Related Experiment Video
Updated: Mar 15, 2026
Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization
Published on: July 28, 2015
MTMR4 Is Required for the Stability of the Salmonella-Containing Vacuole
Wei X Teo1, Markus C Kerr1, Rohan D Teasdale1
1Institute for Molecular Bioscience, University of Queensland Brisbane, QLD, Australia.
Abstract:
The intracellular pathogen Salmonella enterica servovar Typhimurium (S.typhimurium) modulates the host cell's phosphoinositide (PI) metabolism to establish its intracellular replicative niche, the Salmonella-containing vacuole (SCV). Upon invasion, phosphoinositide 3-phosphate (PI(3)P) and other early endosomal markers are rapidly recruited to and remain associated with the SCV throughout its early maturation. While the phosphoinositide 3-phosphatase myotubularin 4 (MTMR4) has an established role in regulating autophagy and cellular PI(3)P-content, two processes associated with the intracellular survival of S. typhimurium, a direct role for MTMR4 in Salmonella biology has not been examined. Here we demonstrate that GFP-tagged MTMR4 is recruited to the SCV and infection of cells depleted of endogenous MTMR4 results in a decrease in viable intracellular Salmonella. This reflects a significant increase in the proportion of SCVs with compromised integrity, which targets the compartment for autophagy and consequent bacterial cell death. These findings highlight the importance of PI(3)P regulation to the integrity of the SCV and reveal a novel role for the myotubularins in bacterial pathogenesis.
Insights
Myotubularin 4 (MTMR4) regulates Salmonella-containing vacuole (SCV) integrity. Depleting MTMR4 increases SCV breakdown, leading to bacterial cell death and reduced Salmonella Typhimurium survival.
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis
Background:
- Salmonella Typhimurium establishes an intracellular niche within the Salmonella-containing vacuole (SCV).
- Host cell phosphoinositide (PI) metabolism is crucial for SCV maturation and pathogen survival.
- Myotubularin 4 (MTMR4), a phosphoinositide 3-phosphatase, regulates autophagy and PI(3)P levels, processes relevant to Salmonella infection.
Purpose of the Study:
- To investigate the direct role of myotubularin 4 (MTMR4) in Salmonella Typhimurium pathogenesis.
- To determine if MTMR4 is recruited to the Salmonella-containing vacuole (SCV).
- To assess the impact of MTMR4 depletion on intracellular Salmonella survival and SCV integrity.
Main Methods:
- Utilized GFP-tagged MTMR4 to visualize its localization during Salmonella infection.
- Depleted endogenous MTMR4 in host cells using genetic or molecular techniques.
- Quantified intracellular Salmonella viability and assessed SCV integrity via microscopy and autophagy markers.
Main Results:
- GFP-MTMR4 was observed to be recruited to the Salmonella-containing vacuole (SCV).
- Depletion of MTMR4 led to a significant decrease in viable intracellular Salmonella.
- MTMR4-depleted cells exhibited an increased proportion of SCVs with compromised integrity, promoting autophagy.
Conclusions:
- MTMR4 plays a novel role in bacterial pathogenesis by influencing Salmonella-containing vacuole (SCV) integrity.
- Regulation of phosphoinositide 3-phosphate (PI(3)P) by MTMR4 is critical for maintaining the SCV.
- Targeting MTMR4 could represent a strategy to combat Salmonella Typhimurium infections by promoting bacterial clearance via autophagy.
