Ubiquitin-dependent degradation of cyclin B is accelerated in polyploid megakaryocytes

Ying Zhang, Zack Z. Wang, David X. Liu, Michele Pagano, Katya Ravid

Research output: Contribution to journalArticle

Abstract

During the endomitotic cell cycle of megakaryocytic cell lines, the levels of cyclin B1 and the activity of cyclin B1-dependent Cdc2 kinase, although detectable, are reduced as compared with megakaryocytes undergoing a mitotic cell cycle. The levels of cyclin A, however, are comparable during both cell cycles. The expression of cyclin B1 mRNA is also equivalent in proliferating and polyploidizing cells. In the current study, we found that the rate of cyclin B1 protein degradation is enhanced in polyploidizing megakaryocytes. This finding has led us to further investigate whether the ubiquitin-proteo some pathway responsible for cyclin B degradation is accelerated in these cells. Our data indicate that polyploidizing megakaryocytic cell lines and primary bone marrow cells treated with the megakaryocyte proliferation- and ploidy-promoting factor, the c-Mp1 ligand, display increased activities of the ubiquitin-protesome pathway, which degrades cyclin B, as compared with proliferating megakaryocytic cell lines or diploid bone marrow cells, respectively. This degradation has all the hallmarks of a ubiquitin pathway, including the dependence on ATP, the appearance of high molecular weight conjugated forms of cyclin B, and inhibition of the proteolytic process by a mutated form of the ubiquitin- conjugating enzyme Ubc4. Our studies also indicate that the ability to degrade cyclin A is equivalent in both the mitotic and endomitotic cell cycles. The increased potential of polyploid megakaryocytes to degrade cyclin B may be part of the cellular programming that leads to aborted mitosis.

Original languageEnglish (US)
Pages (from-to)1387-1392
Number of pages6
JournalJournal of Biological Chemistry
Volume273
Issue number3
DOIs
StatePublished - Jan 16 1998
Externally publishedYes

Fingerprint

Cyclin B
Cyclin B1
Polyploidy
Megakaryocytes
Ubiquitin
Cell Cycle
Cells
Cyclin A
Degradation
Cell Line
Bone Marrow Cells
Ubiquitin-Conjugating Enzymes
Ploidies
Diploidy
Mitosis
Proteolysis
Phosphotransferases
Adenosine Triphosphate
Molecular Weight
Bone

ASJC Scopus subject areas

  • Biochemistry

Cite this

Ubiquitin-dependent degradation of cyclin B is accelerated in polyploid megakaryocytes. / Zhang, Ying; Wang, Zack Z.; Liu, David X.; Pagano, Michele; Ravid, Katya.

In: Journal of Biological Chemistry, Vol. 273, No. 3, 16.01.1998, p. 1387-1392.

Research output: Contribution to journalArticle

Zhang, Ying ; Wang, Zack Z. ; Liu, David X. ; Pagano, Michele ; Ravid, Katya. / Ubiquitin-dependent degradation of cyclin B is accelerated in polyploid megakaryocytes. In: Journal of Biological Chemistry. 1998 ; Vol. 273, No. 3. pp. 1387-1392.
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