Role of HGCP3-Psoriasin Interaction in Human Breast Cancer

摘要

The core of my hypothesis is that psoriasin, a protein shown to be aberrantly expressed at different stages of breast cancer, physically interacts with hGCP3, an indispensable component of the *-tubulin ring complex involved in centrosome function. Aims for the first year of the project were to determine if a Histidine-tagged hGCP3 (His-hGCP3) construct previously generated in our lab is biologically suitable for this study and to substantiate an interaction between psoriasin and hGCP3 in mammalian cells using immunofluorescent co-localization and biochemical co-immunoprecipitation (co-IP) assays. In the first year I have shown that the His-tag does not interfere with His-hGCP3 ability to interact with *-tubulin by co-IP assays; that expression of this construct does have a mild cytotoxic effect but is not completely lethal; that available psoriasin antibodies are not suitable for IF labeling therefore preventing co-localization studies with hGCP3, that psoriasin and His-hGCP3 cannot be consistently co-IP'ed suggesting at best, a weak or a possible cell-cycle dependent interaction exists. Using two assays to measure centrosome function, a quantitative assay for microtubule (MT) nucleation and a mitotic spindle morphology assay, I've further ascertained that psoriasin expression in does not alter centrosome function.