Using More Than 1 (Path)Way to Kill a Host Cell: Lessons From Clostridium perfringens Enterotoxin

Area of Science:

• Cellular Biology
• Microbiology
• Toxicology

Background:

• Clostridium perfringens enterotoxin (CPE) causes intestinal infections.
• CPE is a pore-forming toxin that binds to claudins.
• Previous research indicated CPE induces apoptosis at low concentrations and necrosis at high concentrations in Caco-2 cells.

Purpose of the Study:

• To investigate the molecular mechanisms underlying CPE-induced cell death.
• To determine the roles of RIP1, RIP3, and MLKL in CPE-mediated apoptosis and necrosis.
• To elucidate the signaling pathway leading to CPE-induced necroptosis.

Main Methods:

• Experiments were conducted using enterocyte-like Caco-2 cells.
• Analysis of apoptosis and necrosis pathways.
• Investigation of RIP1, RIP3, MLKL, and calpain involvement in CPE toxicity.

Main Results:

• RIP1 and RIP3 were found to be involved in both CPE-mediated apoptosis and necrosis.
• MLKL oligomerization is crucial for CPE-induced necrosis, identifying it as programmed necroptosis.
• Calpain activation, triggered by Ca2+ influx through the CPE pore, is essential for MLKL oligomerization and necroptosis.

Conclusions:

• CPE induces programmed necroptosis in Caco-2 cells via a pathway involving RIP1, RIP3, calpain, and MLKL.
• Calcium influx through the CPE pore is a critical step for initiating necroptosis.
• These findings enhance understanding of CPE pathogenesis and may apply to other pore-forming toxins.