Disease relevance of mus209

• Functional analysis using the reconstituted simian virus 40 in vitro DNA replication system demonstrated that Drosophila PCNA could substitute, albeit with reduced efficiency, for human PCNA in stimulating simian virus 40 DNA synthesis [1].
• The cellular transcription factor DRTF1/E2F is implicated in the control of early cell cycle progression due to its interaction with important regulators of cellular proliferation, such as pocket proteins (for example, the retinoblastoma tumour suppressor gene product), cyclins and cyclin-dependent kinase subunits [2].
• We describe two temperature-sensitive lethal alleles (mus209(B1) and mus209(2735)) of the Drosophila PCNA gene that, at temperatures permissive for growth, result in hypersensitivity to DNA-damaging agents, suppression of position-effect variegation, and female sterility in which ovaries are underdeveloped and do not produce eggs [3].
• Procedures were also developed for purification of unmodified wild-type Drosophila PCNA after induction of expression in Escherichia coli [4].

High impact information on mus209

• Negative regulation of dE2F1 by cyclin-dependent kinases controls cell cycle timing [5].
• While Drosophila fizzy has previously been shown to be required for cyclin destruction during M phase, fzr is required for cyclin removal during G1 when the embryonic epidermal cell proliferation stops and during G2 preceding salivary gland endoreduplication [6].
• Loss of fzr causes progression through an extra division cycle in the epidermis and inhibition of endoreduplication in the salivary gland, in addition to failure of cyclin removal [6].
• A cyclin-dependent kinase inhibitor, Dacapo, is necessary for timely exit from the cell cycle during Drosophila embryogenesis [7].
• Therefore, mitosis and consequently cyclin degradation might be triggered at a time when cyclins have reaccumulated to a critical level [8].

Chemical compound and disease context of mus209

• Bacteria were transformed with Escherichia coli expression plasmids coding for either unmodified proliferating cell nuclear antigen (PCNA) or PCNA containing a genetically engineered polyhistidine tract (his-tag) located at its NH2 terminus [9].

Biological context of mus209

• The eukaryotic DNA polymerase processivity factor, proliferating cell nuclear antigen, is an essential component in the DNA replication and repair machinery [10].
• Identification of plu genes and cis-acting elements of PCNA in the Drosophila genus using conservation of gene order [11].
• Dacapo, a cyclin-dependent kinase inhibitor, stops cell proliferation during Drosophila development [12].
• Temperature shift studies reveal that the vital function of PCNA is required throughout virtually all stages of fly development, and that maternally encoded PCNA is essential for embryogenesis [13].
• All three ts mutants strongly suppress PEV, which suggests a role for PCNA in chromatin assembly or modification [13].

Anatomical context of mus209

• Site-specific mutagenesis of Drosophila proliferating cell nuclear antigen enhances its effects on calf thymus DNA polymerase delta [14].
• The PCNA mRNA was detected at a high level in adult ovaries, unfertilized eggs, and early embryos and at low levels in the other developmental stages [15].
• On the basis of cell cycle markers and genetic interactions, we conclude that dcr-1 mutant GSCs are delayed in the G1 to S transition, which is dependent on the cyclin-dependent kinase inhibitor Dacapo, suggesting that miRNAs are required for stem cells to bypass the normal G1/S checkpoint [16].
• Chromatin assembly linked to the repair of single-strand breaks was disrupted by depletion of PCNA from a cell-free system [17].
• This pattern of Cdk1 inactivation would be consistent with local cyclin destruction at centrosomes or kinetochores [18].

Associations of mus209 with chemical compounds

• In Drosophila melanogaster, the cell cycle control gene, plutonium (plu), is located between the PCNA and RpS18 genes at position 56F on chromosome arm 2R [11].
• The coding sequence for a 260-amino-acid residue polypeptide was interrupted by a single short intron of 60 base pairs (bp), and about 70% of the deduced amino acid sequence of the Drosophila PCNA was identical to the rat and human PCNA polypeptides, with conserved unique repeats of leucine in the C-terminal region [15].
• NH2-terminal amino acid sequence analysis revealed that the putative Drosophila PCNA was highly homologous to human PCNA [1].
• Bromodeoxyuridine, origin recognition complex, and the elongation factors minichromosome maintenance proteins (MCM)2-7 and proliferating cell nuclear antigen were precisely localized, and the DNA copy number along the third chromosome chorion amplicon was quantified during multiple developmental stages [19].
• Interaction of DNA polymerase delta, proliferating cell nuclear antigen, and synthetic oligonucleotide template-primers. Analysis by polyacrylamide gel electrophoresis-band mobility shift assay [20].

Physical interactions of mus209

• The Drosophila cyclin-dependent protein kinase complex CycD/Cdk4 has been known to drive cellular growth (accumulation of mass) as well as proliferation (cell cycle progression) [21].
• During cell cycles 2-7, Cdc2/Cyclin complexes are continuously present and show little fluctuation in abundance, phosphomodification, or activity [22].
• The N-termini of xPontin and xReptin, which mediate the mitogenic effect were mapped to contain c-Myc interaction domains. c-Myc protein promotes cell cycle progression either by transcriptional activation through the c-Myc/Max complex or by repression of cyclin dependent kinase inhibitors (p21, p15) through c-Myc/Miz-1 interaction [23].
• Here, we demonstrate that the translational repressor Bruno binds the 3' UTR and inhibits the translation of the mitotic cyclin Cyclin A during prophase of meiosis I [24].

Enzymatic interactions of mus209

• BACKGROUND: We and others have shown four distinct and presumably related effects of mammalian proliferating cell nuclear antigen (PCNA) on DNA synthesis catalyzed by mammalian DNA polymerase delta(pol delta) [14].

Regulatory relationships of mus209

• Armadillo/Pangolin regulates PCNA and DREF promoter activities [25].
• Rca1 inhibits APC-Cdh1(Fzr) and is required to prevent cyclin degradation in G2 [26].
• Furthermore, a mutant form of the mitotic kinase Cdk1 that cannot be inhibited by phosphorylation drove a mitotic cyclin into the nucleus and overcame the delay of mitosis induced by irradiation [27].
• Here, we address whether these changes in cyclin expression are required for endoreduplication by continuously expressing Cyclin A, B, B3 or E in the salivary glands of Drosophila throughout late embryonic and larval development [28].

Other interactions of mus209

• G1 cyclin-dependent kinases are insufficient to reverse dE2F2-mediated repression [29].
• To test this, we genetically reduced mitotic cyclin levels and also examined repair in grp (DmChk1) and lok (DmChk2) mutants [30].
• We have found sequences similar to the transcription factor E2F recognition site within the Drosophila proliferating cell nuclear antigen (PCNA) gene promoter [31].
• Using primers within coding regions of PCNA and RpS18, we amplified and sequenced the intervening region from twelve Drosophila species [11].
• By transient luciferase expression assays and band mobility shift assays, we demonstrated the PCNA gene to be a direct target gene for the Armadillo/Pangolin complex [25].

Analytical, diagnostic and therapeutic context of mus209

• Genomic Southern blot hybridization analysis indicates the presence of a single gene for PCNA per genome [15].
• Affinity-purified anti-Drosophila PCNA antibodies cross-reacted with human PCNA and were able to recognize specifically Drosophila PCNA both on crude homogenate immunoblots and by indirect immunofluorescence analysis of proliferating cells in larval tissues in situ [1].
• Germline genomic instability in PCNA mutants of Drosophila: DNA fingerprinting and microsatellite analysis [32].
• However, Western blots showed that the level of PCNA protein in M phase-arrested embryos did not decrease [33].

References