Survival signals

Definition

Survival signals are essential biochemical cues that promote cell survival by inhibiting apoptosis, the programmed cell death process. These signals ensure that cells continue to function and proliferate by preventing the activation of pro-apoptotic pathways, allowing the organism to maintain homeostasis and respond appropriately to various stimuli.

5 Must Know Facts For Your Next Test

1. Survival signals can be provided by extracellular factors such as growth factors and cytokines, which bind to receptors on the cell surface and activate intracellular signaling cascades.
2. The phosphoinositide 3-kinase (PI3K)/Akt pathway is a well-known signaling pathway involved in mediating survival signals, promoting cell survival by inhibiting apoptotic factors.
3. In the absence of survival signals, cells may undergo apoptosis due to the activation of intrinsic pathways that respond to cellular stress or damage.
4. Cancer cells often exploit survival signals to evade apoptosis, which contributes to tumor growth and resistance to therapy.
5. Cellular responses to survival signals are tightly regulated, and dysregulation can lead to various diseases, including cancer and neurodegenerative disorders.

Review Questions

• How do survival signals prevent apoptosis at the molecular level?
  • Survival signals prevent apoptosis by activating specific signaling pathways that inhibit pro-apoptotic proteins and promote anti-apoptotic proteins. For example, growth factors can activate the PI3K/Akt pathway, which leads to the phosphorylation of downstream targets that inhibit caspase activation. This cascade of events ensures that cells can continue to thrive and avoid entering the apoptotic program.
• Discuss the role of growth factors in providing survival signals and their implications in cancer biology.
  • Growth factors play a crucial role in providing survival signals by binding to their respective receptors on target cells, triggering intracellular signaling pathways that promote cell survival and proliferation. In cancer biology, tumors often exploit these growth factor signaling pathways to evade apoptosis, allowing for unchecked growth and resistance to treatments. This highlights the importance of targeting growth factor signaling in developing cancer therapies.
• Evaluate how dysregulation of survival signal pathways can contribute to disease progression, particularly in cancer and neurodegenerative disorders.
  • Dysregulation of survival signal pathways can lead to a variety of disease states, especially in cancer where aberrant signaling can cause cells to avoid apoptosis, contributing to tumorigenesis. For instance, overactive PI3K/Akt signaling may enhance cell survival even under adverse conditions. In neurodegenerative disorders, insufficient survival signals can result in increased apoptosis of neurons, exacerbating disease progression. Understanding these mechanisms is crucial for developing targeted therapies aimed at restoring normal signaling pathways.

Related terms

Apoptosis: A form of programmed cell death that occurs in multicellular organisms, characterized by distinct morphological changes and cellular dismantling.

Caspases: A family of cysteine proteases that play a crucial role in the execution of apoptosis, being activated in response to pro-apoptotic signals.

Growth factors: Proteins that stimulate cell proliferation, differentiation, and survival, often acting as survival signals by activating specific signaling pathways.