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Investigating neuronal function with optically controllable proteins.

Zhou XX, Pan M, Lin MZ - Front Mol Neurosci (2015)

Bottom Line: For example, neurite extension and synaptogenesis both involve localized and transient activation of cytoskeletal and signaling proteins, allowing changes in microarchitecture to occur rapidly and in a localized manner.These tools have demonstrated versatility in controlling various proteins and thereby cellular functions, and possess enormous potential for future applications in nervous systems.Just as optogenetic control of neuronal firing using opsins has changed how we investigate the function of cellular circuits in vivo, optical control may yet yield another revolution in how we study the circuitry of intracellular signaling in the brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Stanford University Stanford, CA, USA.

ABSTRACT
In the nervous system, protein activities are highly regulated in space and time. This regulation allows for fine modulation of neuronal structure and function during development and adaptive responses. For example, neurite extension and synaptogenesis both involve localized and transient activation of cytoskeletal and signaling proteins, allowing changes in microarchitecture to occur rapidly and in a localized manner. To investigate the role of specific protein regulation events in these processes, methods to optically control the activity of specific proteins have been developed. In this review, we focus on how photosensory domains enable optical control over protein activity and have been used in neuroscience applications. These tools have demonstrated versatility in controlling various proteins and thereby cellular functions, and possess enormous potential for future applications in nervous systems. Just as optogenetic control of neuronal firing using opsins has changed how we investigate the function of cellular circuits in vivo, optical control may yet yield another revolution in how we study the circuitry of intracellular signaling in the brain.

No MeSH data available.


Uses of opsins.(A) Opto-α1-AR consists of bovine visual opsin with the intracellular loops of Gq-coupled human α1a-adrenergic receptor. Opto-β2-AR consists of bovine visual opsin with the intracellular loops of Gs-coupled hamster β2-adrenergic receptor. When excited with blue light, opto-α1-AR and opto-β2-AR activate production of IP3 and cAMP, increasing and decreasing neuronal firing in vivo, respectively. (B) Opto-MOR consists of rat visual opsin with the intracellular loops of the mu-opioid receptor. Optical stimulation results in inhibition of adenylate cyclase via Gi/o, activation of ERK via β-arrestin and Gi/o, and activation of GIRK via Gβγ. (C) Photoactivatable serotonin receptors can be produced by conjugating light-sensitive vertebrate opsins (here, denoted vOpsins) at various excitation wavelengths with the C terminal portion of a specific serotonin receptor subtype, which mediates proper localization within the cell via sorting proteins. Excitation with 400–600 nm light triggers activation of GIRK via Gβγ, decreasing neuronal firing.
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Figure 1: Uses of opsins.(A) Opto-α1-AR consists of bovine visual opsin with the intracellular loops of Gq-coupled human α1a-adrenergic receptor. Opto-β2-AR consists of bovine visual opsin with the intracellular loops of Gs-coupled hamster β2-adrenergic receptor. When excited with blue light, opto-α1-AR and opto-β2-AR activate production of IP3 and cAMP, increasing and decreasing neuronal firing in vivo, respectively. (B) Opto-MOR consists of rat visual opsin with the intracellular loops of the mu-opioid receptor. Optical stimulation results in inhibition of adenylate cyclase via Gi/o, activation of ERK via β-arrestin and Gi/o, and activation of GIRK via Gβγ. (C) Photoactivatable serotonin receptors can be produced by conjugating light-sensitive vertebrate opsins (here, denoted vOpsins) at various excitation wavelengths with the C terminal portion of a specific serotonin receptor subtype, which mediates proper localization within the cell via sorting proteins. Excitation with 400–600 nm light triggers activation of GIRK via Gβγ, decreasing neuronal firing.

Mentions: Based on the structural and functional similarities found in other families of GPCRs and vertebrate visual opsins, and following earlier work by the Khorana lab (Kim et al., 2005), Airan et al. (2009) proposed optoXRs, engineered opsins that control specific G proteins and downstream second messengers (Kim et al., 2005). They exchanged the intracellular loops of bovine visual opsin, which activates the G-protein family member Gi/o, with those of the α1a-adrenergic receptor, which activates the G-protein family member Gq, to create opto-α1AR. Likewise, they exchanged the intracellular loops of bovine visual opsin with those of the β2-adrenergic receptor, which specifically activates Gs, to create opto-β2AR (Figure 1A). Upon blue-cyan light illumination, opto-α1AR activated phospholipase C via Gq, leading to increased inositol trisphosphate (IP3) levels, and opto-β2AR activated adenylate cyclase via Gs, leading to increased cyclic adenosine monophosphate (cAMP) levels. Mice expressing opto-α1AR in nucleus accumbens (NAc) exhibited light-induced increases in spike firing, and light was sufficient to induce conditioned place preference in a behavior study. In contrast, opto-β2AR expression in the NAc reduced spontaneous firing.


Investigating neuronal function with optically controllable proteins.

Zhou XX, Pan M, Lin MZ - Front Mol Neurosci (2015)

Uses of opsins.(A) Opto-α1-AR consists of bovine visual opsin with the intracellular loops of Gq-coupled human α1a-adrenergic receptor. Opto-β2-AR consists of bovine visual opsin with the intracellular loops of Gs-coupled hamster β2-adrenergic receptor. When excited with blue light, opto-α1-AR and opto-β2-AR activate production of IP3 and cAMP, increasing and decreasing neuronal firing in vivo, respectively. (B) Opto-MOR consists of rat visual opsin with the intracellular loops of the mu-opioid receptor. Optical stimulation results in inhibition of adenylate cyclase via Gi/o, activation of ERK via β-arrestin and Gi/o, and activation of GIRK via Gβγ. (C) Photoactivatable serotonin receptors can be produced by conjugating light-sensitive vertebrate opsins (here, denoted vOpsins) at various excitation wavelengths with the C terminal portion of a specific serotonin receptor subtype, which mediates proper localization within the cell via sorting proteins. Excitation with 400–600 nm light triggers activation of GIRK via Gβγ, decreasing neuronal firing.
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Figure 1: Uses of opsins.(A) Opto-α1-AR consists of bovine visual opsin with the intracellular loops of Gq-coupled human α1a-adrenergic receptor. Opto-β2-AR consists of bovine visual opsin with the intracellular loops of Gs-coupled hamster β2-adrenergic receptor. When excited with blue light, opto-α1-AR and opto-β2-AR activate production of IP3 and cAMP, increasing and decreasing neuronal firing in vivo, respectively. (B) Opto-MOR consists of rat visual opsin with the intracellular loops of the mu-opioid receptor. Optical stimulation results in inhibition of adenylate cyclase via Gi/o, activation of ERK via β-arrestin and Gi/o, and activation of GIRK via Gβγ. (C) Photoactivatable serotonin receptors can be produced by conjugating light-sensitive vertebrate opsins (here, denoted vOpsins) at various excitation wavelengths with the C terminal portion of a specific serotonin receptor subtype, which mediates proper localization within the cell via sorting proteins. Excitation with 400–600 nm light triggers activation of GIRK via Gβγ, decreasing neuronal firing.
Mentions: Based on the structural and functional similarities found in other families of GPCRs and vertebrate visual opsins, and following earlier work by the Khorana lab (Kim et al., 2005), Airan et al. (2009) proposed optoXRs, engineered opsins that control specific G proteins and downstream second messengers (Kim et al., 2005). They exchanged the intracellular loops of bovine visual opsin, which activates the G-protein family member Gi/o, with those of the α1a-adrenergic receptor, which activates the G-protein family member Gq, to create opto-α1AR. Likewise, they exchanged the intracellular loops of bovine visual opsin with those of the β2-adrenergic receptor, which specifically activates Gs, to create opto-β2AR (Figure 1A). Upon blue-cyan light illumination, opto-α1AR activated phospholipase C via Gq, leading to increased inositol trisphosphate (IP3) levels, and opto-β2AR activated adenylate cyclase via Gs, leading to increased cyclic adenosine monophosphate (cAMP) levels. Mice expressing opto-α1AR in nucleus accumbens (NAc) exhibited light-induced increases in spike firing, and light was sufficient to induce conditioned place preference in a behavior study. In contrast, opto-β2AR expression in the NAc reduced spontaneous firing.

Bottom Line: For example, neurite extension and synaptogenesis both involve localized and transient activation of cytoskeletal and signaling proteins, allowing changes in microarchitecture to occur rapidly and in a localized manner.These tools have demonstrated versatility in controlling various proteins and thereby cellular functions, and possess enormous potential for future applications in nervous systems.Just as optogenetic control of neuronal firing using opsins has changed how we investigate the function of cellular circuits in vivo, optical control may yet yield another revolution in how we study the circuitry of intracellular signaling in the brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Stanford University Stanford, CA, USA.

ABSTRACT
In the nervous system, protein activities are highly regulated in space and time. This regulation allows for fine modulation of neuronal structure and function during development and adaptive responses. For example, neurite extension and synaptogenesis both involve localized and transient activation of cytoskeletal and signaling proteins, allowing changes in microarchitecture to occur rapidly and in a localized manner. To investigate the role of specific protein regulation events in these processes, methods to optically control the activity of specific proteins have been developed. In this review, we focus on how photosensory domains enable optical control over protein activity and have been used in neuroscience applications. These tools have demonstrated versatility in controlling various proteins and thereby cellular functions, and possess enormous potential for future applications in nervous systems. Just as optogenetic control of neuronal firing using opsins has changed how we investigate the function of cellular circuits in vivo, optical control may yet yield another revolution in how we study the circuitry of intracellular signaling in the brain.

No MeSH data available.