EFFECTOR BOTTLENECK: MICROBIAL REPROGRAMMING OF HUMAN NEUTROPHIL TRANSCRIPTION BY ANAPLASMA PHAGOCYTOPHILUM

Anaplasma phagocytophilum;neutrophils;epigenetics;DNA methylation;host pathogen interactions;nuclear effector proteins;nucleomodulins;not listed

Sinclair, Sara HidekoYegnasubramanian, Srinivasan ;

Johns Hopkins University

关键词: Anaplasma phagocytophilum;    neutrophils;    epigenetics;    DNA methylation;    host pathogen interactions;    nuclear effector proteins;    nucleomodulins;    not listed;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/39362/SINCLAIR-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, is an obligate intracellular bacterium that infects human neutrophils. Once infected, the neutrophil shows marked functional aberrations, notably reduced antimicrobial activity, delayed apoptosis, and increased proinflammatory responses. The altered functions allow for bacterial propagation and spread to new host cells. Many of the observed phenotypic changes of the neutrophil are a result of transcriptional alterations. Furthermore, AnkA, a bacterial-derived effector localizes to the nucleus where it directly binds DNA, such as at the promoter of CYBB which encodes the NADPH oxidase component gp91phox. Binding of AnkA at CYBB results in downregulated transcription. Furthermore, histone deacetylase 1 (HDAC) activity is important for bacterial propagation and downregulation of multiple host defense genes. While the lab previously focused on characterizing the interaction between AnkA, CYBB, and HDAC1, we felt the data strongly suggested that A. phagocytophilum must have additional transcription-regulating effectors (nucleomodulins) to act on a global scale and to explain the magnitude of phenotypic changes observed within the neutrophil during the course of infection. A bioinformatic screen of the A. phagocytophilum genome for genes which could encode putative eukaryotic nuclear localization signals, and mass spectrometry of proteins in the infected cell nucleus yielded nearly 50 candidate nucleomodulins. Tracking of cellular localization with GFP-fusion peptides confirmed nuclear localization of seven genes, one of which (APH_0455) is also a type IV secretion substrate. Close investigation of microarray data gathered in 2005 comparing A. phagocytophilum-infected and uninfected neutrophils showed that large chromosomal territories were coordinately regulated. In addition, infected neutrophils were characterized by genome hypermethylation. Together these data further suggested that A. phagocytophilum infection influences transcriptional programs on a global scale, rather than relying solely on cis interactions and that AnkA likely is not the sole nucleomodulin at work.