Cholesterol homeostasis and signal transduction through lipid rafts

1
Cholesterol homeostasis and signal transduction
through lipid rafts

• Siyang Peng

2
Cholesterol homeostasis disorder

• Functions of cholesterol
• Cell membrane
• Hormone
• Lipid raft and caveolae
• NPC
• Storage of useless cholesterol

3
NPC kills receptors function

• Receptor signaling disfunction in NPC1 deficient
  cells
• Insulin receptor
• TrKB receptor (BDNF)
• No expression change
• Lipid Raft disorder

4
Lipid rafts organize membrane signal complex

• Lipid rafts function to segregate and concentrate
  membrane proteins.
• What else receptor signaling is affected by lipid
  rafts disorder?

5
Aim

• To find out membrane signal proteins, which
  change distribution pattern, in response to
  cholesterol depletion from the plasma membrane.
• In NPC
• In other cholesterol homeostasis disorder
  diseases
• Provide evidence for the mechanism of symptoms of
  the disease and possible therapeutic target.

6
Step by Step

• Isolation of lipid raft
• Detergent Resistant Membrane/ 1 Triton X-100
• Generation of antibody library
• Phage library
• Visualize distribution of proteins by
  immunostaining
• Software analysis
• Identify proteins
• Get back to proteins to detect their functional
  change

7
How good cell image can be

• x-ray tomography
• The relatively high energy of x-rays gives rise
  to images with higher spatial resolution than is
  possible using light based imaging techniques,
  and with greater penetration depth than is
  achievable with electron based microscopies.
• http//ncxt.lbl.gov/YeastMovies/

8
Edge Detection --- Derivative

• Translate the cell image to a language that can
  be understood by computer.

9
Software analysis

• Learn the pattern
• Polar or non-polar
• Patch or disperse
• Big cluster or small dot
• Cell surface or intracellular
• Match the pattern

10

• Protein profile of lipid rafts
• Technique for cell map proteomics