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Updated: Jun 29, 2025
Deciphering the Molecular Mechanism and Function of Pore-Forming Toxins Using Leishmania major
Published on: October 28, 2022
Role of Macrophage PIST Protein in Regulating Leishmania major Infection
Sourav Banerjee1, Mandip Pratham Gadpayle1, Suman Samanta1
1Department of Biological Sciences, Indian Institute of Science Education & Research Kolkata (IISER-Kolkata), Mohanpur Campus, Kolkata, West Bengal 741 246, India.
Abstract:
PDZ protein interacting specifically with Tc10 or PIST is a mammalian trans-Golgi resident protein that regulates subcellular sorting of plasma membrane receptors. PIST has recently emerged as a key player in regulating viral pathogenesis. Nevertheless, the involvement of PIST in parasitic infections remains unexplored. Leishmania parasites infiltrate their host macrophage cells through phagocytosis, where they subsequently multiply within the parasitophorous vacuole (PV). Host cell autophagy has been found to be important in regulating this parasite infection. Since PIST plays a pivotal role in triggering autophagy through the Beclin 1-PI3KC3 pathway, it becomes interesting to identify the status of PIST during Leishmania infection. We found that while macrophage cells are infected with Leishmania major (L. major), the expression of PIST protein remains unaltered; however, it traffics from the Golgi compartment to PV. Further, we identified that in L. major-infected macrophage cells, PIST associates with the autophagy regulatory protein Beclin 1 within the PVs; however, PIST does not interact with LC3. Reduction in PIST protein through siRNA silencing significantly increased parasite burden, whereas overexpression of PIST in macrophages restricted L. major infectivity. Together, our study reports that the macrophage PIST protein is essential in regulating L. major infectivity.
Insights
The PDZ protein PIST, crucial for autophagy, unexpectedly moves to the parasitophorous vacuole during Leishmania major infection. Macrophage PIST protein is essential for controlling Leishmania major infectivity.
Area of Science:
- Cell Biology
- Parasitology
- Immunology
Background:
- PIST (PDZ protein interacting specifically with Tc10) is a Golgi-resident protein regulating receptor sorting and implicated in viral pathogenesis.
- Leishmania major infects macrophages, utilizing host cell autophagy for survival.
- The role of PIST in parasitic infections, particularly Leishmania, is currently unknown.
Purpose of the Study:
- To investigate the role and localization of PIST during Leishmania major infection in host macrophages.
- To determine if PIST influences autophagy pathways within the context of Leishmania infection.
Main Methods:
- Immunofluorescence microscopy to track PIST localization in infected macrophages.
- Co-immunoprecipitation to assess PIST interactions with autophagy proteins (Beclin 1, LC3).
- siRNA-mediated PIST knockdown and PIST overexpression in macrophages to evaluate parasite burden.
Main Results:
- PIST protein expression remained unchanged, but it trafficked from the Golgi to the parasitophorous vacuole (PV) in L. major-infected macrophages.
- PIST associated with Beclin 1 within the PVs but did not interact with LC3.
- siRNA silencing of PIST increased parasite burden, while PIST overexpression restricted L. major infectivity.
Conclusions:
- Macrophage PIST protein is essential for restricting Leishmania major infectivity.
- PIST's translocation to the PV and interaction with Beclin 1 suggest a novel role in host defense against Leishmania parasites.
