Question

Which of the following types of cell death involves activation of caspase enzymes?

• A. Necrosis and apoptosis
• B. Apoptosis and pyroptosis
• C. Apoptosis and necroptosis
• D. Apoptosis only

Hint:

Caspases are important in apoptosis and pyroptosis; necrosis is not caspase-mediated.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify types of regulated cell death that utilize the caspase (Cysteine-Aspartic Proteases) signaling pathway.
Step 2: Detailed Explanation:

Apoptosis: This is the "prototypical" regulated cell death. It involves the activation of initiator caspases (caspase-8, 9) and executioner caspases (caspase-3, 6, 7). Apoptosis is non-inflammatory.

Pyroptosis: This is a form of highly inflammatory regulated cell death. It involves the activation of the inflammasome, which in turn activates caspase-1 (the interleukin-1 converting enzyme) or caspase-4, 5, 11. These caspases cleave gasdermin D, creating pores in the cell membrane.

Necroptosis: Unlike apoptosis and pyroptosis, necroptosis is a caspase-independent regulated cell death pathway. It is mediated by the RIPK1/RIPK3/MLKL signaling complex. Activation of caspases actually \textit{inhibits} necroptosis.

Necrosis: Classic necrosis is an accidental, unregulated form of cell death that does not typically involve a specific caspase-mediated signaling cascade.

Step 3: Final Answer:
Caspases are central to both Apoptosis (Caspase-3, 8, 9) and Pyroptosis (Caspase-1), making option B the correct selection.