Cyclin/PCNA is the auxiliary protein of DNA polymerase-δ

Abstract

Identification of the cellular proteins whose expression is regulated during the cell cycle in normal cells is essential for understanding the mechanisms involved in the control of cell proliferation. A nuclear protein called cyclin of relative molecular mass 36,000 (Mr 36K), whose synthesis correlates with the proliferative state of the cell, has been identified in several cell types of human, mouse, hamster and avian origin. The rate of cyclin synthesis is very low in quiescent cells and increases several fold after serum stimulation shortly before DNA synthesis. Immunofluorescence and autoradiography studies have shown that the nuclear staining patterns of cyclin during S phase have a sequential order of appearance and a clear correlation can be found between DNA synthesis and cyclin positive nuclei. The proliferating cell nuclear antigen (PCNA) and cyclin have many common properties and it has been shown that these two are identical. Recently a protein which is required by DNA polymerase-delta for its catalytic activity with templates having low primer/template ratios has been isolated from calf thymus. We report here that cyclin and the auxiliary protein of DNA polymerase-delta are identical.

Synergic effect of photodynamic therapy using talaporfin sodium with conventional anticancer chemotherapy for the treatment of bile duct carcinoma

“…49,50 More profound suppression of cancer cell proliferation activity in the PDT with anticancer drugs group than in the PDT alone was observed. Song et al 51 reported that leukotrienes and cytokines.…”

“…18 The administered solution was incubated at 37°C for 3 hours, later decantated and then washed three times in PBS. To induce LD 50 PDT conditions, a laser power of 12 J/cm 2 was chosen to irradiate the NOZ cells. The laser was irradiated for 1 minute.…”

Homologous regions of Fen1 and p21Cip1 compete for binding to the same site on PCNA: a potential mechanism to co-ordinate DNA replication and repair

“…PCNA is fundamental to nuclear DNA replication, acting as a sliding clamp that tethers the leading strand DNA polymerase d to its template, enhancing the enzyme's processivity (Prelich et al, 1987;Bravo et al, 1987;Krishna et al, 1994). In addition, PCNA is required for nucleotide excision repair (Shivji et al, 1992;Nichols and Sancar, 1992) and is involved in one pathway of base excision repair (Matsumoto et al, 1994).…”

Characterization of keratin and cell cycle protein expression in cell lines from squamous intraepithelial lesions progressing towards a malignant phenotype

“…PCNA is normally localized in the nucleus as an essential component of the replication mechanism (Bravo et al, 1987;Prelich et al, 1987). Besides its role in replication, it is directly involved in nucleotide excision repair (Shivji et al, 1992), and elevated expression is detected in response to DNA damage in vivo (Hall et al, 1993).…”