A TGFBR2/SMAD2/DNMT1/miR-145 negative regulatory loop is responsible for LPS-induced sepsis

Area of Science:

• Molecular Biology
• Immunology
• Cell Biology

Background:

• Transforming growth factor beta receptor 2 (TGFBR2)/Smad2 signaling is crucial in lipopolysaccharide (LPS)-induced sepsis.
• The precise regulatory mechanisms of this pathway in sepsis remain unclear.

Purpose of the Study:

• To elucidate the regulatory mechanisms of TGFBR2/Smad2 signaling in LPS-induced sepsis.
• To identify novel molecular players involved in sepsis pathogenesis.

Main Methods:

• RNA sequencing to identify microRNAs (miRNAs) affected by LPS.
• Bioinformatics, luciferase reporter assays, and RNA immunoprecipitation (RIP) to determine miRNA targets.
• Chromatin immunoprecipitation (ChIP) assays to investigate protein-DNA interactions.
• In vivo studies using mouse models of sepsis.

Main Results:

• miR-145 was significantly downregulated in human umbilical vein endothelial cells (HUVECs) after LPS treatment.
• miR-145 directly targets and inactivates the TGFBR2/Smad2 axis.
• Smad2 upregulates DNA methyltransferase 1 (DNMT1), leading to miR-145 promoter hypermethylation and reduced miR-145 expression.
• Knockdown of TGFBR2 or overexpression of miR-145 attenuated LPS-induced sepsis and improved survival in mice.
• TGFBR2/SMAD2/DNMT1/miR-145 forms a negative regulatory loop critical for LPS-induced sepsis.

Conclusions:

• The study identifies a novel negative regulatory loop (TGFBR2/SMAD2/DNMT1/miR-145) involved in LPS-induced sepsis.
• This pathway represents a potential therapeutic target for sepsis treatment.
• Understanding this loop provides critical insights into sepsis pathogenesis.