Transcription Factor Stat5 in Invasion and Metastatis of Human Breast Cancer
Abstract
Class IA PI3Ks are regarded the most important in regulating cell proliferation and tumorigenesis. The p55gamma protein is a regulatory subunit of class IA PI3K. In vitro study has demonstrated that the NH2-terminal of p55gamma is sufficient to bind the cell cycle regulatory protein pRb. Direct association between Ca++/calmodulin and p85 subunit of PI3K has been demonstrated by coimmunoprecipitation and affinity chromotography. Ca++/calmodulin directly interact with SH2 domains of p85, resulting inactivation of p110. The NH2-terminal and COOH terminal of p55gamma SH2 domains are 89% and 81% identical with that of p85 ,respectively. Here we addressed the issue of whether p55gamma associates with calmodulin in vitro in human 293T cells. Using calmodulin-conjugated sepharose beads we analyzed the Flag-tagged p55gamma cDNA transfected cells. The cell cycle profile of HEK293 cells stable expressing Flag-tagged p55gamma were analyzed by flow cytometry. Our experiments demonstrated that overexpression of p55gamma in HEK293 cells promoted cell cycle progression. Our data also show a calcium-dependent calmodulin-p55gamma interaction in human 293T cells, and the overexpression of FLAG-tagged p55gamma stabilized the interaction between calmodulin and retinoblastoma protein. We propose that p55gamma protein regulate cell cycle progression through formation of a ternary complex with calmodulin and Rb.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2006
- Accession Number
- ADA456004
Entities
People
- Youhong Wang
Organizations
- Georgetown University