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!