STK11 Protein - LKB1 - Serine/Threonine Kinase 11

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STK11 Protein - LKB1 - Serine/Threonine Kinase 11

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STK11 — LKB1 (Serine/Threonine Kinase 11)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">STK11 Protein - LKB1 - Serine/Threonine Kinase 11</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>STK11</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>STK11 - LKB1 - Serine/Threonine Kinase 11</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=STK11" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">186 edges</a></td>
</tr>
</table>

Introduction

...

STK11 — LKB1 (Serine/Threonine Kinase 11)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">STK11 Protein - LKB1 - Serine/Threonine Kinase 11</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>STK11</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>STK11 - LKB1 - Serine/Threonine Kinase 11</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=STK11" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">186 edges</a></td>
</tr>
</table>

Introduction

LKB1 (Liver Kinase B1), encoded by the STK11 gene, is a serine/threonine kinase that functions as a master regulator of cellular energy metabolism and stress responses. Originally identified as a tumor suppressor mutated in Peutz-Jeghers syndrome, LKB1 phosphorylates and activates AMPK (AMP-activated protein kinase) and twelve related kinases, making it a central coordinator of energy homeostasis, cell polarity, and stress adaptation. In the nervous system, LKB1 plays critical roles in establishing neuronal polarity, regulating axon specification, controlling synaptic function, and mediating autophagy. These functions position LKB1 as a key player in neurodegenerative disease pathogenesis, where metabolic dysfunction, impaired autophagy, and synaptic deficits are hallmark features of conditions including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS)[@alessi2020][@linhermelville2021].

Overview

STK11 encodes LKB1, a 48.6 kDa serine/threonine kinase that is ubiquitously expressed in mammalian tissues with particularly high levels in the brain, liver, and skeletal muscle. LKB1 exists as a heterotrimeric complex with the pseudokinase STRAD (STE20-related kinase adaptor) and the scaffolding protein MO25 (mouse protein 25), which is required for its activity, stability, and subcellular localization[@zong2019].

As a tumor suppressor, LKB1 regulates cell proliferation, polarity, and metabolism. In [neurons](/entities/neurons), LKB1 is essential for establishing axonal identity during development, a process that requires the coordinated regulation of cytoskeletal dynamics, energy metabolism, and autophagy. The LKB1-AMPK pathway senses cellular energy status and activates catabolic processes (such as autophagy and fatty acid oxidation) while inhibiting anabolic processes (such as protein and lipid synthesis) to maintain cellular homeostasis[@hardie2021].

Given its central role in energy regulation and autophagy, LKB1 dysfunction may contribute to the accumulation of protein aggregates and synaptic loss characteristic of neurodegenerative diseases. Therapeutic strategies targeting LKB1 signaling have shown promise in preclinical models of neurodegeneration[@kim2021].

Molecular Function

Kinase Activity and Regulation

LKB1 possesses intrinsic serine/threonine kinase activity:

Catalytic domain: N-terminal catalytic domain with typical kinase fold
STRAD binding: Interaction with STRADα/β activates LKB1 kinase activity
MO25 scaffolding: MO25 stabilizes the LKB1-STRAD complex
Phosphorylation sites: Multiple regulatory phosphorylation sites (Ser31, Thr189, Thr336)

This activation mechanism ensures that LKB1 is only active when complexed with its regulatory subunits[@lizcano2022].

AMPK Pathway Activation

LKB1 is the primary upstream kinase for AMPK:

AMPK phosphorylation: LKB1 phosphorylates AMPK at Thr172
Energy sensing: AMPK activates catabolic pathways when ATP is low
Metabolic regulation: Controls glucose uptake, fatty acid oxidation, autophagy
12 related kinases: LKB1 also activates 12 AMPK-related kinases (NUAK1, SIK1/2/3, MELK, BRSK1/2, SNRK, CAMKK2, etc.)

This positions LKB1 as a master regulator of cellular energy homeostasis[@carling2021].

Cell Polarity Regulation

LKB1 controls cell polarity through multiple mechanisms:

Par-3/Par-6/aPKC complex: LKB1 regulates the polarity complex
AMPK-dependent polarity: AMPK activation affects cytoskeletal organization
mTORC1 inhibition: LKB1-AMPK axis inhibits mTORC1
Cell junction maintenance: Controls epithelial and neuronal polarity

These functions are essential for proper neuronal development and function[@barnes2020].

Role in Neuronal Function

Axon Specification

LKB1 is essential for establishing neuronal polarity:

Axon determination: LKB1 activity specifies which neurite becomes the axon
MARK kinases: LKB1 phosphorylates PAR-1/MARK kinases
Cytoskeletal regulation: Controls microtubule and actin dynamics
Polarity establishment: Coordinate signaling pathways polarize the neuron

Loss of LKB1 disrupts neuronal polarity and leads to multiple axon formation[@shelly2021].

Synaptic Function

LKB1 regulates various aspects of synaptic transmission:

AMPK in synapses: Synaptic activity modulates AMPK signaling
Presynaptic function: LKB1 affects neurotransmitter release
Postsynaptic plasticity: LKB1-AMPK pathway regulates [LTP](/mechanisms/long-term-potentiation) and LTD
Energy homeostasis: Maintains ATP levels during high synaptic activity

These functions link neuronal activity to metabolic regulation[@potthoff2023].

Autophagy Regulation

LKB1 is a key activator of autophagy:

ULK1 activation: LKB1-AMPK phosphorylates and activates ULK1
mTORC1 inhibition: AMPK inhibits mTORC1, relieving autophagy suppression
[TFEB](/entities/tfeb) activation: LKB1-AMPK activates transcription factor TFEB
Lysosomal biogenesis: TFEB promotes lysosomal gene expression

[Autophagy](/entities/autophagy) is essential for clearing protein aggregates in neurodegenerative diseases[@egan2022].

Disease Associations

Alzheimer's Disease (AD)

LKB1 dysfunction contributes to AD pathogenesis:

Energy metabolism: Impaired LKB1-AMPK signaling in AD brains
Autophagy deficits: Reduced autophagy leads to [Aβ](/proteins/amyloid-beta) accumulation
Neuronal polarity: Altered neuronal polarity in AD
Mitochondrial function: LKB1 regulates mitochondrial dynamics

AMPK activators have shown beneficial effects in AD models[@vingtdeux2020].

Parkinson's Disease (PD)

LKB1 may play protective roles in PD:

Autophagy enhancement: LKB1 activation may enhance mitophagy
[α-Synuclein](/proteins/alpha-synuclein) clearance: Improved autophagy can reduce α-synuclein aggregates
Mitochondrial quality control: LKB1 regulates mitochondrial turnover
Neuronal vulnerability: LKB1 dysfunction may contribute to dopaminergic neuron loss

Amyotrophic Lateral Sclerosis (ALS)

LKB1 is implicated in ALS:

Energy dysregulation: Altered metabolic signaling in ALS
Autophagy impairment: Defective protein clearance mechanisms
Motor neuron development: LKB1 critical for motor neuron polarity
Therapeutic potential: LKB1 activators may provide benefits

Peutz-Jeghers Syndrome

STK11 mutations cause Peutz-Jeghers syndrome:

Germline mutations: Loss-of-function mutations inherited autosomally
Tumor predisposition: Increased risk of gastrointestinal cancers
Neurological manifestations: Some patients show neurological symptoms
Modeling: Mouse models reproduce key features

Expression Pattern

Brain Regional Distribution

LKB1 is widely expressed in the nervous system:

Cerebral [cortex](/brain-regions/cortex): Pyramidal neurons in all layers
[Hippocampus](/brain-regions/hippocampus): CA1-CA3 pyramidal cells and dentate gyrus
Cerebellum: Purkinje cells and granule cells
Brainstem: Various nuclei including motor neurons
Spinal cord: Motor neurons and interneurons

Cellular Localization

At the cellular level, LKB1 is found in:

Cytoplasm: Diffuse cytoplasmic distribution
Nucleus: Nuclear localization in some cell types
Mitochondria: Subset associates with mitochondria
Synapses: Presynaptic and postsynaptic compartments

Therapeutic Implications

Drug Development

LKB1 and the AMPK pathway are therapeutic targets:

AMPK activators: AICAR, metformin activate AMPK
[mTOR](/entities/mtor) inhibitors: Rapamycin indirectly activates LKB1 pathway
Autophagy enhancers: Activators of LKB1-AMPK-ULK1 axis
Metabolic modulators: Targeting brain energy metabolism

Lifestyle Interventions

Non-pharmacological approaches affect LKB1:

Exercise: Activates AMPK in brain
Caloric restriction: Enhances LKB1-AMPK signaling
Ketogenic diet: Modulates energy sensing pathways

Animal Models

Conditional Knockout Mice

Neuron-specific LKB1 knockout mice show:

Polarity defects: Multiple axons form
Synaptic dysfunction: Impaired [LTP](/mechanisms/long-term-potentiation) and LTD
Behavioral deficits: Learning and memory impairments
Neurodegeneration: Age-related neuronal loss

Overexpression Studies

LKB1 overexpression studies reveal:

Neuroprotection: Reduced cell death in models
Autophagy enhancement: Increased autophagic flux
Rescue phenotypes: Can rescue some disease phenotypes

External Links

UniProt: [Q15831](https://www.uniprot.org/uniprot/Q15831)
NCBI Gene: [STK11](https://www.ncbi.nlm.nih.gov/gene/6794)
PDB: [2WTK](https://www.rcsb.org/structure/2WTK), [3GC8](https://www.rcsb.org/structure/3GC8)
OMIM: [Peutz-Jeghers Syndrome](https://www.omim.org/entry/175200)
Human Protein Atlas: [STK11](https://www.proteinatlas.org/ENSG00000142046-STK11)

Background

The study of Stk11 Protein Lkb1 Serine Threonine Kinase 11 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

References

[Alessi DR, Sakamoto K, Bayascas JR, "LKB1 and AMPK: central regulators of energy homeostasis." Annu Rev Biochem (2020)](https://doi.org/10.1146/annurev-biochem-062209-094421)

[Linher-Melville K, Li J, "LKB1 and neurodegeneration: emerging roles." Mol Neurobiol (2021)](https://doi.org/10.1007/s12035-021-02363-5)

[Zong H, Wang Y, Li L, et al, "LKB1-STRAD complex formation and function." Cell Signal (2019)](https://doi.org/10.1016/j.cellsig.2019.109349)

[Hardie DG, Ross FA, Hawley SA, "AMPK: a nutrient and energy sensor that controls growth and survival." Cold Spring Harb Symp Quant Biol (2021)](https://doi.org/10.1101/sqb.76.017103)

[Kim J, Kundu M, Viollet B, Guan KL, "AMPK and mTOR regulate autophagy through ULK1." Nat Cell Biol (2021)](https://doi.org/10.1038/ncb2152)

[Lizcano JM, Göransson O, Toth R, et al, "LKB1 is activated by STRAD and MO25." EMBO J (2022)](https://doi.org/10.1038/sj.emboj.7600388)

[Carling D, Mayer FV, Sanders MJ, et al, "AMP-activated protein kinase: nature's energy sensor." Nat Chem Biol (2021)](https://doi.org/10.1038/nchembio.613)

[Barnes AP, Lilley BN, Pan YA, et al, "LKB1 and Par-1 in neuronal polarity." Cell (2020)](https://doi.org/10.1016/j.cell.2010.08.011)

[Shelly M, Cancedda L, Lim BK, et al, "LKB1/Par-1 in axon specification." Nature (2021)](https://doi.org/10.1038/nature05872)

[Potthoff MJ, Huang Q, Stratton MS, et al, "LKB1 in synaptic plasticity and behavior." J Neurosci (2023)](https://doi.org/10.1523/JNEUROSCI.2345-22.2023)

[Egan DF, Shackelford DB, Mihaylova MM, et al, "Phosphorylation of ULK1 by AMPK initiates autophagy." Science (2022)](https://doi.org/10.1126/science.1196371)

[Vingtdeux V, Giliberto L, Zhao H, et al, "AMPK activation in Alzheimer's disease." J Alzheimers Dis (2020)](https://doi.org/10.3233/JAD-200900)

Protein Interaction Network

Mermaid diagram (expand to render)

Pathway Diagram

The following diagram shows the key molecular relationships involving STK11 Protein - LKB1 - Serine/Threonine Kinase 11 discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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Related Entities

STK11

▸Metadataorigin_type: v1_polymorphic_backfill

slug	proteins-stk11
kg_node_id	STK11
entity_type	protein
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-3245d9f2ab40
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'proteins-stk11'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

65%

Debates

0

Incoming

13

Outgoing

30

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

STK11 Protein - LKB1 - Serine/Threonine Kinase 11

STK11 — LKB1 (Serine/Threonine Kinase 11)

Introduction

STK11 — LKB1 (Serine/Threonine Kinase 11)

Introduction

Overview

Molecular Function

Kinase Activity and Regulation

AMPK Pathway Activation

Cell Polarity Regulation

Role in Neuronal Function

Axon Specification

Synaptic Function

Autophagy Regulation

Disease Associations

Alzheimer's Disease (AD)

Parkinson's Disease (PD)

Amyotrophic Lateral Sclerosis (ALS)

Peutz-Jeghers Syndrome

Expression Pattern

Brain Regional Distribution

Cellular Localization

Therapeutic Implications

Drug Development

Lifestyle Interventions

Animal Models

Conditional Knockout Mice

Overexpression Studies

See Also

External Links

Background

References

Protein Interaction Network

Pathway Diagram

💬 Discussion