Protein Folding and Disease Flashcards
(226 cards)
1
Q
What does biological folding require?
A
Elaborate machinery and energy input
2
Q
Give examples of bond formation/isomerisation that is too slow to support life unaided.
A
Spontaneous peptidyl-propyl amide bond isomerisation
Spontaneous disulphide bind formation
3
Q
In the cell what is there a constant competition between?
A
Folding, misfolding and aggregation
- Always in equilibrium to the unfolded polypeptide
4
Q
What does a folding funnel show?
A
The 3D energy landscape
5
Q
Where does aggregation occur from?
A
A partially folded trapped state
OR
Intrinsically unfold proteins - aggregation occurs from the unfolded state
6
Q
What are the to environments in which proteins commence folding?
A
Cytoplasm
Secretory pathway
7
Q
What did Anfinsen teach us?
A
Refolding is spontaneous at low protein concentration and temperature in vivo
8
Q
What do chaperones and folding enzymes allow?
A
Multiple attempts at proper folding
9
Q
What are the three outcomes for misfiling?
A
Degradation - Gauchers disease
Improper trafficking - CF
Toxic conformer - FAP, Lysozyme amyloidosis
10
Q
In the disease lysozyme amyloidosis what is the protein called and what is the precursor?
A
Lysozyme
mixed alpha beta fold
11
Q
In FAP what is the protein called and what is the precursor?
A
Transthyretin, all beta
12
Q
Give examples of functional amyloid
A
Melanin made on pMel17
Secretory hormones - small peptides
13
Q
Define the characteristics of amyloid aggregates
A
Thread like amyloid fibrils about 10nm in diameter and rich in beta sheet structure
14
Q
What are the common properties of amyloid fibrils?
A
Fibre diffraction - cross beta structure
Negative Stain EM
Congo red birefringence - the dye gets ordered
Nucleated growth
15
Q
What are the examples that amyloid like fibrils can be made from?
A
Polylysine
Polyglutamate
Polythreonine
and myoglobin (when under the right conditions)
16
Q
What did cyro-EM studies of amyloid fibrils show?
A
One form of SH3 fibrils is a hollow tube only about 10nm in diameter but several microns in length
Built of four protofilaments each with cross beta structure
17
Q
What are amyloid fibrils composed of?
A
Different numbers of inter twined protofilaments
18
Q
Define the characteristics of human lysozyme
A
Small 130 amino acids 4 disulphide bonds Enzyme glycosidase Soluble, globular protein Mixed alpha beta fold X-Ray and NMR structure available
19
Q
What are the mutations of human lysozyme that form amyloid in vivo?
A
I56T and D67H
20
Q
What did the X-ray structures of human lysozyme tell us?
A
Amyloidogenic variants fold to a native like structure and are catalytically active - highlighting that this is not a folding disease - have the same X-ray structures
21
Q
Which features imbue the amyloidogenic character of these lysozyme variants?
A
Lysozyme variants are less stable than wild type and more aggregation prone
22
Q
What are the common properties of amyloidgoenic lysozyme variants?
A
- Correctly folded and catalytically active
- Less stable
- Aggregation prone
23
Q
Does the reduction in stability explain their ability to form amyloid?
A
No, other variants are found that are equally destabilised yet are not involved in disease
24
Q
How does the D67H variant of lysozyme exchange with solvent?
A
Deuterium/hydrogen exchange
- Exchanges cooperatively - transient unfolding of the entire beta domain
25
What does soft ionisation allow?
Proteins can be introduced into the gas phase whilst maintaining their integrity
26
How does the D67H exchange with the solvent?
Transient unfolding one the entire beta domain
| Cooperatively and concurrently
27
Give brief details about Jeff Kelly
Professor of Chemistry
Molecule to Market
Published 353 papers with a h=73
Discovered tafamidis
28
What type of disease are the transthyretin amyloidosis?
In trans gain of proteotoxcity
29
What type of tissue does TTR aggregation destroy?
post-mitotic tissue
30
What are the two diseases associated with TTR?
SSA - senile systemic amyloidosis
| FAP - familial amyloid polyneuropathy and cardiomyopathy
31
What protein is implicated in SSA?
Wild type
32
What [rotein is implicated in FAP?
mutant and wt TTR
33
What is the age of onset for SSA?
Greater than 60
34
What is the age of onset for FAP?
15-60
35
Describe TTR
127 amino acids
Beta sheet rich
55kDa homotetramer
Present in serum and cerebral spinal fluid
36
What does TTR stand for?
Transport Thyroxine Retinol binding protein
37
What does TTR not do in humans?
Thyroxine carrier function is not used - negative cooperativity whereas there is thyroxine binding protein that has much higher affinity 6x10^9
38
How many mutations are known to give rise to transthyretin amyloidosis?
Over 50
39
What is believed to be the cause of disease?
Tetramer dissociates - monomers misfiled and form oligomers then protofibrils then fibrils
Native monomer is not amyloidogenic
40
Where is the weak point in TTR?
Along the 2 fold axis - dissociates into two dimers here
41
When was the proof of principle that kinetic stabilisation of transthyretin prevents fibril formation?
1996
| - 3 equivalents of small molecule inhibits TTR aggregation
42
What is the most conservative approach?
Do not presuppose what the toxic species is
43
What is the highly penetrant version of FAP in Portugal?
V30M FAP
44
What did the family who had V30M also have that meant they did not develop FAP?
T119M
45
What does the T119M mutation seem to do?
Protect against V30M amyloidogenesis in trans through mixed tetramer formation
46
What does the T119M subunit incorporation do?
Increases the dissociative kinetic barrier preventing amyloidogenesis and amyloidosis
47
What does the addition of small molecules do?
Activation barrier tuning with small molecules mediated by native state kinetic stabilisation
- Prevent amyloidogenesis by kinetic stabilisation of the native state
48
At what pH and time did two equivalents of small molecule inhibit TTR aggregation?
Titrated in different concentrations of thyroxine relative to TTR
pH 5
72 hours
49
What are the properties required for a TTR amyloid drug?
Bind tightly to TTR with negative cooperativity
Bind one or more binding sites
Bind with high selectivity to TTR in plasma
Does not interfere with thyroid hormone receptor
50
What is the efficacy score for TTR amyloid drug?
A combination of binding affinity for TTR and binding selectivity
51
What small molecule can be used with TTR?
A small analogue of thyroxine - TTR can bind thyroxine but this function is not used in vivo
52
What did the attachment of the cysteine to TTR do?
Made a heterotetramer and a place to attach an extra moiety
53
What was discovered about the linker?
The longer the linker the more inhibition - needs to be able to bind round to the AS
Otherwise the biaromatic moiety can't bind round and fit in
Don't need to work against negative cooperativity
54
What type of kinetic stabilisers are excellent for TTR amyloidogenesis inhibitors?
Benzoxazole based TTR kinetic stabilisers
55
What drug was designed with air of X-Ray crystallography?
Tafamidis
56
With tafamidis what neurological examination changes?
Sensation, muscle strength and lower limn reflexes change from baseline
57
What else does tafamidis improve?
Large fibre function, five nerve conduction measurements, vibratory threshold, heart rate and response to deep breathing
Improved cachexia and autonomic neuropathy
58
What statistical significance was found in all endpoints?
Improved small nerve fibre function
Improved large nerve fibre function
Reversal in slope of modified body mass index
Improvement in lower extremity neurological exam
59
What is the proteostasis network?
Compilation of integrated biological pathways that influence the proteome and its function from birth to death - protein synthesis, folding, trafficking and degradation
Maintenance of the proteome
60
Are the proteins involved in maintaining the proteasome conserved?
Yes from yeast to fungi to man
61
Where are chaperone regulators increased greatly?
In higher order eukaryotes
62
How many genes do eukaryotes have to monitor the proteome?
Around 600
63
What are the various types of molecular chaperones and folding enzymes?
```
Hsp70 and Hsp40
Hsp90
sHSPs
Chp
Pfd
```
64
What is Gauchers disease?
A genetic disease in which a fatty substance accumulates in cells and certain organs
65
What type of disease is Gauchers the most common?
Lysosomal storage diseases
66
What is Gauchers disease characterised by?
Bruising, low platelets, enlargement of the liver and spleen, fatigue and anaemia
67
What enzyme is involved in Gauchers disease?
Hereditary deficiency in the enzyme glucosylceramidase
68
What does the enzyme do?
Acts on the fatty acid glucysoylceramide - when the enzyme is absent glucosylceramide accumulates particularly in white blood cells, most often macrophages
69
What is the threshold value for lysosomal GC enzymatic activity?
10%
70
At what percentage do you have Gauchers disease?
8%
Hence why this is a good disease to try and treat - not trying to get 100% of the enzyme folded, just need to increase by 2%
71
What does GC convert glucosylceramide into?
Glucose and ceramide
72
What happens when the mutation N370S is incorporated into GC?
Would be stable in the lysosome, however the large pH difference between the lysosome (5) and ER (7.4) means that the protein is not stable in the ER hence degraded ERAD
73
What did immunofluorescence show?
Wildtype co-localises to the lysosome (LAMP4)
74
What mutation in GC showed trafficking at a permissive temperature?
L444P
75
What happened to this mutation?
At 30 degrees the protein can fold and traffic to the lysosome
At 37 degrees the protein can not make it to the lysosome
76
What are proteostasis regulators?
Small molecules or biologicals that control the concentration, conformation, quaternary structure and location of proteins comprising the proteome by manipulating the proteostasis network, often by influencing the signaling pathways that control the proteostasis network
77
What were the two proteostasis regulators that increased L444P GC activity in patient-derived fibroblasts?
Celastrol and MG-132
78
What concentration of MG-132 increased L44P activity in patient derived fibroblasts?
Around 0.8 microM
79
What sugar side chain is sensitive to endo H?
Mannose rich glycans in the ER
80
What sugar side chain is resistant to EndoH?
Complex glycan in the Golgi
81
What did EndoH analysis of L444P show?
MG-132 allows its trafficking to the Golgi
82
What did immunofluorescence with proteostasis regulators show?
They enhance proper GC trafficking to the lysosome as discerned by immunofluorescence
83
What is the mechanism of protein homeostasis regulators NOT revealed by?
Known pharmacology
Celasrtrol - heat shock response activation of the proteostasis network do not explain
MG-132 - proteasome inhibition does not explain
84
What does the Unfolded Protein Response do?
Remodels the ER proteostasis network through three branches
85
What are the three branches of the UPR?
ATF6
PERK
IRE1
- BiP binds to these proteins and switches them off - when they are activated BiP dissociates off to help the protein folding chaperone activity
86
Where does IRE1 sit?
ER membrane
87
What happens when BiP dissociates from IRE1?
Dimerise and trans-phosphorylate - become active
88
What does IRE1 then do?
Alter a type of mRNA splicing within the cytoplasm - XBP1 - normally an intron however splicing by IRE1 switches XBP1 on
89
What is XBP1 when active?
A TF - turns on transcription and translation of chaperone, lipid synthesis components and ERAD proteins
90
Does MG-132 and Celastrol affect IRE1?
Yes - look at XBP1 splicing
91
What does the AFT6 arm of the UPR do?
The N-terminal section of AFT6 becomes a TF - leads to the induction of ER resident proteins
92
DO MG-132 and celastrol affect the AFT6 arm of UPR?
Yes - induce the cleavage of ATF6 indicating the activation
93
What does the PERK arm of the UPR do?
ER membrane kinase - dimerises and phosphorylates when BiP dissociates - phosphorylates eIF2 that then causes selective translation of GCN4/ATF4 and increase in CHOP
94
Does MG-132 and celastrol effect the PERK arm of the UPR?
Yes - CHOP expression levels increase
95
What are UPR activators?
Proteostasis regulators that re-sculpt the folding free energy landscape through up regulation of the proteostasis network components including chaperones that bind to folding intermediates and enzymes that lower transition states
96
What does the addition of a small molecule do?
Upregulates UPR - through PERK, ATF6 and IRE1
97
What role does MG-132 have in Tay-Sachs disease?
Also facilities this enzyme
98
What do proteostasis regulators do?
Expand the minimal export threshold
99
What do small molecule do when they bind to enzymes?
Stabilise the folded state of the mutant enzyme in the ER - increasing its concentration and enabling its trafficking from the ER
100
What does NN-DNJ do?
At sub-inhibitory concentrations enhance the trafficking of GC to lysosomes
- 2-fold increase in activity of N370S (most common GD mutation)
- Increased activity lasts for 6 days
- Ligand binding stabilises the native state
101
How can NN-DNJ stabilise but inhibits?
The affinity for the substrate much outweighs the affinity for the inhibitor - once in the lysosome will bind the substrate - just gets it out of the ER
102
What fraction of the proteome is synthesised by ribosomes docked on the ER?
⅓
103
What type of proteins fold in the ER before being trafficked?
```
Secreted proteins
PM proteins
ER
Golgi
Eadosomal and lysosomal proteins
```
104
What happens to proteins that fail to fold in the ER?
ERAD
105
Describe the order of the secretory pathway
ER - cis-Golgi - medial-Golgi - trans-Golgi - trans-Golgi network
106
What does the signal recognition particle do?
Recognises signal sequences (typically N-terminal)
pauses translation effectively preventing the protein from folding in the cytosol
Delivers the ribosome and nascent chain to the ER membrane by interaction with SRPR
107
What is the SRP?
Cytosolic ribonucleoportein complex signal recognition particle
108
When is the SRP displaced?
Once the ribosome binds to the SEC61 translocon - translation resumes
109
What is the SEC61 translocon?
An aqueous pore across the ER membrane - opened when proteins translocate across the membrane
Translocated whilst translated
110
Describe BiP
Binding Immunoglobulin protein
- ER luminal hsp70 chaperone
- Roles in protein translocation, folding and degradation
111
What does BiP do?
Binds to proteins as they are inserted into the ER and retains the proteins in the ER
Also has a major role in the assembly of proteins in the ER, particularly non-glycosylated proteins
112
How can BiP bind to unfolded regions of proteins?
ATP hydrolysis
| Exchange of ATP for ADP causes BiP to dissociate and provides an opportunity
113
What kind of environment is the ER?
Oxidising - favours the formation of disulphide bonds
114
What is the protein that promotes the correct pairing of disulphide bonds between cysteine?
Protein Disulphide isomerase
115
What in effect does PDI do?
Make (oxidise), break (reduce) and re-arrange (isomerise) disulphide bonds
116
What chain is used in N-linked glycosylation?
Pre-formed oligosaccharide chain
117
What is the pre-formed oligosaccharide chain transferred from and to?
From the dolichol lipid precursor to asparagine by Oligo-saccharyltransferase
118
What is the pre-formed oligosaccharide chain composed of?
9 mannose
3 terminal glucose
2 N-acetylglucosamines
119
What is the consensus sequence for N-linked glycosylation?
Asn-X-Thr/Ser
| X = anything but proline
120
What roles does glycosylation have?
- Improves protein solubility
- Provides binding sites for calnexin and calreticulin facilitating integration with PDI
- Is used to monitor protein folding
121
How is protein folding monitored with glycosylation?
- After addition, two terminal glucose are trimmed by glucosidase I and II
- This provides a binding site for calreticulin and calnexin that retain the proteins in the ER and prevent aggregation, promote folding by binding to PDI (ERp57)
The final glucose is trimmed by glucosidase II
If folding is complete the protein can exit the ER - if incomplete a glucose residue can be added by UDP-Glucose glycoprotein glycosyl-transferase and the cycle is repeated
122
What does removal of a mannose mean?
Acts as a molecular clock that monitors protein folding
123
What catalyses the removal of mannose? What else does this do?
Mannosidases - slow removal and reduce the addition of glucose by UGT
124
What happens is sufficient mannose residues are removed?
The protein is diverted from the folding pathway to a degradation pathway
125
What percentage of nascent proteins fold correctly in the ER?
>95%
126
What recognises misfiled proteins?
Adaptors in the ER lumen
127
What happens to misfiled proteins?
Retro-translocated into the cytosol
128
What is ERAD a branch of?
UPS
129
Where do the adaptors deliver the misfolded proteins to?
E3 ubiquitin ligases - HRD1 etc
130
What is SEL1L?
A ER membrane protein that recognised misfolded proteins
131
What can SEL1L recruit?
Additional adaptors, the lectins XTP3-B and OS9 which recognise mannose trimmed substrates
132
Where does ubiquination occur?
Cytosolic face of the ER membrane
133
For integral membrane proteins where can ubiquitination take place?
Cytoplasmic regions prior to translocation
134
What do soluble proteins require?
At least partial translocation prior to ubiquitination
135
What are derlins?
Membrane proteins which promote luminal protein transport across the membrane that resemble membrane rhomboid proteases
136
What is the ubiquinated substrate recognised by?
Cytosolic AAA ATPase p97/Cdc48
137
What does p97/Cdc48 do?
Uses ATP hydrolysis to energise the extraction of the protein from the ER
138
How might the proteasome extract some protein substrates from the ER membrane?
Via the AAA ATPase in the 19S cap
139
What do the compensatory mechanisms induced by UPR signals do?
- Reduce bulk protein synthesis
- Promote the production of chaperones
- Increase ERAD
- Increase the amount of the ER
140
What does the N terminus of AFT6 induce?
Expression of proteins involved in ER folding:
- BiP
- GRP94
- PDI
141
What does PERK do?
Phosphorylates the elongation factor eIF2 inhibiting mRNA translation
142
What is IRE1?
An ER transmembrane protein with endoribonuclease activities
143
How does IRE1 directly associate with misfolded proteins?
Via its ER luminal domain promoting oligomerisation
144
What does XBP1 promote?
Expression of genes that regulate lipid biosynthetic enzymes and ERAD components
145
What is XBP1 also required for?
Plasma cell differentiation
146
What type of mRNAs does IRE1 degrade?
Those of secretory pathways
147
What is CFTR?
An ATP gated plasma membrane channel
| Transports chloride ions across the plasma membrane
148
Where is CFTR expressed?
Epithelial cells
149
What fraction of caucasians carry a gene encoding a mutant form of CFTR?
1/27
150
What happens in the absence of CFTR function?
Build up of viscous mucous in the lungs - resulting in inflammation and infection - causes lung damage
151
What type of mutation is F508?
Autosomal recessive
| - 3 nucleotide deletion
152
How is GRASP activated?
IRE1-mediated signalling arm activates GRASP dependent secretion via phosphorylation
153
What does GRASP do?
Binds to CFTR F508 and target it to the cell membrane allowing it to function as a Cl channel
154
What does transgenic expression of GRASP in mice do?
Rescue the phenotype
155
What does human cytomegalovirus do to the ERAD pathway?
Hijack it to degrade MHC class I molecules
156
What does HCMV encode?
US2 and US11 - ER localised integral membrane proteins that target MHC class I molecules for degradation
157
What do US2 and US11 act as?
Virus encoded adaptors for the ERAD pathway - cause MHC molecules to be delivered to E3 ligases
158
What is US2 dependent on?
Signal peptide peptidase for MHC class I degradation
159
What is US11 dependent on?
Derlin-1 and SEL1L for MHC degradation
160
What secretes cholera toxin?
Vibrio Cholerae
161
What does cholera toxin promote?
Electrolyte and water movement into the intestinal lumen resulting in severe diarrhoea and further spread of the bacterium
162
What happens in the ER to cholera?
The CTA1 subunit dissociates - involves PDI
CTA1 is unfolded - retrotranslocated across the ER membrane
Escapes proteasomal degradation (few lysine)
Binds adenylate cyclase increasing cAMP - in turn activates PKA
PKA phosphorylates CFTR - promoting chloride ion secretion
163
What are the cellular roles for protein degradation?
- Constitutive turnover of proteins
- Response to starvation
- Removal of misfolded proteins
- Regulation of cellular pathways
- Antigen presentation
164
Where are the two principal sites for degradation?
Cytosolic proteasome and the lysosome
165
How are cytosolic proteins degraded?
Either the UPS or by autophagy
166
What percentage do lysosomes and proteasome account for degradation?
80-90% of cellular protein degradation
167
What percentage of the human genome is dedicated to the UPS system?
5%
| - Many genes correspond to E3 ubiquitin ligases
168
Describe ubiquitin
76 amino acids
| Highly conserved in eukaryotes
169
How is ubiquitin linked to proteins?
via linkage between glycine 76 of ubiquitin and the amino groups of lysine on the substrate protein
170
What is the typical linkage for polyubiquitinated chains?
Lysine48-Glycine76
171
What other lysine can be used in ubiquitination?
Lysine63
172
What does E1 do?
Forms a thiol ester with the carboxyl group of glycine 76 of ubiquitin
173
What does E2 do?
Transiently carriers ubiquitin as a thiol ester
174
What does E3 do?
Transfers the ubiquitin to the substrate protein
175
How many E1, E2 and E3 enzymes are there in the body?
E1 - 2
E2 - 30
E3 - 600 - confer specificity
176
What is the proteasome formed of?
26S complex composed on the 20S core and 19S cap/lid
177
How is entry into the 20S core restricted?
Narrow channel - meaning proteins must be linearised and unfolded to enter
178
What are the three principal proteolytic activities of the 20S core?
Chemotryptic - hydrophobic
Tryptic - basic
Peptidylglutamylpeptidase - acidic
179
How long are the peptides produced by the proteasome?
3-22 amino acids
| - Further cleaved by cytosolic amino-peptidases
180
What does the 19S cap recognised?
Poly-ubiquitinated proteins
| Cleaves ubiquitin from the substrate (recycling)
181
How is unfolding of the substrate protein mediated?
By AAA ATPase activity of the 19S cap
182
What are defective ribosomal initiation products?
⅓ of newly synthesised proteins that aredegraded and defective
- Inaccurate transcription/translation errors
183
What is one specific class of DRiPs?
Produced from mRNAs that lack stop codons
184
What ubiquinates these DRIPS?
E3 ubiquitin ligase Ltn1
185
How is Ltn1 stimulated?
Stalling of the ribosome at the mRNA poly(A) tail
186
What is Ltn1 part of?
SThe ribosome quality control complex - associates with stalled ribosomes via the 60S subunit
187
Where do chaperones bind?
Surface exposed hydrophobic patches - present on misfolded proteins but not native proteins - therefore recognise proteins that need degrading
188
What is a key link between chaperones and the UPS?
The cytosolic E3 ubiquitin ligase constitutive HSC70 interacting protein (CHIP)
189
What does CHIP do?
Bind to chaperones and hence associated with misfolded proteins
190
What does CHIP mediated ubiquitination promote?
Interaction of CHIP with the 26S proteasome via the co-chaperone BAG-1
191
Define autophagy
A process by which cytoplasmic components are delivered to the lysosome for degradation
192
What are the three classes of autophagy?
Macroautophagy
Chaperone mediated autophagy
Microautophagy
193
What is the typical diameter of a lysosome?
200-400nm
194
What proteins do lysosomes contain?
An array of hydrolases - acidic pH optima
195
What are lysosomal proteases called?
Cathespins
196
What is the specificity of cathespins?
Broad
| Includes endopeptidases and exopeptidase
197
Name three major lysosomal enzymes:
Cathespin D - aspartate endopeptidase
Cathespin L - cysteine endopeptidase
Cathespin B - cysteine protease (endo and carboxypeptidase activity)
198
What is macroautophagy?
Removal of cytoplasmic components for degradation in lysosomes
199
What can be degraded by macroautophagy?
Long lived cytosolic proteins and protein aggregates
200
What is macroautophagy enhanced by?
Starvation of cells - hence recycling amino acids for use by the starved cell, and other cellular stresses
201
What are cytoplasmic components surrounded by in macroautophagy?
Double membranes
202
What donates this membrane to form the autophagosome?
ER, golgi, mitochondria and PM
203
How are autophagosomes transported to lysosomes?
Along microtubules to the MTOC
204
What is autophagosomes fusion with lysosomes dependent on?
SNARE-dependent
205
What does CMA involve?
The direct delivery of proteins to the lysosome and do not involve the formation of membranes bound autophagosomes
206
What does CMA recognise?
KFERQ motifs - present in ⅓ of cytosolic proteins
| Exposed if misfolded or complex disassembles
207
Why does aggregation preclude degradation by the CMA?
Only degrades proteins as single subunits
208
What enhances CMA?
Cellular stress including nutrient depravation
209
What exactly recognises KFERQ motifs?
Hsc70
210
How are substrate proteins bound?
By the cytosolic portion of the lysosome membrane protein LAMP-2A via the KFERQ motif
211
What does substrate binding promote in LAMP2A?
Multimerisation
212
What reasons are there to suggest that aggregation of alpha syncline into amyloid is a failure in proteostasis?
- Proteostasis machinery fails to prevent the misfiling of alpha synuclian
- Aggregates of alpha synuclein are not removed by the protein degradation machinery
- Mutant forms of alpha synuclein and alpha synuclein aggregates can disrupt protein degradation pathways
213
How is alpha synuclein degraded?
Both the UPS and autophagy - CMA may be dominant for monomeric alpha syn
214
What does alpha synuclein possess making key degradation via the CMA?
KFERQ like motif
215
Why are A53T and A30P not degraded?
Bound by Hsc70 and although deliver to the membrane they do not get to the lumen and impair degradation of CMA
216
What can increased amounts of the wild type alpha san do?
Impair CMA
217
What do many cells accumulate in PD?
Autophagosomes - failure in clearance
218
What may LBs not be cleared by and inhibit?
Not cleared by macroautophagy and inhibit macroautophagy
219
What does rapamycin target?
mTOR - hence promotes macroautophagy
220
What does rapamycin regulate?
Macroautophagy
221
What does active mTOR suppress?
Autophagy
222
What does starvation do?
Remove mTOR inhibition promoting autophagy and recycling of amino acids
223
What does rapamycin do to mTOR?
Inhibits - promotes macroautophagy
224
What has rapamycin been reported to do?
Promote clearance of alpha synuclein and reduce neuronal death in animal models
225
What is TFEB and what does it do?
TF
| regulates macroautophagy and lysosome biogenesis
226
What does over expression of feb DO?
Promotes clearance of alpha syncline in cells
