Question

Which of these are executioner caspases?
A. Caspase 3
B. Caspase 6
C. Caspase 8
D. Caspase 5
Choose the most appropriate answer from the options given below:

• A. A and B only
• B. B and C only
• C. C and D only
• D. A and D only

Hint:

A simple way to remember the main caspases:

\textbf{Initiators}: Caspase-8 (Extrinsic path), Caspase-9 (Intrinsic path). Think of them as the "generals" giving the order.
\textbf{Executioners}: Caspase-3, -6, -7. Think of them as the "soldiers" carrying out the order. Caspase-3 is the main soldier. \end{itemize}

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Caspases (cysteine-aspartic proteases) are a family of enzymes that play essential roles in apoptosis (programmed cell death). They are broadly classified into two main groups based on their function in the apoptotic cascade: initiator caspases and executioner (or effector) caspases.

Step 2: Detailed Explanation:
- Initiator Caspases: These caspases (e.g., Caspase-2, -8, -9, -10) are activated at the beginning of the apoptotic pathway by specific signals. Once activated, their role is to cleave and activate the downstream executioner caspases.
- Executioner Caspases: These caspases (e.g., Caspase-3, -6, -7) are activated by initiator caspases. They are responsible for carrying out the "execution" phase of apoptosis by cleaving numerous cellular substrates, leading to the characteristic morphological and biochemical changes of a dying cell (e.g., DNA fragmentation, membrane blebbing).

Step 3: Classifying the Given Caspases:
- A. Caspase 3: This is a key executioner caspase, often considered the central executioner.
- B. Caspase 6: This is also an executioner caspase.
- C. Caspase 8: This is a primary initiator caspase, activated in the extrinsic (death receptor-mediated) pathway of apoptosis.
- D. Caspase 5: This is classified as an inflammatory caspase (along with Caspase-1 and -4 in humans), primarily involved in activating pro-inflammatory cytokines, not directly in the execution of apoptosis.

Step 4: Final Answer:
Based on the classification, Caspase 3 (A) and Caspase 6 (B) are the executioner caspases among the given options. Therefore, the correct choice is (A).