Cell cycle regulation of the endogenous wild type Bloom's syndrome DNA helicase.
Bloom's syndrome (BS) is a rare human autosomal recessive disorder characterized by an increased risk to develop cancer of all types. BS cells are characterized by a generalized genetic instability including a high level of sister chromatid exchanges. BS arises through mutations in both alleles of the BLM gene which encodes a 3' - 5' DNA helicase identified as a member of the RecQ family. We developed polyclonal antibodies specific for the NH2- and COOH-terminal region of BLM. Using these antibodies, we analysed BLM expression during the cell cycle and showed that the BLM protein accumulates to high levels in S phase, persists in G2/M and sharply declines in G1, strongly suggestive of degradation during mitosis. The BLM protein is subject to post-translational modifications in mitosis, as revealed by slow migrating forms of BLM found in both demecolcine-treated cells and in mitotic cells isolated from non-treated asynchronous populations. Phosphatase treatment indicated that phosphorylation events were solely responsible for the appearance of the retarded moieties, a possible signal for subsequent degradation. Together, these results are consistent with a role of BLM in a replicative (S phase) and/or post-replicative (G2 phase) process. Oncogene (2000).
Dutertre
S
S
Centre National de la Recherche Scientifique, Unité Mixte de Recherche 1598, Institut Gustave Roussy, 39 Rue Camille Desmoulins, 94 805 Villejuif Cedex, France.
Ababou
M
M
Onclercq
R
R
Delic
J
J
Chatton
B
B
Jaulin
C
C
Amor-Guéret
M
M
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D001816:Bloom Syndrome / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D003703:Demecolcine / Q000494:pharmacology; D016195:G2 Phase; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis; D010447:Peptide Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational; D053484:RecQ Helicases; D016196:S Phase; D014407:Tumor Cells, Cultured
D011480:Protease Inhibitors; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; D003703:Demecolcine