Introduction
| TMEM175 Protein | |
|---|---|
| Symbol | TMEM175 |
| Full Name | TMEM175 |
| Type | Protein |
| UniProt | Search UniProt |
| Associated Diseases | Aging, Als, Fibrosis, Inflammation, Ms |
| KG Connections | 87 edges |
TMEM175 (Transmembrane Protein 175) is a lysosomal potassium channel that plays critical roles in neuronal function and survival. Originally identified as a susceptibility gene for Parkinson’s disease (PD), TMEM175 has emerged as a key regulator of lysosomal function, autophagy, and cellular proteostasis [1][2][3]. This protein represents a promising therapeutic target due to its central role in lysosomal homeostasis and its genetic association with neurodegenerative diseases. 1Chen & Liu, TMEM175 pharmacology (2020)Open reference
TMEM175 functions as a voltage-gated potassium channel with unique gating properties suited to the lysosomal environment. The protein maintains lysosomal membrane potential and regulates the activity of hydrolytic enzymes within lysosomes [4][5]. Dysfunction of TMEM175 leads to impaired autophagy, accumulation of alpha-synuclein aggregates, and neuronal death—pathological features common to multiple neurodegenerative diseases. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference
Pathway Diagram
flowchart TD
TMEM175["TMEM175"]
style TMEM175 fill:#006494,stroke:#4fc3f7,stroke-width:3px,color:#e0e0e0
Lysosomal_pH_Homeostasis["Lysosomal pH Homeostasis"]
TMEM175 -->|"involved in"| Lysosomal_pH_Homeostasis
PARKINSON_S_DISEASE["PARKINSON'S DISEASE"]
TMEM175 -->|"implicated in"| PARKINSON_S_DISEASE
Lysosomal_Function["Lysosomal Function"]
TMEM175 -->|"regulates"| Lysosomal_Function
Parkinson_s_Disease["Parkinson's Disease"]
TMEM175 -->|"associated with"| Parkinson_s_Disease
REM_sleep_behavior_disorder["REM sleep behavior disorder"]
TMEM175 -->|"associated with"| REM_sleep_behavior_disorder
Aging["Aging"]
TMEM175 -.->|"inhibits"| Aging
Parkinson["Parkinson"]
TMEM175 -.->|"inhibits"| Parkinson
Neurodegeneration["Neurodegeneration"]
TMEM175 -->|"contributes to"| Neurodegeneration
LAMP1["LAMP1"]
LAMP1 -->|"interacts with"| TMEM175
LAMP2["LAMP2"]
LAMP2 -->|"interacts with"| TMEM175
LAMP1 -.->|"inhibits"| TMEM175
LAMP2 -.->|"inhibits"| TMEM175
style Lysosomal_pH_Homeostasis fill:#5d4400,stroke:#4fc3f7,color:#e0e0e0
style PARKINSON_S_DISEASE fill:#455a64,stroke:#4fc3f7,color:#e0e0e0
style Lysosomal_Function fill:#5d4400,stroke:#4fc3f7,color:#e0e0e0
style Parkinson_s_Disease fill:#ef5350,stroke:#4fc3f7,color:#e0e0e0
style REM_sleep_behavior_disorder fill:#ef5350,stroke:#4fc3f7,color:#e0e0e0
style Aging fill:#ef5350,stroke:#4fc3f7,color:#e0e0e0
style Parkinson fill:#ef5350,stroke:#4fc3f7,color:#e0e0e0
style Neurodegeneration fill:#ef5350,stroke:#4fc3f7,color:#e0e0e0
style LAMP1 fill:#4a1a6b,stroke:#4fc3f7,color:#e0e0e0
style LAMP2 fill:#4a1a6b,stroke:#4fc3f7,color:#e0e0e0Structure and Molecular Biology
Protein Topology and Structure
TMEM175 is a 522-amino acid membrane protein with a distinctive topology featuring six transmembrane domains [6][7]. Unlike classical potassium channels that contain a canonical pore loop between transmembrane segments 5 and 6, TMEM175 belongs to the TMEM16/anoctamin family and exhibits a different architectural organization. The protein forms homomeric channels with a conductance of approximately 40 pS. 3TMEM175 subcellular localization (2019)Open reference
The transmembrane domains create a hydrophobic pathway for potassium ion permeation. The channel exhibits voltage-dependent gating with opening probability increasing upon depolarization [8][9]. Unlike canonical potassium channels, TMEM175 shows little sensitivity to intracellular calcium, distinguishing it from other lysosomal ion channels including the TRPML family. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference
Channel Properties
TMEM175 displays unique pharmacological properties that distinguish it from other potassium channels. The channel is relatively insensitive to classical potassium channel blockers including tetraethylammonium (TEA) and 4-aminopyridine (4-AP) [10][11]. This insensitivity has complicated the development of specific pharmacological tools for studying TMEM175 function. 5TMEM175 lysosomal targeting (2016)Open reference
The ion selectivity filter of TMEM175 preferentially conducts potassium over sodium, though some permeability to other monovalent cations has been reported [12]. The channel exhibits weak voltage dependence, with activation occurring at relatively positive membrane potentials consistent with the lysosomal membrane potential. 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference
Subcellular Localization
TMEM175 is predominantly localized to lysosomal and late endosomal membranes throughout the cell [13][14]. Within neurons, TMEM175 is enriched in lysosomes of cell bodies, dendrites, and particularly in synaptic terminals. This strategic localization positions TMEM175 to regulate lysosomal function at synapses where protein turnover is highly active. 7Mindell, Lysosomal acidification mechanisms (2012)Open reference
The trafficking of TMEM175 to lysosomes involves the secretory pathway, with the protein passing through the Golgi apparatus before reaching its final destination [15][16]. Post-translational modifications including glycosylation contribute to proper folding and trafficking. 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference
Normal Biological Functions
Lysosomal Potassium Homeostasis
TMEM175 plays a central role in maintaining potassium concentration within lysosomes. Lysosomes maintain a high internal potassium concentration (~100-150 mM) essential for the optimal activity of hydrolytic enzymes [17][18]. TMEM175 provides a pathway for potassium flux that helps maintain this ionic environment. 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference
The lysosomal membrane potential, generated by V-ATPase proton pumping, is partially dissipated through cation conductances including TMEM175 [19][20]. This potassium efflux prevents excessive membrane polarization that would impair proton pumping and lysosomal acidification. 10Marshansky & Futai, V-ATPase structure (2008)Open reference
Proper lysosomal pH is crucial for the function of over 60 different hydrolytic enzymes active in the lysosomal lumen [21][22]. TMEM175-mediated potassium flux contributes to the regulation of this pH by modulating the lysosomal membrane potential. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference0
Regulation of Autophagy
TMEM175 is a critical regulator of macroautophagy, the process by which cells degrade and recycle cytoplasmic components [23][24]. Autophagy involves the formation of double-membrane autophagosomes that engulf cytoplasmic material and fuse with lysosomes for degradation. TMEM175 function is required for efficient autophagosome-lysosome fusion. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference1
The lysosomal membrane potential regulated by TMEM175 affects the recruitment of autophagy-related proteins to lysosomal membranes [25][26]. TMEM175 deficiency impairs the fusion of autophagosomes with lysosomes, leading to accumulation of undegraded autophagic material. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference2
TMEM175 regulates selective autophagy pathways including mitophagy, the degradation of damaged mitochondria [27][28]. Mitophagy is particularly important in neurons due to their high energy demands and vulnerability to mitochondrial dysfunction. Impaired mitophagy contributes to the pathogenesis of Parkinson’s disease. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference3
Lysosomal Membrane Permeability
Beyond potassium homeostasis, TMEM175 contributes to the overall permeability of the lysosomal membrane to small ions [29][30]. This permeability is essential for the lysosomal membrane’s ability to undergo the fusion and fission events required for autophagosome-lysosome and endosome-lysosome fusion. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference4
The channel’s activity affects the volume of lysosomes, which in turn influences the efficiency of proteolytic degradation [31][32]. Larger lysosomal volumes provide more space for enzyme-substrate interactions and improve the degradation of macromolecules. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference5
Role in Neurodegenerative Diseases
Parkinson’s Disease
TMEM175 was first identified as a Parkinson’s disease risk gene through genome-wide association studies (GWAS) [33][34]. Multiple independent GWAS have replicated the association between TMEM175 variants and PD risk. The most common risk variant results in a loss-of-function allele that reduces channel activity. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference6
Loss of TMEM175 function leads to impaired lysosomal autophagy and accumulation of alpha-synuclein [35][36]. Alpha-synuclein is the primary component of Lewy bodies, the pathological hallmark of PD. TMEM175 deficiency promotes alpha-synuclein aggregation through impaired autophagic clearance. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference7
Mitochondrial dysfunction in PD is exacerbated by TMEM175 deficiency [37][38]. TMEM175-regulated mitophagy is essential for the removal of damaged mitochondria. Loss of TMEM175 function leads to accumulation of dysfunctional mitochondria and increased oxidative stress. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference8
The relationship between TMEM175 and other PD risk genes is an area of active investigation. TMEM175 interacts genetically with GBA1, another major PD risk gene [39][40]. Both genes affect lysosomal function, suggesting converging pathways in PD pathogenesis. 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference9
Alzheimer’s Disease
While primarily associated with PD, TMEM175 dysfunction may contribute to Alzheimer’s disease pathogenesis [41][42]. Lysosomal dysfunction is an early feature of AD, preceding other pathological changes. TMEM175 deficiency exacerbates lysosomal impairment and may accelerate amyloid-beta accumulation. 3TMEM175 subcellular localization (2019)Open reference0
Tau pathology, another hallmark of AD, may be influenced by TMEM175 function [43][44]. The autophagic-lysosomal pathway is the primary route for tau degradation. Impaired TMEM175 function could contribute to tau accumulation and aggregation. 3TMEM175 subcellular localization (2019)Open reference1
The role of TMEM175 in AD remains less well-characterized than in PD. Further research is needed to determine whether TMEM175-targeted approaches could benefit AD patients. 3TMEM175 subcellular localization (2019)Open reference2
Other Neurodegenerative Conditions
TMEM175 dysfunction may contribute to other neurodegenerative diseases characterized by protein aggregation and lysosomal dysfunction [45][46]. These include Huntington’s disease, amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). 3TMEM175 subcellular localization (2019)Open reference3
In Huntington’s disease, mutant huntingtin protein accumulates due to impaired autophagy [47][48]. TMEM175 deficiency could further impair huntingtin clearance. Similarly, TDP-43 pathology in ALS may be affected by lysosomal dysfunction. 3TMEM175 subcellular localization (2019)Open reference4
The potential role of TMEM175 in these conditions represents an important area for future investigation. Therapeutic targeting of TMEM175 may have broad applicability across neurodegenerative diseases. 3TMEM175 subcellular localization (2019)Open reference5
Genetics and Expression
Gene Organization and Variants
The TMEM175 gene is located on chromosome 4p16.3 and consists of 14 exons encoding the 522-amino acid protein [49][50]. Multiple single nucleotide polymorphisms (SNPs) in TMEM175 have been associated with PD risk in genome-wide association studies. 3TMEM175 subcellular localization (2019)Open reference6
The most extensively studied PD-associated variant results in a missense substitution (Q114P) that reduces channel activity [51][52]. This loss-of-function variant is present in approximately 20% of the population, with heterozygosity conferring modest increased PD risk. 3TMEM175 subcellular localization (2019)Open reference7
Expression Patterns
TMEM175 is expressed in most tissues with highest levels in the brain, particularly in regions affected in Parkinson’s disease including the substantia nigra and striatum [53][54]. Within the brain, TMEM175 is expressed in neurons and glia. 3TMEM175 subcellular localization (2019)Open reference8
In neurons, TMEM175 is localized to lysosomes in cell bodies, dendrites, and synaptic terminals [55][56]. This widespread distribution enables TMEM175 to regulate lysosomal function throughout the neuron. 3TMEM175 subcellular localization (2019)Open reference9
Therapeutic Targeting
Small Molecule Activators
TMEM175 channel activity can be enhanced by small molecule activators, representing a potential therapeutic approach for PD [57][58]. These compounds increase channel open probability or improve trafficking to lysosomal membranes. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference0
Natural products including flavonoids have been identified as TMEM175 activators [59][60]. While these compounds show promise in cellular models, their specificity and pharmacokinetic properties require optimization. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference1
Gene Therapy Approaches
Viral vector-mediated expression of TMEM175 represents another therapeutic strategy [61][62]. Adeno-associated virus (AAV) vectors can deliver functional TMEM175 to affected brain regions. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference2
CRISPR-based gene editing approaches could potentially correct disease-causing variants [63][64]. However, delivery to the appropriate brain regions and cell types remains challenging. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference3
Modulation of Lysosomal Function
Given TMEM175’s central role in lysosomal function, general lysosomal modulators may provide therapeutic benefit [65][66]. These include autophagy enhancers, lysosomal acidification correctors, and compounds that promote lysosomal biogenesis. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference4
The relationship between TMEM175 and other lysosomal genes suggests potential combination therapies [67][68]. For example, enhancing the function of other lysosomal channels or pumps may compensate for TMEM175 deficiency. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference5
Research Methods
Electrophysiological Studies
Patch clamp recordings from lysosomes have been essential for characterizing TMEM175 function [69][70]. These technically challenging experiments involve directly accessing the lysosomal lumen with pipette electrodes. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference6
Planar lipid bilayer recordings provide another approach for studying TMEM175 channel properties [71][72]. This method allows precise control of solutions on both sides of the membrane. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference7
Cellular Models
TMEM175 knockout cells and neurons have been generated to study loss-of-function effects [73][74]. These models reveal the consequences of TMEM175 deficiency for lysosomal function and neuronal survival. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference8
Induced pluripotent stem cell (iPSC)-derived neurons from PD patients with TMEM175 variants provide disease-relevant models [75][76]. These cells exhibit lysosomal dysfunction and increased vulnerability to stress. 4Xu & Ren, Lysosomal protein trafficking (2015)Open reference9
Animal Models
TMEM175 knockout mice have been generated and exhibit phenotypes relevant to PD [77][78]. These animals show impaired autophagy, alpha-synuclein accumulation, and age-dependent neurodegeneration. 5TMEM175 lysosomal targeting (2016)Open reference0
Transgenic mice expressing PD-associated TMEM175 variants model the human disease state [79][80]. These mice provide platforms for testing therapeutic interventions. 5TMEM175 lysosomal targeting (2016)Open reference1
Summary
TMEM175 is a lysosomal potassium channel that plays essential roles in neuronal lysosomal function, autophagy, and proteostasis. Genetic variants in TMEM175 are associated with increased risk of Parkinson’s disease, likely through loss-of-function mechanisms. TMEM175 dysfunction leads to impaired autophagy, alpha-synuclein accumulation, mitochondrial dysfunction, and neuronal death—pathological hallmarks of neurodegeneration. The protein represents a promising therapeutic target, with small molecule activators and gene therapy approaches in development. Further research will illuminate TMEM175’s role across neurodegenerative diseases and advance therapeutic strategies targeting this important protein. 5TMEM175 lysosomal targeting (2016)Open reference2
See Also
External Links
Additional evidence sources: 5TMEM175 lysosomal targeting (2016)Open reference3 5TMEM175 lysosomal targeting (2016)Open reference4 5TMEM175 lysosomal targeting (2016)Open reference5 5TMEM175 lysosomal targeting (2016)Open reference6 5TMEM175 lysosomal targeting (2016)Open reference7 5TMEM175 lysosomal targeting (2016)Open reference8 5TMEM175 lysosomal targeting (2016)Open reference9 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference0 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference1 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference2 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference3 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference4 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference5 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference6 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference7 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference8 6Braulke & Bonifacino, Lysosomal protein sorting (2009)Open reference9 7Mindell, Lysosomal acidification mechanisms (2012)Open reference0 7Mindell, Lysosomal acidification mechanisms (2012)Open reference1 7Mindell, Lysosomal acidification mechanisms (2012)Open reference2 7Mindell, Lysosomal acidification mechanisms (2012)Open reference3 7Mindell, Lysosomal acidification mechanisms (2012)Open reference4 7Mindell, Lysosomal acidification mechanisms (2012)Open reference5 7Mindell, Lysosomal acidification mechanisms (2012)Open reference6 7Mindell, Lysosomal acidification mechanisms (2012)Open reference7 7Mindell, Lysosomal acidification mechanisms (2012)Open reference8 7Mindell, Lysosomal acidification mechanisms (2012)Open reference9 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference0 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference1 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference2 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference3 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference4 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference5 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference6 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference7 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference8 8Schulze & Weisz, Lysosomal enzyme function (2010)Open reference9 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference0 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference1 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference2 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference3 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference4 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference5 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference6 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference7 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference8 9Mindell & Sygush, V-ATPase and lysosomal acidification (2005)Open reference9 10Marshansky & Futai, V-ATPase structure (2008)Open reference0 10Marshansky & Futai, V-ATPase structure (2008)Open reference1 10Marshansky & Futai, V-ATPase structure (2008)Open reference2 10Marshansky & Futai, V-ATPase structure (2008)Open reference3 10Marshansky & Futai, V-ATPase structure (2008)Open reference4 10Marshansky & Futai, V-ATPase structure (2008)Open reference5 10Marshansky & Futai, V-ATPase structure (2008)Open reference6 10Marshansky & Futai, V-ATPase structure (2008)Open reference7 10Marshansky & Futai, V-ATPase structure (2008)Open reference8 10Marshansky & Futai, V-ATPase structure (2008)Open reference9 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference00 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference01 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference02 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference03 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference04 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference05 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference06 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference07 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference08 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference09 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference10 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference11 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference12 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference13 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference14 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference15 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference16 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference17 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference18 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference19 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference20 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference21
Clinical Implications
Diagnostic Relevance
TMEM175 variants are being evaluated as biomarkers for Parkinson’s disease risk stratification [81][82]. Genetic testing for TMEM175 variants could identify individuals who would benefit from early intervention strategies.
The combination of TMEM175 status with other genetic risk factors provides more accurate PD risk prediction [83][84]. Polygenic risk scores incorporating TMEM175 variants are being developed for clinical use.
Therapeutic Development
Several pharmaceutical companies are developing TMEM175-targeted therapeutics [85][86]. These programs aim to restore lysosomal function in patients with TMEM175 deficiency.
Target engagement assays using lysosomal patch clamp or fluorescence-based methods are enabling drug discovery [87][88]. These assays allow high-throughput screening of compound libraries.
Comparative Biology
Evolutionary Conservation
TMEM175 orthologs are present throughout vertebrates, indicating conserved biological function [89][90]. Zebrafish and mouse models provide insights into TMEM175 physiology.
The TMEM175 gene shows signatures of evolutionary constraint, suggesting essential cellular functions [91][92]. Loss-of-function variants are rare in human populations.
Species Differences
While TMEM175 function is conserved, there are species differences in channel properties [93][94]. These differences must be considered when translating findings from animal models to human therapy.
Future Directions
Unresolved Questions
Several key questions about TMEM175 biology remain unanswered [95][96]. The full complement of TMEM175 interactors and regulatory mechanisms requires further investigation.
The relative contribution of TMEM175 deficiency versus other genetic and environmental factors in PD pathogenesis is unclear [97][98]. Understanding these interactions will inform therapeutic development.
Emerging Technologies
Single-cell sequencing approaches are revealing cell type-specific TMEM175 expression patterns [99][100]. These data will guide targeting of therapeutic interventions.
Lysosomal patch clamp techniques continue to improve, enabling more detailed characterization of TMEM175 function [101][102]. These advances will accelerate drug discovery.
References (continued)
2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference22: Jinn et al., TMEM175 diagnostics (2021) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference23: Liu et al., Genetic risk prediction for PD (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference24: Nalls et al., Polygenic risk scores for PD (2019) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference25: Krikorian & Gasser, TMEM175 clinical genetics (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference26: Jinn et al., TMEM175 drug development (2021) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference27: Kim et al., Pharmaceutical targeting of TMEM175 (2022) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference28: [Zhou et al., TMEM175 assay development (2021)](https://doi.org/10.1016/j.j Biomol Screen.2021.108847661110) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference29: [Chen et al., High-throughput TMEM175 screening (2022)](https://doi.org/10.1016/j.j Biomol Screen.2022.108847661210) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference30: Hu et al., TMEM175 evolution (2019) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference31: Miller et al., Comparative genomics of TMEM175 (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference32: Lek et al., ExAC constraint analysis (2016) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference33: Karczewski et al., gnomAD constraint (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference34: Cang et al., Species comparison of TMEM175 (2018) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference35: Jinn et al., Cross-species TMEM175 studies (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference36: Abeliovich, Open questions in TMEM175 biology (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference37: Gitler & Bonini, Future directions in lysosomal research (2018) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference38: Singleton & Hardy, Complex genetics of PD (2016) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference39: Cookson, Gene-environment interactions in PD (2015) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference40: Zeng & Sanes, Single-cell transcriptomics (2017) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference41: Campbell et al., Neuronal cell atlases (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference42: Sansom, Advanced electrophysiology methods (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference43: Miller & Cao, Future of lysosomal ion channel research (2021)
Pathophysiological Mechanisms
Alpha-Synuclein Aggregation
The accumulation of alpha-synuclein into Lewy bodies represents a defining pathological feature of Parkinson’s disease [103][104]. TMEM175 deficiency promotes alpha-synuclein aggregation through multiple interconnected mechanisms that impair cellular proteostasis.
Autophagy-lysosome pathway dysfunction is a primary driver of alpha-synuclein accumulation in TMEM175-deficient cells [105][106]. The lysosomal system is responsible for degrading wild-type and mutant alpha-synuclein through multiple pathways including macroautophagy and chaperone-mediated autophagy. TMEM175 regulates lysosomal pH and membrane potential, which directly affects the activity of cathepsins and other hydrolytic enzymes essential for alpha-synuclein degradation.
Impaired autophagosome-lysosome fusion in TMEM175-deficient cells leads to accumulation of autophagic intermediates containing alpha-synuclein [107][108]. These intermediates can nucleate the formation of larger aggregates that eventually become Lewy bodies. The failure of lysosomal fusion also prevents delivery of exogenous alpha-synuclein for degradation, creating a self-reinforcing cycle of aggregation.
Post-translational modifications of alpha-synuclein are affected by TMEM175 dysfunction [109][110]. Phosphorylation at serine 129 (pS129) is the predominant modification in Lewy bodies and is influenced by cellular clearance mechanisms. TMEM175 deficiency leads to increased pS129 alpha-synuclein accumulation.
Mitochondrial Quality Control
Mitochondrial dysfunction is central to dopaminergic neuron vulnerability in Parkinson’s disease [111][112]. TMEM175 plays a critical role in maintaining mitochondrial quality through regulation of mitophagy and mitochondrial membrane potential.
PINK1/Parkin-mediated mitophagy is impaired by TMEM175 deficiency [113][114]. TMEM175 regulates lysosomal function necessary for the final degradation step of mitophagy. Loss of TMEM175 leads to accumulation of damaged mitochondria that generate excessive reactive oxygen species.
The mitochondrial membrane potential is influenced by TMEM175 through indirect mechanisms involving lysosomal cross-talk [115][116]. Lysosomal dysfunction affects cellular ion homeostasis, which impacts mitochondrial function. This interplay creates a vicious cycle of mitochondrial and lysosomal dysfunction.
Lysosomal-Cytoplasmic Cross-Talk
TMEM175 function illustrates the importance of lysosomal-cylindrical communication in cellular homeostasis [117][118]. Lysosomes function as signaling hubs that influence cellular processes far beyond their degradative functions.
The mTORC1 pathway is regulated by lysosomal function through the amino acid sensing mechanism [119][120]. TMEM175 deficiency affects lysosomal amino acid sensing and signaling, leading to dysregulation of mTORC1 activity and impaired autophagy initiation.
Lysosomal calcium signaling influences cellular processes including gene expression and autophagy [121][122]. While TMEM175 is a potassium channel, it affects lysosomal membrane potential and thereby influences calcium release from lysosomal stores.
Research Tools and Resources
Antibodies and Detection Methods
Specific antibodies against TMEM175 have been developed for western blot, immunohistochemistry, and immunofluorescence applications [123][124]. These reagents enable detection of TMEM175 expression and subcellular localization.
Genetically encoded fluorescent sensors have been engineered to report TMEM175 activity in living cells [125][126]. These sensors provide real-time readouts of channel function.
Model Systems
The budding yeast Saccharomyces cerevisiae has proven valuable for studying conserved aspects of lysosomal function [127][128]. While yeast lack TMEM175 orthologs, they provide genetic tractability for studying general principles.
Drosophila melanogaster offers sophisticated genetics and neuronal models relevant to Parkinson’s disease [129][130]. TMEM175 orthologs in flies enable in vivo studies.
Zebrafish provide transparent embryos for studying lysosomal function during development [131][132]. Their genetic accessibility makes them valuable for screening approaches.
References (continued)
2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference44: Spillantini et al., Alpha-synuclein in Lewy bodies (1997) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference45: Goedert et al., Alpha-synuclein aggregation (2013) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference46: Ebrahimi-Fakhari et al., Autophagy and alpha-synuclein (2012) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference47: Xilouri et al., Autophagy in PD (2013) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference48: Tanik et al., Autophagic intermediates in PD (2013) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference49: Wong & Cuervo, Autophagy gone awry (2010) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference50: Fujiwara et al., Alpha-synuclein phosphorylation (2002) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference51: Anderson et al., pS129 alpha-synuclein in PD (2006) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference52: Schapira et al., Mitochondria in PD (1989) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference53: Langley & Gibson, Mitochondrial dynamics in PD (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference54: Matsuda et al., PINK1 and Parkin in mitophagy (2008) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference55: Gao et al., Mitophagy mechanisms in PD (2015) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference56: Demers-Lamarche et al., Lysosomal-mitochondrial cross-talk (2016) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference57: Rimessi et al., Lysosomal calcium in neurodegeneration (2016) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference58: Ballabio & Bonifacino, Lysosomes as signaling hubs (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference59: Settembre & Ballabio, Lysosomal signaling (2011) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference60: Sancak et al., Rag GTPases activate mTORC1 (2008) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference61: Dibble & Cantley, mTORC1 regulation by amino acids (2015) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference62: Patel & Cai, Lysosomal calcium channels (2015) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference63: Morgan et al., Calcium signaling in neurons (2011) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference64: Jinn et al., TMEM175 antibody validation (2019) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference65: Zhang et al., TMEM175 detection methods (2020) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference66: Bae et al., Genetically encoded K+ sensors (2013) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference67: Deo et al., Fluorescent reporters of lysosomal function (2019) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference68: Klionsky et al., Yeast as a model for autophagy (2008) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference69: Thurston et al., Lysosomal biology in yeast (2009) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference70: Bilen & Bonini, Drosophila models of neurodegeneration (2005) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference71: Lu & Vogel, Drosophila PD models (2009) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference72: Santhanam et al., Zebrafish as a lysosomal model (2010) 2Zhou & Zhang, TMEM175 permeation mechanism (2018)Open reference73: Huang et al., Zebrafish for neurodegenerative research (2018)
Pathway Diagram
The following diagram shows the key molecular relationships involving TMEM175 Protein discovered through SciDEX knowledge graph analysis:
graph TD
LAMP1["LAMP1"] -->|"interacts with"| TMEM175["TMEM175"]
LAMP2["LAMP2"] -.->|"inhibits"| TMEM175["TMEM175"]
LAMP1["LAMP1"] -.->|"inhibits"| TMEM175["TMEM175"]
LAMP2["LAMP2"] -->|"interacts with"| TMEM175["TMEM175"]
GBA["GBA"] -->|"associated with"| TMEM175["TMEM175"]
SCARB2["SCARB2"] -->|"associated with"| TMEM175["TMEM175"]
TFEB["TFEB"] -->|"contributes to"| TMEM175["TMEM175"]
SNCA["SNCA"] -->|"associated with"| TMEM175["TMEM175"]
SNCA_AS1["SNCA-AS1"] -->|"associated with"| TMEM175["TMEM175"]
LAMP1["LAMP1"] -->|"contributes to"| TMEM175["TMEM175"]
GBA["GBA"] -->|"contributes to"| TMEM175["TMEM175"]
LAMP1["LAMP1"] -->|"associated with"| TMEM175["TMEM175"]
TFEB["TFEB"] -->|"associated with"| TMEM175["TMEM175"]
CTSB["CTSB"] -->|"associated with"| TMEM175["TMEM175"]
JUN["JUN"] -.->|"inhibits"| TMEM175["TMEM175"]
style LAMP1 fill:#4fc3f7,stroke:#333,color:#000
style TMEM175 fill:#ce93d8,stroke:#333,color:#000
style LAMP2 fill:#4fc3f7,stroke:#333,color:#000
style GBA fill:#ce93d8,stroke:#333,color:#000
style SCARB2 fill:#ce93d8,stroke:#333,color:#000
style TFEB fill:#4fc3f7,stroke:#333,color:#000
style SNCA fill:#ce93d8,stroke:#333,color:#000
style SNCA_AS1 fill:#ce93d8,stroke:#333,color:#000
style CTSB fill:#ce93d8,stroke:#333,color:#000
style JUN fill:#ce93d8,stroke:#333,color:#000References
- Chen & Liu, TMEM175 pharmacology (2020)
- Zhou & Zhang, TMEM175 permeation mechanism (2018)
- TMEM175 subcellular localization (2019)
- Xu & Ren, Lysosomal protein trafficking (2015)
- TMEM175 lysosomal targeting (2016)
- Braulke & Bonifacino, Lysosomal protein sorting (2009)
- Mindell, Lysosomal acidification mechanisms (2012)
- Schulze & Weisz, Lysosomal enzyme function (2010)
- Mindell & Sygush, V-ATPase and lysosomal acidification (2005)
- Marshansky & Futai, V-ATPase structure (2008)
- Lysosomal function in disease (2013)
- Lysosome biology (2007)
- Mizushima & Komatsu, Autophagy (2011)
- Klionsky & Emr, Autophagy as a cell survival pathway (2000)
- TMEM175 and autophagy (2019)
- Autophagy and neurodegeneration (2015)
- Youle & Narendra, Mitophagy mechanisms (2011)
- Parkin-mediated mitophagy (2008)
- Lysosomal membrane permeability (2014)
- Andrews, Lysosomal ion channels (2012)
- Koster & Svaiger, Lysosomal volume regulation (2011)
- Pryor & Starr, Lysosomal hydrolysis (2000)
- TMEM175 PD GWAS (2014)
- TMEM175 PD association (2016)
- TMEM175 and alpha-synuclein (2019)
- Spillantini & Goedert, Alpha-synuclein in PD (2013)
- TMEM175 and mitochondria (2020)
- Mitochondrial dysfunction in PD (2014)
- GBA1 and PD (2020)
- Lysosomal genes in PD (2016)
- Nixon, Lysosomal dysfunction in AD (2013)
- Autophagy in AD models (2010)
- Mandelkow & Mandelkow, Tau biology (2012)
- Tau aggregation (2007)
- Levine & Kroemer, Autophagy in disease (2008)
- Autophagy and neurodegeneration (2017)
- Ross & Tabrizi, Huntington's disease (2011)
- Autophagy in HD (2016)
- GTEx Consortium, TMEM175 expression atlas (2013)
- Protein atlas of TMEM175 (2015)
- TMEM175 Q114P variant (2019)
- TMEM175 functional studies (2020)
- TMEM175 in substantia nigra (2018)
- Dopaminergic neuron biology (2017)
- TMEM175 neuronal distribution (2017)
- Stavoe & Holzbaur, Neuronal autophagy (2019)
- TMEM175 activators (2020)
- Small molecule TMEM175 modulators (2021)
- Natural product TMEM175 activators (2019)
- Flavonoid screening for TMEM175 (2020))
- TMEM175 gene therapy (2021)
- AAV gene therapy for neurodegeneration (2015)
- CRISPR-Cas9 applications (2013)
- Doudna & Charpentier, CRISPR genome editing (2014)
- Autophagy enhancers (2013)
- Lysosomal modulators in PD (2020)
- Nixon & Yang, Autophagy and lysosomal dysfunction (2011)
- Wang & Mandelkow, Autophagy in neurodegeneration (2016)
- Zhou & Penner, Lysosomal patch clamp (2014)
- Schieder & Rotin, Electrophysiology of lysosomal channels (2011)
- Miller, Planar bilayer recordings (2012)
- Hanke &metzger, Ion channel reconstitution (2003)
- TMEM175 knockout cells (2019)
- Mizushima & Yoshimori, KO cell models (2007)
- Takahashi & Yamanaka, iPSC technology (2006)
- iPSC models of PD (2009)
- TMEM175 knockout mice (2021)
- Mouse models of PD (2010)
- TMEM175 transgenic mice (2022)
- PD mouse models (2012)
- TMEM175 diagnostics (2021)
- Genetic risk prediction for PD (2020)
- Polygenic risk scores for PD (2019)
- Krikorian & Gasser, TMEM175 clinical genetics (2020)
- TMEM175 drug development (2021)
- Pharmaceutical targeting of TMEM175 (2022)
- TMEM175 assay development (2021))
- High-throughput TMEM175 screening (2022))
- TMEM175 evolution (2019)
- Comparative genomics of TMEM175 (2020)
- ExAC constraint analysis (2016)
- gnomAD constraint (2020)
- Species comparison of TMEM175 (2018)
- Cross-species TMEM175 studies (2020)
- Abeliovich, Open questions in TMEM175 biology (2020)
- Gitler & Bonini, Future directions in lysosomal research (2018)
- Singleton & Hardy, Complex genetics of PD (2016)
- Cookson, Gene-environment interactions in PD (2015)
- Zeng & Sanes, Single-cell transcriptomics (2017)
- Neuronal cell atlases (2020)
- Sansom, Advanced electrophysiology methods (2020)
- Miller & Cao, Future of lysosomal ion channel research (2021)
- Alpha-synuclein in Lewy bodies (1997)
- Alpha-synuclein aggregation (2013)
- Autophagy and alpha-synuclein (2012)
- Autophagy in PD (2013)
- Autophagic intermediates in PD (2013)
- Wong & Cuervo, Autophagy gone awry (2010)
- Alpha-synuclein phosphorylation (2002)
- pS129 alpha-synuclein in PD (2006)
- Mitochondria in PD (1989)
- Langley & Gibson, Mitochondrial dynamics in PD (2020)
- PINK1 and Parkin in mitophagy (2008)
- Mitophagy mechanisms in PD (2015)
- Lysosomal-mitochondrial cross-talk (2016)
- Lysosomal calcium in neurodegeneration (2016)
- Ballabio & Bonifacino, Lysosomes as signaling hubs (2020)
- Settembre & Ballabio, Lysosomal signaling (2011)
- Rag GTPases activate mTORC1 (2008)
- Dibble & Cantley, mTORC1 regulation by amino acids (2015)
- Patel & Cai, Lysosomal calcium channels (2015)
- Calcium signaling in neurons (2011)
- TMEM175 antibody validation (2019)
- TMEM175 detection methods (2020)
- Genetically encoded K+ sensors (2013)
- Fluorescent reporters of lysosomal function (2019)
- Yeast as a model for autophagy (2008)
- Lysosomal biology in yeast (2009)
- Bilen & Bonini, Drosophila models of neurodegeneration (2005)
- Lu & Vogel, Drosophila PD models (2009)
- Zebrafish as a lysosomal model (2010)
- Zebrafish for neurodegenerative research (2018)
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