| 1. |
- Ehinger, Mats, et al.
(författare)
-
Involvement of the tumor suppressor gene p53 in tumor necrosis factor-induced differentiation of the leukemic cell line K562
- 1995
-
Ingår i: Cell Growth and Differentiation. - 1044-9523. ; 6:1, s. 9-17
-
Tidskriftsartikel (refereegranskat)abstract
- The cDNA of the human wild-type p53 tumor suppressor gene was constitutively overexpressed in the leukemic cell line K562 (which lacks detectable amounts of p53 protein) in order to investigate the consequences for growth and differentiation. Several stable clones were established by transfection of the expression vector pc53SN3. Expression of p53 protein was characterized by biosynthetic labeling and immunoprecipitation with the monoclonal antibodies pAb 1801 (reacting with wild-type and mutant human p53), pAb 240 (reacting with mutant human p53) and pAb 1620 (reacting with wild-type human p53). All clones which were 1801+, 240-, 1620- or 1801+, 240-, 1620+ were defined as "wild-type-like p53-expressing" clones. Our results show that expression of p53 protein is compatible with continuous proliferation of K562 cells. The growth characteristics of wild-type-like p53-expressing clones did not differ from that of control clones. However, the former were more sensitive than p53-negative control clones to growth inhibition by tumor necrosis factor (TNF), a cytokine with a potential role in growth and differentiation of myeloid leukemic cells. In addition, a 2- to 4-fold increase of the amount of hemoglobin, a marker of erythroid differentiation, was observed when wild-type-like p53 protein-expressing clones were incubated with TNF. This suggests that differentiation is the mechanism responsible for the increased TNF sensitivity of these clones. Our results support a role for p53 in mediating growth inhibitory and differentiation inducing signals by TNF.
|
|
| 2. |
- Lind, Thomas, et al.
(författare)
-
cDNA cloning and expression of UDP-glucose dehydrogenase from bovine kidney
- 1999
-
Ingår i: Glycobiology. - 0959-6658 .- 1460-2423. ; 9:6, s. 595-600
-
Tidskriftsartikel (refereegranskat)abstract
- We have isolated a cDNA encoding UDP-glucose dehydrogenase from a bovine kidney cDNA-library, the first mammalian cDNA clone published. [After submission of the manuscript, a study appeared describing the molecular cloning and characterization of the human and mouse UDP-glucose dehydrogenase genes(Spicer et al., 1998).] The enzyme catalyzes the conversion of UDP-glucose to UDP-glucuronicacid, an essential precursor in glycosaminoglycan biosynthesis. The cDNA has an open reading frame of 1482 nucleotides coding for a 55 kDa protein. Expression of the enzyme in COS-7 cells showed a 3-fold increase inUDP-glucose dehydrogenase activity; also, the C-terminal 23 amino acidswas shown not to be necessary for enzyme activity. Northernblots from human and mouse tissues reveal high expression in liver and low in skeletal muscle. Human tissues have a majortranscript size of 3.2 kilobases and a minor of 2.6 whereas mousetissues have a single 2.6 kilobase transcript. We have also developed a sensitive and direct assay using UDP-[14C]Glc as a substrate for detection of small amounts of UDPGDH activity.
|
|
