Cellular Signaling
Montarop Yamabhai
Suranaree University of Technology
Out line
I.
II.
III.
Principle of Cellular Signaling
Nuclear Receptor
G Protein-Couple Receptors (GPCR) and
Second Messengers
IV. Receptor Tyrosine Kinases
V. Other Signaling Pathway
VI. Interaction and Regulation of Signaling
Pathway
VII. Target intervention in Signal Transduction
I. Principle of cellular signaling
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Extracellular signal molecules bind to specific
receptors
There are two types of receptors
There are 5 types of intercellular signaling
Identification and purification of cell surface
receptor
Responses from cellular signaling
There are three majors classes of cell-surface
receptor
Multiple steps of cell signaling
Different types of intracellular signaling proteins
Methods that are used to study protein-protein
interaction
There are two types of receptors:
Ligands that bind to intracellular
receptors
Ligands that bind to cell surface
receptors
• Water soluble hormone and neuro
transmitters
– Peptide hormones
– Small charged hormones and neurotransmitters
• Prostaglandin and other eicosanoid
hormones
Small molecules that function as neurotransmitters
Eicosanoid hormones
5 Types of Intercellular Signaling
1.
Endocrine signaling
2.
Paracrine signaling
3.
Synaptic signaling
4.
Autocrine signaling
5.
Signaling by plasma
membrane-attached
proteins
Identification of cell surface receptor
Purification of cell surface receptor
Basic Components and Responses
of Cellular Signaling
Chage in ion
permeability
Activation/
repression of
DNA/RNA
synthesis
3 Types of Cell-SurfaceReceptors
1. Ion-channel-linked
receptors
2. G-protein-coupled
receptors
3. Enzyme-linked
receptors
Multi steps of signaling
pathway
• Recognition of stimulus by cell surface
receptor
• Transfer of signal across plasma
membrane
• Transmission of the signal to specific
targets inside the cells
• Cessation of the responses
Types of Signaling Protiens
1. Proteins Kinases / Phosphatases. These
are proteins that involve in
phosphorylation reactions
2. Proteins or GTP-binding proteins
3. Adaptor and scaffold proteins
Protein Kinases &
Phosphatases
Final Target
G-Protein
Accessory proteins
1. GTPase-activating proteins (GAPs)
2. Guanine nucleotide-exchange
factors (GEFs)
3. Guanine nucleotide-dissociation
inhibitors (GDIs)
Adaptor Protein
Scaffold Proteins
Detection of Protein-Protein Interaction
by Yeast two-hybrid system
Detection of Protein-Protein Interaction
by Phage Display Technology
Nuclear Receptor
(Ligand-activated Gene Regulartory Protein)
Responses induced by the activation of
a nuclear hormone
G Protein-Couple Receptors
(GPCR) and Second Messengers
1. Structure and Function of G proteincouple receptor
2. Second messengers
3. The specificity of G protein-coupled
responses
4. The role of G-protein-coupled receptors
in sensory perception
G protien-coupled receptor
Seven membrane spanning a helices
G protein binds to guanine
nucleotides, either
GDP or GTP. It consists of three
different polypeptide subunits,
called a, b, and g.
Mechanism of activation of
GPCR
1. activation of the G protein by the receptor
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Activation of adenylate cyclase to generate cAMP
Activation of phospholipase Cb to generate IP3 and
DAG
2. relay of the signal from G protein to effector
3. ending of the response
I. Activation of the G protein by the receptor
II. Relay of the signal from G protein to
effector
III. Ending of the response
The synthesis and degradation
of cAMP
b-adrenergic receptors mediate the induction
of epinephrine-initiated cAMP synthesis
Agonist and of the
b-adrenergic receptors
-Epinephrine
-isoproterenol
Antagonist of the
b-adrenergic receptors
-Alprenolol
-Propranolol
-Practolol
Hormone-induced activation and
inhibition of adenylate cyclase
Activation of cAMP-dependent
protein kinase (PKA) by cAMP
Table 1
A sample of known PKA
substrates
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Muscle glycogen synthase (Ia)
Phosphorylase kinase a
Protein phosphatase-1
Pyruvate kinase
CREB
Liver tyrosine hydroxylase
Acetylcholine receptor d
Protein phosphatase inhibitor -1
S6 ribosomal proteins
Rabbit heart troponin
Hormone sensitive lipase
Phosphofructokinase
Myosin light-chain kinase
Fructose biphosphatase
Phosphorylase kinase b
Musle glycogen synthase
Acetyl CoA carboxylase
A variety of responses from
cAMP signaling
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Plasma membrane: transport
Microtubule: assembly and disassembly
Endoplasmic recticulum: protein synthesis
Nucleus: DNA synthesis, gene expression
Mitochondria and cytosol: glycogen break
down (phosphorylase) in liver, glycogen
synthase, triglyceride lipase (fatty acid
formation in fat cells
QuickTime™ and a Animation decompressor are needed to see this picture.
Activation of gene transcription by a rise in
cAMP
Regulation of glycogen breakdown and
synthesis by cAMP in liver and muscle cells
The role of cAMP in glucose
metabolism in liver cells
Amplification of the signal via
cAMP signaling pathway
The generation of phosphatidyl inositolderived second messengers
Protein Kinase C (PKC) is activated by
inositol phospholipid pathway
QuickTime™ and a Animation decompressor are needed to see this picture.
Elevation of Ca2+ via the inositol
lipid signaling pathway
Table 20-4. Cellular Responses to Hormone-Induced Rise in Inositol 1,4,5-Trisphosphate (IP3) and
Subsequent Rise in Cytosolic Ca2+ in Various Tissues
Tissue
Hormone Inducinga Rise in IP3
Cellular Response
Pancreas (acinar
cells)
Acetylcholine
Secretion of digestive enzymes, such as
amylase and trypsinogen
Parotid (salivary
gland)
Acetylcholine
Secretion of amylase
Pancreas (b cells of
islets)
Acetylcholine
Secretion of insulin
Vascular or stomach
smooth muscle
Acetylcholine
Contraction
Liver
Vasopressin
Conversion of glycogen to glucose
Blood platelets
Thrombin
Aggregation, shape change, secretion of
hormones
Mast cells
Antigen
Histamine secretion
Fibroblasts
Peptide growth factors, such as
bombesin and PDGF
DNA synthesis, cell division
Sea urchin eggs
Spermatozoa
Rise of fertilization membrane
SOURCE: M. J. Berridge, 1987, Ann. Rev. Biochem. 56:159; M. J. Berridge and R. F. Irvine, 1984, Nature
Ca2+ Calmodulin mediates many
cellular responses
The specificity of G proteincoupled responses
• GPCRs link to different G protein
• G protein regulate different effector proteins
Table 20-5. Properties of Mammalian G Proteins Linked to GPCRs
Ga Subclass
Effect
Associated Effector Protein
2nd Messenger
Gs
Adenylyl cyclase
Ca2+ channel
Na+ channel
cAMP
Ca2+
Change in membrane potential
Gi
Adenylyl cyclase
K+ channel
Ca2+ channel
cAMP
Change in membrane potential
Ca2+
Gq
Phospholipase C
IP3, DAG
Go
Phospholipase C
Ca2+ channel
IP3, DAG
Ca2+
Gt
cGMP phosphodiesterasec
GMP
Gbg
Phospholipase C
Adenylyl cyclase
IP3, DAG
cAMP
The specificity of G protein-coupled responses
G protein in receptor
sensory
Response of a rod photoreceptor cell to light
Receptor Tyrosine Kinases
(RTKs)
Activation of RTKs
Ras function downstream of
RTKs
Activation of Ras by RTKs
Ras activate MAP Kinase
Cascade
Insulin Signaling Pathway
IV Other Signaling Pathways
• Other enzyme-linked signaling pathway
– Jak-STAT signaling pathway
– TGF-b signaling pathway
• Signaling pathways that depend on
regulated proteolysis
– Wnt signaling pathway
– TNF-a signaling pathway
• Nitric oxide signaling pathway
• Apoptotic pathway
• Signaling from contacts between cell
surface and the substratum
Activation of Jak-STAT pathway
by Cytokine Receptors
TGF-b Pathway
Wnt Signaling Pathway
TNF-a signaling Pathway
Nitric Oxide (NO) Signaling
Apoptotic Pathway
Signaling from contacts between
cell surface and the substratum