Which is activated for nuclear fragmentation in apoptosis –
**Core Concept**
Apoptosis is a form of programmed cell death that involves a series of cellular changes, including nuclear fragmentation, which is a hallmark of this process. The activation of specific enzymes and pathways is crucial for the execution of apoptosis.
**Why the Correct Answer is Right**
The correct answer is **Caspase-3**, which is a key executioner caspase activated during the late stages of apoptosis. Caspase-3 is responsible for the cleavage of various cellular substrates, including structural proteins and DNA repair enzymes, leading to nuclear fragmentation and cell death. The activation of Caspase-3 is often a downstream effect of the activation of other caspases, such as Caspase-8 and Caspase-9, which are activated in response to different apoptotic stimuli.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Caspase-1 is primarily involved in the processing and activation of pro-inflammatory cytokines, such as IL-1β and IL-18, through the inflammasome pathway.
**Option B:** This option is incorrect because Caspase-6 is also involved in the execution of apoptosis, but its role is less clear, and it is not the primary caspase responsible for nuclear fragmentation.
**Option C:** This option is incorrect because Caspase-7 is another executioner caspase involved in apoptosis, but it is not the primary caspase responsible for nuclear fragmentation.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the activation of caspases is a crucial step in the execution of apoptosis, and the specific caspase activated can depend on the cellular context and the type of apoptotic stimulus.
**Correct Answer:** C. Caspase-3.