Light-activated chimeric opsins and methods of using the same
Provided herein are compositions comprising light-activated chimeric proteins expressed on plasma membranes and methods of using the same to selectively depolarize excitatory or inhibitory neurons.
1. A mammalian cell comprising a polynucleotide comprising a nucleotide sequence encoding a light-responsive chimeric polypeptide comprising an amino acid sequence having at least 95% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:1, wherein the light-responsive chimeric polypeptide is present in the cell membrane.
2. The mammalian cell of claim 1 , wherein the light-responsive chimeric polypeptide comprises a C-terminal trafficking signal.
3. The mammalian cell of claim 2 , wherein the trafficking signal comprises the amino acid sequence KSRITSEGEYIPLDQIDINV (SEQ ID NO:15).
4. The mammalian cell of claim 1 , wherein the nucleotide sequence is operably linked to a promoter.
5. The mammalian cell of claim 1 , wherein the light-responsive chimeric polypeptide comprises a Glu to Thr amino acid substitution at position 122 relative to the amino acid sequence set forth in SEQ ID NO:1.
6. The mammalian cell of claim 1 , wherein the light-responsive chimeric polypeptide comprises a Glu to Thr amino acid substitution at position 162 relative to the amino acid sequence set forth in SEQ ID NO:1.
7. The mammalian cell of claim 1 , wherein the light-responsive chimeric polypeptide comprises a Glu to Thr amino acid substitution at position 122 and a Glu to Thr amino acid substitution at position 162 relative to the amino acid sequence set forth in SEQ ID NO:1.
8. The mammalian cell of claim 1 , wherein the cell is a neuronal cell, a muscle cell, or a stem cell.
9. The mammalian cell of claim 1 , wherein the cell is an excitatory neuronal cell or an inhibitory neuronal cell.
10. The mammalian cell of claim 1 , wherein the cell further comprises a second light-activated polypeptide present in the cell membrane.
11. The mammalian cell of claim 10 , wherein the second light-activated polypeptide comprises an amino acid sequence having at least 85% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NOs: 11, 12, 13, or 14.
12. A method of depolarizing an excitatory or an inhibitory neuron, the method comprising exposing the neuron to light of a wavelength between about 540 nm to about 560 nm, wherein the neuron expresses in its cell membrane a light-responsive chimeric polypeptide comprising an amino acid sequence having at least 95% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:1.
13. The method of claim 12 , wherein the neuron is an excitatory neuron present in a microcircuit, and where the method further comprises expressing a second light-activated polypeptide in an inhibitory neuron, wherein the second light-activated polypeptide comprises an amino acid sequence having at least 85% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NOs: 11, 12, 13, or 14, and wherein the inhibitory neuron is exposed to light of a second wavelength.
14. The method of claim 12 , wherein the excitatory neuron is present in the prefrontal cortex.
15. The method of claim 12 , wherein the excitatory neuron comprises a pyramidal neuron.
16. The method of claim 12 , wherein the inhibitory neuron is present in the prefrontal cortex.
17. The method of claim 12 , wherein the inhibitory neuron comprises a parvalbumin neuron.
18. The method of claim 13 , wherein the excitatory neuron and the inhibitory neuron are present in the prefrontal cortex.
19. The method of claim 13 , wherein the excitatory neuron and the inhibitory neuron are present in the prefrontal cortex.