Protein Interactomes of the Human Interferon Inducible HIN200 Protein Family

摘要

Recently years have witnessed rapid progress in the understanding of how mammalian cells recognize foreign double stranded DNA as pathogenic molecules, and elicit innate immunity response. The Human Interferon Inducible HIN200 protein family, including four proteins--AIM2, IFI16, IFIX and MNDA, has emerged as a group of novel intracellular sensors that detect exogenous dsDNA and trigger innate immune response (1-3). These proteins all have an N-terminal pyrin domain (for protein interactions) and one or two C-terminus HIN200 domain(s) (for DNA binding). Besides innate immunity, roles in cell cycle regulation and differentiation were also reported for these proteins, as well as antitumor and pro-apoptotic activities. However, we know very little about how their functions are regulated. To gain more insights into their regulations, here we present a systemic study of their protein interactions and post-translational modifications (PTMs), with a focus on the nuclear members IFI16, IFIX & MNDA. To visualize and isolate HIN200 proteins, we tagged them at either N- or C-terminus with EGFP (green fluorescent protein) (4). To avoid the noticed toxicity of overexpression, we constructed stable FlpIn TRex 293 cell lines to express these GFP fusions in a tetracycline inducible manner. As control, a cell line that expresses GFP was also constructed.