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Increased levels of the cell cycle inhibitor protein, dacapo, accompany 20‐hydroxyecdysone‐induced G1 arrest in a mosquito cell line

Gerenday, Anna, Fallon, Ann M.
Archives of insect biochemistry and physiology 2011 v.78 no.2 pp. 61-73
Culex, Aedes albopictus, protein kinases, complementary DNA, Aedes aegypti, proliferating cell nuclear antigen, Western blotting, steroid hormones, binding sites, phosphorylation, exons, interphase, synthetic peptides
When treated with the steroid hormone 20‐hydroxyecdysone (20E), C7‐10 cells from the mosquito, Aedes albopictus, arrest in the G1 phase of the cell cycle. To explore whether 20E‐mediated cell cycle arrest proceeds through increased levels of cell cycle inhibitor (CKI) proteins, we cloned the Ae. albopictus homolog of dacapo, the single member of the Cip/Kip family of CKI proteins known from Drosophila melanogaster. The Ae. albopictus dacapo cDNA encoded a 261‐amino acid homolog of the Aedes aegypti protein XP_001651102.1, which is encoded by an ∼23 kb gene containing three exons. Like dacapo from D. melanogaster, the ∼27 kDa protein from Aedes and Culex mosquitoes contained several S/TXXE/D motifs corresponding to potential protein kinase CK2 phosphorylation sites, and a binding site for proliferating cell nuclear antigen (PCNA). When extracts from cells treated with 20E were analyzed by western blotting, using a primary antibody to synthetic peptides from the mosquito dacapo protein, up‐regulation of an ∼27 kDa protein was observed within 24 h, and the abundance of the protein further increased by 48 h after hormone treatment. This is the first investigation of a cell cycle inhibitory protein in mosquitoes. The results reinforce growing evidence that 20E affects expression of proteins that regulate cell cycle progression. © 2011 Wiley Periodicals, Inc.