We are interested in the mechanisms by which genes are transcriptionally regulated and how these processes can malfunction to cause disease. All genes are packaged in the nucleus as chromosomes (or “chromatin”) by associating with small basic proteins called “histones” and other factors. We have directed our efforts towards understanding how transcriptional regulation is achieved through chromatin using genes that are controlled by very distinct processes: developmental regulation and tumorigenesis. The human ?-globin gene family is an important paradigm of mammalian tissue-specific and developmental gene regulation. Our studies reveal that activation of the adult ?-globin gene by the zinc finger-containing transcription factor EKLF is achieved in combination with a specific mammalian chromatin remodeling complex, SWI/SNF. We have demonstrated that SWI/SNF shows selectivity in the types of transcription factors that it functions with and the genes that it regulates. Using recombinant proteins and chromatin-assembled genes, we demonstrate that only two subunits of SWI/SNF are required to interact with zinc finger DNA-binding proteins to catalyze targeted interaction with chromatinized genes. Moreover, we observe functional specificity among different types of SWI/SNF complexes. We are extending this analysis to address the larger issue of how chromatin remodeling/modifying complexes are directed towards specific gene programs during the transition between tissue proliferation and differentiation. To analyze gene regulation during tumorigenesis, we have focused on the tumor suppressor protein, p53. p53 is a DNA-binding transcription factor that controls distinct programs of gene expression in response to DNA damage and cellular stress. The importance of this protein is that it is mutated in the majority of all human cancers thus impairing the normal processes of cell cycle arrest and apoptosis. To decipher how p53 regulates these critical processes to prevent malignancy, we have conducted biochemical and cell-based analyses that reveal distinct transcriptional mechanisms utilized by this tumor suppressor to determine cell fate. We are currently examining how p53 directs the recruitment of RNAP II and specific cofactors to its diverse target promoters before and after stress to generate the appropriate transcriptional response and how this fails in human cancers. In addition, we are identifying which chromatin complexes are recruited to specific genes and determining the mechanism by which they are selectively targeted to establish programmed patterns of gene expression. These issues are being explored using embryonic stem cells, to analyze normal mechanisms of gene programming that regulate cell fate; and during early stages of tumorigenesis, to examine how these mechanisms go awry to initiate genomic instability.