Investigating the Role of the Nucleosome Remodeling Factor INO80 in Development and NURF in Anti-Tumor Immunity

• Main Author: elsayed, zeinab abdallah, Ms
• Format: Others
• Published: VCU Scholars Compass 2016
• Online Access: http://scholarscompass.vcu.edu/etd/4663; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=5736&context=etd

Understanding how an epigenetic regulator such as ATP-dependent chromatin-remodeling complexes modulate processes such as development and/or immune response is essential for our comprehension of cell biology. Deletion of the ATP-dependent chromatin remodeling factor INO80 is known to be embryonically lethal, however, the mechanism is not known. To identify roles for INO80 in mouse early development we generated Ino80 KO mice. Ino80 KO ESCs (Embryonic stem cells) were viable when maintained at ground state pluripotency but fail to differentiate in vitro and in vivo. Gene expression analysis of Ino80 KO early embryos by in situ hybridization showed elevated Bmp4 expression and reduced expression of DVE (distal visceral endoderm) markers Cer1, Hex, and Lefty1. BMP4 is a known negative regulator of DVE differentiation in the early embryo. Molecular studies in Ino80 KO ESCs demonstrated that INO80 is bound to the Bmp4 promoter, and regulates its chromatin structure, to suppress the positive regulator SP1 from stimulating its transcription. These results, suggest that INO80 directly regulates the chromatin structure of the Bmp4 promoter with consequences to mouse embryo development. These results are significant because they demonstrate a specific role of INO80 in establishing P-D embryonic axis. NURF (Nucleosome remodeling factor) is another ATP-dependent chromatin remodeling complex that is overexpressed in many cancer types including breast cancer. To demonstrate the roles of NURF in breast cancer biology, we knocked-down the NURF essential subunit BPTF (bromodomain PHD finger transcription factor) in mouse breast cancer cell lines. Transplantation of these cell lines into immune-competent mice revealed that BPTF KD enhances NK cell antitumor activity. BPTF KD enhanced NK-92 cytotoxic activity toward BPTF KD cells by NKp30 activation in vitro. NK-92 activity is reduced by the addition of heparin to the culture medium, further indicating the involvement of NKp30 (in human) and NCR1 (in mice) in killing of tumor cells. We found that BPTF controls the abundance of NKp30/NCR1 ligands (heparin sulfate proteoglycans (HSPGs) by regulation of heparanase expression (endoglycosidase that degrades HSPGs). In addition, BPTF depletion in established mouse breast tumors enhanced anti-tumor immunity, without affecting NK or T cell cytotoxic activity, providing a novel immunotherapy target.