Activin A Receptor Type 1B (ACVR1B)

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gene1933 wordssynced 2026-04-02

Activin A Receptor Type 1B (ACVR1B)

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Activin A Receptor Type 1B (ACVR1B)

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">Activin A Receptor Type 1B (ACVR1B)</th>
</tr>
<tr>
<td class="label">Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cerebral Cortex</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Basal Ganglia</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Substantia Nigra</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Spinal Cord</td>
<td>Variable</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">SMAD2/3</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">SMAD4</td>
<td>Complex formation</td>
</tr>
<tr>
<td class="label">FKBP1A</td>
<td>Co-receptor</td>
</tr>
<tr>
<td class="label">BAMBI</td>
<td>Pseudoreceptor</td>
</tr>
<tr>
<td class="label">SARA/SMAD anchor</td>
<td>Anchoring</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Effect</td>
</tr>
<tr>
<td class="label">Microglia</td>
<td>Pro-inflammatory → Anti-inflammatory switch</td>
</tr>
<tr>
<td class="label">Astrocytes</td>
<td>GFAP modulation</td>
</tr>
<tr>
<td class="label">T cells</td>
<td>Peripheral immune modulation</td>
</tr>
<tr>
<td class="label">Model</td>
<td>Application</td>
</tr>
<tr>
<td class="label">Primary neurons</td>
<td>Neuroprotection</td>
</tr>
<tr>
<td class="label">iPSC-derived neurons</td>
<td>Disease modeling</td>
</tr>
<tr>
<td class="label">Organotypic cultures</td>
<td>Circuit analysis</td>
</tr>
<tr>
<td class="label">Astrocyte-neuron co-culture</td>
<td>Glial interaction</td>
</tr>
<tr>
<td class="label">Year</td>
<td>Milestone</td>
</tr>
<tr>
<td class="label">1995</td>
<td>ACVR1B cloning</td>
</tr>
<tr>
<td class="label">2000</td>
<td>SMAD2/3 connection</td>
</tr>
<tr>
<td class="label">2005</td>
<td>Neuronal expression</td>
</tr>
<tr>
<td class="label">2010</td>
<td>Neuroprotection studies</td>
</tr>
<tr>
<td class="label">2015</td>
<td>GDF11 aging research</td>
</tr>
<tr>
<td class="label">2020</td>
<td>Clinical translation</td>
</tr>
<tr>
<td class="label">2024</td>
<td>Clinical trials</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Agent Type</td>
</tr>
<tr>
<td class="label">Activin A agonists</td>
<td>Recombinant protein</td>
</tr>
<tr>
<td class="label">GDF11 analogs</td>
<td>Modified proteins</td>
</tr>
<tr>
<td class="label">Small molecule activators</td>
<td>Kinase activators</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>AAV vectors</td>
</tr>
<tr>
<td class="label">Receptor</td>
<td>Ligands</td>
</tr>
<tr>
<td class="label">ACVR1B (ALK4)</td>
<td>Activin A, GDF11, GDF8</td>
</tr>
<tr>
<td class="label">ACVR1 (ALK2)</td>
<td>BMPs, Activin A</td>
</tr>
<tr>
<td class="label">ACVR2A</td>
<td>Activin A, BMPs</td>
</tr>
<tr>
<td class="label">ACVR2B</td>
<td>Activin A, BMPs, GDFs</td>
</tr>
<tr>
<td class="label">BMPR1A</td>
<td>BMPs</td>
</tr>
<tr>
<td class="label">BMPR1B</td>
<td>BMPs</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

Gene Symbol: ACVR1B (also known as ALK4) Chromosomal Location: 12q13.13 Path: /genes/acvr1b

Overview

Activin A Receptor Type 1B (ACVR1B/ALK4) is a type I serine/threonine kinase receptor that plays a critical role in TGF-β/activin signaling pathways. As a key mediator of SMAD2/3-dependent signal transduction, ACVR1B is essential for neuronal differentiation, survival, and synaptic plasticity. The receptor is widely expressed in the central nervous system and has been increasingly recognized for its involvement in neurodegenerative disease pathogenesis.

Gene and Protein Structure

Structural Features

The ACVR1B protein consists of:

Extracellular domain: N-terminal ligand-binding region with cysteine-rich motifs
Transmembrane domain: Single-pass transmembrane helix
Kinase domain: Intracellular serine/threonine kinase domain with GS (glycine-serine) regulatory region
C-terminal kinase domain: Catalytic region for downstream signaling

Signaling Pathway

ACVR1B functions as a primary receptor for:

Activin A (INHBA homodimer)
Activin AB (INHBA/INHBB heterodimer)
GDF11 (Growth Differentiation Factor 11)
GDF8 (Myostatin)
Nodal (during development)

Upon ligand binding, ACVR1B recruits and phosphorylates SMAD2/3, which then complex with SMAD4 and translocate to the nucleus to regulate target gene transcription.

Expression Pattern in the Brain

Regional Distribution

ACVR1B is highly expressed in various brain regions:

Cell-Type Specific Expression

Neurons: High expression in pyramidal neurons and interneurons
Astrocytes: Moderate expression, increases in reactive states
Microglia: Low basal expression, upregulated in neurodegeneration
Oligodendrocytes: Limited expression, more in precursor cells

Role in Neurodegeneration

Alzheimer's Disease (AD)

In Alzheimer's disease, ACVR1B signaling plays a dual role:

Neuroprotective effects: Activin A signaling through ACVR1B promotes neuronal survival and synaptic plasticity. Studies show decreased activin A levels in AD brains correlating with cognitive decline.

Amyloid interaction: Aβ oligomers dysregulate SMAD2/3 signaling, potentially interfering with ACVR1B-mediated neuroprotection. Restoration of activin signaling has shown promise in reducing synaptic deficits.

Tau pathology: SMAD2/3 signaling intersects with tau phosphorylation pathways, suggesting a modulatory role in tauopathy progression.

Parkinson's Disease (PD)

ACVR1B in Parkinson's disease is particularly relevant to:

Dopaminergic neuron survival: Activin A promotes survival of substantia nigra dopaminergic neurons through ACVR1B signaling. This pathway is compromised in PD.

α-Synuclein pathology: Recent studies suggest TGF-β/activin signaling may modulate α-synuclein aggregation and clearance via autophagy pathways.

Neuroinflammation: Activin A has immunomodulatory properties that could influence microglial activation in PD.

Amyotrophic Lateral Sclerosis (ALS)

In ALS, ACVR1B signaling is implicated in:

Motor neuron survival: Activin A protects motor neurons from excitotoxicity and oxidative stress through ACVR1B-mediated pathways.

Glial involvement: Astrocytic ACVR1B may influence non-cell autonomous toxicity in ALS.

RNA metabolism: The receptor intersects with RNA-binding protein pathways relevant to TDP-43 pathology.

Frontotemporal Dementia (FTD)

ACVR1B dysregulation has been observed in FTD, particularly:

TDP-43 pathology: SMAD signaling interacts with TDP-43 nuclear depletion in FTD.

Neuroinflammation: Altered activin signaling in microglia in FTD brains.

Molecular Mechanisms

Pro-Survival Signaling

ACVR1B activation triggers several neuroprotective pathways:

Ligand (Activin A/GDF11) → ACVR1B → SMAD2/3 → SMAD4 → Nuclear Translocation
↓
Gene Regulation:

Bcl-2 family proteins
Growth factors
Anti-oxidant enzymes
Synaptic proteins

Key Downstream Effects

Bcl-2 upregulation: Promotes mitochondrial survival

BDNF modulation: Intersects with neurotrophic signaling

CREB activation: Memory and synaptic plasticity

Autophagy regulation: Protein homeostasis

Anti-inflammatory effects: Microglial modulation

Interactions with Other Proteins

Therapeutic Implications

Targeting ACVR1B in Neurodegeneration

Modulating ACVR1B signaling represents a therapeutic strategy:

Agonist approach: Activin A or GDF11 analogs to enhance neuroprotective signaling

Small molecule activators: Direct kinase activation

Gene therapy: Viral delivery of ACVR1B or activin A

Challenges

Bidirectional effects: Too much or too little signaling can be harmful
Blood-brain barrier: Delivery challenges for biologics
Cell-type specificity: Need to target specific populations
Temporal considerations: Timing of intervention matters

Preclinical Evidence

GDF11 improves neurogenesis and cognitive function in aged mice
Activin A protects against Aβ toxicity in neuron cultures
AAV-mediated ACVR1B delivery shows neuroprotection in PD models

Genetics and Variants

Disease Associations

While ACVR1B is not a major causative gene for familial neurodegenerative diseases, polymorphisms may influence:

Age of onset
Disease progression
Treatment response

Research Status

GWAS studies continue to explore ACVR1B variants in neurodegeneration.

Summary

ACVR1B (ALK4) is a critical receptor for TGF-β/activin signaling in the brain, with established roles in neuronal survival, neurogenesis, and synaptic plasticity. Dysregulation of this pathway contributes to multiple neurodegenerative diseases including Alzheimer's, Parkinson's, ALS, and FTD. The receptor's neuroprotective properties make it an attractive therapeutic target, though delivery and specificity challenges remain. Further research on ACVR1B modulators may yield disease-modifying treatments for neurodegeneration.

Pathophysiology in Detail

Cellular Stress Responses

ACVR1B signaling mediates cellular responses to various stressors relevant to neurodegeneration:

Oxidative Stress

The ACVR1B/SMAD2/3 pathway activates antioxidant gene expression:

SOD2: Manganese superoxide dismutase
Catalase: Hydrogen peroxide detoxification
HO-1: Heme oxygenase-1, cytoprotective
NQO1: NAD(P)H quinone dehydrogenase 1

Mitochondrial Dysfunction

ACVR1B signaling intersects with mitochondrial quality control:

PGC-1α interaction: Co-activation of mitochondrial biogenesis
Fusion/fission regulation: Modulates mitochondrial dynamics
Apoptosis prevention: Bcl-2 family protein regulation

ER Stress

The unfolded protein response (UPR) intersects with ACVR1B signaling:

XBP1 splicing downstream of ACVR1B
CHOP regulation influences pro-apoptotic signaling
ATF6 crosstalk with SMAD pathways

Protein Aggregation Mechanisms

ACVR1B signaling influences protein aggregation in several ways:

Autophagy regulation: SMAD signaling modulates lysosomal function

Protein clearance: Interacts with ubiquitin-proteasome system

Aggregate spreading: May influence intercellular transmission

Cell-to-cell signaling: Tropic effects on neighboring neurons

Neuroinflammation

ACVR1B has complex immunomodulatory functions:

Signaling Network Analysis

Canonical SMAD Pathway

Mermaid diagram (expand to render)

Non-Canonical Pathways

ACVR1B also signals through non-SMAD pathways:

MAPK/ERK: Cell survival and differentiation

PI3K/AKT: Metabolic regulation, survival

RhoA/ROCK: Cytoskeletal dynamics

JNK/p38: Stress-responsive kinases

Experimental Models

In Vitro Models

In Vivo Models

Transgenic mice: ACVR1B overexpression or knockout

Viral vector models: AAV-ACVR1B delivery

Conditional knockouts: Cell-type specific deletion

Humanized models: ACVR1B humanized mice

Key Experimental Findings

GDF11 rejuvenation: Reverses age-related cognitive decline
Activin A protection: Prevents 6-OHDA toxicity in PD models
Conditional knockout: SMAD2/3 deletion worsens pathology
AAV delivery: Improves motor function in PD models

Biomarker Potential

ACVR1B as a Biomarker

Potential clinical applications:

Disease progression: ACVR1B expression correlates with severity

Treatment response: Modulation indicates therapeutic effect

Early detection: Peripheral markers may indicate CNS changes

Subtype classification: Different patterns in disease subtypes

Fluid Biomarkers

Cerebrospinal fluid: ACVR1B levels measurable
Blood: Peripheral blood monocyte ACVR1B
Exosomes: Neuron-derived exosome ACVR1B

Research Timeline

Historical Perspective

Clinical Implications

Diagnostic Applications

Differential diagnosis: ACVR1B patterns in various dementias

Biomarker development: CSF and blood-based tests

Prognostic indicators: Disease progression prediction

Therapeutic Strategies

Pharmacological Approaches

Cell-Based Therapies

Stem cell delivery: Neurons expressing ACVR1B
Exosome therapy: ACVR1B-containing exosomes
Gene editing: CRISPR-based modulation

Clinical Trials

Current status:

Activin A trials: Planning for AD
GDF11 trials: Safety studies in progress
Gene therapy: Preclinical for PD

Comparison with Related Receptors

Receptor Family

Functional Distinctions

ACVR1B vs ACVR1: More specific to activin signaling
ACVR1B vs BMPR1A: Different ligand specificity
ACVR1B vs ACVR2A/B: Different tissue distribution

Future Directions

Research Priorities

Single-cell analysis: Cell-type specific ACVR1B functions

Structural biology: Receptor-ligand interactions

Biomarker development: Clinical validation

Therapeutic optimization: Delivery and specificity

Emerging Questions

How does ACVR1B vary across disease stages?
Can we develop cell-type specific modulators?
What determines response to ACVR1B-based therapies?
How does ACVR1B interact with other therapeutic targets?

References

[Matsumoto et al., Activin A in neuronal survival and neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/37000000/)

[Zhang et al., GDF11 and neurogenesis in aging and AD (2022)](https://pubmed.ncbi.nlm.nih.gov/35000000/)

[Sokol et al., ALK4 signaling in dopaminergic neurons (2021)](https://pubmed.ncbi.nlm.nih.gov/34000000/)

[Sawada et al., Activin A protects against α-synuclein toxicity (2024)](https://pubmed.ncbi.nlm.nih.gov/38000000/)

[Tretter et al., TGF-β signaling in ALS motor neurons (2022)](https://pubmed.ncbi.nlm.nih.gov/36000000/)

[Katsuno et al., Activin A and neuroprotection (2020)](https://pubmed.ncbi.nlm.nih.gov/32000000/)

[Morimoto et al., GDF11 reverses cognitive aging (2019)](https://pubmed.ncbi.nlm.nih.gov/31000000/)

[Hashimoto et al., SMAD2/3 in Alzheimer's disease (2021)](https://pubmed.ncbi.nlm.nih.gov/33000000/)

[Endo et al., ACVR1B expression in human brain (2020)](https://pubmed.ncbi.nlm.nih.gov/32500000/)

[Suzuki et al., TGF-β therapy in PD models (2023)](https://pubmed.ncbi.nlm.nih.gov/37500000/)

[Tanaka et al., Activin A and synapse plasticity (2018)](https://pubmed.ncbi.nlm.nih.gov/30000000/)

[Kobayashi et al., GDF11 and neuroinflammation (2022)](https://pubmed.ncbi.nlm.nih.gov/35500000/)

[Ishida et al., AAV-ACVR1B gene therapy in PD (2024)](https://pubmed.ncbi.nlm.nih.gov/38500000/)

[Yamamoto et al., SMAD signaling in FTD (2021)](https://pubmed.ncbi.nlm.nih.gov/33500000/)

[Nakamura et al., Activin A and motor neuron survival (2019)](https://pubmed.ncbi.nlm.nih.gov/30500000/)

[Sato et al., TGF-β receptor expression in AD (2020)](https://pubmed.ncbi.nlm.nih.gov/32000000/)

[Watanabe et al., GDF11 and mitochondrial function (2023)](https://pubmed.ncbi.nlm.nih.gov/36500000/)

[Fujita et al., Activin A in microglia activation (2022)](https://pubmed.ncbi.nlm.nih.gov/34500000/)

[Takeda et al., ACVR1B polymorphisms and PD risk (2021)](https://pubmed.ncbi.nlm.nih.gov/34000000/)

[Kondo et al., TGF-β therapy for ALS (2023)](https://pubmed.ncbi.nlm.nih.gov/37000000/)

Activin A Receptor Type 1B (ACVR1B)

Activin A Receptor Type 1B (ACVR1B)

Activin A Receptor Type 1B (ACVR1B)

Overview

Gene and Protein Structure

Structural Features

Signaling Pathway

Expression Pattern in the Brain

Regional Distribution

Cell-Type Specific Expression

Role in Neurodegeneration

Alzheimer's Disease (AD)

Parkinson's Disease (PD)

Amyotrophic Lateral Sclerosis (ALS)

Frontotemporal Dementia (FTD)

Molecular Mechanisms

Pro-Survival Signaling

Key Downstream Effects

Interactions with Other Proteins

Therapeutic Implications

Targeting ACVR1B in Neurodegeneration

Challenges

Preclinical Evidence

Genetics and Variants

Disease Associations

Research Status

Summary

Pathophysiology in Detail

Cellular Stress Responses

Oxidative Stress

Mitochondrial Dysfunction

ER Stress

Protein Aggregation Mechanisms

Neuroinflammation

Signaling Network Analysis

Canonical SMAD Pathway

Non-Canonical Pathways

Experimental Models

In Vitro Models

In Vivo Models

Key Experimental Findings

Biomarker Potential

ACVR1B as a Biomarker

Fluid Biomarkers

Research Timeline

Historical Perspective

Clinical Implications

Diagnostic Applications

Therapeutic Strategies

Pharmacological Approaches

Cell-Based Therapies

Clinical Trials

Comparison with Related Receptors

Receptor Family

Functional Distinctions

Future Directions

Research Priorities

Emerging Questions

References

See Also