0 10 Dependence dependence NN 11 14 for for IN 15 18 the the DT 19 32 proliferative proliferative JJ 33 41 response response NN 42 44 to to TO 45 59 erythropoietin erythropoietin NN 60 62 on on IN 63 65 an an DT 66 77 established established JJ 78 87 erythroid erythroid JJ 88 103 differentiation differentiation NN 104 111 program program NN 112 114 in in IN 115 116 a a DT 117 122 human human JJ 123 136 hematopoietic hematopoietic JJ 137 141 cell cell NN 142 146 line line NN 146 147 , , , 148 152 UT-7 UT-7 NNP 152 153 . . . 155 164 Erythroid erythroid JJ 165 180 differentiation differentiation NN 181 189 involves involve VBZ 190 193 the the DT 194 204 activation activation NN 205 207 of of IN 208 209 a a DT 210 216 number number NN 217 219 of of IN 220 238 erythroid-specific erythroid-specific JJ 239 244 genes gene NNS 244 245 , , , 246 250 most most JJS 251 253 of of IN 254 259 which which WDT 259 260 , , , 261 270 including include VBG 271 274 the the DT 275 281 globin globin NN 282 287 genes gene NNS 288 291 and and CC 292 295 the the DT 296 310 erythropoietin erythropoietin NN 311 319 receptor receptor NN 320 321 ( ( ( 321 326 Epo-R Epo-R NNP 326 327 ) ) ) 328 332 gene gene NN 332 333 , , , 334 337 are be VBP 337 338 , , , 339 341 at at IN 342 347 least least JJS 348 350 in in IN 351 355 part part NN 355 356 , , , 357 366 regulated regulate VBN 367 369 by by IN 370 373 the the DT 374 387 transcription transcription NN 388 394 factor factor NN 395 401 GATA-1 gata-1 NN 401 402 . . . 403 405 In in IN 406 411 order order NN 412 414 to to TO 415 425 understand understand VB 426 429 the the DT 430 442 relationship relationship NN 442 443 , , , 444 446 if if IN 447 450 any any DT 450 451 , , , 452 459 between between IN 460 470 expression expression NN 471 473 of of IN 474 480 GATA-1 gata-1 NN 480 481 , , , 482 490 response response NN 491 493 to to TO 494 497 Epo Epo NNP 498 501 and and CC 502 511 erythroid erythroid JJ 512 527 differentiation differentiation NN 527 528 , , , 529 531 we we PRP 532 540 analyzed analyze VBD 541 544 the the DT 545 555 expression expression NN 556 558 of of IN 559 565 GATA-1 gata-1 NN 565 566 , , , 567 572 Epo-R epo-r NN 573 576 and and CC 577 583 globin globin NN 584 589 genes gene NNS 590 592 in in IN 593 595 an an DT 596 609 Epo-dependent epo-dependent JJ 610 615 human human JJ 616 620 cell cell NN 621 625 line line NN 625 626 , , , 627 631 UT-7 UT-7 NNP 632 635 Epo Epo NNP 635 636 . . . 637 640 The the DT 641 648 results result NNS 649 653 were be VBD 654 662 compared compare VBN 663 665 to to TO 666 671 those those DT 672 680 obtained obtain VBN 681 685 with with IN 686 689 the the DT 690 698 parental parental JJ 699 721 granulocyte-macrophage granulocyte-macrophage JJ 722 740 colony-stimulating colony-stimulating JJ 741 747 factor factor NN 748 749 ( ( ( 749 766 GM-CSF)-dependent gm-csf)-dependent JJ 767 771 cell cell NN 772 776 line line NN 776 777 , , , 778 782 UT-7 UT-7 NNP 782 783 , , , 784 789 which which WDT 790 793 has have VBZ 794 795 a a DT 796 809 predominantly predominantly RB 810 826 megakaryoblastic megakaryoblastic JJ 827 836 phenotype phenotype NN 837 840 and and CC 841 843 is be VBZ 844 850 unable unable JJ 851 853 to to TO 854 865 proliferate proliferate VB 866 878 continuously continuously RB 879 881 in in IN 882 885 the the DT 886 894 presence presence NN 895 897 of of IN 898 901 Epo Epo NNP 901 902 . . . 903 907 UT-7 UT-7 NNP 908 911 Epo Epo NNP 912 915 and and CC 916 920 UT-7 UT-7 NNP 921 930 expressed express VBD 931 938 similar similar JJ 939 945 levels level NNS 946 948 of of IN 949 955 GATA-1 gata-1 NN 956 960 mRNA mrna NN 961 964 and and CC 965 972 binding binding NN 973 981 activity activity NN 981 982 . . . 983 986 The the DT 987 990 two two CD 991 996 lines line NNS 997 1001 also also RB 1002 1011 expressed express VBD 1012 1022 comparable comparable JJ 1023 1029 levels level NNS 1030 1032 of of IN 1033 1038 Epo-R Epo-R NNP 1039 1043 mRNA mRNA NNP 1044 1049 while while IN 1050 1053 the the DT 1054 1060 number number NN 1061 1063 of of IN 1064 1075 Epo-binding epo-binding JJ 1076 1081 sites site NNS 1082 1084 on on IN 1085 1089 UT-7 UT-7 NNP 1090 1093 Epo Epo NNP 1094 1099 cells cell NNS 1100 1103 was be VBD 1104 1113 one-sixth one-sixth JJ 1114 1117 the the DT 1118 1124 number number NN 1125 1127 of of IN 1128 1132 UT-7 ut-7 NN 1133 1138 cells cell NNS 1139 1140 ( ( ( 1140 1144 2400 2400 CD 1145 1148 +/- +/- SYM 1149 1150 3 3 CD 1151 1154 vs. vs. IN 1155 1161 13,800 13,800 CD 1162 1165 +/- +/- SYM 1166 1169 300 300 CD 1169 1170 ) ) ) 1170 1171 . . . 1172 1176 This this DT 1177 1187 difference difference NN 1188 1190 in in IN 1191 1194 the the DT 1195 1201 number number NN 1202 1204 of of IN 1205 1212 binding bind VBG 1213 1218 sites site NNS 1219 1224 could could MD 1225 1227 be be VB 1228 1231 due due JJ 1232 1234 to to TO 1235 1246 differences difference NNS 1247 1249 in in IN 1250 1254 cell cell NN 1255 1262 surface surface NN 1263 1264 ( ( ( 1264 1268 UT-7 ut-7 NN 1269 1274 cells cell NNS 1275 1278 are be VBP 1279 1281 20 20 CD 1281 1282 % % NN 1283 1290 smaller small JJR 1291 1295 than than IN 1296 1299 the the DT 1300 1308 parental parental JJ 1309 1313 UT-7 ut-7 NN 1314 1319 cells cell NNS 1319 1320 ) ) ) 1321 1323 or or CC 1324 1326 in in IN 1327 1335 receptor receptor NN 1336 1344 turnover turnover NN 1344 1345 . . . 1346 1348 By by IN 1349 1357 Northern northern NN 1358 1366 analysis analysis NN 1366 1367 , , , 1368 1372 UT-7 UT-7 NNP 1373 1378 cells cell NNS 1379 1388 expressed express VBD 1389 1399 detectable detectable JJ 1400 1406 levels level NNS 1407 1409 of of IN 1410 1415 beta- beta- NN 1416 1419 and and CC 1420 1432 gamma-globin gamma-globin NN 1433 1436 but but CC 1437 1440 not not RB 1441 1453 alpha-globin alpha-globin NN 1453 1454 . . . 1455 1457 In in IN 1458 1468 comparison comparison NN 1468 1469 , , , 1470 1474 UT-7 UT-7 NNP 1475 1478 Epo Epo NNP 1479 1484 cells cell NNS 1485 1494 expressed express VBD 1495 1507 alpha-globin alpha-globin NN 1508 1511 and and CC 1512 1518 higher high JJR 1519 1525 levels level NNS 1526 1528 of of IN 1529 1541 gamma-globin gamma-globin NN 1542 1543 ( ( ( 1543 1549 5-fold 5-fold JJ 1549 1550 ) ) ) 1551 1554 and and CC 1555 1566 beta-globin beta-globin NN 1567 1568 ( ( ( 1568 1572 from from IN 1573 1579 barely barely RB 1580 1582 to to TO 1583 1590 clearly clearly RB 1591 1603 detectable). detectable). VB 1604 1610 Globin globin NN 1611 1617 chains chain NNS 1618 1619 ( ( ( 1619 1624 alpha alpha NN 1624 1625 , , , 1626 1630 beta beta NN 1631 1634 and and CC 1635 1640 gamma gamma NN 1640 1641 ) ) ) 1642 1646 were be VBD 1647 1654 clearly clearly RB 1655 1665 detectable detectable JJ 1666 1668 by by IN 1669 1677 affinity affinity NN 1678 1692 chromatography chromatography NN 1693 1695 in in IN 1696 1700 UT-7 UT-7 NNP 1701 1704 Epo Epo NNP 1705 1708 but but CC 1709 1712 not not RB 1713 1715 in in IN 1716 1720 UT-7 ut-7 NN 1721 1726 cells cell NNS 1726 1727 . . . 1728 1731 The the DT 1732 1741 frequency frequency NN 1742 1744 of of IN 1745 1748 the the DT 1749 1754 cells cell NNS 1755 1760 which which WDT 1761 1770 expressed express VBD 1771 1776 beta- beta- NN 1777 1780 and and CC 1781 1787 gamma- gamma- NN 1788 1794 globin globin NN 1795 1800 genes gene NNS 1801 1803 in in IN 1804 1807 the the DT 1808 1811 two two CD 1812 1816 cell cell NN 1817 1828 populations population NNS 1829 1832 was be VBD 1833 1841 measured measure VBN 1842 1844 by by IN 1845 1863 immunofluorescence immunofluorescence NN 1864 1868 with with IN 1869 1874 beta- beta- NN 1875 1878 and and CC 1879 1893 gamma-specific gamma-specific JJ 1894 1904 antibodies antibody NNS 1904 1905 . . . 1906 1909 The the DT 1910 1916 number number NN 1917 1919 of of IN 1920 1934 gamma-positive gamma-positive JJ 1935 1940 cells cell NNS 1941 1944 and and CC 1945 1950 their their PRP$ 1951 1963 fluorescence fluorescence NN 1964 1973 intensity intensity NN 1974 1978 were be VBD 1979 1985 higher high JJR 1986 1988 in in IN 1989 1993 UT-7 UT-7 NNP 1994 1997 Epo Epo NNP 1998 2002 than than IN 2003 2005 in in IN 2006 2010 UT-7 ut-7 NN 2011 2016 cells cell NNS 2017 2018 ( ( ( 2018 2019 0 0 CD 2020 2022 to to TO 2023 2025 17 17 CD 2025 2026 % % NN 2027 2033 barely barely RB 2034 2042 positive positive JJ 2043 2048 cells cell NNS 2049 2052 and and CC 2053 2055 23 23 CD 2056 2058 to to TO 2059 2061 40 40 CD 2061 2062 % % NN 2063 2070 clearly clearly RB 2071 2079 positive positive JJ 2080 2085 cells cell NNS 2085 2086 , , , 2087 2099 respectively respectively RB 2099 2100 ) ) ) 2100 2101 , , , 2102 2112 indicating indicate VBG 2113 2117 that that IN 2118 2121 the the DT 2122 2130 increase increase NN 2131 2133 in in IN 2134 2140 globin globin NN 2141 2145 mRNA mRNA NNP 2146 2154 observed observe VBN 2155 2157 in in IN 2158 2162 UT-7 UT-7 NNP 2163 2166 Epo Epo NNP 2167 2169 is be VBZ 2170 2173 due due IN 2174 2176 to to TO 2177 2181 both both CC 2182 2184 an an DT 2185 2193 increase increase NN 2194 2196 of of IN 2197 2201 gene gene NN 2202 2212 expression expression NN 2213 2216 per per IN 2217 2221 cell cell NN 2222 2225 and and CC 2226 2228 an an DT 2229 2237 increase increase NN 2238 2240 in in IN 2241 2248 numbers number NNS 2249 2251 of of IN 2252 2257 cells cell NNS 2258 2268 containing contain VBG 2269 2281 gamma-globin gamma-globin NN 2281 2282 . . . 2283 2286 The the DT 2287 2293 levels level NNS 2294 2296 of of IN 2297 2303 GATA-1 gata-1 NN 2303 2304 , , , 2305 2310 Epo-R epo-r NN 2311 2314 and and CC 2315 2321 globin globin NN 2322 2326 mRNA mrna NN 2327 2336 expressed express VBN 2337 2341 were be VBD 2342 2345 not not RB 2346 2354 affected affect VBN 2355 2357 by by IN 2358 2359 a a DT 2360 2367 24-hour 24-hour JJ 2368 2378 incubation incubation NN 2379 2381 of of IN 2382 2388 either either DT 2389 2393 cell cell NN 2394 2398 line line NN 2399 2403 with with IN 2404 2407 Epo Epo NNP 2407 2408 , , , 2409 2415 GM-CSF GM-CSF NNP 2416 2418 or or CC 2419 2432 interleukin-3 interleukin-3 NNP 2433 2434 ( ( ( 2434 2440 IL-3). IL-3). NNP 2441 2442 ( ( ( 2442 2450 ABSTRACT ABSTRACT NNP 2451 2460 TRUNCATED truncated VBN 2461 2463 AT at IN 2464 2467 400 400 CD 2468 2473 WORDS words NNS 2473 2474 ) ) )