Biology subjects

Seipelt-Thiemann, R. L.

Publications and source records attributed to Seipelt-Thiemann, R. L..

2 recordsLinked to original sources

bioRxiv2022

Regulation of Macrophage IFNγ-Stimulated Gene Expression by the Transcriptional Coregulator CITED1

Macrophages are highly dynamic innate immune cells that adopt temporary phenotypes, known as polarization states, in response to changing environmental signals to combat microbial infection and contribute to the maintenance of tissue homeostasis. During the early stages of an infection, exposure to interferon-gamma (IFN{gamma}) and microbial ligands induce M1 polarization, a heightened proinflammatory anti-microbial state, by regulating the expression of interferon stimulated genes (ISGs). While this response must be sufficiently vigorous to ensure the successful clearance of invading pathogens, it must also be spatially and temporally restricted to prevent uncontrolled inflammation that could result in tissue damage and disease. This is controlled by a variety of cell-extrinsic and -intrinsic mechanisms, including the expression of CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2), a transcriptional coregulator that limits IFN{gamma}-stimulated proinflammatory gene expression by inhibiting STAT1- and IRF1-regulated ISGs. In this study, we show that CITED1, another member of the CITED family of proteins, is itself an ISG and is expressed in a STAT1-dependent manner, and that IFN{gamma} stimulates the nuclear accumulation of fluorescently tagged CITED1 proteins. In contrast to CITED2, ectopic expression of CITED1 enhanced the expression of a subset of ISGs, including Ccl2, Ifit3b, Isg15, and Oas2. This effect was reversed in a Cited1 null cell line produced by CRISPR-based genomic editing. Collectively, these data show that CITED1 helps to maintain proinflammatory gene expression during periods of prolonged IFN{gamma} exposure and suggests a distinct and antagonistic relationship between CITED proteins in the regulation of macrophage inflammatory function.

immunology↗

bioRxiv2020

Intracellular Cryptococcus neoformans disrupts the transcriptome profile of M1- and M2-polarized host macrophages

Macrophages serve as a first line of defense against infection with the facultative intracellular pathogen, Cryptococcus neoformans (Cn). However, the ability of these innate phagocytic cells to destroy ingested Cn is strongly influenced by polarization state with classically (M1) activated macrophages better able to control cryptococcal infections than alternatively (M2) activated cells. While earlier studies have demonstrated that intracellular Cn minimally affects the expression of M1 and M2 markers, the impact on the broader transcriptome associated with these states remains unclear. To investigate this, we used an in vitro cell culture model of intracellular infection together with RNA sequencing-based transcriptome profiling to measure the impact of Cn infection on gene expression in both polarization states. The gene expression profile of both M1 and M2 cells was extensively altered to become more like naive (M0) macrophages. Gene ontology analysis suggested that this involved changes in the activity of the Janus kinase-signal transducers and activators of transcription (JAK-STAT), p53, and nuclear factor-{kappa}B (NF-{kappa}B) pathways. Analyses of the principle polarization markers at the protein-level also revealed discrepancies between the RNA- and protein-level responses. In contrast to earlier studies, intracellular Cn was found to increase protein levels of the M1 marker iNos. In addition, we identified common gene expression changes that occurred post-Cn infection, independent of polarization state. This included upregulation of the transcriptional co-regulator Cited1, which was also apparent at the protein level. These changes constitute a transcriptional signature of macrophage Cn infection and provide new insights into how Cn impacts gene expression and the phenotype of host phagocytes.

immunology↗