Title: 1035 - The Role of Transportin IMB-2 in Infection
Ali Al Hatem (Presenter)
University of Houston
Ali Naji, The University of Texas School of Dentistry at Houston
Ransome van der Hoeven, The University of Texas School of Dentistry at Houston
Objectives: The mitis group streptococci such as Streptococcus gordonii, S. mitis and S. oralis are ubiquitous microorganisms that colonizes the human oropharynx. In immunocompromised hosts, they cause a multitude of infectious clinical complications. Using the nematode Caenorhabditis elegans, hydrogen peroxide (H2O2) produced by these organisms has been identified as a virulence factor. In the worm, the insulin-signaling pathway regulates the expression of genes involved in antioxidant stress-response. This pathway consists of a receptor DAF-2 and PI3-kinase signaling cascade culminating with the forkhead box O (FOXO/DAF-16) transcription factor. Additionally, a recent study confirmed the nuclear localization of DAF-16 in C. elegans is facilitated by IMB-2, a homologue of the mammalian transportin TNPO1 in response to the superoxide generator paraquat. However, no studies were conducted to ascertain the role of IMB-2 during infection. We hypothesize IMB-2 will recruit DAF-16 to the nucleus, thereby activating the expression of ROS-scavenging enzymes in response to H2O2 produced by S. gordonii.
Methods: We determined the survival of imb-2, daf-16 and daf-2 knockdowns in wild-type N2 and intestinal specific knockdown vha6p::sid-1 worms relative to the vector control treated worms on S. gordonii. Furthermore, using confocal microscopy, we observed the nuclear localization of DAF-16 in a transgenic worm expressing DAF-16 fused to GFP when imb-2 and daf-16 were knockdown relative to the vector control in response to the infection.
Results: Knockdown of imb-2 and daf-16 resulted in significantly reduced survival of N2 and vha6p::sid-1 worms relative to the vector control on S. gordonii. Moreover, compared to the vector control, we observed significant loss of localization of DAF-16::GFP in imb-2 and daf-16 knockdown worms during infection.
Conclusions: Our data suggests IMB-2 is required for the survival of the worms and is important for the translocation of DAF-16 in response to the H2O2 produced by S. gordonii.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE