Week 6 Modern pain management
SMDs/biologics, targeting GPCR signaling in pain
LE GPCRs mediated signaling
Signaling molecules
Signal transduction is the overall process of converting extracellular signals into intracellular
responses. Cells constantly receive signals from signaling molecules, mechanical changes or action
potentials. Cells respond by metabolize, motility, apoptosis, cellular differentiation, immunity.
Signaling molecules/ligands: small molecules (gasses and ATP), peptides (vasopressin), soluble
proteins (growth hormone), and proteins bound to cell surface or extracellular matrix (chemokines)
- Hormones are special kind of signaling molecule because they are released by cell or gland in
on part of the body that affect other parts of the body. There are 3 classes.
o Peptide hormones (vasopressin), protein hormones (insulin, growth hormone), or
glycoprotein hormones (LS, FSH)
o Lipid-derived hormones (like steroids as testosterone)
o Monoamines derived from amino acids (epinephrine)
5 intracellular signaling methods:
5th method = Synaptic signaling
Intracellular receptors
There are many types of receptors.
1. Cytosolic receptors: ligands should be able to pass the membrane (small and hydrophobic)
a. Lipophilic ligands (like steorids) can pass the membrane (expect if theyre large).
Ligand-binding serum protein can help ligand to cell. When ligands are in the cell,
they bind cytosolic receptors, dimerization of receptors (now they are transcription
factors), moving into nucleus, transcription or inhibition of transcription of DNA.
2. Cytokine receptors: have extracellular, transmembrane, and intracellular domain
3. RTKs: have extracellular, transmembrane, and intracellular domain
4. Ligand-gated ion channels
5. GPCRs
, Cell-surface ion channels
Ion channels: ligand binding -> conformation change opening the channel, ions can pass. Some ion
channels can also be stimulated intracellularly
Cell-surface GPCRs
G-protein coupled receptors (GPCR) have 7 transmembrane helixes, some extracellular and
intracellular loops and tails. Loops are important for interaction with G-proteins. Different families
(ABC) that have differences in the loops
GPCRs is the largest class of drug targets because the human genome encodes about 720 GPCRs They
cause taste, smell, and vision. GPCRs cause short-term changes: rapid responses to changes in the
environment (instead of receptors that regulate gene transcription).
Many GCPRs are regulated by neurotransmitters (epinephrine, dopamine, serotonin etc). Most
hormone receptors that control metabolism (carbohydrates, amino acids, fat metabolism (e.g.
epinephrine), regulate GPCRs.
Activation mechanism of GPCRs
The membrane helix has conformational change in response to ligand binding. Space opens so G-
proteins can bind.
Receptors that are always in active conformation without ligand binding can cause serious diseases
SMDs/biologics, targeting GPCR signaling in pain
LE GPCRs mediated signaling
Signaling molecules
Signal transduction is the overall process of converting extracellular signals into intracellular
responses. Cells constantly receive signals from signaling molecules, mechanical changes or action
potentials. Cells respond by metabolize, motility, apoptosis, cellular differentiation, immunity.
Signaling molecules/ligands: small molecules (gasses and ATP), peptides (vasopressin), soluble
proteins (growth hormone), and proteins bound to cell surface or extracellular matrix (chemokines)
- Hormones are special kind of signaling molecule because they are released by cell or gland in
on part of the body that affect other parts of the body. There are 3 classes.
o Peptide hormones (vasopressin), protein hormones (insulin, growth hormone), or
glycoprotein hormones (LS, FSH)
o Lipid-derived hormones (like steroids as testosterone)
o Monoamines derived from amino acids (epinephrine)
5 intracellular signaling methods:
5th method = Synaptic signaling
Intracellular receptors
There are many types of receptors.
1. Cytosolic receptors: ligands should be able to pass the membrane (small and hydrophobic)
a. Lipophilic ligands (like steorids) can pass the membrane (expect if theyre large).
Ligand-binding serum protein can help ligand to cell. When ligands are in the cell,
they bind cytosolic receptors, dimerization of receptors (now they are transcription
factors), moving into nucleus, transcription or inhibition of transcription of DNA.
2. Cytokine receptors: have extracellular, transmembrane, and intracellular domain
3. RTKs: have extracellular, transmembrane, and intracellular domain
4. Ligand-gated ion channels
5. GPCRs
, Cell-surface ion channels
Ion channels: ligand binding -> conformation change opening the channel, ions can pass. Some ion
channels can also be stimulated intracellularly
Cell-surface GPCRs
G-protein coupled receptors (GPCR) have 7 transmembrane helixes, some extracellular and
intracellular loops and tails. Loops are important for interaction with G-proteins. Different families
(ABC) that have differences in the loops
GPCRs is the largest class of drug targets because the human genome encodes about 720 GPCRs They
cause taste, smell, and vision. GPCRs cause short-term changes: rapid responses to changes in the
environment (instead of receptors that regulate gene transcription).
Many GCPRs are regulated by neurotransmitters (epinephrine, dopamine, serotonin etc). Most
hormone receptors that control metabolism (carbohydrates, amino acids, fat metabolism (e.g.
epinephrine), regulate GPCRs.
Activation mechanism of GPCRs
The membrane helix has conformational change in response to ligand binding. Space opens so G-
proteins can bind.
Receptors that are always in active conformation without ligand binding can cause serious diseases
