Related Experiment Video
Updated: May 3, 2026
Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes
Published on: May 31, 2018
Inhibition of interleukin-1β production by extracellular acidification through the TDAG8/cAMP pathway in mouse
Ye Jin1, Koichi Sato, Ayaka Tobo
1Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan.
Abstract:
Interleukin-1β (IL-1β) is released from activated microglia and involved in the neurodegeneration of acute and chronic brain disorders, such as stroke and Alzheimer's disease, in which extracellular acidification has been shown to occur. Here, we examined the extracellular acidic pH regulation of IL-1β production, especially focusing on TDAG8, a major proton-sensing G-protein-coupled receptor, in mouse microglia. Extracellular acidification inhibited lipopolysaccharide -induced IL-1β production, which was associated with the inhibition of IL-1β cytoplasmic precursor and mRNA expression. The IL-1β mRNA and protein responses were significantly, though not completely, attenuated in microglia derived from TDAG8-deficient mice compared with those from wild-type mice. The acidic pH also stimulated cellular cAMP accumulation, which was completely inhibited by TDAG8 deficiency. Forskolin and a cAMP derivative, which specifically stimulates protein kinase A (PKA), mimicked the proton actions, and PKA inhibitors reversed the acidic pH-induced IL-1β mRNA expression. The acidic pH-induced inhibitory IL-1β responses were accompanied by the inhibition of extracellular signal-related kinase and c-Jun N-terminal kinase activities. The inhibitory enzyme activities in response to acidic pH were reversed by the PKA inhibitor and TDAG8 deficiency. We conclude that extracellular acidic pH inhibits lipopolysaccharide-induced IL-1β production, at least partly, through the TDAG8/cAMP/PKA pathway, by inhibiting extracellular signal-related kinase and c-Jun N-terminal kinase activities, in mouse microglia.
Insights
Extracellular acidic pH inhibits interleukin-1β (IL-1β) production in microglia via the TDAG8 receptor. This pathway involves cAMP and PKA, impacting neuroinflammation in brain disorders.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Interleukin-1β (IL-1β) is implicated in neurodegeneration in conditions like stroke and Alzheimer's disease.
- Extracellular acidification is a characteristic of these brain disorders.
- Microglia are key immune cells in the brain involved in neuroinflammation.
Purpose of the Study:
- To investigate how extracellular acidic pH regulates IL-1β production in mouse microglia.
- To identify the role of the proton-sensing G-protein-coupled receptor TDAG8 in this process.
Main Methods:
- Utilized mouse microglia cultures, including TDAG8-deficient and wild-type.
- Stimulated microglia with lipopolysaccharide (LPS) under varying pH conditions.
- Measured IL-1β production (mRNA and protein), cAMP levels, and kinase activities (ERK, JNK).
- Employed forskolin, cAMP analogs, and PKA inhibitors to probe signaling pathways.
Main Results:
- Extracellular acidification inhibited LPS-induced IL-1β production and expression.
- TDAG8 deficiency partially attenuated the inhibitory effect of acidic pH on IL-1β.
- Acidic pH increased cAMP accumulation, mediated by TDAG8, which activated PKA.
- PKA activation mimicked and PKA inhibition reversed the acidic pH effects on IL-1β mRNA.
- Acidic pH inhibited ERK and JNK activities, a process reversed by PKA inhibition and TDAG8 deficiency.
Conclusions:
- Extracellular acidic pH inhibits IL-1β production in microglia through the TDAG8/cAMP/PKA signaling pathway.
- This pathway modulates ERK and JNK activities, contributing to the regulation of neuroinflammation.
