Date of Award
Classical dendritic cells (cDCs) are a critical component of the immune system due to their roles in the maintenance of immune tolerance and the induction of adaptive immune responses. However, distinguishing cDCs from other myeloid populations is complicated by the lack of highly specific cDC markers. For example, high expression of the integrin CD11c is used to define cDCs, but this marker is also expressed at lower levels by plasmacytoid dendritic cells, monocyte and macrophage subsets, and some lymphocytes. Similarly, the use of the CD11c promoter to drive the expression of different reporters in cDCs likewise affects these additional populations. To identify a novel and more specific cDC marker, I compared the gene expression profiles of differentiated cDCs, committed cDC precursors (pre-DCs), monocytes, and myeloid progenitor populations by gene array. Enriching cDCspecific genes identified an uncharacterized zinc finger transcription factor that I call zDC (Zbtb46, Btbd4). This factor is expressed by cDCs but not other myeloid or lymphoid immune populations. The characterization of zDC expression and function involved three major directions. (1) To exploit cDC-specific expression of zDC, I produced zDC-DTR knock-in mice that express diptheria toxin receptor (DTR) regulated by the zDC locus. Consistent with zDC expression, DTR expression is limited to cDCs among hematopoietic cells and diptheria toxin (DT) injection depletes cDCs but not other populations. (2) To identify the target genes occupied and regulated by zDC, I performed chromatin immunoprecipitation-sequencing (ChIP-seq) on zDC from steady state cDCs. zDC bound upstream of the transcription start sites of over 1,000 genes at sequence-specific motifs. (3) To interrogate zDC function, I generated zDC-deficient mice by knocking out the second exon of the zDC locus. cDC development is unimpaired in zDCâ€“/â€“ mice, but steady state zDC-deficient cDCs upregulated zDC target genes identified by ChIP-seq in addition to maturation gene pathways. This steady state maturation results in impaired peripheral tolerance as well as enhanced skin-draining lymph node vascularization. Therefore, the zinc finger transcription factor zDC uniquely defines the cDC lineage and serves as a transcriptional repressor which maintains cDC quiescence in the steady state.
Meredith, Matthew M., "The Expression of the Zinc Finger Transcription Factor zDC Defines the Classical Dendritic Cell Lineage" (2012). Student Theses and Dissertations. 169.