Biology subjects

Catizone, A. N.

Publications and source records attributed to Catizone, A. N..

3 recordsLinked to original sources

bioRxiv2019

Locally acting transcription factors are required for p53-dependent cis-regulatory element activity

The master tumor suppressor p53 controls transcription of a wide-ranging gene network involved in apoptosis, cell cycle arrest, DNA damage repair, and senescence. Recent studies revealed pervasive binding of p53 to cis-regulatory elements (CRE), which are non-coding segments of DNA that spatially and temporally control transcription through the combinatorial binding of local transcription factors (TFs). Although the role of p53 as a strong trans-activator of gene expression is well known, the co-regulatory factors and local sequences acting at p53-bound CREs are comparatively understudied. We designed and executed a massively parallel reporter assay (MPRA) to investigate the effect of transcription factor binding motifs and local sequence context on p53-bound CRE activity. Our data indicate that p53-bound CREs are both positively and negatively affected by alterations in local sequence context and changes to co-regulatory TF motifs. We identified a SP1/KLF family motif located in an intronic p53 CRE that is required for the endogenous expression of the p53-dependent gene CCNG1. We also identified ATF3 as a factor that co-regulates the expression of the p53-dependent gene GDF15 through binding with p53 in an upstream CRE. Loss of either p53 or ATF3 severely reduces CRE activity and alters endogenous GDF15 mRNA levels in the cell. Our data suggests that p53 has the flexibility to cooperate with a variety of transcription factors in order to regulate CRE activity. By utilizing different sets of co-factors across CREs, we hypothesize that p53 activity is guarded against loss of any one regulatory partner allowing for dynamic and redundant control of p53-mediated transcription.

molecular biology↗

bioRxiv2018

Comparison of genotoxic vs. non-genotoxic stabilization of p53 provides insight into parallel stress-responsive transcriptional networks

The tumor suppressor protein p53 is activated in response to diverse intrinsic and extrinsic cellular stresses and controls a broad cell-protective gene network. Whether p53:DNA binding and subsequent transcriptional activation differs downstream of these diverse intrinsic and extrinsic activators within the same cell type is controversial. Using primary human fibroblasts, we assessed the genome-wide profile of p53 binding, chromatin structure, and transcriptional dynamics after either genotoxic or non-genotoxic activation of p53. Activation of p53 by treatment with either etoposide or the small molecule MDM2 inhibitor nutlin 3A yields strikingly similar genome-wide binding of p53 and concomitant changes to local chromatin modifications and structure. DNA damage, but not p53 activation per se, leads to increased expression of genes in an inflammatory cytokine pathway. Etoposide-mediated activation of this inflammation signature is inhibited by treatment with the NF-kB pathway inhibitor Bay 11-7082, but does not affect expression of canonical p53 target genes. Our data demonstrate that differential activation of p53 within the same cell type leads to highly similar genome-wide binding, chromatin dynamics, and gene expression dynamics, and that DNA damage-mediated signaling through NF-{kappa}B likely controls the observed pro-inflammatory cytokine gene expression pattern.

genomics↗

bioRxiv2018

The transcription factor Tfap2e/AP-2ε plays a pivotal role in maintaining the identity of basal vomeronasal sensory neurons

The identity of individual neuronal cell types is defined by the expression of specific combinations of transcriptional regulators that control cell type-specific genetic programs. The epithelium of the vomeronasal organ of mice contains two major types of vomeronasal sensory neurons (VSNs): 1) the apical VSNs which express vomeronasal 1 receptors (V1r) and the G-protein subunit Gi2 and; 2) the basal VSNs which express vomeronasal 2 receptors (V2r) and the G-protein subunit Gao. Both cell types originate from a common pool of progenitors and eventually acquire apical or basal identity through largely unknown mechanisms.\n\nThe transcription factor AP-2{varepsilon}, encoded by the Tfap2e gene, plays a role in controlling the development of GABAergic interneurons in the main and accessory olfactory bulb (AOB), moreover AP-2{varepsilon} has been previously described to be expressed in the VSNs. Here we show that AP-2{varepsilon} is expressed in postmitotic VSNs after they commit to the basal differentiation program. Loss of AP-2{varepsilon} function resulted in reduced number of basal VSNs and in an increased number of neurons expressing markers of the apical lineage. Our work suggests that AP-2{varepsilon}, which is expressed in late phases of differentiation, is not needed to initiate the apical-basal differentiation dichotomy but for maintaining the basal VSNs identity by preventing the expression of apical genes. Moreover, our data suggest that differentiated VSNs of mice retain a notable level of plasticity.\n\nHighlightsO_LIThe VNO contains two major cell types that are segregated in apical and basal regions of the VNO\nC_LIO_LIAP-2{varepsilon} is expressed in postmitotic basal vomeronasal sensory neurons.\nC_LIO_LIAP-2{varepsilon} is essential to maintain the identity of basal vomeronasal sensory neurons.\nC_LI

developmental biology↗