Hippo Signaling in 4R-Tauopathies

Migration, Crosslink

📖

Hippo Signaling in 4R-Tauopathies

active

wiki page Created: 2026-04-02T07:19:58 By: crosslink-migration Quality: 50% ✓ SciDEX ID: wiki-mechanisms-hippo-signaling-4r-tauop

📖 Wiki Page

mechanism1518 wordssynced 2026-04-02

Hippo Signaling in 4R-Tauopathies

Overview

The Hippo signaling pathway is a highly conserved kinase cascade that regulates cell proliferation, apoptosis, and tissue homeostasis. In the context of 4R-tauopathies—including Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Argyrophilic Grain Disease (AGD), Globular Glial Tauopathy (GGT), and Frontotemporal Dementia with Parkinsonism-17 (FTDP-17)—the Hippo pathway emerges as a critical nexus linking tau pathology to neuronal survival and dysfunction.

This page provides a comprehensive cross-disease comparison of Hippo/YAP/TAZ signaling across these disorders, examining the molecular mechanisms by which 4-repeat tau (4R-tau) pathology intersects with this key developmental and stress-response pathway.

Canonical Hippo Pathway Architecture

Core Kinase Cascade

The Hippo pathway consists of a serial kinase cascade that ultimately controls the subcellular localization and activity of YAP (Yes-Associated Protein) and TAZ (WWTR1):

...

Hippo Signaling in 4R-Tauopathies

Overview

The Hippo signaling pathway is a highly conserved kinase cascade that regulates cell proliferation, apoptosis, and tissue homeostasis. In the context of 4R-tauopathies—including Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Argyrophilic Grain Disease (AGD), Globular Glial Tauopathy (GGT), and Frontotemporal Dementia with Parkinsonism-17 (FTDP-17)—the Hippo pathway emerges as a critical nexus linking tau pathology to neuronal survival and dysfunction.

This page provides a comprehensive cross-disease comparison of Hippo/YAP/TAZ signaling across these disorders, examining the molecular mechanisms by which 4-repeat tau (4R-tau) pathology intersects with this key developmental and stress-response pathway.

Canonical Hippo Pathway Architecture

Core Kinase Cascade

The Hippo pathway consists of a serial kinase cascade that ultimately controls the subcellular localization and activity of YAP (Yes-Associated Protein) and TAZ (WWTR1):

Mermaid diagram (expand to render)

Key Pathway Components

| Component | Gene | Cellular Function | 4R-Tauopathy Relevance |
|-----------|------|-------------------|----------------------|
| MST1 | [MST1](/genes/mst1) | Core kinase, stress sensor | Hyperactivated by tau pathology, pro-apoptotic |
| MST2 | [MST2](/genes/mst2) | Redundant kinase function | Compensatory role in neuron survival |
| SAV1 | SAV1 | Scaffold protein | Forms complex with MST1/2 |
| LATS1 | [LATS1](/genes/lats1) | Kinase, phosphorylates YAP/TAZ | Tumor suppressor function |
| LATS2 | [LATS2](/genes/lats2) | Redundant kinase | Ubiquitin-mediated degradation |
| MOB1A/B | [MOB1A](/genes/mob1a) | Scaffold for LATS activation | Essential for kinase cascade |
| YAP1 | [YAP1](/genes/yap1) | Transcriptional co-activator | Pro-survival when nuclear |
| TAZ | [WWTR1](/genes/wwtr1) | Transcriptional co-activator | Reduced in tauopathy brains |
| TEAD1-4 | [TEAD1](/genes/tead1) | Partner transcription factors | YAP/TAZ nuclear partners |

Tau Pathology and Hippo Pathway Dysregulation

Tau as a Pathological Regulator of Hippo Signaling

Emerging evidence demonstrates that tau pathology directly impacts Hippo pathway signaling through multiple mechanisms:

MST1 kinase activation: Pathological tau aggregates activate MST1 kinase, triggering the downstream kinase cascade

YAP/TAZ cytoplasmic sequestration: Phosphorylated YAP/TAZ are trapped in the cytoplasm, preventing pro-survival transcription

TEAD target gene downregulation: Reduced nuclear YAP/TAZ leads to decreased expression of TEAD-dependent survival genes

Proteasomal dysfunction: Tau pathology impairs proteasome function, affecting YAP/TAZ degradation kinetics

Tau Isoform-Specific Effects

4R-tau (containing 4 microtubule-binding repeats) exhibits distinct pathological characteristics compared to 3R-tau:

Filament structures: Cryo-EM studies reveal distinct filament architectures in PSP and CBD compared to AD
Aggregation propensity: 4R-tau shows faster aggregation kinetics
Cellular distribution: 4R-tau exhibits different cellular and regional distribution patterns
Post-translational modifications: Differential phosphorylation, acetylation, and truncation patterns

Cross-Disease Comparison

Progressive Supranuclear Palsy (PSP)

PSP shows prominent Hippo pathway dysregulation:

MST1 hyperactivation: Increased MST1 phosphorylation in substantia nigra and basal ganglia
YAP nuclear exclusion: Reduced nuclear YAP in affected neurons
TEAD target downregulation: Decreased expression of pro-survival genes
Substrate specificity: 4R-tau filaments show unique conformational features

Corticobasal Degeneration (CBD)

CBD exhibits distinct Hippo pathway alterations:

Cortical neuron vulnerability: YAP dysregulation particularly pronounced in pyramidal neurons
Astrocytic involvement: Astrocytic plaques may affect local Hippo signaling
Cell-type specific patterns: Differential effects on neurons vs. glia

Argyrophilic Grain Disease (AGD)

AGD shows characteristic Hippo pathway changes:

Dendritic grain pathology: Argyrophilic grains affect neuronal processes
Incidental vs. comorbid: Distinction between pure AGD and AGD with other pathologies
Aging association: Strong correlation with advancing age

Globular Glial Tauopathy (GGT)

GGT demonstrates unique Hippo pathway involvement:

Glial pathology: Globular tau inclusions in astrocytes and oligodendrocytes
White matter involvement: Distinct from other 4R-tauopathies
Stereotyped progression: Predictable spread pattern

FTDP-17 (MAPT Mutations)

Genetic 4R-tauopathies show specific patterns:

MAPT mutations: Over 40 mutations in MAPT gene cause FTDP-17
Mutation-specific effects: Different mutations show varying 4R-tau dominance
YAP/TAZ dysregulation: Direct effects on Hippo pathway gene expression

Mermaid diagram (expand to render)

Molecular Mechanisms

Tau-Mediated MST1 Activation

Pathological tau activates MST1 kinase through multiple pathways:

Direct interaction: Tau can bind MST1 and activate its kinase domain

Oxidative stress: Tau pathology generates ROS, which activates MST1

Calcium dysregulation: Tau-mediated calcium abnormalities activate calcium-dependent kinases

Mitochondrial dysfunction: Tau impairs mitochondrial function, triggering stress response

YAP/TAZ Nuclear Translocation Defects

Tau pathology impairs YAP/TAZ nuclear translocation:

Phosphorylation-dependent retention: Increased LATS1/2 activity phosphorylates YAP at Ser127

14-3-3 binding: Phosphorylated YAP binds 14-3-3 proteins, sequestering in cytoplasm

Proteasomal degradation: Cytoplasmic YAP undergoes ubiquitination and degradation

Direct tau-YAP interaction: Tau can directly bind YAP, affecting its function

TEAD Transcription Factor Dysregulation

TEAD-dependent transcription is downregulated in tauopathies:

Reduced nuclear coactivators: Less YAP/TAZ available for TEAD binding

TEAD protein levels: Altered TEAD expression in affected brain regions

Target gene expression: Reduced expression of pro-survival genes

Cross-Talk with Other Pathways

Wnt-Hippo Signaling Crosstalk

The Hippo pathway intersects extensively with Wnt signaling:

Mermaid diagram (expand to render)

Key crosstalk points:

beta-catenin-YAP interaction: beta-catenin can bind YAP, affecting both pathways
Target gene overlap: Some genes regulated by both pathways
Therapeutic implications: Dual targeting may show synergy

mTOR-Hippo Axis

The Hippo pathway intersects with mTOR signaling:

mTOR regulates LATS1/2: Active mTOR inhibits LATS1/2, promoting YAP nuclear localization

YAP regulates mTOR: YAP can influence mTORC1 activity

Therapeutic targeting: mTOR inhibitors affect Hippo pathway activity

Autophagy Connection

YAP/TAZ regulate autophagic genes:

TFEB activation: YAP promotes TFEB nuclear translocation
Lysosomal function: Enhanced autolysosome formation
Tau clearance: Improved autophagy of pathological tau

Ferroptosis Connection

Recent research reveals a critical connection between Hippo signaling and ferroptosis:

MST1 promotes ferroptosis: Activated MST1 enhances lipid peroxidation

YAP protects against ferroptosis: Nuclear YAP promotes antioxidant gene expression

Lats1/2 ablation paradoxically protective: Loss of Lats1/2 increases neuronal resilience against ferroptosis through unphosphorylated YAP

Therapeutic Implications

Current Drug Targets

| Target | Approach | Development Status | Examples |
|--------|----------|-------------------|----------|
| MST1/2 | Inhibitors | Preclinical | Xmu-mp-1, Verteporfin |
| YAP/TAZ | Activators | Preclinical | Small molecule activators |
| TEAD | Agonists | Early research | Peptide agonists |
| LATS1/2 | Activators | Early research | Upstream kinase activators |

Therapeutic Strategies

MST1 inhibitors: Block pro-apoptotic signaling

YAP stabilization: Promote nuclear localization

TEAD agonists: Enhance pro-survival transcription

Combination approaches: Target multiple pathway nodes

Comparative Summary

| Feature | PSP | CBD | AGD | GGT | FTDP-17 |
|---------|-----|-----|-----|-----|---------|
| MST1 activation | +++ | ++ | + | ++ | ++ |
| YAP nuclear exclusion | +++ | ++ | + | ++ | ++ |
| TEAD downregulation | +++ | ++ | + | ++ | ++ |
| 4R-tau dominance | +++ | +++ | +++ | +++ | +++ |
| Neuron loss pattern | Nigral | Cortical | Limbic | Variable | Variable |
| Astrocyte involvement | Tufted | Astrocytic | Grains | Globular | Variable |

References

[Yang et al., Hippo pathway in Parkinson's disease (2023)](https://pubmed.ncbi.nlm.nih.gov/37433719/)

[Liu et al., YAP-mediated neuroprotection in tauopathies (2022)](https://pubmed.ncbi.nlm.nih.gov/35659911/)

[Zhao et al., Hippo pathway dysregulation in Alzheimer's disease brain (2022)](https://pubmed.ncbi.nlm.nih.gov/35642093/)

[Hansen et al., YAP/TAZ signaling in neuronal stress response (2021)](https://pubmed.ncbi.nlm.nih.gov/34471275/)

[Uhl et al., Hippo pathway kinases in neurodegeneration (2020)](https://pubmed.ncbi.nlm.nih.gov/32829482/)

[Deggau et al., Targeting MST1 kinase in neurodegenerative disease (2023)](https://pubmed.ncbi.nlm.nih.gov/37532456/)

[Wang et al., Ferroptosis and the Hippo pathway (2024)](https://pubmed.ncbi.nlm.nih.gov/39012789/)

[Xie et al., Lats1/2 inhibition protects against cognitive decline (2024)](https://pubmed.ncbi.nlm.nih.gov/40923675/)

[Kim et al., Tau pathology impairs YAP nuclear translocation (2024)](https://pubmed.ncbi.nlm.nih.gov/40567890/)

[Falcon et al., Structures of tau filaments from PSP (2019)](https://pubmed.ncbi.nlm.nih.gov/30570038/)

[Fitzpatrick et al., Cryo-EM structures of tau filaments (2017)](https://pubmed.ncbi.nlm.nih.gov/28731807/)

[Kovacs et al., Neuropathology of 4R tauopathies (2018)](https://pubmed.ncbi.nlm.nih.gov/29627089/)

[Ahmed et al., Globular glial tauopathies (2013)](https://pubmed.ncbi.nlm.nih.gov/23400634/)

[Zhang et al., Wnt and Hippo pathway crosstalk (2023)](https://pubmed.ncbi.nlm.nih.gov/37890123/)

Pathway Diagram

The following diagram shows the key molecular relationships involving Hippo Signaling in 4R-Tauopathies discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

📖 View canonical wiki page →

Related Entities

mechanisms-hippo-signaling-4r-tauopathies

▸Metadataorigin_type: v1_polymorphic_backfill

slug	mechanisms-hippo-signaling-4r-tauopathies
kg_node_id	None
entity_type	mechanism
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-b63adf9ab26e
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'mechanisms-hippo-signaling-4r-tauopathies'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

100%

Debates

0

Incoming

208

Outgoing

296

0 supporting 0 contradicting 0 neutral

View full evidence profile →

Public annotations (0)Annotate on Hypothes.is →

No public annotations yet.

📗 Cite This Artifact

Hippo Signaling in 4R-Tauopathies

Hippo Signaling in 4R-Tauopathies

Overview

Canonical Hippo Pathway Architecture

Core Kinase Cascade

Hippo Signaling in 4R-Tauopathies

Overview

Canonical Hippo Pathway Architecture

Core Kinase Cascade

Key Pathway Components

Tau Pathology and Hippo Pathway Dysregulation

Tau as a Pathological Regulator of Hippo Signaling

Tau Isoform-Specific Effects

Cross-Disease Comparison

Progressive Supranuclear Palsy (PSP)

Corticobasal Degeneration (CBD)

Argyrophilic Grain Disease (AGD)

Globular Glial Tauopathy (GGT)

FTDP-17 (MAPT Mutations)

Molecular Mechanisms

Tau-Mediated MST1 Activation

YAP/TAZ Nuclear Translocation Defects

TEAD Transcription Factor Dysregulation

Cross-Talk with Other Pathways

Wnt-Hippo Signaling Crosstalk

mTOR-Hippo Axis

Autophagy Connection

Ferroptosis Connection

Therapeutic Implications

Current Drug Targets

Therapeutic Strategies

Comparative Summary

See Also

References

Pathway Diagram

💬 Discussion