Protein Kinase C

Definition

Protein Kinase C (PKC) is a family of serine/threonine kinases that play crucial roles in various signal transduction pathways, particularly in the regulation of cell growth, differentiation, and apoptosis. PKC is activated by signals such as growth factors and hormones, leading to a cascade of cellular responses that impact multiple biological processes including immune responses, neurotransmitter release, and smooth muscle contraction.

5 Must Know Facts For Your Next Test

1. PKC is involved in multiple signaling pathways that regulate important cellular functions such as gene expression, cell proliferation, and apoptosis.
2. There are several isoforms of PKC, each with distinct tissue distributions and functions, including conventional, novel, and atypical PKC types.
3. PKC is activated by the presence of diacylglycerol (DAG) and calcium ions, which are generated during the activation of phospholipase C.
4. Aberrant PKC activity has been implicated in various diseases, including cancer, diabetes, and cardiovascular disorders.
5. Research has shown that targeting PKC may have therapeutic potential for conditions such as cancer by modulating its signaling pathways.

Review Questions

• How does Protein Kinase C integrate signals from different extracellular stimuli to initiate cellular responses?
  • Protein Kinase C integrates signals from various extracellular stimuli like growth factors and hormones through the generation of second messengers such as diacylglycerol (DAG) and calcium ions. Once activated by these second messengers, PKC phosphorylates specific target proteins to influence key cellular processes like growth, differentiation, and apoptosis. This ability to respond to diverse signals makes PKC a central player in numerous signal transduction pathways.
• Discuss the role of diacylglycerol (DAG) in the activation of Protein Kinase C and its implications for cell signaling.
  • Diacylglycerol (DAG) is a critical second messenger produced by the action of phospholipase C when it hydrolyzes phosphatidylinositol 4,5-bisphosphate. DAG remains embedded in the cell membrane and acts as an important activator of Protein Kinase C. The binding of DAG to PKC facilitates its translocation to the membrane where it becomes fully activated in conjunction with calcium ions. This activation leads to a variety of downstream signaling events that affect cellular behavior and function.
• Evaluate how dysregulation of Protein Kinase C can contribute to disease progression, particularly in cancer.
  • Dysregulation of Protein Kinase C can significantly contribute to disease progression by altering normal cellular signaling pathways. In cancer, for example, aberrant activation or expression of specific PKC isoforms can promote uncontrolled cell proliferation and inhibit programmed cell death (apoptosis), leading to tumor growth. Additionally, altered PKC activity may affect pathways related to inflammation and immune responses, further complicating disease pathology. Therefore, targeting PKC offers a promising therapeutic avenue for managing cancer and potentially other diseases characterized by similar signaling disruptions.

Related terms

Phospholipase C: An enzyme that generates inositol trisphosphate (IP3) and diacylglycerol (DAG) from phosphatidylinositol 4,5-bisphosphate, playing a key role in the activation of PKC.

Second Messengers: Intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules, which include DAG and calcium ions that activate PKC.

Apoptosis: A form of programmed cell death that can be regulated by various kinases, including PKC, which influences cellular survival and death pathways.