Regulation of proliferating cell nuclear antigen during the cell cycle

Morris, G. F., Mathews, M. B. (August 1989) Regulation of proliferating cell nuclear antigen during the cell cycle. J Biol Chem, 264 (23). pp. 13856-64. ISSN 0021-9258



The proliferating cell nuclear antigen (PCNA), also known as cyclin and DNA polymerase delta auxiliary factor, is present in reduced amounts in nongrowing cells and is synthesized at a greater rate in the S phase of growing cells. The recently discovered involvement of PCNA in DNA replication suggested that this pattern of expression functions to regulate DNA synthesis. We have investigated this possibility further by examining the synthesis, stability, and accumulation of PCNA in HeLa cells fractionated by centrifugal elutriation into nearly synchronous populations of cells at various positions in the cell cycle. In these fractionated cells we found that there is an increase in the rate of PCNA synthesis with a peak in early S phase of the cell cycle, but the magnitude of the increase is only 2-3-fold. This change reflects similar changes in the amount of PCNA mRNA. The fluctuating synthesis of PCNA maintains this protein at a roughly constant proportion of the total cell protein, although the amount doubles/cell in the cell cycle. Consistent with this observation, the stability of PCNA does not differ significantly from that of total cellular protein in synchronized HeLa cells. We also observed that a maximum of one-third of the total PCNA is tightly associated with the nucleus, presumably in replication complexes, at the peak of S phase. We conclude that the cyclic synthesis of PCNA in cycling HeLa cells maintains PCNA in excess of the amount involved directly in DNA replication and the amount of the protein neither fluctuates significantly with the cell cycle nor is limiting for DNA synthesis.

Item Type: Paper
Uncontrolled Keywords: Antigens, Neoplasm/isolation & purification *Cell Cycle Chromatin/metabolism DNA Replication DNA, Neoplasm/genetics/isolation & purification Flow Cytometry Hela Cells/cytology Humans Kinetics Methionine/metabolism Nuclear Proteins/*biosynthesis/genetics/isolation & purification Plasmids Proliferating Cell Nuclear Antigen Protein Binding RNA, Messenger/genetics/metabolism Research Support, U.S. Gov't, P.H.S. Thymidine/metabolism
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > Cyclins
organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > cell cycle
CSHL Authors:
Communities: CSHL labs
Depositing User: Gail Sherman
Date: 15 August 1989
Date Deposited: 26 Jun 2017 14:42
Last Modified: 26 Jun 2017 14:42
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