The Impact of M1775K Variant in BRCA1 Regulation

Abstract

The missense mutations of the BRCT domain of human BRCA1 have been argued to be associated with predisposition to hereditary breast/ovarian cancer. Mutations at the C-terminus of the protein are critical for function and structural excellence. This mutation has been associated with changes in the structure of the protein and loss of interaction with other peptides involved in cell cycle control. In previous studies we have shown that the modification of various mutants in BRCT domain, such as Met1775K is strongly affecting the functional and structural integrity of the domain and the binding affinity with phospopeptides.In the present study we have attempted to determine the effect of the M1775K mutation on the intracellular localization of the protein. For this purpose, GFPBRCA1-BRCT M1775K mutant was created and expressed in MCF-7 cell lines. Due to fluorescence microscopy determined that the mutation affects the protein's mislocalization in relation to wtBRCA1-BRCT protein. Mutant EGFP-BRCA1-BRCT M1775K form is mainly determined in the cytoplasm in contrast to the EGFPwtBRCA1-BRCT protein that localizes into nucleus and cytoplasm.Cytoplasmic mislocalization of M1775K mutation, presented here, may be related to disruption of BRCA1-BRCT folding. The M1775K mutation influences the nuclear transport of BRCA1-BRCT domain to the nucleus, suggesting that the impact of the integrity of the BRCA1-BRCT domain is crucial in functional and structural level.