| mechanism | in vitro | (Jinn, 2017 #1393) TMEM175 KO → unstable lysosomal pH, ↓ lysosomal catalytic activity, ↓ GBA activity, ↓ Protein levels of CTSD, and CTSB, impaired autophagy. ↓ mitochondrial respiration (OCR, ATP. ↑ susceptibility to exogenous α-syn fibrils (increased phosphorylated and detergent-insoluble α-syn deposits.) |
(Jinn, 2019 #1394) TMEM175 KD (50%) → ↑ (2-3x) pSyn,
| ||
| Correction: | in vitro | (Jinn, 2019 #1394) overexpression of WT TMEM175 protein reduced pSyn, while overexpression of the p.M393T variant resulted in no change in α-syn phosphorylation |
Effect size
| GBA | TMEM-M393t (rs34311866) | TMEM-M393t | |
|---|---|---|---|
| OR | 5 | 1.2 | |
| AAO | 2.6-0.9 y | 0.6 y | |
| Motor progression | yes | No |
MOA
| M393T mutation | ↓ Lyso localization of TMEM175 protein | ↓ K channel activity (outward cation flux 즉 counter-flux가 안 됨) | ↑ lyso pH (in starvation) | ↓ lysosomal function | ↑ mito function | ↑ aSyn | NDGN |
|---|---|---|---|---|---|---|---|
(Wie, 2021 #1395) *
| Derek's side: normal autophagosome formation, ↑ autophagosome/lysosome fusion (이게 이상, compensation?) | (Wie, 2021 #1395)
| (Wie, 2021 #1395)
|
| Tx goal (↑ 이겠네) | ↑ Lyso localization of TMEM175 protein | (↑ 이겠네) Lyso pH | (↓ 이겠네) LAMP1 | Lyso morphology | ↑ GBA activity | |
|---|---|---|---|---|---|---|
| CRL success criteria | See CRL slide! | |||||
| CRL Assay dev status |
| Method development complete using FabFluor-pH antibody | Method development complete using Lysotracker | Alternative GBA readout will be considered when required | ||
| 이 lyso readout 들을 test할 cell system with lyso dysfunction을 구축중: SH-SY5Y + starvation/bafilomycin, chlroquine, hydroxychlroroquine, Bcl-2, M393T mutation |
liii) Arthur: We need to determine the impact of increasing TMEM175 on lysosomal function in some relevant models to determine the degree of efficacy that we can expect. One important question is whether this may work in patients who do not have a TMEM175 polymorphism and how much additional benefit there is likely to be in mutation carriers.
Pipeline
| Caraway (project Cumin) | TMEM175 agonist → ↑ GBA activity, ↓ GlcCer | Cf, Amber(Amathus)) upfront: $12 mil, Total: 300 mil |
TMQB
MQB materials are stored in the 2nd library listed on the top left of the home page, at this link: https://mytakeda.sharepoint.com/sites/NSTM/NSTDIB/Forms/AllItems.aspx
liv)
Toxins
Paraquat
lv) Mechanism (Paraquat-and Rotenone-Induced Models of Parkinson’s Disease-R. Nistico 2011) J. Neurosci. 2013; 33(6): 2398-407
a. ↑ OS, [20, 21].
i. In vitro
-
↑ redox cycle, ↑ NADPH consumption, ↑ ROS (mainly H2O2, Hydroxyl radical), ↑ lipid peroxidation
-
→ ↑ POR (cytochrome P450 oxidoreductase), ATP7A (copper transporter), and SLC45A4 (sucrose transporter) → ↑ OS
https://parkinsonsnewstoday.com/2017/10/27/technique-explains-herbicide-link-parkinsons-disease/
b. α-syn
i. In vivo
- ↑ aggregation of α-syns, nigral degeneration (by 20-30%), but no significant dopamine or behavioral changes (
c. ↑ Apoptosis
i. BLC2 family, TNF-receptor and ligand family, CIDE and caspase family, Bak-dependent-mitochondrial outer membrane permeabilization, cytochrome c release, caspase-e and c-Jun-N-terminal kinase (JNK) activation
d. Electrophysiology
i. ↓ AMPA-Mediated synaptic event on DA neurons, ↓ EPSP (rat spinal cord)
e. Ion
i. No studies on ionic changes, especially calcium
MPTP
lvi) Definition
a.
lvii) Delivery
a. lipid-soluble, readily penetrates the blood—brain barrier and → enters the brain cells. → Because it is amphiphilic, it is captured into acidic organelles, mostly lysosomes, of astrocytes. → MPTP itself does not appear to be toxic, but its oxidized product, 1-methyl-4-phenylpyridinium (MPP+), is toxic. Astrocytes and serotonergic neurons contain MAO-B, which converts MPTP to MPP+. → The toxic oxidation product reaches the extracellular fluid → and then is transported by the DA transporter into DA nerve terminals.
lviii) Mechanism
a. Energy-driven mitochondrial uptake of MPP+ results in sufficiently high concentrations of the toxin to interfere with mitochondrial respiration. The site at which MPP+ acts, complex I, appears to be at or near the region where several other agents, such as rotenone, act to block mitochondrial oxidation.
b. Once inside the brain, in glial cells and, to a much lesser extent, in serotonergic neurons, MPTP is oxidized to 1-methyl-4-phenyl-2,3-dihydropyridium (MPDP+) by monoamine oxidase B (MAO-B) (Chiba et al., 1984, Furtado and Mazurek, 1991). MPDP+ is then released from astrocytes and serotonergic neurons by passive diffusion across the cell membranes and converted to MPP+ in the extracellular space by nonenzymatic oxidation (Schildknecht et al., 2015). MPP+ is then taken up into catecholaminergic neurons via the DAT (Chiba et al., 1985). MPP+ is not sequestered into storage vesicles but exerts its toxic effects within the cytosol (Reinhard et al., 1988). It has been shown that neuromelanin binds to MPP+, serving as a depot to continuously release MPP+ (D’Amato et al., 1987). MPP+ is taken up into the mitochondria via an energy-dependent uptake system and accumulates inside the mitochondria (Furtado and Mazurek, 1991).
c. MPTP□ DAT을 통하므로, catecholaminergic neuron에만 들어감, ↓ respiration, ↓ ATP production, ↑ ROS,
- ↓ (50%) NDUFB8 (MC1) ((Franco-Iborra, 2018 #1042, cell line)
mes. We analyzed NADH:ubiquinone oxidoreductase subunit B8 (NDUFB8, complex I), succinate dehydrogenase complex iron sulfur subunit B (SDHB, complex II), ubiquinol cytochrome c reductase core protein 2 (UQCRC2, complex III) and ATP synthase F1 subunit alpha (ATP5A, complex V), which are nuclear-encoded, while cytochrome c oxidase subunit II (COX II, complex IV) is encoded by the mtDNA21. MPP+ intoxication led to a downregulation of all the proteins, except ATP5A (Fig. 3a). 즉 MC V, 제외하곤 I, II, III, IV 모두 줌.
- Effects on ATP
MPP+ (MPTP’s active metabolite) causes a rapid and profound depletion of cellular ATP levels in isolated hepatocytes (Di Monte et al. 1986), in brain synaptosomal preparations (Scotcher et al. 1990) and in whole mouse brain tissues (Chan et al. 1991). In mice, however, MPTP causes only a mild (~20%) and transient reduction in striatal and midbrain ATP levels (Chan et al. 1991). It appears that complex I activity should be reduced by more than 50% to cause significant ATP depletion in nonsynaptic brain mitochondria (Davey and Clark 1996). Because complex I activity is only reduced by 25-30% in PD patients (Parker et al. 1989; Schapira et al. 1990), this argues against a major role for ATP depletion in PD-related dopaminergic neurodegeneration.
- Animal model
a. Rodents
Uncertain Spans
- The first MOA-table empty cell under the ”↓ K channel activity” header on the top sub-row is reproduced as observed; the surrounding evidence cell only fills part of the row and whether the empty cell is intentionally empty or is a continuation of a merged cell from above could not be determined unambiguously.
- Several Tx goal column header annotations carry parenthetical Korean comments such as ”(↑ 이겠네)” and ”(↓ 이겠네)” which appear to be the author’s hypothesis annotations placed inside the column header; reproduced verbatim.
- The hierarchy mark “MPTP□” (where □ is a glyph that did not OCR cleanly and is rendered as a square box in the source line “MPTP□ DAT을 통하므로…”) could be either a degree symbol, an arrow, or an em-dash; it is reproduced as-is rather than guessed.
- The Franco-Iborra 2018 bar-chart caption was clipped at the bottom of the photo; only the labels NDUFB8 / SDHB / UQCRC2 / COX II / ATP5A are confidently readable, and the y-axis title is not visible.