GAPDH Released from Lactobacillus johnsonii MG Enhances Barrier Function by Upregulating Genes Associated with Tight...

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Extracellular glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Lactobacillus johnsonii MG interacts with gut epithelial components, including junctional adhesion molecule-2 (JAM-2).
• The precise role and specificity of GAPDH in enhancing Caco-2 cell tight junctions were previously unclear.

Purpose of the Study:

• To investigate the effect of Lactobacillus johnsonii MG-derived GAPDH on tight junction regeneration in Caco-2 cells.
• To identify specific GAPDH peptide fragments responsible for JAM-2 interaction and bacterial cell surface binding.

Main Methods:

• Assessing GAPDH's impact on hydrogen peroxide-induced tight junction damage in Caco-2 cells.
• Utilizing High-Performance Liquid Chromatography (HPLC) and Time-of-Flight Mass Spectrometry (TOF-MS) to purify and predict interacting GAPDH peptide sequences.
• Molecular docking simulations to analyze peptide-JAM-2 interactions.

Main Results:

• GAPDH specifically bound to JAM-2 and restored H2O2-damaged tight junctions in Caco-2 cells, leading to gene upregulation.
• Two specific GAPDH peptides, 11GRIGRLAF18 (N-terminus) and 323SFTCQMVRTLLKFATL338 (C-terminus), showed significant interaction and docking with JAM-2.
• A separate peptide (52DSTHGTFNHEVSATDDSIVVDGKKYRVYAEPQAQNIPW89) was predicted to bind to the bacterial cell surface.

Conclusions:

• Lactobacillus johnsonii MG GAPDH plays a novel role in promoting the regeneration of damaged intestinal tight junctions.
• Specific N-terminal and C-terminal peptide sequences of GAPDH are crucial for JAM-2 binding, while other sequences mediate bacterial cell interaction.