Science Bite (3 minute oral presentation with PPT in live session with pre-recorded e-poster) Lorne Infection and Immunity 2021

The role of SMG1 in regulating innate immunity (#111)

Hui-Chi Lai 1 , Alexander James 1 , Uda Ho 2 , Tara Roberts 1 3
  1. UNSW/Ingham Institute, Liverpool, NEW SOUTH WALES, Australia
  2. School of Biomedical Science, University of Queensland, Brisbane, Queensland, Australia
  3. School of Medicine, Western Sydney University, Liverpool, New South Wales, Australia

SMG1 (Suppressor of Morphogenesis in Genitalia 1), is a member of the PIKK (phosphoinositide 3-kinase related kinase) family that includes ATM, ATR and DNA-PK. We have identified the protein kinase SMG1 as a regulator of TLR response and SMG1 knockout mice are early embryonic lethal. To further study the role of SMG1 in inflammation we have generated mice lacking SMG1 in myeloid cells (LysMCreSmg1fl/fl) and control littermates (Smg1fl/fl). We treated bone marrow derived macrophages (BMM) from Smg1 deficient mice and wild type mice with lipopolysaccharide (an activator of TLR4) and measured their pro-inflammatory cytokine responses. BMMs from LysMCreSmg1fl/fl male mice showed less induction of the pro-inflammatory cytokines IL-1β, IFNβ, and TNFα, while increased pro-inflammatory cytokines production only can be observed of BMMs from LysMCreSmg1fl/fl female mice as compared with control, which indicating Smg1 deficiency alters toll-like receptor induced inflammatory gene expression. Interestingly, loss of Smg1 also affects pro-inflammatory cytokine production between male and female mice. Characterisation of LysMCre mice showed SMG1 only knocked out in myeloid lineage cells(macrophages), but cre efficiency is based on the cre-recombination. Firstly, we found cre efficieny affects pro-inflammatory cytokine production, however, does not show effect on female mice. To test whether loss of SMG1 may be implicated X chromosome inactivation, we compared several target genes by qPCR in female and male BMMs from LysMCreSmg1fl/fl(Cre mice) and Smg1fl/fl(control) and found that loss of SMG1 affects pro-inflammatory cytokine production by up-regulating of Xist regulation(Eif1 and Rasa1), but not involve in mRNA degradation(Upf1). Additionally, results from qPCR and western blots showed increased TLR4 mRNA expression and protein level among BMMs from female but not male LysMCreSmg1fl/fl(Cre mice) at 2 hours post-LPS treatment. In summary, loss of SMG1 may involve in the regulation of innate immunity with potential sex differences affecting pro-inflammatory cytokine production in response to LPS treatment.