0 4 Role role NN 5 7 of of IN 8 13 HIV-1 HIV-1 NNP 14 17 Nef Nef NNP 18 28 expression expression NN 29 31 in in IN 32 42 activation activation NN 43 51 pathways pathway NNS 52 54 in in IN 55 59 CD4+ cd4+ JJ 60 61 T t NN 62 67 cells cell NNS 67 68 . . . 70 73 The the DT 74 78 role role NN 79 81 of of IN 82 85 the the DT 86 91 human human JJ 92 108 immunodeficiency immunodeficiency NN 109 114 virus virus NN 115 116 ( ( ( 116 121 HIV-1 HIV-1 NNP 121 122 ) ) ) 123 126 Nef Nef NNP 127 134 protein protein NN 135 137 in in IN 138 139 T t NN 140 144 cell cell NN 145 155 activation activation NN 156 164 pathways pathway NNS 165 168 was be VBD 169 181 investigated investigate VBN 182 187 using use VBG 188 189 a a DT 190 196 Jurkat Jurkat NNP 197 201 CD4+ cd4+ JJ 202 206 cell cell NN 207 211 line line NN 212 218 stably stably RB 219 230 transfected transfecte VBN 231 235 with with IN 236 237 a a DT 238 241 Nef Nef NNP 242 252 expression expression NN 253 259 vector vector NN 259 260 . . . 261 270 Secretion Secretion NNP 271 273 of of IN 274 278 IL-2 IL-2 NNP 279 282 and and CC 283 292 TNF-alpha TNF-alpha NNP 292 293 , , , 294 301 surface surface NN 302 312 expression expression NN 313 315 of of IN 316 321 IL-2R IL-2R NNP 321 322 , , , 323 326 and and CC 327 338 DNA-binding dna-binding JJ 339 347 activity activity NN 348 350 of of IN 351 359 NF-kappa NF-kappa NNP 360 361 B B NNP 362 365 and and CC 366 370 AP-1 AP-1 NNP 371 372 ( ( ( 372 379 Fos/Jun Fos/Jun NNP 379 380 ) ) ) 381 388 complex complex NN 389 391 in in IN 392 400 response response NN 401 403 to to TO 404 411 phorbol phorbol NN 412 421 myristate myristate NN 422 429 acetate acetate NN 429 430 , , , 431 440 TNF-alpha TNF-alpha NNP 440 441 , , , 442 444 or or CC 445 456 immobilized immobilize VBN 457 467 antibodies antibody NNS 468 470 to to TO 471 474 CD3 CD3 NNP 475 479 were be VBD 480 489 monitored monitor VBN 489 490 . . . 491 496 These these DT 497 507 parameters parameter NNS 508 512 were be VBD 513 516 not not RB 517 525 modified modify VBN 526 528 by by IN 529 532 Nef Nef NNP 533 543 expression expression NN 544 546 in in IN 547 553 Jurkat Jurkat NNP 554 559 cells cell NNS 559 560 , , , 561 568 whereas whereas IN 569 580 stimulation stimulation NN 581 585 with with IN 586 589 the the DT 590 594 same same JJ 595 602 stimuli stimulus NNS 603 611 resulted result VBD 612 614 in in IN 615 622 partial partial JJ 623 633 inhibition inhibition NN 634 636 of of IN 637 640 LTR LTR NNP 641 651 activation activation NN 652 654 in in IN 655 659 Nef+ nef+ JJ 660 666 Jurkat Jurkat NNP 667 672 cells cell NNS 672 673 . . . 674 678 This this DT 679 689 inhibition inhibition NN 690 693 was be VBD 694 697 not not RB 698 706 mediated mediate VBN 707 714 through through IN 715 718 Nef Nef NNP 719 734 phosphorylation phosphorylation NN 735 737 on on IN 738 744 Thr-15 Thr-15 NNP 745 747 or or CC 748 759 GTP-binding gtp-binding JJ 760 768 activity activity NN 769 776 because because IN 777 786 mutations mutation NNS 787 789 in in IN 790 798 critical critical JJ 799 804 sites site NNS 805 808 did do VBD 809 812 not not RB 813 818 alter alter VB 819 823 this this DT 824 834 inhibition inhibition NN 834 835 . . . 836 844 Analysis Analysis NNP 845 847 of of IN 848 857 truncated truncate VBN 858 862 LTRs ltr NNS 863 872 confirmed confirm VBD 873 877 that that IN 878 888 inhibition inhibition NN 889 891 of of IN 892 895 LTR LTR NNP 896 906 activation activation NN 907 910 was be VBD 911 914 not not RB 915 923 mediated mediate VBN 924 931 through through IN 932 940 NF-kappa NF-kappa NNP 941 950 B-binding b-binding JJ 951 959 activity activity NN 960 963 but but CC 964 971 through through IN 972 975 the the DT 976 982 region region NN 983 993 containing contain VBG 994 997 the the DT 998 1006 negative negative JJ 1007 1017 responding respond VBG 1018 1026 elements element NNS 1027 1028 ( ( ( 1028 1032 NREs NRE NNP 1032 1033 ) ) ) 1033 1034 . . . 1035 1040 These these DT 1041 1048 results result NNS 1049 1056 suggest suggest VBP 1057 1061 that that IN 1062 1065 Nef Nef NNP 1066 1079 downmodulates downmodulate VBZ 1080 1083 LTR LTR NNP 1084 1094 activation activation NN 1095 1102 without without IN 1103 1116 significantly significantly RB 1117 1127 inhibiting inhibit VBG 1128 1131 the the DT 1132 1140 capacity capacity NN 1141 1143 of of IN 1144 1145 T t NN 1146 1151 cells cell NNS 1152 1154 to to TO 1155 1162 respond respond VB 1163 1165 to to TO 1166 1179 immunological immunological JJ 1180 1191 activations activation NNS 1191 1192 . . .