CPPS 325 VERGE 2025 Signalling #13 to upload (1) Flashcards
What is the role of PI3-kinase in cell signaling?
PI3-kinase can be activated by binding to specific phospho-tyrosines on activated RTKs.
This activation leads to the activation of Akt/PKB and is critical in various cellular processes.
How does phosphorylation of FOXO relate to cell survival?
Phosphorylation of FOXO is linked to cell survival.
This relationship is part of the signaling pathways that regulate cell fate.
What similarities exist between cytokine activation and RTK activation?
Cytokine activation has similarities to activation of RTKs.
Both pathways involve receptor activation and subsequent signaling cascades.
What are the short and long-term regulations of JAK-STAT pathways?
Short-term regulation dampens the JAK-STAT pathway, while long-term regulation involves taking the receptor off the membrane.
These regulatory mechanisms help control the intensity and duration of the signaling.
What impact does cytokine signaling gone awry have on melanoma cells?
Cytokine signaling gone awry can lead to changes in melanoma cancer cells that make them more prone to metastasize.
This indicates a critical role of cytokine signaling in cancer progression.
Define RNA interference (RNAi).
RNA interference (RNAi) is an evolutionary conserved cellular defense mechanism for controlling the expression of alien genes.
It is mediated by sequence-specific mRNA degradation and involves double-stranded RNA.
What are the two key steps of how RNAi works?
- Processing the dsRNA into 21-23 nt fragments.
- Binding of short RNA fragments to the RNA-induced silencing complex (RISC).
The first step involves the enzyme Dicer recognizing and chopping up the dsRNA.
What effect does increasing SOCS1 have on melanoma cells?
Increasing SOCS1 expression decreases the incidence of melanoma metastasizing to the brain.
SOCS1 acts as a negative regulator of STAT3 activation.
What is the role of Janus kinase (JAK) in cytokine signaling?
Janus kinase (JAK) becomes activated by phosphorylation of each other when receptors dimerize.
JAK is crucial for the activation of downstream signaling pathways.
True or False: The loss of SOCS1 is linked to the promotion of brain metastasis in melanoma cells.
True.
The loss of SOCS1 contributes to increased STAT3 activation, promoting metastasis.
Fill in the blank: RNA interference is caused by sequence-specific mRNA _______.
degradation.
What happens to STATs after they are phosphorylated?
Phosphorylated STATs dissociate from the receptor and spontaneously dimerize.
This dimerization allows them to translocate to the nucleus and regulate transcription.
What is the significance of the SOCS regulatory feedback loop?
The SOCS regulatory feedback loop helps regulate the JAK/STAT signaling pathway.
This loop ensures that excessive signaling is curtailed, maintaining cellular homeostasis.
How does RNAi contribute to therapeutic treatments?
RNAi can be used in therapeutic treatments for cancer, viral infections, and parasitic infections.
It allows for targeted gene silencing, which can inhibit disease progression.
What is the function of small interfering RNA (siRNA)?
siRNA binds to the RNA-induced silencing complex (RISC) to facilitate mRNA degradation.
This action leads to the silencing of specific genes.
What is the role of the enzyme Dicer in RNAi?
Dicer processes double-stranded RNA into small RNA fragments.
These fragments are essential for the RNAi mechanism.
What enzyme chops up double-stranded RNA into small fragments?
Dicer
What are the small RNA fragments called that are produced by Dicer?
small interfering RNA (siRNA)
What is the length of siRNA fragments?
21-23 base pairs
What is the role of the guide strand in siRNA?
It is incorporated into the RNA-induced silencing complex (RISC) and pairs with complementary sequences in the cell.
What does the RISC complex do once activated?
It binds to complementary target mRNA and cleaves it.
What is the enzyme in the RISC complex that cleaves bound mRNA?
Slicer
What happens to mRNA after it has been cleaved by Slicer?
It can no longer be translated into functional protein and is vulnerable to degradation by RNases.
How does RNA interference (RNAi) affect gene expression?
It suppresses specific genes of interest.
