Identification of PGRMC1 as a regulator of the TLR3-TICAM1-IFNβ1 signaling axis in RAW264.7 macrophages
Hiroya Ohta1, Kiyoshi Takahashi1, Kayoko Takeda1
1Dept. of Pharmaceutical Education, Faculty of Pharmaceutical Sciences, Hokkaido University of Science, Japan.
Abstract:
PGRMC1 is a member of the membrane-associated progesterone receptor (MAPR) family, which plays various roles under both pathological and physiological conditions. Although PGRMC1 is expressed in macrophages, its functions in macrophages remain to be fully elucidated. In this study, we aimed to investigate the roles of PGRMC1 in regulating Toll-like receptor (TLR) signaling in macrophages by inhibiting PGRMC1. The expression levels of Pgrmc1 in RAW264.7 cells, a monocyte/macrophage-like cell line, were significantly increased by TLR3 stimulation but not by TLR4 stimulation. Inhibition of PGRMC1 in RAW264.7 cells significantly suppressed the increased expression of interferon beta1 (Ifnb1) induced by TLR3 stimulation. Additionally, inhibition of PGRMC1 significantly suppressed the upregulation of Ticam1, an essential regulator of TLR3 signaling. However, inhibition of PGRMC1 had little effect on the expression levels of interferon regulatory factor 3 (Irf3), a key transcriptional regulator of IFNβ1. Inhibition of PGRMC1 in RAW264.7 cells also exhibited a minimal effect on the increased expression of interleukin-6 (Il-6) induced by TLR4 stimulation. PGRMC2, another member of the MAPR family, was expressed in RAW264.7 cells, but it did not compensate for the absence of PGRMC1, despite the high homology between the amino acid sequences of PGRMC1 and PGRMC2. In conclusion, our results suggest that PGRMC1 in RAW264.7 cells modulates Ifnb1 expression by regulating Ticam1 expression. To the best of our knowledge, this is the first study to demonstrate that PGRMC1 contributes to regulating IFNβ1 production in response to TLR3 stimulation in RAW264.7 cells.
Insights
Progesterone receptor membrane component 1 (PGRMC1) regulates interferon beta1 (IFNβ1) production in macrophages. Inhibiting PGRMC1 suppresses IFNβ1 expression by affecting Toll-like receptor 3 (TLR3) signaling via Ticam1.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Progesterone receptor membrane component 1 (PGRMC1) is a membrane-associated progesterone receptor family member with diverse roles.
- The specific functions of PGRMC1 in macrophages, particularly in immune signaling, are not fully understood.
- Toll-like receptor (TLR) signaling pathways are crucial for innate immunity and macrophage activation.
Purpose of the Study:
- To investigate the role of PGRMC1 in regulating TLR signaling pathways in macrophages.
- To determine the effect of PGRMC1 inhibition on the expression of key immune mediators.
- To elucidate the molecular mechanisms by which PGRMC1 influences TLR-mediated responses.
Main Methods:
- Utilized RAW264.7 macrophage cell line to study PGRMC1 expression and function.
- Stimulated cells with TLR3 and TLR4 agonists to assess differential responses.
- Inhibited PGRMC1 using specific inhibitors and analyzed the expression of downstream genes, including Ifnb1, Ticam1, Irf3, and Il-6.
Main Results:
- PGRMC1 expression was upregulated by TLR3 stimulation but not TLR4 stimulation in RAW264.7 cells.
- Inhibition of PGRMC1 significantly suppressed TLR3-induced interferon beta1 (Ifnb1) and Ticam1 expression.
- PGRMC1 inhibition had minimal effects on TLR4-induced interleukin-6 (Il-6) and did not significantly alter Irf3 expression.
Conclusions:
- PGRMC1 plays a critical role in modulating Ifnb1 expression in response to TLR3 stimulation in macrophages.
- PGRMC1 regulates Ifnb1 production by influencing Ticam1 expression, a key component of the TLR3 signaling pathway.
- PGRMC2 does not compensate for the loss of PGRMC1 function, highlighting the specific role of PGRMC1 in this context.
