Characterization of ABF-1 in C. elegans and regulation of cellular growth and ID3 by human ABF-1
ABF -1 is a human class II bHLH transcription factor that is expressed predominantly in activated B cells and EBV immortalized cell lines. A portion of this study sought to characterize the homolog of ABF- l in Caenorhabditis e/egans. The nematode gene product, ceABF -1, is capable of forming heterodimers with E2A gene products and binding E box binding sites. HeLa cells transfected with ceABF-1 reveal that it is capable of blocking E2A mediated gene transcription. In order to maintain full repression capabilities, two conserved amino acid residues within helix I ofthe HLH domain are required. These results show a conserved mechanism of gene repression between invertebrates and vertebrates. This study also sought to analyze ABF-1 mediated regulation of both ld3 and cellular growth. Using a human ABF-1 stably transfected cell line, ID3 protein levels and transcript levels were shown to increase in response to overexpression of ABF-1 via western and northern blot, respectively. Flow cytometry analysis and Real-time PCR revealed that ABF-1 programs a slow down in the cell cycle, however this growth arrest is not mediated by ID3.
Genetic transcription, Cellular control mechanisms, Caenorhabditis elegans, B cells, Biology, Life Sciences
Networked Digital Library of Theses and Dissertations