General introduction into optogenetics
Represented by Cuong, Pham Van
http://www.cairn-research.co.uk/applications/optogenetics-the-led-light-switch-neurons
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
What is optogenetics?
“Optogenetics is the combination of geneticand optical methods to achieve gain or lossof function of well-defined events in specificcells of living tissue”
Karl Deisseroth (2011)
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
Timeline of development of optogenetics
Early 20th century
Functional unit of nervous system: Neuron
1970s 2002 2005…
Functional unit of nervous system: Neuron- signal transmitter
• By changes in membrane potential due to opening/closing specific ion pump channel
• 2 type of changes: depolarizing (excitatory stimulus)hyperpolarization (inhibitory stimulus)
http://classes.midlandstech.edu/carterp/Courses/bio210/chap11/lecture1.html
Timeline of development of optogenetics
Early 20th century
Functional unit of nervous system: Neuron
1970s
Idea of neural control by light
2002 2005…
Idea of neural control by light
• Challenge: how to control one type of cells in brain while not influence others?
• Inappropriate factors: electorde (no precisely target), drug ( broaden effect, too much slowly)
• Light might have properties as a control tool
“Thinking about brain”, Francis Crick (1979)
Timeline of development of optogenetics
Early 20th century
Functional unit of nervous system: Neuron
1970s
Idea of neural control by light
Discovery of opsins: BacteriorhodopsinHalorhodopsin
2002 2005…
Discovery of opsins: visible-light-activated ion pumps
• (1971) Bacteriorhodopsin:Extrude proton to create proton gradient for production of ATP
• (1977) Halorhodopsin (NpHR)
Transport chloride into cytoplasm to maitain osmotic balance
•Microbial ion pump activated by visible light
Oesterhelt and Stoeckenius, 1971MatsunoYagi and Mukohata, 1977
10.1016/B978-0-444-59426-6.00001-X
Timeline of development of optogenetics
Early 20th century
Functional unit of nervous system: Neuron
1970s
Idea of neural control by light
Discovery of opsins: BacteriorhodopsinHalorhodopsin
2002
Channelrodopsinsdescribed
2005…
Channelrodopsins
• From unicellular photosynthetic organism• Used for light orientation
• 2 type: ChR1 (permeable to photon)
ChR2 (permeable to other cations)
10.1016/B978-0-444-59426-6.00001-XNagel et al., 2002
Timeline of development of optogenetics
Early 20th century
Functional unit of nervous system: Neuron
1970s
Idea of neural control by light
Discovery of opsins: BacteriorhodopsinHalorhodopsin
2002
Channelrodopsinsdescribed
2005
First application of opsins to neurosciense
…
First application of opsins to neurosciense
• By Boyden et al., 2005• Successful expression
of ChR2 in cultured mammalian hippocampal neurons
• ChR2 activation by light was enough to produce action potential
http://www.cell.com/cms/attachment/2007954326/2030561053/gr1.jpg
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
Process of optogenetics
1. Choosing opsins of interest
2. Using viral carrier to express opsins
3. Delivering light into brain
http://optogenetics.weebly.com/why--how.htmlPama et al., 2013
Process of optogenetics
1. Choosing opsins of interest
2. Using viral carrier to express opsins
3. Delivering light into brain
http://optogenetics.weebly.com/why--how.htmlPama et al., 2013
Choosing opsin of interest• Excitatory by ChR2
with blue light
• Inhibitory by NpHR with yellow light
Pama et al., 2013
Process of optogenetics
1. Choosing opsins of interest
2. Using viral carrier to express opsins
3. Delivering light into brain
http://optogenetics.weebly.com/why--how.htmlPama et al., 2013
Using viral carrier to express opsin• Lenti and adeno-associated virus
(AAV) is commonly usedhigh expression level over long time period, no adverse effects
• Site-specific enhance by cell-type-specific-promoter or Cre recombinase-dependent expression system
(Pama et al., 2013; Yizhar et al., 2011)
Process of optogenetics
1. Choosing opsins of interest
2. Using viral carrier to express opsins
3. Delivering light into brain
http://optogenetics.weebly.com/why--how.htmlPama et al., 2013
Delivering light into brain
• Using chronically implanted cannula (ống cấy
ghép cố định) (affixed to skull)
• Attached optical fiber: to delivering laser light directly into brain
Pama et al., 2013
http://www.nytimes.com/2011/05/17/science/17optics.html?_r=1
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
Application of optogenetics
Example:• In neuromodulation research
Using optogenesis to show how symptoms of Parkinson’s disease can be either aggravated or improved (Kravitz et al., 2010)
• In sleep researchExamining boundaries between sleep and wakefulness by applying optogenetics to control neural circuit
Advantage: fast (in millisecond scale) and precision (cell type- specific)
Karl Deisseroth, 2010Pama et al., 2013
Outline
1. What is optogenetics?2. Timeline of development of optogenetics3. Process of optogenetics4. Application of optogenetics5. Beyond the neuroscience
Beyond the neuroscience
• Appropriate for the target tissue of choice• With regard to electrical or biochemical
effector function, speed and other properties
• Example: Control biochemical, electrical drive in culturing stem cell
Karl Deisseroth, 2010
Thanks for attending and listening!