strand 3 Flashcards
(153 cards)
1
Q
intracellular signalling
steps?
A
- extracellular signal molecule activates membrane receptor
- intracel molecules transduced via pathway
- cellular response activated
1st messenger (extracellular) 2nd messenger (intracellular) transducers (membrane proteins)
2
Q
high blood sugar response?
A
insulin release from pancreas (beta islets)
insulin> tissue for glucose conversion to glycogen
3
Q
low blood sugar response
A
glucagon release from alpha islets in pancreas
glycogen > glucose
4
Q
types of response
A
altered: ion transport/ metabolism/ gene expression/ cell shape/ movement/cell growth/ division
5
Q
receptor locations
response speed?
A
cell surface (fast response)
intracellular/ nuclear (slow response)
6
Q
cell surface receptor molecules
membrane crossing?
pathways?
A
for hydrophilic signalling molecules
can’t cross membrane therefore must bind
variety of pathways
7
Q
intracellular / nuclear receptor molecules
membrane crossing
responses?
A
hydrophobic molecules
cross PM via simple diffusion
txn factors
8
Q
4 main receptor classes
A
ligand-gated ion channels (ionotropic)
G-protein coupled receptors (metabotropic)
enzyme-linked receptors
nuclear receptors
9
Q
3 types of cell surface receptors
A
ligand gated ion
G protein coupled
kinase-linked
10
Q
ionotropic receptor examples
A
nicotinic ACh receptor
gabaA (gamma-amino butyric acid)
11
Q
nicotinic ACh receptor
A
mediated ACh effect on muscle
ACh binding opens channel/ allows Na+/Ca+ entry
binds nicotine
12
Q
GABAa receptor
activators? ion selection? role?
A
activated by GABA (CNS neurotransmitter)/ benzodiazepines
Cl- ion selectivity
role in CNS
inhibitory receptor
13
Q
metabotropic receptor
example?
A
indirect link w ion channels on PM via signal transduction
e.g. Muscarinic ACh receptor/ GABAb
role in cell function regulation
14
Q
Muscarinic ACh receptor
A
favour muscarine over nicotine
15
Q
GABAb
A
activate potassium channels
16
Q
no. transmembrane domains/ polypeptide chains of metabotropic
no. sub-units per polypeptide chain?
A
7 transmembrane domains
3 polypeptide chains (alpha beta and gamma)
alpha (16) beta (5) gamma (11)
17
Q
metabotropic polypeptide structure
A
beta and gamma bind tightly to each other (Bgamma subunit)
alpha has guanine nucleotide site binding GTP/GDP
complexes in PM
18
Q
alpha GTP/ GDP affinity for beta gamma sub-unit
A
alpha GTP> High affinity
alpha GDP> low affinity
19
Q
G protein cycle
A
- adr binds beta-adrenoreceptor
- g protein interaction
- GTP/GDP exchange
- a sub-unit liberation
- AC activation
- adr unbinding/ GTP hydrolysis
20
Q
what does cAMP activate
structure of protein activated?
A
PKA (protein kinase A)
2 polypeptide chains (C catalytic and R regulatory)
bound together when
21
Q
PKA C and R polypeptide chain sub-units
A
2R and 2C form tetramer
R has 2 cAMP binding sites> allows sub-unit dissociation, activation and phosphorylation of other proteins
22
Q
PKA function
A
catalyzes transfer of serine/ threonine res on substrate proteins
23
Q
physio responses mediated by cAMP/PKA
A
kidney collecting duct
vascular smooth muscle
colonic eipthelium
pancreas
24
Q
termination of signal transduction
A
removal/ inactivation of: signal/receptor, signalling proteins, 2nd messengers
dephosphorylation
25
removal of second messengers
cAMP hydrolysed by phosphodiesterase/ unbound from R ^affin C
| tetramer reassembly
26
PDE inhibition
caffeine prolongs cellular response
27
receptor desensitization example
beta adrenoceptor kinase
1. PKA phosphorylates BARK ^ activity
2. BARK phosphorylates beta adrenoceptor decreasing adrenaline affin and therefore response
28
PKA and CREB
PKA phosphorylates CREB and activates txn of target genes
29
G protein sequence
G > adenlyl cyclase> cAMP> activated PKA
30
types of G protein
GS
G1
Gq
31
dual control of adenlyl cyclase
alpha s stimulates AC
alpha i inhibits AC
| a(s) GTP bound
32
beta adrenoreceptors
| (vasopressin receptor)
A(2a/b)> adenosine receptors couple Gs
33
alpha 2 adrenoceptors
| mu/ delta opioid receptors
A1/3 couple to Gi
34
cholera toxin target
## Footnote
where does this occur
alpha s sub-unit
| causes ADP ribosylation/ prevents GTP hydrolysis
## Footnote
occurs in colon in PKA-dependent Cl- channels (CFTR) >> diarrhoea
35
pertussis toxin target
## Footnote
where does this occur?
locks alpha i into inactive config> no receptor activation/ inhib control of AC
| in airway (whooping cough)
36
Gq
| sub-units?? activating target?
## Footnote
how does it affect ACh
contains alpha(q11)
allow hormones/neurotrans to activate PLC
## Footnote
underlies autonomic ACh effects
37
PLC
| action?
Phospholipase C
amplifier enzyme
| cleaves PIP2 (membrane phospholipid)
38
autonomic effects of ACh
| why?
H1 receptor responses (GI smooth muscle contraction)
| due to ^Ca2+
39
PIP2 cleavage products
> IP3 + DAG
| Inositol 1,4,5-phosphate + diacylglycerol
40
IP3 action
| characteristic enabling action
water-soluble so travels through cytosol to stimulate Ca release from ER
41
DAG action
| characteristic enabling action
hydrophobic therefore stays in membrane and recruits PKC
| ^Ca2+-dependent protein kinase
42
Calmodullin
| complex action?
Ca binding protein
each binds 4 Ca2+
| Ca2+-CaM complex activates PDE/ CaM kinases
43
# [](http://)
CaM kinase action
phosphorylate ser/thre on substrate proteins
smooth muscle contraction
44
example of Gq coupled receptor
| action?
alpha 1 adrenoreceptor
| ^ intra free Ca2+ and activate CaMKs
## Footnote
causes vasoconstriction
45
DAG
Ca2+ dependent PKA
^cell response w phosphorylation ^PKC
mediates BARK densensitisation
regulates: cell shape/ proliferation/ txn factor activity
| PKC mediates IPC
46
alpha 1 adrenoreceptor
vasoconstriction via Gq
| Gq> PLC>IP3>CaMK
47
muscarinic receptors
| G protein involvement/ no. sub-types?
Gq/Gi coupled
ACh activated (metabotropic)
5 sub-types (1,3,5 Gq-coupled) (2,4 Gicoupled)
| autonomic ACh effects
48
enzyme linked receptors examples
guanlyl cyclases
tyrosine/serine/threonine kinase
tyrosine phosphatase
tyrosine kinase assoc.
49
receptor guanlyl cyclase
2 guanlyl cyclase domains
| convert GTP>cGMP
## Footnote
cGMP activates downstream kinases
50
guanlyl cyclase mechanism
1. ANP binding (dimerisation/ activation)
2. guan cyc generates cGMP
3. other signalling molecules activated
## Footnote
e.g. response of vasodilation
51
beta 2 adrenoreceptors
vasodilation
| via Gs>cAMP>PKA
52
serine/ threonine kinases
domains target proteins
53
serine/ threonine kinase mechanism
1. 1st messenger binds tII receptor
2. TI binds (ternary complex w TII/1st messenger)
3. TII phosphorylates TI (activting TI kinase)
4. TI phosph target proteins
| e.g. response of cell proliferation
54
receptor tyrosine kinases
domains phosphorylate selves/ other proteins
55
receptor tyr kinase mechanism
1. binds 2 insulin molecules (receptor dimerization)
2. cytoplasmic tyr kinase phosp each other at tyr res (phosphotyrosine motifs)
3. motifs recruit intra signalling molecules (response)
## Footnote
e.g. insulinmediated glu uptake
MAP kinase signalling pathway
56
MAP kinase pathway
1. activated Ras protein phosphorylates MAP kinase *3
2. 4 proteins produced (X,Y > activity change /txn reg A,B >gene exp change)
57
tyrosine kinase associated receptors
non-covalently association w cyto domains
58
tyrosine kinase associated receptor mechanism
1. 1st messenger binds receptor> dimerization
2. tyr phos on selves/ receptor (phosphotyrosine motifs)
3. motifs recruit intra signal molecules
59
tyrosine phosphatase receptor
domains dephosphorylate target proteins
60
tyrosine phosphatase mechanism
1. CD45 binds receptor
2. target dephosph by tyr phosp
3. downstream cell-signalling event regulation
61
GPCR sequence
- activate intra signal via G> conform change> intra^>signa,lling cascade
| 2nd messengfer system (cAMP/IP3/DAG)
no enzyme
62
RTK sequence
ligand binding> ^kinase activity> tyr phosph self/downswtream
| SH2 domains/ Ras/ MAP kinase/ PI3
direct phosphorylation
enzymatic activ
63
circulating glucose concentration
~5mM
64
types of islets of Langerhan
| percentages of each/ products
alpha (15-20%) > glucagon
beta (65-80%)>insulin
gamma (3-10%)> somatostatin
65
insulin
structure?
| inactive form?
polypeptide hormone processed in golgi
2 polypep chains held by disulfide bridges (A> 21aa B> 30aa)
| pro-insulin is inactive form
66
pro-insulin activation
prohormone convertase 1/2 remove C chain of 33 aa
67
insulin storage
secretory granules of beta cells w pro-insulin/ c peptide
68
2 phases of glucose infusion against insulin production
1. rapid transient response
2. slower sustained response
| - phase 1: insulin release from secretory granules
- phase 2: synthesis/
69
insulin circulation and degradation
circulated in free form
degraded by insulinase
| degradation in liver/muscles/kidney
70
plasma half-life
~6 mins
71
C chain
stable
assayed to indicate insulin secretion
72
insulin and glucose concentration relations
| experiments
continuous glucose infusion
| max insulin when [glu]>9mM
73
glucose transport into beta cell
beta cell express GLUT2 transport system
| hormone insensitive therefore always active
74
glucose production of ATP/ADP
glucose phosphorylated to glucose-6-P (via glucokinase) / metabolized by glycolysis/ mito oxidation > ATP/ADP
| in beta cell
75
what is concentration of ATP produced affected by?
circulating glucose conc
(also affects intracellular glucose conc)
76
beta cell channels
ATP-sensitive K+ channels
v-gated Ca2+ channels
| ATP sensitive K+= drug target for diabetes
77
ATP-sensitive K+ channel
| opening/ closing
open at normal [ATP]
close at high [ATP]
78
v-gated Ca2+ channels
close at normal Vm
depolarization opens v-gated Ca2+ channels / ^membrane permeability to Ca2+
| cell membrane impermeable to Ca2+
79
normal glucose concentration sequence
normal [glu]> normal ATP> K+ open> Vm hyperpolarised> Ca2+channels close> no insulin secretion
80
high [glu] sequence
^[glu]> ^ATP>K+close> Vm depolarised> Ca2+ open> beta cell secretes insulin
81
insulin release from pancreas
into hepatic portal vein
liver exposed to insulin
portal circulation gut to liver
82
insulin receptor
2 sub-units (alpha/beta)
| insulin binding ^ receptor dimerization/ activation
## Footnote
dimerization entails phosphorylation of each other at multiple tyrosine res
83
beta sub-units
960> substrate binding
1146/1150/1151> phosphorylation
1293/1294/136> atenuates kinase activity
1316/ 1322> ass. w growth signal
84
insulin receptor signalling
1. insulin binding > dimerization
2. IRS-1 phosphorylation> ^PI3K/ MAPK cascade
3. PI3K > insulin cellular response
| MAPK cascade> cell growth and survival
85
GLUT4
intracellular membrane in unstimulated cells
| not PM
86
insulin activation of PI3K
| > activating protein kinase B
evokes translocation of GLUT4 to PM
| allows glucose uptake into hepatocyte
87
PKB action
phosphorylates/ inhibits GSK3> inhibits glycogen synthase
| glyc synthase catalyzes glucose addition to glycogen chain
## Footnote
THEREFORE PIK3 ^PKB which ^GLYCOGEN SYNTHASE
88
Where does glycogen synthase action occur
liver/ skeletal muscle
| (and all cells but less so)
## Footnote
if glycogen stores are full > glucose> fatty acids in circulation for fat storage
89
brain's only energy source
glucose
(no fatty acids)
90
action of hormone-deprived fat cell
low permeability to glucose
fatty acid release to fuel metabolic processes
hormone sensitive lipase breaks down fat
91
insulin supplies adipocyte action
high permeability to glucose > metabolised to glycerol and synthesised to fat
insulin inactivated lipase >
excess fatty acids
92
insulin promotion of protein synthesis
1. ^ circulating amino acid conc ^ beta insulin release
2. insulin receptors ^TORC1
3. Protein synthesis regulation
| insulin receptor>PI3K>TORC1> Protein synthesis
93
TORC 1
Target of Rapamycin complex 1
| 2nd PI3K-dependent kinase
94
what happens when amino acids are abundant
insulin stimulates protein incorporation to protein
95
glucagon structure
single pp chain
29 aa
| hypoglycaemia > glucagon release
hyperglcaemia> glucagon suppression
## Footnote
no glucagon receptor on skeletal muscle cells
96
glucagon receptor
G-protein coupled receptor
7 transmembrane domains
couple to Gs
activate lipase
| ^cAMP/ PKA dependent pathway
## Footnote
adrenaline can also activate via beta adrenoreceptors
97
amino acid effect on insulin/ glucose
aa ^insulin/glucagon
| ^insulin > ^ aa uptake and decrease plasma glucose
^glucagon ^plasma glu
98
# [](http://)
gluconeogenesis
glucose formation from lipids/ aa
99
diabetes blood glucose concentration
>7mM
| hyperglycaemia!!!
100
T1 diabetes
insulin secretion failure
| low [insulin] high [glucose]
sudden young onset
~5%
101
type 2 diabetes
insulin resistance
| insulin in circulation but ^[glucose]
obesity assoc. later in life
102
T1 pathogenesis
autoimmune beta cell destruction via CD8 Cyto T
103
autoimmune beta cell destruction
CD8 reactive against insulin peptides/ MHC complexes
recognized by cytotoxic T lymphocytes
| associated w HLA-DR3/DR4
104
hyperglycaemia effect on urinary system
^[glucose] in glomerular filtrate ^fluid osmolarity in tubuless
more water into PCT ^urine flow
decreases water reabsorption
105
hyperglycaemic acidotic coma
more fat broken down as no glucose for fuel
more fatty acid > lower pH
metabolic acidosis
106
prediction of glucose values
glycosylated Hb used to predict gluc values of past 6-8 weeks
107
lipohypertrophy
fat deposit around injection site subject to ^[insulin]
| negative effect of exogenous insulin injection
108
side effects of insulin therapy
lipohypertrophy
unpredictable rate of insulin absorption
109
insulin forms used for therapy
animal insulin (Porcine/bovine)
human insulin
human insulin analogue
110
types of human insulin
soluble (rapid/ short-lived/ IV emergency)
isophane (forms ppt/ intermediate acting)
insulin Zn suspension (forms ppt/ long-lasting)
111
insulin analogues
lispro (Lys28> Pro29/ rapid/ short)
glargine and detemir (long/ micro-ppt at physio pH at subcut/ slow absorption)
112
teplizumab
targets autoimmune reaction in diabetes 1
113
# hyperinsulemia
hyperinsulemia
beta compensate for peripheral resistance > exhausted and decrease secretion
114
free fatty acids
| > insulin resistance in muscle/liver
1. transformed in 2nd messeger DAG
2. DAG> PKC> IRS-1 Phosphorylation on ser
3. insulin receptor pathway changed
115
adipokines
| (released by adipocytes)
adiponectin (anti-hyperglycaemic)
activate AMPK/IRS1/2
^insulin sensitivity/ glucose uptake
116
AMPK
enzyme promoting liver lypolysis
117
PPAR gamma
nuclear receptor > adipocyte differentiation
^secretion of anti-hyperglycaemic adipokines
| in liver/ muscle
118
inflammation
| via adipocytes
adipocytes> IL-6/IL-1
| attracts macrophages to fat deposits
119
diabetes T2 therapy
diet/ exercise to prevent
medication (thiazolidinediones/ metformin/ sulphonylureas)
insulin (when fully developed)
selective beta 3 agonists
alpha 2 adrenoreceptor antagonists
GLP-1 receptor antagonists
SGLT-2 inhibitors
120
thiazolidinediones
PPAR gamma agonist
^expression/ secretion of anti-hyperglycaemic adipokines
sensitizing cells
| ^lipolysis
121
metformin
decreases glucose liver release
AMPK activation
^liver lipolysis/insulin receptor signalling
122
sulphonylureas
bind to sulphonylurea receptors on beta membranes
block K+ beta channels depolarize
Ca2+ open / allow insulin secretion via exo
123
selective beta 3 agonists
b 3 adrenoreceptors control fat cell lipolysis
124
alpha 2 adrenoreceptor antagonists
^insulin secretion
125
GLP-1 receptor agonists
| glucagon-like peptide
^insulin secretion from beta
pro-survival effect on beta
renoprotective
126
SGLT-2 inhibitors
^glu excretion in urine
^ketogenesis
127
long term T2 Diabetes complications
macrovascular disease (med/l bv damage)
microvascular disease (small bv damage)
| caused by ROS/AGEs generation
128
macrovascular disease results
coronary artery disease
cerebrovascular disease
peripheral vascular disease
129
microvascular disease results
retinopathy
nephropathy
neuropathy
130
ROS generation
generated by FFA/ glucose increase
>micro/macrovascular complications
131
AGEs generation
AGE cross-linking to proteins/ receptor binding (RAGE/ AGE-R1)
| RAGE> ROS generation/inflam/metab defect
## Footnote
AGE-R1> AGE clearance and ROS decrease
132
AGE collagen cross-linking lead to vessel damage
endothelium basal membrane thickening/ LDL trap/ IgG
inflam/ complement/oxidation
133
NFkappaB pathway sequence
| effector, signalling pathway and response
1. TNF receptor
2. IkappaB kinase comple
3. NF kappa B txn factors
134
what activates NF-kappa B complex
DNA damage
infection
hypoxia
physical stress
| environmental challenges
135
responses to NF kappa B pathway
repair
gene expression
programmed death
immune response
136
2 types of NF-kappa-B signalling pathways
canonical
non-canonical
137
canonical NF kappa beta pathway
| e.g?
1. TNF receptor stimulated
2. IKK complex activated
3. p50/p65 enter nucleus and ^ txn of target genes
| e.g. inflam programme
138
IKK Complex activation
| in canonical
1. beta phosphorylates IkBalpha inhibitor
(p50/65 kept in cytoplasm)
2. IkBalpha proteasome targetted
| Complex = IKK alpha beta gamma
139
IKK complex
alpha / beta > catalytic activity
gamma> regulatory
140
non-canonical NFkappaB pathway
| LTbetaR example
1. NIK kinase phosphorylates IKK alpha
2. IKK alpha phosphorylates p100> p52 (NFkB active dimer)
141
RHD
| Rel homology domain
encodes DNA binding/ dimerisation functions of NFkB
142
P100/105
- proteolytically processed to p50/52
- ankyrin repeats in C-terminal
- (function as IkappaB inhibitors!!@!!!!)
143
non-conserved txn activation domains
TA1/TA2/ TAD/SD1/SDII
144
Cancer associated inducers of aberrant NF-kappa B activity
cytokines/ injection/ microflora
oncogene activation
carcinogens/ tumour promoters
stress RO1 inducers
genetic alteration
carcinogen/ tumour promoters
cancer therapies
145
tumor promoting functions of aberrant NFkB activity
inflammation
angiogenesis
metastasis
survival
proliferation
immortality
| tumours expressing aberrantly active NFkB have altered NF-kB proteins
## Footnote
normal = cytoplasmic and controlled
disease= uncontrolled and nuclear
146
p53 structure
N-terminal domain (trans act./ proline rich)
core domain (seq spec DNA binding)
C-terminal domain (tetramerization/ reg non spec DNA binding)
147
P53 inducers
hypoxia
nutrient deficiency
oncogenic signalling
oxidative stress
hormones
physio processes
148
P53 inactivator
HDM2
| degraded when proteasome degrades
149
results of p53-casued cell cycle arrest
DNA repair
metabolic switch
cell differentiation
senescence
programmed cell death
| programmed cell death > apoptosis/ necrosis/ ferroptosis/ necroptosis
150
cross-talk
| between non-canonical NFkB and P53 pathways
p53 can inhibit p52 target genes
p52 can repress some p53 target genes/ co-regulate p53 target genes
151
NFkB in cancer cells
- can become tumor promoter
- loss of tumor suppressor/ reg genes> aberranty activation
152
senescence regulation
| regarding cross-talk between non-canonical NFkB and p53
p53 activates p21
p52/RelB/BCl3 ass. senescence p53 dependent
| induces senescence growth arrest
blocks pRB E2F pathway for cell prolife
153
EZH2
expression induced upon CD40L stimulation of primary B cell lymphocytic Leukaemia cells
| can work as oncogene
