Molecular Analysis of the cellular function of PAX3-FKHR

[[abstract]]PAX3 is an important transcription factor in muscle cell development. The PAX3-FKHR fusion protein is formed as a result of t(2;13)(q35;q14) chromosomal transcription, and it functions as a transcription factor like PAX3, but with a higher transcriptional activity than PAX3. In cancer research, PAX3-FKHR is a marker for alveolar rhabdomyosarcoma (ARMS). ARMS cells have not only PAX3-FKHR but also PAX3. Do these two different proteins affect each other’s transcriptional ability? Furthermore, during mitotic phase, transcription factors will leave mitotic chromosomes, but our laboratory had found that PAX3 still resided on mitotic chromosomes during mitotic phase. Therefore, we would like to know if PAX3-FKHR has a different localization pattern from that of PAX3. We found that PAX3-FKHR and PAX3 affected each other’s transcriptional activity on PAX3 target promoters, c-Met and MyoD core enhancer, by transcriptional assay. To determine if PAX3-FKHR located on mitotic chromosomes, we found, using fluorescence microscopy, that PAX3-FKHR have two different distribution patterns during mitotic phase. To understand why PAX3-FKHR has two different distribution patterns during mitotic phase, we performed co-immanoprecipitation and found that the PAX3-FKHR FKHR domain can interact with the PAX3PD domain. In summary, these results show that PAX3-FKHR and PAX3 affected each other’s transcriptional activity on their target promoters. During mitotic phase, PAX3-FKHR had two different distribution patterns, which might be caused by the FKHR domain