BRCA2 has an important role in the maintenance of genome stability by interacting with RAD51 recombinase through its C-terminal domain. This interaction is abrogated by cyclin A-CDK2-mediated phosphorylation of BRCA2 at serine 3291 (Ser3291). Recently, we showed that cyclin D1 facilitates RAD51 recruitment to BRCA2-containing DNA repair foci, and that downregulation of cyclin D1 leads to inefficient homologous-mediated DNA repair. Here, we demonstrate that cyclin D1, via amino acids 20-90, interacts with the C-terminal domain of BRCA2, and that this interaction is increased in response to DNA damage. Interestingly, CDK4-cyclin D1 does not phosphorylate Ser3291. Instead, cyclin D1 bars cyclin A from the C-terminus of BRCA2, prevents cyclin A-CDK2-dependent Ser3291 phosphorylation and facilitates RAD51 binding to the C-terminal domain of BRCA2. These findings indicate that the interplay between cyclin D1 and other cyclins such as cyclin A regulates DNA integrity through RAD51 interaction with the BRCA2 C-terminal domain.

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Background: Allergen extracts have been applied to treat allergic diseases. Accordingly, a housefly (Musca domestica) extract is commonly used to treat patients severely allergic to housefly. Objective: To evaluate 3 common methods, including grinding, sonication, and homogenization, for effective preparation of housefly allergen extracts. Methods: Housefly allergens were extracted from Musca domestica using 3 different methods, including grinding, sonication, and homogenization. Protein concentrations and profiles in the extracts were determined by Bradford assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. Results: The protein concentrations of the extracts prepared by grinding (mean [SD], 911.3 [159.7] µg/µL) and sonication (mean [SD], 905.7 [188.6] µg/µL) as measured by Bradford assay were significantly higher than those prepared by homogenization (mean [SD], 674.5 [60.0] µg/µL). Moreover, SDS-PAGE showed more protein bands in the extracts prepared using grinding and sonication compared to those prepared using homogenization. Conclusions: In comparison to homogenization, both grinding and sonication methods are superior ways to prepare housefly allergen extracts as evidenced by the higher quantities and composition of proteins.