Which one of the following is an antiapoptotic protein/ gene?
**Core Concept**
Antiapoptotic proteins are a class of proteins that play a crucial role in inhibiting programmed cell death, or apoptosis. These proteins help maintain cellular homeostasis by preventing excessive cell death, which can occur due to various stressors, such as DNA damage or oxidative stress.
**Why the Correct Answer is Right**
Bcl-2 (B-cell lymphoma 2) is a well-known antiapoptotic protein that functions by inhibiting the activation of proapoptotic proteins, such as Bax and Bak. By binding to and sequestering these proapoptotic proteins, Bcl-2 prevents the formation of the apoptosome, a multiprotein complex that initiates the caspase cascade and leads to cell death. Overexpression of Bcl-2 has been implicated in various cancers, where it can contribute to tumor growth and resistance to chemotherapy.
**Why Each Wrong Option is Incorrect**
* **Option A:** Bax (Bcl-2-associated X protein) is a proapoptotic protein that promotes cell death by facilitating the release of cytochrome c from the mitochondria.
* **Option C:** P53 is a tumor suppressor protein that often has proapoptotic effects by inducing the expression of proapoptotic genes, such as Bax and Puma.
* **Option D:** Caspase-3 is a key executioner caspase that plays a central role in the apoptosis pathway, promoting cell death rather than inhibiting it.
**Clinical Pearl / High-Yield Fact**
Bcl-2 overexpression is a common feature of follicular lymphoma, a type of non-Hodgkin lymphoma. This knowledge can help you identify the underlying molecular mechanisms driving lymphoma development and guide targeted therapies.
**Correct Answer:** C.