AbuArish_CPPS325_March12_2025_Lecture 3_Upload (1) Flashcards
What enzyme cleaves the phosphocholine group off sphingomyelin to generate ceramide?
Sphingomyelinase (SMase)
This enzyme is activated in response to various stimuli.
What do ceramide lipids form when they coalesce?
Ceramide-enriched domains (gel-like domains)
These domains lead to larger platforms enriched in lipid raft proteins and signaling molecules.
What are the different fatty acyl chain lengths of ceramides mentioned?
- C8 Ceramide
- C12 Ceramide
- C18 Ceramide (Long Chain Ceramide)
- C24 Ceramide (Very Long Chain Ceramide)
- Short Chain Ceramides (SCC)
Each type has different inflammatory properties.
Which ceramide is associated with pro-inflammatory properties?
Long Chain Ceramides (LCC)
Specifically, C18 Ceramide is noted for its pro-inflammatory effects.
What is the role of ceramide-rich platforms in the plasma membrane?
Increase protein stability and expression at the plasma membrane
This is achieved by reducing mobility and internalization of proteins.
True or False: Ceramide-rich platform formation decreases CFTR membrane expression.
False
Ceramide-rich platform formation increases CFTR membrane expression and stability.
What effect does Vasoactive Intestinal Peptide (VIP) have on CFTR?
Causes massive reorganization of CFTR inside platforms
This leads to increased CFTR recruitment and tethering at the plasma membrane.
What is the primary function of ASMase in airway epithelial cells?
Facilitates the hydrolysis of sphingomyelin into ceramide lipids
This activity leads to ceramide-rich platform formation.
Fill in the blank: ASMase localization inside lipid rafts facilitates the hydrolysis of _______ into ceramide lipids.
sphingomyelin
What activates ASMase leading to the formation of ceramide-rich platforms?
Reactive oxygen species (ROS) generation
ROS activates ASMase upon stimulation.
What is the relationship between CFTR and lipid rafts?
CFTR is preferentially localized inside lipid rafts
This localization is essential for CFTR’s clustering and platform formation.
What technique allows the analysis of protein behaviors in living systems under physiological conditions?
Fluorescence correlation spectroscopy
This technique is sensitive and non-invasive.
What do stress conditions cause CFTR to partition into?
Ceramide-rich platforms
Under control conditions, WT-CFTR partitions inside lipid rafts.
What is the significance of ASMase and CFTR colocalization in ciliated airway epithelial cells?
Indicates a preferential localization inside lipid rafts
This colocalization is vital for CFTR function.
Which ceramide type is considered anti-inflammatory?
Very Long Chain Ceramides (VLCC)
Specifically, C24 Ceramide is noted for its anti-inflammatory properties.
What does the study of protein molecular behaviors help us understand?
How lipids modulate CFTR membrane expression, stability, and function
This includes understanding the impact of various lipids on CFTR.
What happens to ASMase activity in response to stress?
It is activated without translocation from the cytoplasm
This reveals variability in ASMase behavior among different cell types.
Fill in the blank: CFTR clustering occurs at the _______ membrane of ciliated cells.
apical
What activates acid SMase?
Cells and secreted extracellularly.
What is the focus of the study on CFTR?
The role of protein-protein interactions and the cell cytoskeleton in CFTR expression, clustering, and stability at the PM of human airway epithelial cells.
Which two scaffold proteins are emphasized in the study?
- NHERF1
- Filamin A
What is NHERF1?
Cytoskeletal scaffold protein that connects membrane proteins to F-actin.
What is the hypothesis regarding PKC activation?
PKC activation leads to CFTR-NHERF1 interaction, which results in membrane CFTR stability and aggregation.
What happens if there is no CFTR-NHERF1 interaction?
No CFTR stability and aggregation.
What does truncating the PDZ-motif imply?
It affects CFTR stability and clustering.
What is Filamin A (FLNA)?
A cytoskeletal scaffold protein that forms dimers and interacts with both CFTR and F-actin.
What is the expected outcome of Filamin A gene knockdown?
- Decrease membrane CFTR expression
- Reduce CFTR clustering
- Decrease CFTR stability at the PM
True or False: CFTR clustering and platform formation are modulated by Filamin A interactions.
False.
What is the take-home message from the lecture?
Known protein-protein interactions (NHERF1 & Filamin A) and F-actin don’t modulate CFTR clustering inside lipid rafts or ceramide-rich platforms; membrane CFTR distribution and stability are modulated by membrane lipids (Cholesterol & Ceramide).
What do Latrunculin B and Cytochalasin D do?
They disrupt the actin cytoskeleton.
What is the relationship between CFTR and the actin cytoskeleton?
CFTR clustering and platform formation are NOT modulated by the actin cytoskeleton.
What is the role of Filamin A in CFTR stability/clustering?
Filamin A is expected to increase CFTR stability at the PM and induce CFTR clustering.
What evidence was found regarding CFTR and Filamin A interactions?
No evidence of interaction between CFTR and Filamin A.
What is the significance of membrane lipids in CFTR stability?
Membrane lipids modulate CFTR distribution and stability, particularly Cholesterol and Ceramide.
