0 10 UV-induced uv-induced JJ 11 17 CYP1A1 cyp1a1 NN 18 22 gene gene NN 23 33 expression expression NN 34 36 in in IN 37 42 human human JJ 43 48 cells cell NNS 49 51 is be VBZ 52 60 mediated mediate VBN 61 63 by by IN 64 74 tryptophan tryptophan NN 74 75 . . . 77 86 Induction Induction NNP 87 89 of of IN 90 100 cytochrome cytochrome NN 101 109 P-4501A1 p-4501a1 NN 110 111 ( ( ( 111 117 CYP1A1 cyp1a1 NN 117 118 ) ) ) 119 127 activity activity NN 128 130 by by IN 131 133 UV UV NNP 134 137 has have VBZ 138 142 been be VBN 143 151 observed observe VBN 152 159 earlier earlier RBR 160 162 in in IN 163 169 animal animal JJ 170 177 studies study NNS 178 181 via via IN 182 183 a a DT 184 193 mechanism mechanism NN 194 198 that that WDT 199 202 has have VBZ 203 206 not not RB 207 210 yet yet RB 211 215 been be VBN 216 224 resolved resolve VBN 224 225 . . . 226 229 Our our PRP$ 230 238 previous previous JJ 239 243 data datum NNS 244 248 have have VBP 249 258 indicated indicate VBN 259 263 that that IN 264 274 formylated formylate VBN 275 291 indolocarbazoles indolocarbazole NNS 292 297 which which WDT 298 301 are be VBP 302 308 formed form VBN 309 311 by by IN 312 314 UV UV NNP 315 326 irradiation irradiation NN 327 329 of of IN 330 340 tryptophan tryptophan NN 341 350 solutions solution NNS 351 354 are be VBP 355 359 very very RB 360 366 potent potent JJ 367 378 Ah-receptor Ah-receptor NNP 379 387 agonists agonist NNS 387 388 . . . 389 391 To to TO 392 400 evaluate evaluate VB 401 404 the the DT 405 411 effect effect NN 412 414 of of IN 415 417 UV UV NNP 418 423 light light NN 424 426 on on IN 427 437 cytochrome cytochrome NN 438 445 P4501A1 p4501a1 NN 446 450 gene gene NN 451 461 expression expression NN 461 462 , , , 463 465 we we PRP 466 473 studied study VBD 474 477 the the DT 478 487 induction induction NN 488 490 of of IN 491 497 CYP1A1 CYP1A1 NNP 498 502 mRNA mRNA NNP 503 505 by by IN 506 508 UV UV NNP 509 520 irradiation irradiation NN 521 523 of of IN 524 532 cultured culture VBN 533 538 human human JJ 539 552 keratinocytes keratinocyte NNS 553 554 ( ( ( 554 559 HaCaT HaCaT NNP 560 564 cell cell NN 565 569 line line NN 569 570 ) ) ) 570 571 , , , 572 579 primary primary JJ 580 585 human human JJ 586 591 blood blood NN 592 603 lymphocytes lymphocyte NNS 604 607 and and CC 608 613 mouse mouse NN 614 620 Hepa-1 hepa-1 NN 621 626 cells cell NNS 626 627 . . . 628 631 The the DT 632 637 cells cell NNS 638 642 were be VBD 643 650 exposed expose VBN 651 653 to to TO 654 656 UV UV NNP 657 662 light light NN 663 672 delivered deliver VBN 673 675 by by IN 676 677 a a DT 678 682 bank bank NN 683 685 of of IN 686 687 6 6 CD 688 695 Philips Philips NNP 696 705 TL20/12RS TL20/12RS NNP 706 709 sun sun NN 710 715 lamps lamp NNS 716 724 emitting emit VBG 725 734 primarily primarily RB 735 737 in in IN 738 741 the the DT 742 745 UVB uvb NN 746 751 range range NN 752 754 in in IN 755 758 the the DT 759 766 absence absence NN 767 770 and and CC 771 779 presence presence NN 780 782 of of IN 783 793 tryptophan tryptophan NN 793 794 . . . 795 796 A a DT 797 813 semiquantitative semiquantitative JJ 814 821 reverse reverse JJ 822 842 transcriptase-linked transcriptase-linked JJ 843 853 polymerase polymerase NN 854 859 chain chain NN 860 868 reaction reaction NN 869 870 ( ( ( 870 876 RT-PCR RT-PCR NNP 876 877 ) ) ) 878 881 was be VBD 882 886 used use VBN 887 890 for for IN 891 899 analysis analysis NN 900 902 of of IN 903 907 gene gene NN 908 918 expression expression NN 919 921 in in IN 922 925 the the DT 926 933 treated treat VBN 934 939 cells cell NNS 939 940 . . . 941 944 The the DT 945 952 results result NNS 953 957 show show VBP 958 962 that that IN 963 966 the the DT 967 973 CYP1A1 cyp1a1 NN 974 978 mRNA mrna NN 979 984 level level NN 985 992 induced induce VBN 993 995 by by IN 996 998 UV UV NNP 999 1001 in in IN 1002 1005 the the DT 1006 1014 presence presence NN 1015 1017 of of IN 1018 1028 tryptophan tryptophan NN 1029 1032 was be VBD 1033 1039 higher high JJR 1040 1044 than than IN 1045 1049 that that DT 1050 1057 induced induce VBN 1058 1060 by by IN 1061 1063 UV UV NNP 1064 1069 alone alone RB 1070 1072 in in IN 1073 1077 both both CC 1078 1083 HaCaT hacat NN 1084 1089 cells cell NNS 1090 1093 and and CC 1094 1105 lymphocytes lymphocyte NNS 1106 1111 after after IN 1112 1113 3 3 CD 1114 1115 h h NN 1116 1118 of of IN 1119 1129 incubation incubation NN 1130 1137 post-UV post-uv JJ 1138 1149 irradiation irradiation NN 1149 1150 . . . 1151 1153 To to TO 1154 1158 find find VB 1159 1162 out out RP 1163 1165 if if IN 1166 1169 the the DT 1170 1179 induction induction NN 1180 1182 by by IN 1183 1185 UV UV NNP 1186 1191 light light NN 1192 1194 is be VBZ 1195 1201 caused cause VBN 1202 1204 by by IN 1205 1208 the the DT 1209 1218 formation formation NN 1219 1221 of of IN 1222 1224 an an DT 1225 1227 Ah ah NN 1228 1236 receptor receptor NN 1237 1243 ligand ligand NN 1243 1244 , , , 1245 1251 Hepa-1 hepa-1 NN 1252 1261 wild-type wild-type JJ 1262 1265 and and CC 1266 1268 Ah ah NN 1269 1277 receptor receptor NN 1278 1287 deficient deficient JJ 1288 1291 c12 c12 NN 1292 1296 cell cell NN 1297 1302 lines line NNS 1303 1307 were be VBD 1308 1315 applied apply VBN 1315 1316 . . . 1317 1326 Wild-type wild-type JJ 1327 1328 ( ( ( 1328 1330 wt wt JJ 1330 1331 ) ) ) 1332 1337 cells cell NNS 1338 1342 were be VBD 1343 1352 inducible inducible JJ 1353 1359 either either CC 1360 1362 by by IN 1363 1366 the the DT 1367 1377 tryptophan tryptophan NN 1378 1390 photoproduct photoproduct NN 1391 1421 6-formylindolo[3,2-b]carbazole 6-formylindolo[3,2-b]carbazole NN 1422 1423 ( ( ( 1423 1427 FICZ FICZ NNP 1427 1428 ) ) ) 1429 1431 or or CC 1432 1434 by by IN 1435 1449 UV-irradiation UV-irradiation NNP 1450 1453 but but CC 1454 1458 very very RB 1459 1462 low low JJ 1463 1465 or or CC 1466 1478 undetectable undetectable JJ 1479 1485 levels level NNS 1486 1490 were be VBD 1491 1499 observed observe VBN 1500 1502 in in IN 1503 1506 the the DT 1507 1510 c12 c12 NN 1511 1516 cells cell NNS 1516 1517 . . . 1518 1522 This this DT 1523 1528 shows show VBZ 1529 1533 that that IN 1534 1537 the the DT 1538 1547 induction induction NN 1548 1550 of of IN 1551 1555 gene gene NN 1556 1566 expression expression NN 1567 1569 by by IN 1570 1574 FICZ FICZ NNP 1575 1578 and and CC 1579 1581 UV UV NNP 1582 1584 is be VBZ 1585 1587 Ah ah NN 1588 1596 receptor receptor NN 1597 1606 dependent dependent JJ 1606 1607 . . . 1608 1616 Together together RB 1616 1617 , , , 1618 1623 these these DT 1624 1631 results result NNS 1632 1640 indicate indicate VBP 1641 1645 that that IN 1646 1656 UV-induced uv-induced JJ 1657 1663 CYP1A1 cyp1a1 NN 1664 1668 gene gene NN 1669 1679 expression expression NN 1680 1682 in in IN 1683 1692 mammalian mammalian JJ 1693 1698 cells cell NNS 1699 1701 is be VBZ 1702 1710 mediated mediate VBN 1711 1713 by by IN 1714 1716 an an DT 1717 1719 Ah ah NN 1720 1728 receptor receptor NN 1729 1735 ligand ligand NN 1736 1742 formed form VBN 1743 1747 from from IN 1748 1758 tryptophan tryptophan NN 1758 1759 . . . 1760 1764 Thus thus RB 1764 1765 , , , 1766 1769 the the DT 1770 1783 photoproducts photoproduct NNS 1784 1786 of of IN 1787 1797 tryptophan tryptophan NN 1798 1801 are be VBP 1802 1811 suggested suggest VBN 1812 1814 to to TO 1815 1817 be be VB 1818 1827 mediators mediator NNS 1828 1830 of of IN 1831 1836 light light NN 1837 1840 via via IN 1841 1848 binding bind VBG 1849 1851 to to TO 1852 1855 the the DT 1856 1858 Ah ah NN 1859 1867 receptor receptor NN 1868 1871 and and CC 1872 1874 as as IN 1875 1879 such such JJ 1880 1884 also also RB 1885 1890 could could MD 1891 1895 have have VB 1896 1897 a a DT 1898 1902 role role NN 1903 1905 in in IN 1906 1921 light-regulated light-regulated JJ 1922 1932 biological biological JJ 1933 1940 rhythms rhythm NNS 1940 1941 . . .