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UBC Theses and Dissertations

The function of ABCF1 in immunity and mouse development. Wilcox, Sara Morgen


ABCF1 is an ABC (ATP binding cassette) transporter protein that lacks trans-membrane domains. Gene expression of ABCF1 has been shown to increase upon tumour necrosis factor alpha (TNFα) stimulation [1]. This is significant as TNFα is a pro-inflammatory cytokine produced by macrophages and T cells and has a number of functions in the immune response [2]. ABCF1 is thought to function in translational initiation by interacting with the eukaryotic initiation factor 2 (eIF2) [3]. We have determined that ABCF1 is an essential gene in development by the generation and characterization of mice that have a gene trap insertion in the ABCF1 gene, which terminates the expression of the ATP binding cassettes. Homozygous ABCF1 knock-out (ABCF1-/-) mice are embryonic lethal at 3.5 days post coitus (dpc) while heterozygous ABCF1 knock-out (ABCF1+/-) mice appear to be developmentally normal. This thesis utilizes the ABCF1 gene trapped mouse model which contains a β-geo (β-galactosidase /neomycin) reporter gene in the ABCF1 gene to examine the endogenous ABCF1 promoter expression. This allows us to concurrently observe the activity of the ABCF1 promoter in all tissues through sectioning and X-Gal staining. This analysis provides further insight into the physiological function of ABCF1 by identifying the tissues and cell types that have the highest levels of promoter activity. Interestingly, ABCF1 appeared to be expressed in the marginal zone of the spleen and areas surrounding the lymphoid follicles. Macrophages, which were isolated from spleens of ABCF1+/- mice, were found to be hyper-responsive to stimulation by TLR ligands, particularly LPS, while macrophages derived from the bone marrow were found to be hypo-responsive. When challenged with LPS, ABCF1+/- mice produced altered cytokine production compared to their wild-type controls. Upon challenge with Listeria monocytogenes, ABCF1+/- mice succumbed to infection sooner than their ABCF1+/+ littermates. Taken together, these data indicate that ABCF1 is necessary for survival and development and likely has a role in the regulation of cytokines. Thus ABCF1 may play a significant role in regulating inflammation and pathogen induced “cytokine storm”.

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