| transporters (active transport) | Primary active transporter (=pump, which generate an electrochemical gradient in an ATP-dependent manner) | vacuolar-type H+-translocating ATPase [V-ATPase], P-type ATPase [P-ATPase], The ATP13A2 gene encodes a transmembrane lysosomal P5-type ATPase (ATP13A2=ATPase cation transporting 13A2) (Dehay et al., 2010). xiii) Function a. active transport of cations across the lysosomal membrane | ||||||||
| secondary active transporters/antiporters/exchangers, (=co-transporters/antiporters/exchangers, which obtain energy from the electrochemical gradient of ions [usually Na+]) | SLC [solute carrier] family proteins) are typically driven by the Na+ gradients established by Na/K ATPases | |||||||||
⊞PhReT
| function | LSD | LSD Ix? | LSD BM | Familial PD | sPD genetics | sPD pathology | Pt selection | Animal model | |
|---|---|---|---|---|---|---|---|---|---|
| TRPM1 (=MCOLN1) (Ca2), | pH, Ca, autophagy, phagophore formation, TFEB-correction (MK6-83) → ↓ aSyn | LOF mutation → type IV mucolipidosis | ML IV, (lipid accumulation)&iron? But negative experimental evidence Cao 2015 | pph: Gastrin? Lysosomal pH & vacuole in fibroblast? CNS: DTI, Calbindin(csf) | X | X | |||
| NPC (experimental evidence Cao 2015) | |||||||||
| TMEM175 a novel K+-selective | lysosomal pH, ↓ lysosomal catalytic activity, ↓ GBA activity, ↓ CTSD, ↓ CTSB ↓ mito respiratio ↑ αsyn, ?autophagy, KO/KD → ↓ TH neurons -correction: O (overexpression) | X | X | p.M393T (17.5%) → ↑ PD risk (OR 1.4) & AAO | M393T | ||||
| P5-type ATPase (ATP13A2=ATPase cation transporting 13A2) (cation & polyamine) | xiv) pH, degradation, fusion, ↑ aSyn xv) correctionO | X | (NPC, pph) UNESTERIFIED CHOLESTEROL, cholestanetriol CSF Calbindin ((Bradbury, 2016 #1725) ), plasma 24(S)-HC (a sterol) | O (KRS) (park9) | xvi) | ↑ or ↓, found in LBs | KO mouse |
[target-disease relationship]
- xvii) Evidence of TRPM1 dysregulation in NPC?
- xviii) Mechanism that TRPM1 boosting → ↓ NPC pathology (lipid accumulation)?
- xix) in PD, is there evidence of lipid accumulation?
BM: should be disease-specific (from patient, ips, animal model) + general (cathepsin) (panel?), no lysosomal imaging, when ph should be important, but LSD has peripheral
| Gene | In vitro phenotype by KO/KD | Improvement by O/E or activator |
|---|---|---|
| TMEM175 |
|
|
| ATP13A2 |
|
|
| TRPML1 |
|
Reference
- Hum Mol Gen, 2018, 28, 19
- Jinn et al. PNAS 2017, 114, 9
- Nature 591, 431(2021)
- PNAS 117, 31196-31207 (2020)
- Nature 372, 419 (2020)
- PNAS 2012, 109, 24
- [blank]
- Scientific Reports (2019) 9:10743
- J. Neurosci, 2019 39 (29)
- Developmental Cell 33, 427-441
→ Showing potential benefit of activators
BMs
M393T for PD: explore correlation which CSF lysosomal BM (eg CSF cathepsin activity ) vs brain (p-aSyn ) pathology in M393T-PD ? But should then we look at proteolytic capacity?
- Proteolytic, imaging, small effect size, directional change, pk/pd not possible,
- Comp bio할까?
- Target date of KONDO AQB ?
- Review: {Parenti, 2021 #1656}{Elmonem, 2020 #1657}
End more in PhreT section!
RD-DDU
Thanks for forwarding and pleased to meet you Jaewon. We have an active project in NPC with an exosome therapy company Evox to deliver the NPC1 protein directly into the brain via IT/ICV. We will likely soon be winding down this exosome based effort for protein delivery based on pharmacologic futility, scale-up needs, and manufacturing challenges. This collaboration with Evox was our first foray into NPC and we do not have any cell or animal models established internally. Working with Evox, we do have knowledge of which fibroblast line works better for the filipin assays and we have been working with Charles River labs on a mass spec-based cholesterol esterification assay. We have outsourced our pharmacology studies to QPS which has the NPC KO mouse model. Aside from academic groups, QPS had the most experience with the NPC mouse.
Apart from saying yes for the DDU’s interest in NPC and assay/model insights, there may be little we can directly contribute from the data generation side. Additionally while there is still future interest in NPC with the DDU, there are a number of indications that have higher priority for us and will command resourcing though in the short term. Below is a list of LSD’s we are prioritizing for the DDU. Even within the top tier, there are a couple of indications here that are ‘must win’ for us and will justify our funding of multiple approaches.
- I tier LSD’s: Fabry, Gaucher, Pompe, MPSII, MPSIIIA, MLD
- II tier LSD’s: MPSI, MPSVI, NPC
Hope this info helps.
Regards,
Y.H. Park, Ph.D. The Metabolic Research Strategy Lead
Lysosomal changes in PD
xx) Disruptions in the lysosomal autophagy pathway might differ between early and advanced stages of PD pathogenesis.
| Source | Reference | Sample | Findings |
|---|---|---|---|
| postmortem brain | (Chu, 2009 #266) NOT A review, PD patients n=10, | In SN: ↓ LAMP1, ↓ Cathepsin D, ↓ HSC73 (and ↓ 20s proteasome-ir neurons) | |
| increased numbers of autophagosomes are present in post-mortem brain tissues from patients with PD and cellular models of PD21 | |||
| fibroblast | Carling 2020 | N=100 Spd, n=50 control, ) ↑ (slightly) lysosome count & area, ↑ (~15%) LAMP2, ↓ (~50%) Cathepsin D activity | |
| thesis | 내 thesis | autophagic degeneration including an increased number of autophagosome in neurons of the SN of post-mortem PD brains (Anglade et al., 1997). Another post-mortem study also reported significantly reduced levels of lysosomal markers (e.g. LAMP2A and HSC70) in the substantia nigra and amygdala in PD brains (Alvarez-Erviti et al., 2010). Additionally, autophagic markers (e.g. LC3/ATG8) were enhanced in cell lines following treatment with MPP+, 6-hydroxydopamine (6-OHDA), and the inhibitor of complex I (rotenone) (Chen et al., 2007, Dagda et al., 2008, Zhu et al., 2007). | |
| (Youn, 2018 #643) early PD patients n=32, ELISA, CrossSectional | (FIG1) ↓ LC3B (LC3B level was significantly correlated with the severity of motor symptoms, dopamine transporter imaging data (correlated with the Asymmetry Index in the putamen and caudate nucleus, BUT not with SUV), and conventional CSF biomarkers, including α-syn and total tau.), ↓ beclin-1, ↓ ATG5, (maybe due to excessive trapping of ATG proteins in autophagosomes due to the lack of lysosomal activity tissue), ↓ LAMP2, =ATG7, =p62, | ||
| CSF levels of autophagy marker proteins in patients with PD are likely affected by the dynamics of ATG proteins and may not reflect an actual change in the autophagy process | |||
| investigation of autophagy markers in brain specimens should be simultaneously conducted along with the monitoring of autophagy flux in vivo | |||
Reference: 2019 xicoy review
2018 Youn: ↓ autophagy flux, ↓ autophagosome formation, → ↑ accumulation of lysosomes in the brain in early PD level might not only be due to reduced autophagosome formation but also to increased autophagosome degradation
Lysosomal Enzymes
xxi) Lysosomal enzymes a. 60 different lysosomal enzymes b. Classification
proteases, nucleases, glucosidases, phosphatases, polysaccharide hydrolyzing enzymes or lipid degrading enzymes
[lysosomal hydrolases]
| Its substrate | Normally | arguments | Counterarguments | |
|---|---|---|---|---|
| Cathepsin B | cysteine protease | (Wyczałkowska-Tomasik, 2012 #1511) aging/cell damage → leakage of proteolytic enzymes from lysosomes into cytosol and then into the serum | (2018 Nelson) Negative correlation with a-syn | (2018 Nelson) Postmortem: no change in temporal cortex in PD |
| Cathepsin D | aspartic acid protease | (Abbott, 2010 #1510) CD is synthesized as a pro-form (Pro-CD), undergoes several post-translational modifications and ultimately is converted to mature active enzyme in the lysosomes.4,5 Under normal conditions, less than 10% of CD is secreted as Pro-CD into the extracellular milieu and is also detected in the serum. 그런데 결과 살짝 보면, not correlated with tissue, so not supporting serum Cathepsin D activity as a biomarker! |
(2018 Nelson) Negative correlation with a-syn, (Chu et al. 2009, PMID) ↓ in PD (McGlinchey and Lee 2015, PMID) CTSB degrades a-syn, CTSD degrades a-syn fibril.
| (2018 Nelson) Postmortem: a significant decrease in Cat D activity only in Stage IV PD (temporal cortex) |
Uncertain Spans
| location | transcription | uncertainty |
|---|---|---|
| Top wide table column header row | function / LSD / LSD Ix? / LSD BM / Familial PD / sPD genetics / sPD pathology / Pt selection / Animal model | The table is a dense matrix with many empty cells; column boundaries are inferred from the visible header row and cell alignments. |
| TRPM1 first row “(Ca2),” subscript | ”Ca2” | Subscript notation may be “Ca²⁺”; transcribed as seen on the page. |
| TMEM175 KD reference ”(#L,3)” or ”(#1,3)” / ”(#1,L,3)" | "(#1,3)“ | OCR rendered as ”(#L,3)”; image shows ”(#1,3)” but small font; transcribed as 1,3. |
| TMEM1175 KD bullet | ”TMEM1175” | Bullet appears as “TMEM1175” rather than “TMEM175”; transcribed as seen. |
| Reference 4 “PNAS 117, 31196-31207 (2030)“ | year 2020 | OCR shows “(2030)”; image likely “(2020)”; small superscript-like digits hard to confirm; transcribed as 2020. |