, a Novel Transcription Factor and a Coregulator of Nuclear Factor B p65: Single Nucleotide Polymorphism and Estrogen Dependence.

T-cell leukemia 1A () single-nucleotide polymorphisms (SNPs) have been associated with aromatase inhibitor-induced musculoskeletal adverse events. We previously demonstrated that TCL1A is inducible by estradiol (E) and plays a critical role in the regulation of cytokines, chemokines, and Toll-like receptors in a SNP genotype and estrogen-dependent fashion. Furthermore, SNP-dependent expression phenotypes can be "reversed" by exposure to selective estrogen receptor modulators such as 4-hydroxytamoxifen (4OH-TAM). The present study was designed to comprehensively characterize the role of TCL1A in transcriptional regulation across the genome by performing RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) assays with lymphoblastoid cell lines. RNA-seq identified 357 genes that were regulated in a SNP- and E-dependent fashion with expression patterns that were 4OH-TAM reversible. ChIP-seq for the same cells identified 57 TCL1A binding sites that could be regulated by E in a SNP-dependent fashion. Even more striking, nuclear factor-B (NF-B) p65 bound to those same DNA regions. In summary, TCL1A is a novel transcription factor with expression that is regulated in a SNP- and E-dependent fashion-a pattern of expression that can be reversed by 4OH-TAM. Integrated RNA-seq and ChIP-seq results suggest that TCL1A also acts as a transcriptional coregulator with NF-B p65, an important immune system transcription factor.