivc DV-cannula ^ E > I G ^IVC cannula "V 1 X BV V Time Walisser et al., J Biol Chem 2004;279:16326-31 BaP nenf karcinogennf v AhR KO mysich AhR fl- Ac tin Fig. 1. Cyp1s1, Cypla2, and AhR gene expression in the skin and liver of AhR(-i-/-i-)< AhR(+/-), and AhR(-/-) micer with and without B[a]P treatment. One-rnicrograrn aliquots of R N A extracted f ro m skin and liver of control and B[a]P-treated mice of the three genotypes we re reverse-transcribed and analyzed by PCR using specific primers for the Cyplal, Cyp1s2, and AhR and 3-actin genes. ahr( ) AhR(+/-) AhH(+/+) i i 3 « 9 e 7 t t 9 10 11 15 13 14 15 If 17 16 Weeks Fig. 2. Subcutaneous tumor induction in wild-type (a) and AhR-deficient male mice (+/-, □; -/-, o) injected with B[a]P. Fig. 3. Gross appearance of flank skins in AhR-wild-type mice [+/+), AhR-heterozygous mice (+/-), and AhR-deficient mice (-/-) injected subcutane-ously with B[a]P. Shimizu et ai, PNAS 2000;97: 779-82 I AhR a imunitní systém - or ? Aryl hydrocarbon Receptor expression + Eo Innate ^—S NKT J (T) Adaptive Seminars in Immunology 23 (2011) 99-105 AhR a imunitní systém Endogenous ligands Pollutants JT Dietary ligands Commensal flora AHR activation Foxp3 transactivation Foxp3 demethylation lSTAT-1 activation tCD39 +IL-2 production tlL-10 t IL-21 t Granzyme B tlL-22 t IL-21 ISTAT-5 activation t Aiolos IIL-2 production Seminars in Immunology 23 (2011) 99-105 AhR je nezbytný pro imunotoxické účinky TCDD: Koncepce toxických ekvivalentních faktorů (TEF) I vzhledem k tomu, že látky dioxinového typu mají společný mechanismus účinku - aktivaci AhR, lze předpokládat, že jejich schopnost aktivovat tento receptor je úměrná jejich toxicitě; referenční toxikant - TCDD; TEF pro jsou definovány WHO; Toxicita směsi - TEQ = Z[Cj] x TEFj Toxické ekvivalentní faktory (TEF) TABLE 1 Summary of WHO 1998 and WHO 2005 TEF Values Compound WHO 1998 TEF WHO 2005 TEF Chlorinated dibenzo-p-dioxins 2,3,7,8-TCDD 1 1 1,2,3,7,8 -PeCDD 1 1 1,2,3,4,7,8-HxCDD 0.1 0.1 1,2,3,6,7,8-HxCDD 0.1 0.1 1,2,3,7,8,9-HxCDD 0.1 0.1 1,2,3,4,6,7,8-HpCDD 0.01 0.01 OCDD 0.0001 0.0003 Chlorinated dibenzofurans 2,3,7,8-TCDF 0.1 0.1 1,2,3,7,8-PeCDF 0.05 0.03 2,3,4,7,8-PeCDF 0.5 0.3 1,2,3,4,7,8-HxCDF 0.1 0.1 1,2,3,6,7,8-HxCDF 0.1 0.1 1,2,3,7,8,9-HxCDF 0.1 0.1 2,3,4,6,7,8-HxCDF 0.1 0.1 1,2,3,4,6,7,8-HpCDF 0.01 0.01 1,2,3,4,7,8,9-HpCDF 0.01 0.01 OTDF n mm ftftilfrt Non-ort/u>-substituted PCBs 3,3',4,4-tetraCB (PCB 77) 0.0001 0.0001 3,4,4' ,5-teiraCB (PCB 81) 0.0001 0.0003 3,3',4,4',5-peniaCB (PCB 126) 0.1 0.1 33'A4'^^'-hexaCB (PCB 169) 0.01 (►.03 Mono-tfrt/io-subsriluled PCBs 2,3,3',4,4-pentaCB (PCB 105) 0.0001 0.00003 23,4,4',5-pentaCB (PCB 114) 0.0005 0.00003 2,3',4,4',5-pentaCB (PCB 118) 0.0001 11.00003 2',3,4,4',5-pentaCB (PCB 123) 0.0001 0.00003 2,3,3',4,4',5-hexaCB (PCB 156) 0.0005 0.00003 2,3,3,4,4',5'-hexaCB (PCB 157) 0.0005 0.00003 2,3',4,4',5,5'-hexaCB (PCB 167) 0.00001 0.00003 2,3,3 ,4,4,5,5 -heptaCB (PCB 189) 0.0001 0.00003 Bold values indicate a change in TEF value. van den Berg et ai, Toxicol Sci, 2006;93:223-41 AhR interaguje s řadou dalších proteinů TABLE 1. Interactions Between Signal Transduction Pathways and AhR"'' Interactions Refermcts Direct interactions with AhR HSP90 [79] XAP2 [80-82] ER, ERRu [24] NFKB(RelA/p65) [39] Rb [44-46] RlP140rp30O/CBP [41,51,53] SRC-l,NCoA-2,pCIP [41,54] ERAF140,SMRT [49,50] COUP-TF1 [24] pp60"rc [70,71] tyrosine phosphorylation [69] Direct interactions with AhR complex proteins HIF-la, PAS proteins (ARNT) [32,35 ] p300/CBP(ARNT) [52] SRC-l,NCoA-2(ARNT) [54] SHP (ARNT) [78] AhRR (ARNTj [20] ARNT Repressor (ARNT) [21] CK2(XAP2) 1741 p23 (HSP90) [76] XAP2 (HSP90) [80] Indirect interactions (cross talk) with AhR ER [8,2529] hypoxia [33,36] NFkB [40-42] PKC [59-66] tyrosine kinases/phospha tases [69,72,73] c-?nyr,AP-l,CK2 [72] TCF-fJ [7] p27(Kipl) [43] NF-1 [27] C2-ceramide 1471 J.R Petrultx. G.H. Perdew Chemlco-Biological Interactions 141 (2002) 25-40 r0$> AhR XAP2 Fig. 4, Model for the arrangement of prciteins found in the imliganckd AliR complex O. Hankinson I Archives of Biochemistry una Biophysics 433 (2005) 379 386 XREs CCA AT TATA Fig. 3. Hypothetical model of to activator recruitment at the Cyplal gene. J Biochem Mol Toxicol 16:317-325, 2002; AhR-ERoc crosstalk E2 CYP1A1 I CYP1B1 + * Decreased E2 ■+■ Inhibition of E2-inducad genes Direct Inhibition of deactivator binding E2 ^_ Limiting levels \A reactivators E2 tf2 #3 #4 ERp ciovm*roguijtlt>n \^ Limit (prolaa somes | 1 levels of ERa Figure 3, Proposed mechanisms of inhibitory AhR-KRa crosstalk {123- 126). Safe et Wormke, Chem Res Toxicol, 2003;16:807-16 Využití AhR-ERa crosstalk v nádorové terapii? TABLE I Effects of 17/3-Estradlo] and TCDD on Cell Cycle Distribution of MCF-7 Human Breast Cancer Cells3 Treatment Cell cycle phase (%) (time, h) s Gz/M ( oiit.ro! 89.9 ± 2.1 4.9 + 1.6 5.2 ± 0.6 E2 (12) 87.7 ± 2.1 6.0 1 -1 4.4 ± 0.7 E2 + TCDD (12) 87.2 ± 0.2 7.9 + 0.7 4.9 ± 0.5 TCDD (12) 89.1 ± 0.8 C.7 + 0.S 4.2 ± 0.2 I 1-2 (24) 75.1 ± Ü.C 23.4 + 1.7* 1.5 ± 1.2 1 E2 + TCDD (24) S 1.0 ± 1.3ř 1S.S + 1.8rf 3.2 ± 0.7 TCDD (24) 90.8 ± 0.6 5.2 0.5 4.0 ± 0.9 r E2 I E2+T Tirnc(h) U G 12 24 6 12 24 r T n 12 24 cd k4 activity**>m i GST-Rií cdk2 activity-*- h1 2 3 10 1200c I 10000 u hm ^ 6000 > a. 4000 0 1 2000 B 1200 0 10000 g 300« 600 0 4o00 2o00 n o > o I- C 12000 I 10000 Control -*~TAM 100 jig/kg TAM 50 jig/kg TAM 25 ng/kg 3 5 -*- Control -*- 6-MCDF 100 ng/kg — 6-MCDF 50 ng/kg -°-6-MCDF 25 ^g/kg 17 19 £1 17 19 21 *-• • Control -^*-TAM 100 ng/kg + 6-MCDF 100 ^g/kg -*-TAM 50 ^g/kg +■ 6-MCDF 50 ngfl• cdk2 activity g »1 M I SO * 1511 ■ DM50 PCB 136 cdk4 activity 8 u DMSO FCB 1ZE Histone H1 ■ B Kŕ f ŕ ŕ a* to cyclin A/cdk2 activity WB-F344 Ulona Ann v reguiaci buněčného cyklu je pravděpodobně složitější MCF-7 Control Early S-phase (left): 2.6% Late S-phase : 3.7% Total BrdU positive: 6.6% BaA Early S-phase (left): 7,6% Late S-phase fright): 7 3% Total BrdU positive: 14.9% ARNT - zakladni dimerizacni partner: AhR Fig. 4, ARNT is central to transcriptional regulation within the Mill I PAS family of proteins. ARNT forms both homodimers and heterodimers with the AhR, HIF-a and SIM which play roles both during mammalian development and in response to environmental stimuli in mammals. Symbol '?' indicates where these roles have yet to be characterised. The InternationalJournal of Biochemistry & Cell Biology 36 (2004) 189-204 Faktor indukovaný hypoxií- HIF1 HIF-a The International journal of Biochemistry & Cell Biology 36 (2004) 189-204 HIF proteiny: HIF-1cc HIF-2a HIF-3a1 IPAS/HIF-3a2 HIF-3a3 HIF-3a4 HIF-3a5 HIF-3a6 bHLH PAS ODD Ň-TAD c-tad 1-1 I I 870 -- -' ■ LZIP ( ■ 8 1 ■ 632 m j 663 Biochimica et Biophysica Acta 1755 (2005) 107 -120 Buněčné prostředí mění hladinu HIF: Induction enzyme expression /m of 11 Iron Ascorbate 2-Oxoglutarate Growth, differentiation and apoptosis Iron metabolism Intermediates and cofactors of energy metabolism reactions Graded HIF responses to O2 and cellular environment ODD / \ Phosphorylation Acetylation Growth factors, oncogenes, tumour suppressor pathways Mosson, N. et a I. J Cell Sci 2003;116:3041-3049 Table 2. HIF-1 target genes. Function Gene (abbreviation) Rjeference Ervxhropoieds/ iron metaboliiiu Er-JnopoLetm (IPO) Tim^ferrin (Tf) Ti^^ferrin receptor (T&) i">r.ilr.iVfmiiii (Semenza et al, 1991) (Rjolfs et al, 1997) (Bianchiet al., 1999) [Lok and Psnka. 1999) Angiogenesis. Vascular endothelial growth factor (VEGF) EndscTine-glacd-derived VEGF (EG-VEGF) Leptin (LEP) _::m-;ibmur,g growth factor-betaj (TGF- |V3) (Levyet al., 1995) (LeCouter et al, 2001) (Grosfeld et al. 2002) (Scheid e: al.. 2002) Vascular tone Nlttíc oxide ^jTitha^e (NOS2) Heme cxygenease'. Endsthelin 1 (ET1) A.drenorjoedulin (ADM) ijl3-adre^er2Íc- :ecep:cr (Melillo et al, 1995) [Lee e: al.. '.99 7) [Fm e: al.. 1995) [Nguyen and Clavcomb, 1999) (EckhartetaL 199/) Matrix metabolism Mhtlx Eaetalloproteinase& fMMFs) Plasminogen activator recepton and mbibrcrs (PAls) Collagen prolyl hydroxylase [Ben-Yo&ef et al. 2002) [Kie:zmami ec al, 1999) (Takahashi et al, 2000) Glucose metabolism adenylate kinase-3 A.ldolase-A_C (ALDA:C) Carbonic aimydraíe-9 Enolase-1 (ENOl) Glucose transporter-l .3 (GLU1,3) GlyceTaldelryde phosphate dekvdrosenase (GAPDH) HeKokinase 1:2 (HK1,2) Laerate dehydrogenase-A (LDHA) PyniYarekinaseM(FKM) rWphofructoltiiia&e L (PFKL) Pho^phcgrycerate kinase 1 (PGK1) 5-pho&phořhic:3 -2 -k inase-;.gnicto£e-2,6-bisphos.pha:e-3 ÍPFKTB3) (ORourke et al, 1996) (Semenza et al.. 1996) (Wykoffetal,2000) (Semenza et al.. 1996) (Chen etal, 2001) (Graven et al, 1999) (Mathupala et al, 2001) (Semenza et al, 1996) (Semenza et al, 1994) (Semenza et al, 1994) (Semenza et al, 1994) (Minclienko ec aL 2002) Cell proliferation/ survival [n&ulin-like growth facr.or-2 (IGF2) Transforming growth factor-a {TGF- a) AdrenoDQfidullin (AD\-Q (Feldser et al, 1999) (Knshnaniacliarv et al.. 2003) (Cormier-Re eard et al, 199S) Apoptosia Bcl-2-'adenovirus: EJB 19kD-inceractÍDí prctein 3 (BNip3) Nip3-like prorem X (X2v> (Carrerc et al, 2000) (Bruick 2000) Molecular Pharmacology doi:10.1124/mol.106.0270 29 ARNT - zakladni dimerizacni partner - vzajemna kompetice?? Yfa\ L|aal<1 1 Transcription —( XRE [)—H Target gene Arnt Hypoxia Normoxia * Prolyl hydroxylase (HIF-1a Degradation Ubiq u rtin-proteasome 1 Transcription —Q "1 - ~Q—H Target gene (4 (HIM^) Pathway V^^^ OH Myre a Imbeoult, 2013, Obesity Reviews, doi: 10.1111/obr.l2086 ? AhR-HIF-1a crosstalk ? PL1A1N Integrated CYP1AVDRE3 SV40 LUC O 75 S 5D ° 25 WT HIM a null (b) 21% 02 I I 1%02 7ig. 3. Enzymatic activity (A) and gene expressions} of CYPIAI. late of conversion of ethoxyresorufim (A) was assayed in WT and lIF-la null cultures under norraoxia {21% O2, black bars) or hy-joxia (1% 02. groy bars) with 5 3-MC tor24 b. CYP1AI mKNA evels (B) were measured by real time PGR after 8 h of normoxia black} or hypoxia (grey) with 5 jjl.M >MC and normalized to un-reated, nonnoxic controls. Values are the mean and standard error or n = 3: *p <0.05; 44/> < 0.01; "*p < 0.001. JBC274, 12115-12123, 1999 Toxicology Letters 155 (2005) 151-159 Regulace cirkadiánních rytmů (Comprehensive Toxicology, vol. 14) Regulace cirkadiánních rytmů CL0CK/BMAL1 heterodimer kontroluje expresi genů závislou na cirkadiáních rytmech - PER, CRY-zpětněvazebná regulace vlastní exprese; Clock outputs - Sleep-wake cycle Hormonal oscillations « Body temperature • Cell cycle • Metabolism - Feeding rhythms Nature Rev Cancer 9 (2009): 886-896 AhR-retinoid receptors crosstalk SOME SYNTHETIC RETINOIDS Physiological and Pharmacological Levels Pharmacological RARa RAR ß RAR y ATRA CQ2H AhR I FIGURE 2 Schematic representation of the AhR/Arnt signaling pathway indicating the five steps (see text for descriptions) that have been shown to be modulated by specific retinoids. AhR HipaoJ) —► TCDD a naphthoflavone benzo[a]pyrene |CYP1A1 dre -* J. Nutr. 133: 277S-281S, 2003. TABLE 2 Effects of Ah Receptor Ligands on Enzyme Activities Involved in Retinoid Metabolism1 Effect Tissue Reference Rctinoic acid glucuronidation T T liver, kidney liver Bank et al. 19&9 Sass et al 1994 Retinole acid oxidation t T" liver liver liver Spear et al 1988 Fiorella et al. 1995 Andreo la et al. 1997 Retinol esterification hepatic stellate cells Nilsson ct ah 1996 kidney Nilsson et al. 200Ü Retiny 1 ester hydrolysis ±0 liver Nilsson et al. 2000 1 TCDD was used in all stjdies except Sass el al. 1994 (3-meihylGholanthrerie) and Spear et al. 1998 (3,3\4,4\5,5,4iexabromobipheny1). All stjdies were on rats except Andreola et a\. 1997 {mice) JBC (2004) 279(24):25284-93.